The effect of feeding varying levels of Leucaena leucocephala on intake and digestibility of low-quality forages in the Highveld of South Africa
AbstractThe purpose of this study was to determine the effect of varying levels of Leucaena supplement on the intake, flow and digestibility of nutrients of two low-quality forages. Partial digestion methods were used. The overall results showed that the supplementation of veld grass with Leucaena hay improved the performance of veld grass more significantly (P < 0.05) than the supplementation of Eragrostis grass with Leucaena hay. The crude protein of Diets 2–4, which contained veld grass, increased by 67.1%, 95.3% and 130.6%, compared with the control diet, while the in vitro organic matter digestibility increased by 15.5%, 25.7% and 15.24%, respectively. Similarly, neutral detergent fibre content decreased by 6.5%, 14.7% and 23.3%, respectively. Feed intake increased by 22.7%, 14.9% and 11.3%, and crude protein intake increased by 2.13, 2.25 and 2.57 times, respectively. The production of ammonia nitrogen increased by 17%, 38.4% and 44.3%, and volatile fatty acids increased by 31.3%, 28% and 26%, respectively. The flow of non-ammonia nitrogen through the abomasum increased by 3.28, 3.9 and 4.76 times, respectively. The disappearance of organic matter from the rumen increased by 29.3%, 36.2% and 24.7% and in the small intestine increased by 1.8, 2.3 and 2.2 times, respectively. The overall digestibility of organic matter in the whole digestive tract was increased by 9.9%, 16.3% and 9.7%, respectively. In comparison, the crude protein of Diets 6–8, which contained Eragrostis grass, increased by 37.5%, 80% and 103.3%, compared with the control, while the neutral detergent fibre content decreased by 4.8%, 14.8% and 21.6%, respectively. Feed intake increased by 41.3%, 36% and 28.4%, and crude protein intake by 1.93, 2.43 and 2.52 times, respectively. The production of ammonia nitrogen increased by 13.8%, 25% and 21.7%, and volatile fatty acids increased by 18.8%, 17.4% and 14.7%, respectively. The flow of nonammonia nitrogen through the abomasum increased by 1.27, 166 and 1.50 times, respectively. However, there was no significant effect on the flow of the other nutrients. However, the overall digestibility of organic matter was not significantly different from that of the control diet. The conclusion was that the supplementation of the poorer forage with Leucaena was more beneficial and more cost-effective than the supplementation of the better-quality forage with Leucaena.
Keywords: multi-purpose fodder trees, partial digestion, protein supplementation
African Journal of Range & Forage Science 2006, 23(3): 177–183