Department of Animal Sciences

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Die aanwending van die CPM dairy model in formulering van voerrantsoene in 'n melkkudde
(Stellenbosch : Stellenbosch University, 2005-04) Vermaak, Jacobus Vermaak; Cruywagen, C. W.; Stellenbosch University. Faculty of Agrisciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: CPM Dairy was developed to maintain amino acid balance. because the correct amino acid relationship has an influence on milk production and milk composition (Schwab e/ af. 1992, Rulquin e/ af. 1993). Rulquin e/ af. (1993) found that an increase in lysine and methionine concentration in the diet had no meaningful effect on milk production and milkfat production. However, milk protein production is described as a function of lysine and methionine concentration. In order to balance the amino acid relationships, the CNCPS model has been adopted, using the following guidelines: I. a dairy cow feed characteristic scheme, described by Van Soest e/ af. (1991) and Sniffen e/ aI. (1992), II. a model for rumen fermentation and bacterial growth in the dairy cow, described by Russel e/ af. (1992), Ill. feed val ues for dairy cow feeds, described by Sniffen e/ af. (1992). IV. a set of formulas describing the feeding needs of dairy cows under different circumstances, assembled by Fox e/ af. (1992). Bateman e/ af. (2001) studied the accuracy of formulation models according to crude protein (CP) and amino acid (AA)-flow to the duodenum in lactating dairy cow diets. CPM Dairy does not calculate direct flow of CP to the duodenum, but the following adjustment was made: the change-over of metabolizable protein (MP) to CP is done by increasing bacterial protein from 60% to 100% of bacterial-CP. Intestinal digestion of fraction B3-protein is increased from 80% to 100%, whereas fraction C-protein is increased from 0 to 100% to change feed-MP to feed-CP. CP from feed and microbes are summed to indicate total CP-flow to the duodenum. AA-flow, as calculated by CPM Dairy, is used without adjustments. A rise in MUN-Ievels are typical to spring and summer months. which can be ascribed to high soluble protein and low soluble carbohydrates in grasses and legumes. This gives rise to an excess N-uptake in the bloodstream. Grass silage, when fed as primary feeding source. has the same reaction. Blood-urea-nitrogen (BUN) is the amount of urea-N found in the blood of the cow. MUN is the fraction ofN in the milk in the form of urea. MUN is normally 85% the concentration of BUN. Studies show that an increase in BUN/MUN levels leads to a negative effect on the reproductive ability of the cow. An increase in BUN-levels leads to an increase in urea in the reproductive tract of the animal. Urea passes between the blood plasma and the reproductive tract. It is therefore obvious that a high BUN-concentration leads to high levels of urea in the reproductive tract. In order to eradicate this problem. the use of deodorise in the supplemental feed of the lactating dairy cow \vas recommended. Deodorise is a natural product manufactured by Alltech. The product is derived from the Yuccha Schidigera plant. Two glycocomponents (CI and C II) of this plant binds gasses such as N1-I3. (Alltech information sheet) During .June to August 2002 data were collected regarding the effect of deodorise on lactating dairy cows. No meaningful difference between the two groups in this experiment was found.
Across flock genetic parameter estimation for yearling body weight and fleece traits in the South African Dohne Merino population
(South African Society for Animal Science, 2008) Van Wyk, J. B.; Swanepoel, J. W.; Cloete, S. W. P. (Schalk Willem Petrus van der Merwe); Olivier, J. J.; Delport, G. J.
Accurate genetic parameter estimates are needed upon which to perform multiple-trait across flock breed analyses. Genetic parameters for yearling body weight (BW), clean fleece weight (CFW) and mean fibre diameter (MFD) were estimated using records of 107 389 individuals (the progeny of 1 530 sires and 45 178 dams) collected between 1992 and 2004 in the South African Dohne Merino population. Fixed effects included in the model were flock-year-season-sex- management group (1 594 classes), type of birth (singles, multiples), age of dam (2 - 7+ years) and age at measurement, fitted as a linear covariate (385 ± 12 days). Six different single-trait animal models were fitted, where different combinations of the following random effects were fitted: direct additive, the sire-flock interaction, the sire-flock-year-season interaction (SFYS), the dam genetic effect, the direct-maternal correlation and the dam permanent environmental effect. These analyses were followed by a three-trait analysis structured according to the log likelihood ratios obtained for the single-trait analysis. This analysis allowed the calculation of relevant correlations among traits together with their respective standard errors. Direct heritability estimates from the three-trait analysis were 0.17 for BW, 0.19 for CFW and 0.45 for MFD. Maternal heritability estimates were 0.01 for BW and 0.006 for CFW, with corresponding dam permanent environmental ratios of respectively 0.03 and 0.02. The genetic correlation between animal effects amounted to 0.48 for BW. Derived proportions of the total phenotypic variance due to SFYS were 0.02, 0.02 and 0.02, respectively. Genetic correlations of BW with CFW and MFD were 0.11 and 0.13, respectively, and of CFW with MFD 0.16. It was concluded that the inclusion of some form of a genotype by environmental interaction as part of the national evaluation is essential, although it controlled only a modest portion of the overall phenotypic variation.
Actual and predicted performance of broiler chickens
(Stellenbosch : Stellenbosch University, 2004-03) Van Niekerk, S. J. (Sarel Johannes); Ekermans, L. G.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: The aim of this study was to evaluate the performance and profitability of different dietary specifications for broiler chickens slaughtered at 35 days of age. Two trials were performed to evaluate different production parameters. The results of these trials were compared to the predicted results of the EFG broiler model. No carcass data were available for the two trials mentioned above. Therefore, in order to evaluate the accuracy of the broiler model when predicting carcass characteristics, two published data sets (Leeson et al., 1996a) were used. Predicted and actual values were compared, evaluated and discussed. Two broiler trials were performed. In Trial One the amino acid density decreased throughout the range of three treatments from prestarter to finisher diets. In Trial Two the amino acid density decreased only in the four finisher diets. The main difference between predicted and actual results was the response to body weight. The model predicted a steady increase in feed intake to compensate for the lower dietary specifications while body weight did not change significantly. This increase in feed intake seems to be enough to maintain body weight. Trial birds also increased their feed intake as dietary amino acid density decreased, but this compensation seemed to be too low to maintain body weight compared to the control diet. The birds may find it easier to compensate when they have time to adapt to the specification. There is evidence in the literature that birds need seven days to adapt their feed intake to a lower feed specification (Leeson et al., 1996a). It can be speculated that the trial birds started to loose body weight due to a lower amino acid intake in this period. The model seems to adapt feed intake immediately after a change in diet specification. The simulation on literature data lead to the following conclusions: 1) Broilers posses the capacity to increase their feed intake with at least 65% should finisher diets with lower amino acid and energy concentrations be supplied. If only the energy concentration of finisher diets were decreased, the increase in feed intake will be around 30%. (see Table 16 and 23) 2) The accurate prediction of feed intake from the given dietary specification has a major influence on the accuracy of the prediction of broiler performance. 3) Amino acid density and DLys:ME ratio plays a significant role in the control and prediction of feed intake. The EFG broiler model is based on sound scientific principles. The model is comprehensive and can be used for a wide range of environmental and management conditions as well as dietary conditions. The nutritionist can use the model with confidence to assist in practical feed formulation. The actual strength of the model lies in the time and money being saved compared to practical trials.
