ABSTRACT
BACKGROUND AND OBJECTIVE: The sub-saharan livestock feed industry depends on imported soyabean meal (SBM) as a dietary protein source in feeds thus making livestock production costly. This calls for the search and development of local dietary protein sources. Using Sprague Dawley rats to model monogastric animals, this study evaluated the potential of Ximenia caffra kernel meal (XCKM) to substitute SBM as a dietary protein source in feeds. MATERIALS AND METHODS: Five diets were formulated wherein XCKM replaced SBM on a crude protein basis at 0, 25, 50, 75 and 100%. In the digestibility trial, 20 adult male SD rats were randomly assigned to the 5 diets. After a 12-day adaptation period feed and nutrient intake, faeces and urine output were determined over a 5-day collection period. Apparent Total Tract Digestibility (ATTD) of nutrients and nitrogen absorption and retention were determined. In the growth trial, 40 weanling male SD rats were randomly assigned to the five dietary treatments and fed for 38 days. The rats were weighed twice weekly. Following euthanasia, gastrointestinal viscera were harvested and their macro-morphometry determined. Linear growth was determined from tibiae and femora indices. RESULTS: In adult rats dietary XCKM had no (p>0.05) effect on ATTD of nutrients. At 100% substitution of SBM, XCKM increased (p<0.05) faecal nitrogen loss while at 75% substitution level it increased (p<0.05) nitrogen retention. In growing SD rats, although dietary XCKM had no effect (p>0.05) on the terminal body and empty carcass mass and viscera macro-morphometry, at 100% SBM substitution, it significantly compromised (p<0.05) body mass gain and average daily gain. Femora and tibiae mass and seed or index significantly decreased (p<0.05) with increased dietary XCKM. CONCLUSION: The XCKM could replace SBM as a dietary protein source in adult SD rat feeds without compromising ATTD digestibility of nutrients and nitrogen utilization thus it could be speculated that XCKM can be utilized as a dietary protein source in feeds of mature monogastrics. Caution must be exercised in using XCKM in grower rat diets as its use at higher inclusion levels compromised growth performance and long bone health.
