Masters Degrees (Animal Sciences)

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The use of ICT in small-scale farming: a case of primary food production in Stellenbosch, South Africa
(Stellenbosch : Stellenbosch University, 2023-12) Feju, Philasande; Malgas, Rhoda R.; Phiri, E. E.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Science.
ENGLISH ABSTRACT: Information Communication Technologies (ICT) have been recognised globally as a beneficial set of technologies that can be used to develop agriculture, especially in small-scale farming systems. ICT helps small-scale farmers by facilitating relevant agricultural information, which assists farmers to make sensible decisions. The study aimed to achieve the following objectives a) review agricultural mobile applications available to small-scale primary food producers and evaluates their user experiences more broadly in a peri- urban town in the Western Cape Province of South Africa, namely, Stellenbosch; b) to evaluate the use of ICT tools and social media applications in small-scale farming. The review of the agricultural mobile applications was conducted on the search databases which include Cab abstracts, Scopus, and ISI Web of Science. A semi- structured questionnaire survey was utilised to conduct face-to-face interviews with small-scale farmers in Stellenbosch. The interviews (n=18) were conducted to understand farmers’ user experience and to explore the opportunities and challenges agricultural mobile apps present in small-scale farming. The survey was also used to evaluate ICT tools used by small-scale farmers in Stellenbosch. Descriptive statistics and multiple response analyses was used to analyse quantitative data in STATISTICA version 24. Thematic analyses and descriptive statistics were utilised in Atlas.ti version 24 to analyse the qualitative data. Findings revealed that farmers are aware of existing agriculture apps (55.6%) but usage of agricultural mobile applications in Stellenbosch is low (22.2%). Farmers faced several challenges in utilising agricultural mobile applications. Farmers found agriculture mobile apps challenging to use, due to unfamiliarity with the apps, and thus finding them time-consuming to navigate. Despite the low uptake, small-scale farmers in Stellenbosch who did make use of agriculture mobile apps were observed found to use ICT tools and social media applications extensively. Results from the thematic analysis demonstrated that ICTs and social media applications were used for advertisement of farm produce, communication, and obtaining agricultural information. Regarding the findings of the study, it can be concluded that small-scale farmers require education and training in the use of agricultural mobile applications, which could assist them in primary food production. Furthermore, small-scale farmers could be supported by monthly mobile data subsidies to increase use of ICT tools and social media applications in food production. Where ICT use may facilitate improvements in food production, they may offer one approach to addressing food security in Stellenbosch and further afield.
The effect of extrusion, fat coating and increased protein content of calf starter feed on growth performance of Angus calves and feedlot bulls
(Stellenbosch : Stellenbosch University, 2023-12) Orffer, Christiaan Johannes; Van Zyl, Johan Hendrik Combrink; Strydom, P. E.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Science.
Hydrolysed insect proteins as fish meal alternatives in the diets of South African abalone (Haliotis midae)
(Stellenbosch : Stellenbosch University, 2023-12) Van Schalkwyk, Mighael; Van Zyl, Johan Hendrik Combrink; De Wet. L. F.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Science.
ENGLISH ABSTRACT: This research forms part of the global effort towards reduced reliance on fish meal (FM) in aquafeeds. The utilisation of hydrolysed insect protein (HIP) was therefore evaluated against the performance obtained from fish meal-based aquafeed fed to South African abalone. The research presented in this thesis was conducted in three phases and is subsequently presented as such. Phase A evaluated chitin-target hydrolysis through dietary chitinase inclusion within extruded abalone feeds. Chitinase inclusion resulted in significant (P < 0.05) deterioration in water stability (WS). The lowest chitinase inclusion of 0.1% differed significantly (P < 0.05) from the control following 60 min water exposure. A significant reduction in the drying times of the respective treatments was observed. Drying times were correlated with WS and a rapid protocol for WS determination using drying times and drying curves was proposed. However, drying curves did not appear to correlate with WS, but was ascribed to prior drying and prolonged storage of the feeds. Due to the resulting feed disintegration and compromised WS, dietary chitinase inclusion in abalone feeds was not viable. Phase B subsequently evaluated the WS of aquafeeds containing pre-treated hydrolysed insect proteins (HIP), produced via hydrolysis by endogenous (autolysis), or chitinase or amylase enzymes. The respective HIPs were used to replace 20, 40, 60, 80 and 100% of the FM component. A significant (P < 0.05) deterioration in the WS of the amylase and chitinase treatments compared to the control was observed following 360 min WS. Hydrolysed insect protein inclusion resulted in a significant, linear reduction in WS, with 80 and 100% FM replacement (11% and 14% inclusion respectively) yielding significantly (P < 0.05) lower WS compared to the FM control. Moreover, the high HIP amylase treatment consistently yielded lower WS compared to that of the control and chitinase treatments. Despite the significant reduction, the WS of the feeds was determined suitable for a growth-trial. Phase C consisted of a commercial trial to evaluate the growth performance obtained from the respective diets. Eight baskets, stocked with 50 abalone (90 ± 10 g). Moreover, three individual abalone from each basket were tagged with a marked research tag to allow for individual weight and length measurements. No significant differences were observed for any of the measured production parameters between the respective enzymes. Similarly, HIP inclusion had no significant effect on the measured growth parameters. However, the final individual weight of the control treatment was significantly (P < 0.05) lower compared to all other treatments, but similar to the 100% HIP treatment. Dry matter feed intake significantly (P < 0.05) increased with increased HIP inclusions, however, FCR remained largely unaffected, with only the HIP60 treatment significantly (P < 0.05) higher compared to the control. Processing parameters were significantly influenced by the respective enzymes, with the dressing % of amylase treatment yielding the highest visceral weight and percentage. Enzymatic hydrolysis significantly (P < 0.05) increased the brining loss, although canning and cooking resulted in no significant differences in marketable yield. Marketable yield remained unaffected by HIP inclusion, despite a significant reduction in meat mass index with increased HIP inclusions. This study concludes that hydrolysed insect protein is a viable alternative for FM within the diets of South African abalone. The results can contribute towards reduced dependency on FM produced from wild-caught fishers and increase the sustainability of the local abalone industry.