The adaption of the South Africa sheep industry to new trends in animal breeding and genetics : a review
(South African Society for Animal Science, 2014-10-11) Cloete, S. W. P. (Schalk Willem Petrus van der Merwe); Olivier, J. J.; Sandenbergh, L.; Snyman, M. A.
The history of sheep breeding research in South Africa can be divided roughly into four eras, namely the research and development phase, the commencement of recording and evaluation, the expansion of recording schemes, and, most recently, the adaptation of schemes to international benchmarks. The most recent era has presented scientists with the greatest challenges, namely the inclusion of genomic breeding values in routine sheep recording and of disease-resistance traits during routine evaluation. The establishment of reference populations for the major South African sheep breeds to estimate genomic breeding values is an immediate challenge. This process may be facilitated by a number of genetic resource flocks that are phenotyped for traits that are not routinely recorded in the national evaluation. A limited number of these animals are also genotyped. There is strong evidence that resistance of sheep to external and internal parasites is heritable, and may be improved by purposeful selection. Efforts should be concentrated on the inclusion of disease resistance traits in national analyses where appropriate. However, seen against the background that South African investment in research is appreciably less than in developed countries, lack of funding and high-capacity manpower may impede rapid progress. There thus seem to be many challenges for future generations of sheep breeding scientists.
Allometric description of ostrich (Struthio camelus var. domesticus) growth and development
(Stellenbosch : University of Stellenbosch, 2011-03) Kritzinger, Werne Jacobus; Brand, T. S.; Hoffman, Louwrens C.; Mellett, F. D.; University of Stellenbosch. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: The ostrich industry has overcome many challenges since it originated. However, it is still vulnerable to sudden changes in customer preferences and economic cycles. As feed costs are the greatest expense in ostrich production, optimising feed formulations is vital. This will be possible if the growth and development of the ostrich can be simulated by modelling software. Various studies were conducted to describe ostrich growth in the form of equations that can be used in modelling software to increase the accuracy of predictions. In the first study, birds were given the choice of four diets with varying energy (8.5 or 13.5 MJ ME/kg feed) and protein (180 or 120 g/kg feed) levels. The birds preferred the high density diet (high energy and protein) in each growth phase. A growth curve of assumed optimal growth was constructed. The chemical fractions of the body were shown to increase non-linearly with advancing age and equations were established to predict the change of the body composition over time. In the second trial, birds received a formulated growth diet and were fed according to their nutrient requirements. Growth data was collected on the separate body components of maturing birds. Feather and skin nodule growth was defined for birds hatched in the summer. Allometric equations were set up to determine, predict and model the ostrich skin size and skin weight, some bones, some organs and the commercially valuable muscles through the growth cycle. The final trial was conducted to determine the effect of diet density (energy and amino acid level) on the growth of ostrich body components. A four-stage, 3 x 5 (energy x protein) factorial design was developed with varying energy and protein feeding regimes. Protein (amino acid) level had no influence on body component growth. Energy level had no effect on feather growth, skin nodule growth, bone and organ growth and muscle growth. Increased levels of dietary energy increased the skin size and skin weight. Increasing the dietary energy level also had a significant effect on the total body fat of the birds. Allometric equations were set up for each variable to predict the effect of diet on ostrich growth. Results in this study provide a framework for simulation modelling. Predicting ostrich growth and development is paramount to accurate diet formulations and lower feeding costs.
Alternatives to replace antibiotics in broiler diets : effects on protein utilization and production performance
(Stellenbosch : Stellenbosch University, 2008-12) Kritzinger, Magdel; Lambrechts, Helet; Ciacciariello, Mariana; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: Different substances were evaluated and compared to an antibiotic, in terms of their effect on nitrogen - and amino acid digestibilities. Two digestibility trials and one performance trial were conducted. Trials one and two apparent nitrogen (AND)- and amino acid (AAD) digestibilities were determined from digesta collected at the terminal ileum (ileal digestibility method). In Trial 3 the substances were evaluated in terms of their potential to improve production performance. Broilers were fed a maizesoya based diet throughout the three trails. In the first trial, garlic and a commercial prebiotic (Bio-Mos®), were tested and compared in terms of AND and AAD, to an antibiotic (doxycyclin, Doxyvete-SOS). A starter and finisher diet were fed as either mash or pellets. The garlic was included at 8g/kg, 13g/kg and 18g/kg to the starter and finisher diets. Bio-Mos® was added at 1g/kg, 2g/kg and 3g/kg to the starter diet, and 0.5g/kg, 1g/kg and 1.5g/kg to the finisher diet. The doxycyclin was added at 0.3 g/kg. None of the treatments had any beneficial effects in terms of AND. Feeding a pellet seem to have some negative effects in terms of AND. In general most of the treatments did not show any improvement in AAD at any determination period (day 21, 28 or 35). At day 21 and day 35, the mash diet supplemented with 18g/kg garlic had a negative effect on AAD, when compared to the negative and positive control. It doesn’t seem that feeding either a mash or a pellet had an influence on the effects exerted by the different treatments. In the second trial the influence of Bio-Mos®, a blend of organic acids, probiotics and electrolytes (Acid-Pak 4-way®) and a medium-chain triglyceride (MCT) were evaluated and compared in terms of AAD and AND, to the effect of an antibiotic, doxycyclin. The starter and finisher diets were fed as a mash. Bio-Mos® was included at 1g/kg, 2g/kg, and 3g/kg in the starter diet, and at 0.5g/kg, 1g/kg, 1.5g/kg in the finisher diet, respectively. Acid-Pak 4-way® was included at 0.4g/kg, 1g/kg and 1.6g/kg for both the starter and finisher diets. Medium-chain triglycerides (MCT) were allocated at 3g/kg, 3.6g/kg, 4.2g/kg for the starter diet, and 