Browsing by Author "Van Niekerk, Marguerite"
Now showing 1 - 1 of 1
Results Per Page
Sort Options
- ItemAn in vitro comparison of plant‐based protein sources and their effects on feedlot lamb growth parameters(Stellenbosch : Stellenbosch University, 2022-12) Van Niekerk, Marguerite; Van Zyl, Johan Hendrik Combrink ; Cruywagen, C. W.; Van Wyngaard, J. D. V.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.ENGLISH ABSTRACT: Protein supplements are a very costly component of animal feed and the importance of allocating high-quality protein sources that is economically viable, consistent, and sustainable is important. By feeding human-inedible feed to ruminant animals to produce human-edible animal proteins will advance sustainability. An example of such an alternative high in protein feed source, is distiller’s dried grains with solubles (DDGS). It is also a potentially low-cost protein source compared to oil seed meals. This study investigated the nutritional potential of DDGS to replace soybean meal in comparison with other protein raw materials, dried brewer grains (DBG), cottonseed meal (CSM), and the effect of the least cost optimal formulated diet with these protein sources in growing lamb diets. In the first study (Chapter 3) the extent and rate of ruminal protein degradation of the different protein sources was determined against dried DDGS for ruminants. Five different protein samples, soybean meal, cottonseed meal, dried brewers grain, canola meal and DDGS were incubated for 0, 2, 4, 8, 16, 24, and 48 h. The effective degradability was calculated with an hourly disappearance rate of 5% and 8% per hour. The observed rumen undegradable protein content (kp = 0.08/h) was the lowest for soybean meal (47%) followed by canola meal (49%), distillers’ grains and solubles (50%), cottonseed meal (64%) and then dried brewers grain (68%). Non-significant differences were observed in the ruminal degradation rates between soybean meal and DDGS. The second study (Chapter 4) investigated how the different protein treatment diets affected growth parameters, carcass characteristics and profitability of feedlot lambs. The treatment diets were formulated to be iso-nitrogenous, iso-energetic and contained one of five different protein sources, soybean meal, DDGS, cottonseed meal, dried brewers grain, and the least cost optimal formulation. Thirty-five Dohne Merino wethers were allocated to treatments in a completely randomized design, with five treatments and seven replicates. No differences were observed in final body weight and feed efficiency as a result of the dietary treatment. Carcass weights also did not differ (P > 0.05). In conclusion, this trial determined that DDGS could economically replace soybean meal as a feed source to use in feedlot diets, and could be a valuable cost effective feed source to farmers and feed manufacturers.