Essential oils as natural alternatives to growth promotors: the effect on growth performance, gut health, meat quality, and profitability in feedlot sheep
(Stellenbosch : Stellenbosch University, 2023-12) Maritz, Zane; Van Zyl, Johan Hendrik Combrink; Strydom, P. E.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Science.
ENGLISH ABSTRACT: In an effort to improve animal performance and feed efficiency, ionophore antibiotics have been regularly provided to ruminants since the 1900’s. However, consumer concerns are being raised against the proposed use of antibiotics as feed additives in livestock nutrition, particularly due to antibiotic resistance concerns and antibiotic residues discovered in animal products intended for human consumption. Individual essential oil compounds, as well as blends of these compounds have the potential to replace ionophores because they are considered safe for both human and animal consumption. The current study aimed to evaluate the effects of a commercial essential oil compound (containing citral, gingerol and linalool) to ionophores (monensin) and no supplementation on the production performance, gut health, carcass characteristics and meat quality of feedlot lambs. A total of 48 Merino whether lambs weighing 30.15 ± 2.43 kg were randomly assigned to one of three treatment groups: control (CON), monensin (MON; 20 ppm), or an essential oil compound containing citral, gingerol, and linalool (EOC; 1 g/ lamb/ day). Each group's dry matter intake (DMI) and growth over a 42-day period were recorded, and the feed conversion ratio and profitability were subsequently calculated. Post mortem, a gut health analyses and carcass (classification, fatness, pH temperature) and meat quality analyses (meat proximate composition, water holding capacity, colour stability, lipid oxidation and texture) was conducted on the longissimus thoracis (LT) muscle. The first part of the study found that neither the addition of a blend of essential oil compound or monensin to the diet of feedlot lambs had any effect on DMI, growth, FCR or carcass weights. Dressing percentage of the MON group was higher (P < 0.05) than the EOC group. Furthermore, the histomorphology study of the rumen and small intestine (specifically duodenum and jejunum) revealed no association between MON and EOC supplementation on the determined gut health parameters of feedlot lambs. Despite not differing from the control, it was concluded that the commercial EO blend could effectively replace monensin in the diets of feedlot Merino whether lambs. From an economic perspective, no changes in margin above specified cost per lamb were observed between treatments. Even though there has been a significant improvement in recent years in our knowledge of the potential use of essential oils to modify rumen microbial fermentation and improve animal performance, additional research on dosage rates, rumen microbe degradation, and the fate of essential oils in the gastro-intestinal tract, is still required. The apparent lack of benefit from monensin supplementation on lamb feedlot performance should also be revisited. In the carcass and meat quality analyses, initial and final pH, temperature, and carcass classification were unaffected by EOC or MON supplementation. Increase in drip loss (day 2 and 8) and cooking loss was observed with the addition of the EOC when compared to CON and MON. Some changes in meat colour in comparison to CON and MON of specific measured parameters have also been observed. Despite no alterations in meat chemical composition or overall ratios of fatty acids, the addition of an EOC and MON showed a decrease (P < 0.05) in total fatty acid content, as well as levels of specific fatty acids. Overall lipid oxidation was reduced (P < 0.05) by the addition of the EOC. No difference in tenderness was observed between the different treatment groups, while the CON group had the highest (P < 0.05) cooking loss. Considering all, it was concluded that the specific EO compound used in the current study could serve as multipurpose feed supplement to feedlot lambs, influencing meat quality characteristics and lipid oxidation. Due to the inconsistent findings reported in the literature and the current study, further research into the application and results of dietary essential oils to improve the quality of lamb meat is necessary.