2.1g/kg, 2.7g/kg and 3.4g/kg for the finisher diet. An antibiotic, doxycyclin, was included at 0.3 g/kg. With AND, no treatment had any significant effect for the entire experimental period. At day 21, the treatment supplemented with MCT (3.4g/kg) had the most significant beneficial effect on AAD, when compared to the negative- and positive controls, as it increased AAD for the majority of the amino acids. The treatment with Acid-Pak 4-way® (1g/kg) had the most significant negative effect on AAD when compared to the positive control. At day 28, the treatments with Bio-Mos® (0.5g/kg and 1.5g/kg) and Acid-Pak 4-way® (0.4g/kg) had the most significant beneficial effect on AAD when compared to the positive control. It increased AAD for more than half of the 17 amino acids evaluated. The treatment supplemented with MCT (2.7g/kg) has shown the most significant negative effect on AAD, when compared to the positive control. In the third trial the effect of Bio-Mos®, Acid-Pak 4-way® and MCT on production performance was evaluated, and compared to the effects of the presence or absence of doxycyclin. Body weight (BW), body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR) were measured. The starter and finisher diets were fed as a mash. Bio-Mos®, MCT and Acid-Pak 4-way® were included at 3.0g/kg, 4.2g/kg and 1.6g/kg, respectively in the starter and finisher diets. Birds were weighed (per pen) on arrival and on days 7, 14, 21, 28, 35. Feed intake (FI) per pen was measured at days 7, 14, 21, 28 and 35, and mortality was recorded daily. In terms of BWG, Acid-Pak 4-way® had a higher BWG, when compared to the negative control, Bio-Mos® and MCT. It can be concluded that Bio-Mos®, Acid-Pak 4-way®, as well as MCT can be a possible alternatives to antibiotic supplementation. These three treatments did not necessary prove to be more effective than antibiotics, but are definitely competitive alternatives.
Amino acid requirements of feedlot cattle according to the duodenal and whole empty body essential amino acid profile
(Stellenbosch : Stellenbosch University, 2001-12) Erasmus, Morné; Ferreira, A. V.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: The purpose of this study was to determine the essential amino acid requirements of beef cattle under feedlot conditions through evaluation of the duodenal and whole empty body essential amino acid compositions. To define the ideal protein required for growth, the whole empty body essential amino acid compositions of 8 beef steers (Simmental and Hereford crosses) was investigated. The amino acid composition of the components (carcass, metabolic organs and residual fraction), was pooled relative to their respective mass and protein contribution, resulting in the calculated whole empty body amino acid composition: arginine 6.81; histidine 2.69; isoleucine 4.02; leucine 6.96; lysine 7.43; methionine 2.01; phenylalanine 4.03; threonine 4.01; valine 5.30; tryptophan 0.82. Variations in profiles were found between scientific reports, either indicating that ratios change with growth and implants or possibly through genotype. The present study's body amino acid ratios were used to estimate dietary amino acid requirements through evaluation of the duodenal essential amino acid compositions from three different maize based feedlot diets. Although there was a general increase in the biological value of protein after rumen fermentation, the duodenal essential amino acids in comparison with the whole empty body recorded deficient/unbalanced profiles of essential amino acids for growth. The chemical scores suggested that the first-to-thirdlimiting amino acids in the duodenal digesta of beef cattle, that received three different commercially available feedlot diets, were: histidine, lysine, methionine/arginine (Diet 1), histidine, arginine, lysine (Diet 2) and arginine, methionine, histidine (Diet 3). Thedisproportionate duodenal amino acid concentrations obtained from the three diets, emphasise the necessity to enhance the intestinal delivery of amino acid profiles through different undegradable protein sources, with the objective to maximise protein utilisation and obtain the genetic potential for optimal growth in feedlot cattle. When amino acid requirements and flows to the duodenum were simulated using the Cornell Net Carbohydrate and Protein system (CNCPS), predictions indicated that lysine amino acid flow was limiting the metabolizable allowable average daily gain in Diet 1 and 3. Predicted profiles indicated that the order of limitation was: lysine, arginine, histidine (Diet 1), lysine, arginine, histidine, methionine (Diet 2) and lysine, arginine, histidine (Diet 3). The predicted profiles were in accordance with observed duodenal values, except for methionine that was observed limiting in Diet 1 and 3; however, the sequence and extent of limitation varied. Results indicate that prediction models have potential in predicting requirements; however there are still limitations for use to accurately define requirements for particular EAA's. From the present study, it is clear that the protein accretion was constrained by quantity and/or disproportionality of amino acids available for absorption. Further research should therefore be directed towards obtaining a more desirable array of amino acids to the lower digestive tract that is digestible, absorbable and an economically viable option for the feedlot operator.
Amino acid requirements of South African Mutton Merino lambs 3. Duodenal and whole empty body essential amino acid profile
(South African Society for Animal Science, 1999) Ferreira, A. V.; Van der Merwe, H. J.; Loest, C. A.
The duodenal and whole empty body essential amino acid (EAA) profile of South African Mutton Merino lambs fed a standard growth diet was investigated. The data of 20 lambs were used. With the exception of phenylalanine, significant (p < 0.05) differences between the EAA concentrations of the duodenal digesta and whole empty body occurred. From the chemical score, it was concluded that the duodenal digesta was first-limiting in histidine and second-limiting in methionine, followed by threonine and arginine for the whole empty body growth of South African Mutton Merino ram lambs fed a standard diet high in rumen degradable protein. A calculated essential amino acid composition for the correction of imbalances in duodenal digesta was as follows (%): 11.21 arginine; 14.53 histidine; 8.17 isoleucine; 9.97 leucine; 8.64 lysine; 13.87 methionine; 9.97 phenylalanine; 12.54 threonine and 11.11 valine.
Analysis of carcass characteristics and fat deposition of Merino, South African Mutton Merino and Dorper lambs housed in a feedlot
(South African Society for Animal Science, 2018-02-15) Brand, T. S.; Van der Westhuizen, E. J.; Van der Merwe, D. A.; Hoffman, L. C.
