Browsing by Author "Ferreira, A. V."

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    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.
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    A comparison between the effects of two cropping methods on the meat quality of impala (Aepyceros melampus)
    (South African Society for Animal Science, 2003) Kritzinger, B.; Hoffman, L. C.; Ferreira, A. V.
    Impala (Aepyceros melampus) constitute one of the most commercially important species in game farming in South Africa. The purpose of this study was to compare the effects of day and night cropping on the meat quality characteristics of impala. Emphasis was placed on the influence of the cropping method on muscle pH45 (45 minutes post mortem), pHu (ultimate pH), pH decline, and the related influence on drip loss, cooking loss, toughness and colour of the meat in the M. longissimus lumborum. Measurements taken from 16 animals cropped at night were compared to those taken from 24 animals cropped in daytime. A mean PH45 of 6.67 ± 0.11 was recorded for the night cropped animals compared to a mean pH45 of 6.55 ± 0.23 for the day cropped animals. A mean pHu of 5.39 ± 0.08 for animals cropped at night was recorded compared to a mean pHu of 5.45 ± 0.11 for the animals cropped in the day. Regression analysis showed the rate of pH decline to be slower in the night cropped animals compared to those cropped in the day. This persisted when the pH values were adjusted to correct for ambient temperature. The cooling rate of the M. longissimus lumborum was twice as fast in the night cropped group. Shear force values and drip losses respectively, for the night-cropped animals were 19.11 ± 5.68 g/mm2 and 2.93 ± 1.59%, whereas for the day cropped animals the values were 23.42 ± 8.13 g/mm2 and 4.15 ± 2.34%. The results of this study indicate that night-time cropping does have a beneficial effect on certain meat quality parameters.
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    The effect of dietary protein degradability on production characteristics of lactating Saanen does
    (South African Society for Animal Science, 2004) Ferreira, A. V.; Thornton, J. D.
    Twenty-one lactating Saanen goats of similar milk yield and lactation number were fed one of three experimental protein diets: low UDP (160 g CP/kg DM), high UDP, low protein (128 g CP/kg DM), and high UDP high protein (160 g CP/kg DM). The aim of the study was to determine whether an increased UDP and decreased RDP content would increase production and also whether a decreased CP content and an increased UDP content would sustain the production of lactating Saanen does. The does on the low UDP diet had significantly higher feed intakes and were significantly heavier at the end of the trial period of 120 days. No differences in milk production or composition were observed. The CP intake/kg milk yield was 113 ± 0.01 g (4% butterfat). The low protein (20% less CP) high UDP diet was able to sustain a similar milk production with a significantly better conversion (29.3%) of N into milk protein than the other diets. In contrast the decrease in RDP and increase in UDP content, at the same CP level, did not improve the production potential of the does.
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    The effect of rumen degradable protein level and source on the duodenal essential amino acid profile of sheep
    (South African Society for Animal Science, 2005) Nolte, J. Van E.; Ferreira, A. V.
    Two trials were conducted to determine the effects of rumen degradable protein (RDP) level and source on the duodenal essential amino acid (AA) composition of Dohne Merino wethers. The animals had ad libitum access to wheat straw (32 g crude protein (CP)/kg DM; 742 g neutral detergent fibre (NDF)/kg DM) and water. In the first experimental treatments casein provided 0, 40, 80, 120 and 160 g supplemental RDP/d. In experiment two, urea-nitrogen replaced 0, 25, 50, 75 and 100% of the true protein in the isonitrogenous treatments. Expressing essential AA concentration as a percentage of duodenal protein indicated that increasing RDP levels tended to decrease arginine, but significantly increased tryptophan concentrations. Histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, valine and total essential AA concentrations were not affected by dietary RDP level. Increasing the urea-N content of RDP supplements significantly decreased isoleucine, leucine, lysine, phenylalanine, tryptophan, valine and total essential amino acid (TEAA) concentrations. Histidine and threonine proportions also tended to decrease with higher non-protein N levels. When the essential AA profile is expressed in relation to lysine, the concentrations of histidine, leucine, phenylalanine and threonine decreased significantly. Arginine and valine showed a decreasing trend and tryptophan increased significantly as RDP levels were raised. The largest differences appeared between 0 and 40 g RDP supplementation, while the AA patterns for the rest of the treatments remained relatively constant. Substituting urea for true RDP induced a variable response in arginine and isoleucine, but did not affect any of the other AA's. Increasing RDP intakes significantly increased the duodenal flow of every essential AA, except arginine, and showed a strong tendency to increase TEAA flow as well. Replacing true RDP with urea significantly reduced the flow of methionine and tryptophan and also tended to decrease lysine availability in the duodenum. Individual AA and TEAA flow to the duodenum were also numerically decreased by a minimum of 34% as urea-N was increased. It appears that the qualitative duodenal essential AA profile in sheep fed low quality forages is relatively insensitive to RDP level or source. The daily essential AA flow to the duodenum seems to be compromised by urea substitution for true RDP.