The extent and mitigation of mycotoxins in commonly used feed commodities in South African beef feedlots
(Stellenbosch : Stellenbosch University, 2023-12) Van der Merwe, Anel; Van Zyl, Johan Hendrik Combrink; Strydom, P. E.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Science.
ENGLISH ABSTRACT: The global occurrence of mycotoxins in agricultural commodities, including feed intended for livestock, is a topical concern. Research suggests that up to 88% of global commodities and 89% of South African feed commodities are contaminated with mycotoxins. The exposure to or consumption of these natural contaminants results in detrimental health and production disorders in livestock and cause substantial economic losses. Consequently, mycotoxins pose a significant threat to feed and food safety on a global scale. The presence of mycotoxins in feed commodities is affected by numerous factors, including cultivation methods, environmental conditions, processing, storage, and transportation conditions. As a result, the occurrence of mycotoxins varies between seasons and geographical areas. A national survey was performed to determine the current extent of mycotoxin contamination in feed commodities commonly used in South African beef feedlot diets and the subsequent risk posed to the industry. Five feed commodities, namely maize, maize silage, hominy chop, gluten 20 and wheat bran were sampled from four provinces, including the Free State, KwaZulu-Natal, North-West and the Western Cape. The results showed that the major mycotoxins present in South Africa are deoxynivalenol, fumonisin and zearalenone. The presence and concentration levels of other major mycotoxins observed globally, such as aflatoxin, ochratoxin, and ergot alkaloids were low in the current study. Since the latter toxins are considered storage mycotoxins, this observation can be attributed to optimal handling, transportation, and storage conditions in the local agricultural sector. Overall, 3.33, 6.67, 92.50, 62.90, 10.83 and 67.50% of the feed samples were contaminated with aflatoxin, ergot alkaloids, deoxynivalenol, fumonisin, ochratoxins and zearalenone, respectively. Moreover, most of the mycotoxins were present at medium to high risk levels for beef cattle. A significant interaction (P < 0.01) between the main effects (commodity and province) was observed in co-contamination. There were significant differences (P < 0.01) in the concentration of deoxynivalenol between the respective feed commodities, where hominy chop, followed by gluten 20, had the highest concentration levels. This could be attributed to the uneven distribution of deoxynivalenol in the different milling fractions of maize. In contrast, no differences were found in fumonisin or zearalenone concentrations between the different feed commodities. Finally, despite the varying climatic conditions throughout South Africa, no significant differences in mycotoxin concentrations were observed between the respective provinces. The survey concluded that the current occurrence of mycotoxins in feed commodities in South Africa is significant and poses a meaningful risk to the beef feedlot industry. Although ruminants are considered more resistant to the adversities of mycotoxins, their inherent detoxification ability is variable and satiable. High-producing cattle receive diets rich in energy, which alters their microbial population and increases the feed passage rate, which subsequently decreases the capacity and time available to degrade mycotoxins. Additionally, feedlot cattle are subjected to substantial production stress, which has a depressive effect on their immune system and further increases their sensitivity to mycotoxins. Effective detoxification strategies should thus be implemented to reduce the adversities of mycotoxicosis. Mycotoxin adsorbents or deactivating feed additives have proven efficacy in attenuating or preventing mycotoxicosis in livestock. To determine the effect on feedlot steers, two mycotoxin-deactivating feed additives, namely Mycofix® Secure and Mycofix® Select 5.0 (Biomin [DSM], Getzersdorf, Austria), were investigated. A total of 186 cross- bred steers of similar age and body weights were randomly divided into three treatment groups comprising of 62 animals each. The first group served as a control group, whereas the second and third groups received Mycofix® Select 5.0 and Mycofix® Secure at an inclusion rate of 15 g/head/day. The animals were challenged with the naturally occurring mycotoxin levels throughout the study. The group that received Mycofix® Select 5.0 showed improved body weight gain and feed conversion efficiency over the total duration of the trial, in terms of measured average daily gain (P = 0.03) and calculated Kleiber ratio (P = 0.04). Additionally, both treatment groups had higher (P < 0.01) dry matter intakes as a percentage of their body weight during the adaptation period in the feedlot than the control group. The higher feed intake can partly explain the improved performance of the two groups compared to the control group. However, over the total period of the trial, no differences were observed in body weight, dry matter intake as a percentage of body weight, or feed conversion ratio between the groups. Since mycotoxin adsorbents and/or deactivating feed additives are known to improve the performance of cattle, these similarities were attributed to the overall low naturally occurring mycotoxin challenge experienced during the trial. Further, no differences were observed in slaughter parameters, including carcass weights, dressing percentage, or fat content classification. Finally, despite the increased feed costs from the addition of the feed additives, no differences were observed in the margin above feed cost.

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