The objective of this study was to determine the effect of time spent in a feedlot on the size of the various fat depots and the distribution of the main tissues (muscle, bone, and fat) of three common South African sheep breeds. Lambs were supplied with a balanced diet (16% protein, 10 MJ ME/kg feed) ad libitum and had free access to water. Lambs from each breed were divided into six groups, which were slaughtered at 21-day intervals until a production period of 105 days had been reached. During carcass dressing, visceral and renal fat was removed and expressed as a percentage of carcass weight. The subcutaneous fat (SCF) depth was measured on the longissimus lumborum at the 13th rib position using an electronic calliper. The proportion of muscle, bone and fat was determined by dissecting a three-rib cut made on the prime rib between the 9th and 11th ribs. The percentage of visceral and renal fat increased throughout the production period for all breeds. The percentage of renal fat was up to 2.9% higher than the percentage visceral fat in both SAMM production groups. Dorper lambs tended to have high SCF levels (5.6 mm fat after 42 days) due to the early maturing nature of the breed. They reached a maximum fat depth of 20.4 mm fat after 105 days. The SAMM lambs tended to deposit SCF at a slower rate and the late maturing Merino breed was found to be much leaner, and did not reach the high fat levels of the SAMM or Dorper lambs. The percentage of muscle and bone in all carcasses decreased with an increase in the number of days in the feedlot, while the percentage of carcass fat increased during this period. The increase in late maturing adipose tissue in all breeds as they become older is amplified by the restricted movement in the feedlot and high energy diet that the lambs receive.
Analysis of genetic diversity and population structure of indigenous (fat-tailed) sheep in South Africa
(Stellenbosch : Stellenbosch University, 2022-03) Malan, Isaack Nichol; Molotsi, Annelin H.; Cloete, Schalk W. P. ; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Science.
ENGLISH ABSTRACT: Indigenous fat-tailed sheep breeds are primarily kept by rural peoples, especially in developing countries. These livestock species contribute to household income, is a source of food security, plays a role in social and crop production (fertilizer) systems. The diversity within these indigenous breeds allows them to be productive under harsh environmental conditions, thus genetic and phenotypic characterization is pivotal for future sustainable farming practices. The aim of this study was to elucidate the genetic structure of indigenous fat-tailed sheep in South Africa and to trace selection pressure applied to fat-tailed sheep for adaptation. The first objective was to elucidate the genetic variation and population structure of indigenous fat-tailed sheep in South Africa. The second objective was to determine if selection pressure has been placed on these indigenous sheep breeds for adaptation traits. The first objective was achieved by sampling blood from indigenous sheep breeds (30 Damara, 30 Pedi, 30 Zulu, 20 Meatmaster and 54 Karakul animals). The extracted DNA was genotyped using the OvineSNP50K BeadChip. Genotype data from 48 Namaqua Afrikaners and 98 Merinos were included for comparative purposes. Several genetic parameters were analysed to determine the genetic diversity within and between the sheep populations: observed heterozygosity (Ho), expected heterozygosity (He), inbreeding coefficients (F) and Linkage disequilibrium (LD). The highest and lowest observed heterozygosity was seen in the Pedi and Damara sheep (0.4 and 0.34 respectively). The Merino exhibited the highest expected heterozygosity of 0.38 and the Namaqua Afrikaner the lowest at 0.345. The highest LD was reported in the Namaqua Afrikaner at r²= 0.45 and the lowest LD was observed in the Merino at r²= 0.37. The population structure of the indigenous sheep breeds was studied by conducting a Principal Component Analysis (PCA), where PC1 (6.8%) and PC2 (5.0%) describes the total genetic variation. A Bayesian approach was used to calculate maximum likelihood estimates in the FastSTRUCTURE program, which elucidate the true ancestral populations (K= 8) of the sheep breeds. Lastly, through hapFLK analysis, Reynolds genetic distances between the different sheep populations were calculated and a neighbour-joining population tree was generated. These could be used to determine the relatedness and dissimilarities (dendogram) found between the indigenous fat-tailed sheep. A close relationship could be seen between the Zulu and Damara sheep breeds. Despite the lower diversity, the Namaqua Afrikaner displays the highest genetic distance from the other indigenous fat-tailed breeds. The Pedi and Karakul populations also exhibited distinct clustering and separation. Admixture within the Meatmaster breed with the Merino was observed. This is to be expected as the Merino could have been used as a parental breed in the make-up of this composite (Meatmaster) sheep. To determine selection sweeps in the indigenous sheep breeds, the hapFLK approach was used and 13 regions were found to be under selection, spanning a total of 11 chromosomes. The candidate genes associated with the SNPs of interest was linked to traits involved in metabolic process such as DNA synthesis and transcription (CEP41, TLL1, EIF1B, SCN5A, SCN8A, SCN10A, SCN11A), immune response (BPIFC, CLDN12, CLDN14, TRL4), ultraviolet exposure and thermoregulation (SLX4, ASCL4, KCNJ5, LAMB1, GPR26, CX3CR1), energy metabolism (MYH9) and meat production (PDEZA, UTRN). These candidate genes give an insight into the adaptive traits of indigenous sheep in South Africa and further genotyping is needed to elucidate more of the robust characteristics exhibited by these locally acclimated genetic resources.
Animal performance from natural pastures and the effects of phosphorus supplementation
(Stellenbosch : Stellenbosch University, 1984-03) Read, Marion Victoria Pearl; Smith, W. A.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
INTRODUCTION: This study was initiated by the various reports of improved animal performance resulting from supplementary feeding of grazing ruminants and in this respect, it may be regarded as a feasibility study of the ability of the natural pasture at the applied stocking rates, to supply the animal with its nutrient requirements, since before providing the animal with supplementary nutrients, it is necessary to identify those which may possibly limit animal production. The criti= cal test of such a limiting nutrient would be an improved animal performance, resulting from supplementation of the nutrient suspected as being limiting, under grazing conditions.