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    Essential amino acid requirements of meat and milk goats
    (South African Society for Animal Science, 2004) Ferreira, A. V.
    The essential amino acid (EAA) profile of the Boer goat and Saanen kids was investigated. The EAA composition of the components differed from the whole empty body (WEB) concentration. No significant differences between the two species WEB EAA composition were found. Therefore, the average empty body EAA composition (g EAA/100 g crude protein) for goats was as follows: 5.65 arginine; 2.69 histidine; 2.94 isoleucine; 7.86 leucine; 6.83 lysine; 1.83 methionine; 3.04 phenylalanine; 5.55 threonine; 4.86 valine. This composition can serve as the ideal EAA requirements for growth in meat and milk goats.
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    Feed intake and growth of Saanen kids weaned at 42 and 70 days of age
    (South African Society for Animal Science, 2004) Ferreira, A. V.; Thornton, J. D.
    The effect of weaning age (42 vs. 70 days) on the feed intake and growth performance from seven to 140 days of age was investigated, using 58 male Saanen kids. Final body weight, average daily gain and feed conversion efficiency did not differ significantly between weaning ages during the creep (days 7-80), growth diet (days 81-140) or the total (days 7-140) experimental periods. Only feed intake, cumulative feed intake, dry matter (DM) intake and cumulative DM intake differed significantly in the creep (days 7-80) period. The creep intake (days 7-80) of the 42 day weaning treatment was 48%, which was significantly higher than the 70 day treatment due to creep feed replacing milk intake. Corresponding with a feed intake of 240 g/day and a total metabolisable energy intake of 295 ± 1.4 MJ/kid over the 7 to 42 day period, the kids underwent no post-weaning shock in terms of their growth performance and had the same final weight (29.9 ± 2.0 kg) as the 70 day weaning treatment at 140 days of age.
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    Nitrogen retention response to the abomasal infusion of amino acids in South African Mutton Merino lambs
    (South African Society for Animal Science, 2002) Ferreira, A. V.; Van der Merwe, H. J.; Fair, M. D.
    The nitrogen (N) retention response to the abomasal infusion of amino acids in South African Mutton Merino ram lambs fed a standard finishing diet was investigated. The basal diet consisted of (g/kg air dry weight): 300 lucerne, 80 wheat straw, 561.5 maize meal, 35 molasses meal, 10 urea, 5 salt, 7.5 ammonium chloride, 1.0 vitamin/mineral premix and 0.29 taurotec®. Twenty-eight lambs (ca. 38 kg live weight) were randomly allocated to four treatments consisting of different abomasal infusion rates of an amino acid mixture, formulated to contain essential amino acids in the same ratio as that of the whole empty body. The mixture consisted of (g/kg): 119.7 arginine, 154.9 histidine, 22.1 isoleucine, 106.5 leucine, 91.5 lysine, 146.9 methionine, 105.6 phenylalanine, 133.8 threonine and 118.7 valine. The mixture was infused at levels of (g/d): 0.00, 38.27, 51.02 or 63.78. Glycine was used to balance the various mixtures on an iso-nitrogenous basis. Infusion of 51.02 g/d of the essential amino acid mixture resulted in a significant increase in N retention, expressed as a percentage of N intake, compared to the control group which received the test diet and glycine (Phase 1). The omission of histidine, methionine or threonine from the infusate (Phase 2) had no significant decrease in N retention or plasma amino acid concentrations compared to the infusion of the mixture of nine essential amino acids.