Ante- and post-mortem factors influencing impala (Aepyceros melampus) meat quality
(Stellenbosch : Stellenbosch University, 2019-04) Engels, Retha Annette; Hoffman, Louwrens C.; Needham, T.; Stellenbosch University. Faculty of Agrisciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: The aim of this research was to investigate the influence of sex, muscle (Longissimus thoracis et lumborum/LTL, biceps femoris/BF, semimembranosus/SM, semitendinosus/ST, infraspinatus/IS, and supraspinatus/SS), production system (intensive, semi-extensive and extensive), and post-mortem ageing on the meat quality of impala (Aepyceros melampus) to provide baseline data for the South African game industry. This was done by gathering data on the carcass yields, overall meat quality (physical attributes and chemical composition) and sensory meat quality of impala, as well as investigating the optimum post-mortem ageing period for maximum tenderness of LTL steaks. The sex-muscle comparison (Trial 1) consisted of 11 male and 11 female impala that were culled from a semi-extensive production system in the Central Sandy Bushveld region near Modimolle in Limpopo, South Africa. No sexual dimorphism (P > 0.05) was recorded for the undressed (36.4 ± 1.30 kg males; 37.8 ± 1.30 kg females) or dressed carcass weights (21.6 ± 0.82 kg males; 21.0 ± 0.82 kg females). However, male impala had a higher (P = 0.004) mean dressing percentage than females (59.1 ± 0.76 % vs. 55.6 ± 0.76 %). For the production system comparison (Trial 2), 12 sub-adult (±15- 18 months old) male impala were culled per production system (n = 36). The intensive and semiextensive production systems were also located near Modimolle, and the extensive production system was located in the Central Rûens Shale Renosterveld region near Bredasdorp in the Western Cape of South Africa. Extensive system impala had higher (P ≤ 0.05) undressed and dressed carcass weights (46.5 ± 1.12 kg and 26.6 ± 0.79 kg) than intensive (37.9 ± 0.92 kg and 21.9 ± 0.65 kg) and semiextensive system impala (36.4 ± 0.96 kg and 21.3 ± 0.68 kg, respectively), while the latter two systems did not differ significantly from each other. No differences (P = 0.364) were recorded between production systems for the dressing percentages (57.9 ± 0.58 % pooled mean) or total offal yields (39.7 ± 0.48 % pooled mean) of sub-adult male impala. The physical meat quality attributes of impala were significantly influenced by sex, muscle, and production system. Sex-muscle interactions were found for the CIE a* values, drip loss percentages and cooking loss percentages (Trial 1). Higher (P = 0.021) ultimate pH (pHu) values and lower (P = 0.002) Warner-Bratzler shear force (WBSF) values were recorded in male impala than in females. The IS and SS muscles from the forequarter were the most tender, whereas the BF and SM muscles from the hindquarter were the least tender. The pHu of both sexes, all muscles (Trial 1) and both intensive and semi-extensive system impala (Trial 2) fell within the acceptable normal range (5.6- 5.9), but the extensive system impala produced meat with an exceptionally high pHu (6.2 ± 0.06) due to extrinsic factors caused by the production and culling process. Consequently, extensive system impala produced meat with DFD-like (dark, firm, dry) characteristics, such as the lowest drip loss percentage (0.9 ± 0.14 %), cooking loss percentage (28.1 ± 0.79 %) and darkest, least red and least saturated surface colour (L* = 26.8; a* = 10.0; b* = 5.2; chroma = 11.4). With the exception of the extensive system impala, impala from both sexes, all muscles and both the intensive and semiextensive systems (Trial 1 & 2) had CIE Lab colour measurements within the acceptable range of expectation for game meat (L* = 30.9-36.8; a* = 11.4-13.6; b* = 6.0-8.8). Furthermore, all fresh impala meat in this study (Trial 1 & 2) produced meat with shear force values < 43 N (range of 19.2-39.3 N) at 24 hours post-mortem and may thus be classified as tender. The chemical meat quality of impala was also significantly influenced by sex, muscle and production system. Sex-muscle interactions were recorded for all four chemical components (moisture, protein, intramuscular fat/IMF and ash), while a strong negative correlation (r = -0.49; P < 0.001) was observed between the protein and IMF content of the muscles (Trial 1). Extensively produced impala were recorded to have LTL muscles with the lowest (P ≤ 0.05) mean IMF (1.5 ± 0.06 g/100 g) and the highest protein (23.4 ± 0.12 g/100 g) content, whereas intensive system impala had the highest IMF content (2.0 ± 0.05 g/100 g). The proximate composition of all impala meat in this study (Trial 1 & 2) ranged from 74.7-77.0 % moisture, 20.7-23.5 % crude protein, 1.2-2.2 % IMF and 1.1-1.3 % ash content. While the differences between sex, muscle and production system were significant, the differences were marginal and thus may not be of biological consequence with regards to human nutrition. Regardless, all impala meat had a high protein and low IMF content which is considered desirable by health-conscious consumers. With the differences in dietary regime, management strategies and daily activity between production systems, it can be expected that the sensory profile and fatty acid composition of impala meat will also be influenced by differences in these factors. The influence of production system on sensory meat quality was significant (Trial 2), with the highest (P ≤ 0.05) sensory ratings for gamey, beef-like, herbaceous and sweet-associated aromas and flavours found in extensive system impala during descriptive sensory analysis (DSA). However, the sensory meat quality of the intensive and semi-extensive system impala from the same production region did not differ (P > 0.05) except for a few textural attributes and a higher (P < 0.05) gamey flavour intensity found in semi-extensive system impala. The ideal post-mortem ageing period of impala LTL steaks was also determined. The LTL muscles of 11 male and 11 female impala (Trial 1) were divided into eight portions each, with each portion was randomly allocated to age for 1, 2, 4, 6, 8, 10, 12, or 14 days, vacuum-sealed and stored at 4°C. This research found that maximum tenderness (13.5 ± 0.91 N) and improvement of bloomed surface colour of impala LTL steaks was reached at eight days post-mortem, whereas prolonged ageing beyond this point resulted in some discolouration and no further improvement in meat tenderness. The ageing of meat to eight days post-mortem also successfully negated the initial significant differences in tenderness between the sexes. Therefore, it is recommended that impala LTL steaks should be vacuum-aged at 4°C for eight days to achieve optimum tenderness and minimize variability between individual animals irrespective of sex.
Anti-nutritional factors in canola produced in the Western and Southern Cape areas of South Africa
(South African Society for Animal Science, 2007) Brand, T. S.; Smith, N.; Hoffman, L. C.
ABSTRACT: The development of low erucic acid, low glucosinolate cultivars of canola seed has led to the availability of a feed ingredient with considerable potential to replace soyabean meal in diets for all classes of farm animals. The sinapine and glucosinolate content of various canola cultivars cultivated in two areas of the Western Cape, South Africa were compared. There were no significant differences in sinapine content between the canola produced in the Western and Southern Cape (mean value of 9.95 mg sinapine/g grain). There were cultivar differences, with Varola 54 and Rainbow cultivars having significantly higher sinapine concentrations than Varola 50. There were no significant differences between the aliphatic, indolyl or aromatic glucosinolate content of the canola originating from either the Swartland or the Ruens areas in South Africa (mean value of 17.84 umol total glucosinolates/g grain). There were significant differences in the total glucosinolate content of the various canola cultivars. Varola 44 and Hylite 200TT had the lowest total glucosinolate concentration and Varola 50 had the highest glucosinolate concentration. The results obtained seem to indicate a maximum dietary inclusion level of up to 14% for South African produced canola with an average of 17.83 umol glucosinolates per gram to ensure optimal animal production.
Application of dietary bentonite clay as feed addictive on feed quality, water quality and production performance of African catfish (Clarias gariepinus)
(Stellenbosch : Stellenbosch University, 2016-03) Ayoola, Mathew Oluwaseyi; Salie, Khalid; De Wet, Lourens; Stellenbosch University. Faculty of Agrisciences. Dept of Animal Sciences.
ENGLISH ABSTRACT: Aquaculture remains the fastest growing animal food producing sector and is gradually overtaking capture fisheries as a source of food fish. The challenges of poor feed quality, feed utilisation and water quality are recurring issues that hinder the growth of aquaculture industry. This study investigated the effects of natural bentonite (NB) and its acid activated form (AB) as feed additives on aquafeeds with reference to the physical quality, growth performance, gut evacuation rate and water quality with African catfish (Clarias gariepinus) as the experimental species. Bentonite clay has found application as a feed additive in animal science and aquaculture. It is used as a mycotoxin binder to improve feed utilisation. Application of dietary activated bentonite form is yet to be fully elucidated to the best of our knowledge. Aquafeeds’ physical qualities, including water stability, feed durability, feed bulk density and nutrient leaching, were investigated. Dietary bentonite clay was added to commercial aquafeeds and each treatment were replicated four times. Water stability, feed durability, feed bulk density and nutrient leaching were all significantly affected (p<0.05) by treatments. Measured parameters (water stability, feed density and feed durability) increased (p<0.05) with the quantity of AB in the clay blend and at high inclusion level as compared to control. Values increased with an increased inclusion level of clay in feed, while nutrient leaching value decreased with quantity of AB and high inclusion. AB had higher values as compared to NB and the control. These results validated the potential utilisation of NB and AB as feed binders. Their ability to improve pellet physical qualities is expected to enhance feed utilisation, maintain good water quality and increase fish growth. Aquafeeds with bentonite clay blend, and each at different inclusion levels improved (p<0.05) growth performance, feed conversion ratio (FCR), specific growth rate (SGR), red blood cell (RBC), and haematocrits (HCT). Parameters improved with an increase in quantity of natural bentonite and at low inclusion level. Growth performance increased (p<0.05) as compared to control with bentonite inclusion up to 1500 mg/kg and decline at 3000 mg/kg. The contents of crude protein (CP), fat, moisture, ash and abdominal fat in the whole body composition were significantly affected (p<0.05) by the treatment diets. Abdominal fat and tissue fat content increased with bentonite inclusion. To evaluate the effect of NB and AB on gut evacuation rate of Clarias gariepinus, fish were randomly allocated to treatment diets and fed ad libitum. Four (4) fish were randomly selected per treatment to measure post feeding stomach content (SC) and intestinal filling (IC) content at (5, 30, 60 and 120 min). The control diet had higher values for SC at 5 min which differed significantly (p<0.05) as compared to clay diets. SC decreased (p<0.05) with time in all diets and clay diets had higher value (p<0.05) between (30 – 120 min) as compared to control. In clay diets, SC decreased faster over time with reduced quantity of AB and low inclusion level. The IC of control diets had higher values (p<0.05) over time as compared to clay diets. The water quality parameters (pH, N02-, NH3-N and TSS) were evaluated in a static aerated tank. Aquafeeds were fed to adult fish at 3% body ratio twice daily. Each treatment diet was replicated four (4) times, and 10 fish were randomly allotted to each tank. The water temperature was 25 ± 2°C and dissolved oxygen (DO) was 3-9 mg/L. Water samples were collected daily from each tank. In phase I, water quality was evaluated over seven (7) days, and in phase II over five (5) days. No mortality was recorded during the study. The values of pH, N02-, NH3-N and TSS increased significantly (p<0.05) in all treatment diets over time. In both phases, clay treated diets had lower values for measured parameters (p<0.05) compared to those of control. In clay diets, values increased (p<0.05) with quantity of AB and high inclusion level. Fish feed intake reduced as water quality deteriorated, and uneaten feeds contributed to increase in poor water quality. Thus, high water stability of clay treated diets attributed to maintenance of good water quality as compared to the control. The results showed that dietary clay enhanced feed binding, which affected digesta viscosity. This reduced the rate of feed evacuation in the gut, and, thus, enhanced proper breakdown and absorption of nutrients. Higher inclusion levels of bentonite clay and increased quantity of AB are not suitable for improved growth and feed utilisation, as increased in digesta viscosity led to fermentation in the gut. An optimum level of performance was recorded at 1500 mg/kg inclusion with natural bentonite (B1500) with a significantly (p<0.05) better performance as compared to control and acid activated bentonite. A clay combination blend up to 50% (A50B50) at low inclusion level (500 mg/kg) of acid activated bentonite is considered optimum.
Application of European standards for health and quality control of game meat on game ranches in South Africa
(AOSIS, 2011) Van der Merwe, M.; Jooste, P. J.; Hoffman, L. C.
The health and quality compliance of game carcasses (n = 295) intended for the South African export market and aspiring to comply with the strict hygiene requirements of the European Union were compared with game carcasses (n = 330) available for the local market and currently not subjected to meat safety legislation. Samples were collected in similar seasons and geographical areas in South Africa from 2006 to 2009. Aerobic plate counts (APC) of the heart blood verified that both groups possessed similar ante mortem bacterial status. For health compliance APC, tests for Escherichia coli, Salmonella spp. and Staphylococcus aureus were performed on the carcasses. Surfaces of the local carcasses were swabbed using the European Enviro-biotrace sponge technique at 3 and 72 h post mortem. Unskinned but eviscerated export carcasses in the abattoir were skinned and sampled by incision using a cork borer 72h post mortem. Temperature andpHreadings were recorded at 3 and 72 h post mortem from the longissimus dorsi muscle and the readings at 3 h differed (P = 0.035). Temperatures at 72 h were lower for export than local carcasses (P < 0.001) because of earlier introduction and maintenance of the cold chain. The pH readings also differed between groups at 3 and 72 h (P<0.001). APC results for the local group exceeded the maximum permissible count (<105). S. aureus results showed differences (P <0.001), with readings from the local group being higher. The same tendency was exhibited for E. coli (P = 0.008). Imposition of hygiene guidelines for game ranchers producing meat for the local market is therefore recommended.
Application of exogenous enzymes in Haliotis midae diets with soybean meal as fish meal replacement
(Stellenbosch : Stellenbosch University, 2012-03) De Villiers, Christopher Murray; De Wet, Lourens; Pieterse, Elsje; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: A 240-day growth study was conducted to determine the suitability of soybean meal (SBM) as an alternative protein source to fish meal (FM) in the diet of commercially produced South African abalone (Haliotis midae). The suitability of SBM was determined by a close evaluation of the following key factors: feed water stability, morphological impact on the abalone intestine and the effect on the growth performance of abalone. The study was comprised of two phases: a fish meal replacement phase (Phase A) and an enzyme treatment phase (Phase B). Diets used in Phase A consisted of a control fish meal diet (Control=22%FM, 0%SBM), a fish meal-soybean meal diet (FMSBM=20%FM, 15%SBM), a soybean meal-low diet (SBMlow=0%FM, 15%SBM) and a soybean meal diet (SBM=0%FM, SBM30%). In Phase B, the FM diet and SBM diet were used as basal diets (FME0 and SBME0). These diets were then treated with three commercial enzyme products, namely, a β- glucanase (FME1 and SBME1), xylanase (FME2 and SBME2) and α-D-galactosidase (FME3 and SBME3). Subsequently, all three enzymes were combined to make two treatments (FME123 and SBME123). With regard to the gut morphology and growth trials, a thirteenth energy enhanced commercial animal protein-free diet (ECO) was used. In Phase A (fish meal replacement), the findings revealed that water stability did not differ significantly between treatments. In Phase B (enzyme treatment) however, the water stability of β- glucanase treated feeds was significantly lower than that of the control FM diet. It was also observed that in comparison to the control FM diet, soybean meal based diets have a significantly greater effect on intestinal morphology. With reference to Phase A (fish meal replacement), by the end of the 240 day growth trial period, it was evident that animals fed on the commercial (ECO) diet were significantly heavier than those given the control FM diet. With regard to final length in mm, feed conversion ratio (FCR) and specific growth rate (SGR) for mass and length, no differences between the treatments were noted. It was also found that the condition of the ECO fed animals was significantly better in comparison to the other treatment fed animals. No significant differences were observed between the FM and three FMreplaced diets however. With reference to Phase B (enzyme treatment), it was noted that once again, after the 240 day period, abalone fed on the ECO diet were significantly heavier in terms of their final weight when compared to those fed on the other diets. As in Phase A, no differences in FCR and SGR for mass and length were observed. Measurements of the animals’ final length (as observed on day 240) revealed that those fed on the ECO diet were significantly longer than those given the FME1, SBME1 and SBME3 diets. At the end of the trial, abalone fed on the ECO diet were also in significantly better condition than those fed on the SBM, FME3 and FME123 diets. In terms of production performance, no significant difference was found between the SBM diets and FM diets and enzyme supplementation did not significantly increase the production performance either. The results of this study therefore show that SBM has great potential to be used as a FM-replacement diet. The improved performance of the ECO diet was expected due to its energy content.
Application of fat-tailed sheep tail and backfat to develop novel warthog cabanossi with distinct sensory attributes
(MDPI, 2020-12-08) Mahachi, Leo Nyikadzino; Rudman, Monlee; Arnaud, Elodie; Muchenje, Voster; Hoffman, Louwrens Christiaan
This study compared the use of pork backfat (PF) and fat-tailed sheep tail and backfat (SF) on the physicochemical, fatty acids and sensory attributes of warthog cabanossi. There were no differences between weight loss during drying, moisture content, pH, water activity, salt content and lipid oxidation between the cabanossi types. However, protein and ash contents were higher in PF cabanossi whilst fat content was higher in SF cabanossi. The PF cabanossi had higher polyunsaturated fatty acids (especially n-6), lower monounsaturated fatty acids whilst the saturated fatty acid content was similar between the two cabanossi products. The n-3:n-6 ratio was more beneficial in the SF cabanossi. The descriptive sensory analysis showed two distinct products where PF cabanossi scored higher for most attributes. Although SF cabanossi scored less for these attributes, this cabanossi had unique and acceptable sensory attributes. This study concluded that fat-tailed sheep tail and backfat could be used to produce a unique cabanossi product of acceptable quality.
The application of genomics and transcriptomics for the characterization of the genetic diversity of tick-resistance in Angus, Brahman, Nguni, and Santa Gertrudis cattle artificially infested with Rhipicephalus microplus and Rhipicephalus decoloratus
(Stellenbosch : Stellenbosch University, 2022-04) Marima, Jacqueline Keena; Dzama, Kennedy; Jonsson, Nicholas N.; Dube, Bekezela; Marufu, Munyaradzi Christopher; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
ENGLISH ABSTRACT: Tick resistance is a complex polygenic trait that is governed by immuno-genetic mechanisms that are currently not fully understood. It is, however, currently accepted that the Bos indicus, Zebu and Sanga breeds, which are better adapted to the harsh environmental conditions of the tropical and subtropical regions, often exhibit superior tick resistance as opposed to their Bos taurus counterparts. Breeding for natural host resistance presents a transformational alternative for tick control that will see cattle production industries move away from the excessive and often incorrect usage of chemical acaricides for tick control. However, selective breeding for this trait using tick count data, which varies according to the environment, is unreliable and often produces variable results. Marker-assisted selected breeding and the development of accurate prediction tests with practical feasibility in the field will enhance the accuracy of selection and increase genetic gains. Omics technologies, including transcriptomics, genomic and proteomics are tools that have been instrumental in uncovering putative genes, pathways, and potential biomarkers in cattle. Despite the progress made, there is still a lot that remains misunderstood about the tick resistance trait. Further studies are required. While previous studies have investigated tick resistance in the different breeds and tick species in isolation of each other, in this study a comparison between two tick species (Rhipicephalus microplus and R. decoloratus) and three cattle breeds of different lineages was presented; the Bos indicus Brahman breed, the Bos taurus Angus breed and the indigenous Bos taurus africanus Nguni breed. The differentially expressed genes and their single nucleotide polymorphisms (SNPs) genotypes were of particular interest when studying the different host tick associations presented in this study. The study also included the transcriptome analysis of samples from the Santa Gertrudis, a composite breed recognised for its superior tick resistance while simultaneously boasting good reproductive and production efficiency and meat quality. Using a 150K Bovine SNP chip to genotypes samples from the Angus, Brahman and Nguni breeds, the SNP genotypes, allele frequencies and dosages of SNPs of 37 candidate genes were determined. A total of 257 SNPs were discovered but the SABT2 gene produced a SNP (ARS-BFGL- NGS-94983) that showed a significant correlation with tick count and significantly different allele frequencies between breeds. No functional information regarding the role of the SATB2 gene in host resistance to tick, their further investigations are warranted. The microarray analysis of blood samples from Santa Gertrudis cattle artificially infested with the invasive R. microplus tick species revealed variable levels of tick resistance accompanied by variable gene expression profiles across the tick-resistant and tick-susceptible phenotypes. It was evident that upon long term exposure to the R. microplus the tick-resistant Santa Gertrudis cattle displayed an increased ability to develop and mount more robust adaptive responses against the tick infestations than the tick-susceptible animals Lastly, the RNA sequencing study allowed the identification of several putative genes that have featured in previous studies of tick resistance in cattle. Using inter-breed and inter-tick species contrast across the Angus, Brahman, and Nguni cattle breeds as well as between the R. microplus and R. decoloratus tick species, variable gene expression profiles were observed. The CCL26 and MZB1 appeared as two of the factors to note in the inter-tick species comparisons, while the MMP12 gene was identified in the inter-breed comparison. The Nguni breed produces significantly different gene expression patterns than both the Angus and the Brahman breeds. The differential expression of the highlighted gene led to the conclusion that tick resistance is not only characterised by innate and adaptive immune responses but there are other crucial role players, presented in this study as components of the extracellular matrix. The three studies included here inform further investigations into the roles of the highlighted genes and SNPs to further elucidate the complex phenotype of host resistance to ticks.
Application of immunocastration in a commercial Dohne Merino ram flock before weaning
(South African Society for Animal Science, 2019-01-03) Needham, T.; Lambrechts, H.; Hoffman, L. C.
The influence of pre-weaning immunocastration on the growth, incidences of reaction to vaccination, serum testosterone concentration and slaughter performance of ram lambs was determined and compared to that of physically castrated lambs. Immunocastration was performed using two doses of 2 mL Improvac® administered subcutaneously in the shoulder, alternating sides per vaccination, using a Sterimatic® needle guard system. The first vaccination was administered to 50 lambs with an average weight (± SD) of 16.0 ± 3.05 kg, and the second vaccination was carried out six weeks later, when the lambs weighed on average (± SD) 20.5 ± 4.11 kg. An additional 50 lambs were physically castrated using elastrator bands at the same time as the primary vaccination given to the immunocastrates. Data were collected during four sessions over the 25-week period, at time points which fitted into the normal management activities of the commercial operation (Weeks 1, 6, 16 and at slaughter). During these sessions, all lambs were weighed, and blood samples were collected from immunocastrates. The immunocastration injection site was also scored for adverse reactions. Immunocastration was successful in preventing testosterone secretion for the duration of the trial and no differences were reported regarding weight gain or slaughter performance between the treatments. The Sterimatic® and Stericap® system, as used in this study, proved to be an easy-to-use and safe system for the commercial administration of Improvac®, with no adverse reactions to vaccinations recorded at the injection sites. Pre-weaning immunocastration in lambs is thus possible, and the growth rate, carcass weight and carcass fatness of immunocastrates are similar to that of elastrator-castrated lambs.
Application of the condition factor in the production of African sharptooth catfish Clarias gariepinus
(Stellenbosch : University of Stellenbosch, 2005-03) Luckhoff, Paul Daniel; De Wet, Lourens; Brink, Danie; University of Stellenbosch. Faculty of AgriSciences. Dept. of Animal Sciences.
In recent years there has been a renewed interest in the commercial culture of African Sharptooth Catfish. Its robust characteristics and its air breathing capabilities makes the African catfish a good candidate for culture in intensive recirculating systems. In light of the size variation in offspring spawned from undomesticated fish, that may eventually increase cannibalism, suitable methods for the quantification of some production performance parameters such as growth and health measurements need to be established for application in intensive catfish culture. In fish the condition factor (CF) reflects information on the physiological state of the fish in relation to its welfare. This factor is expressed as Fulton’s condition index, or the K-factor. African Sharptooth Catfish fry with average weight of 1.9g ± 0.7867 and average length of 59.375mm ±8.812 were equally allocated into ten 1000L-recirculating tanks. The fish were fed a commercial feed to apparent saturation at a frequency of 5 times per day. Sixteen fish were sampled out of each treatment. Weight (g) and length (mm) of each fish were recorded every seven days over a trial period of 175 days from which Fulton’s condition index K was calculated. Results were analysed for significant differences using one-way ANOVA and Tukey’s pair wise comparison test for the various parameters. Growth parameters (a = -5.083, b = 3.004, R2 = 99.4%) derived from the logarithmic relationship between body weight (W) and standard length (L) indicated an isometric growth through the duration of the trail. No significant differences (P>0.05) in condition factors between treatments were found at the beginning of the trail. Significant differences (P<0.05) were found at the end of the trail for weight between ponds and condition factor between treatments. No significant difference (P> 0.05) between length and treatments were found at the end of the trial. Mean condition factor was 0.856 ± 0.187. By using this information on condition factor for African catfish a K-factor calculation chart for African catfish could be calculated, to be used as a practical measurement tool to measure performance goals on catfish farms.

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