Estimation of ruminal degradation and intestinal digestion of tropical protein resources using the nylon bag technique and the three-step in vitro procedure in dairy cattle on rice straw diets.

摘要

This experiment was carried out using fistulated multiparous Holstein-Friesian crossbred (75% Holstein Friesian and 25% Red Sindhi) dairy cows in their dry period fed on untreated rice straw to evaluate the nutritive value of local protein feed resources using the in sacco method and in vitro pepsin-pancreatin digestion. Experimental feeds consisted of cottonseed meal (CSM), soyabean meal (SBM), dried brewery's grains (DBG), palm kernel meal (PSM), cassava hay (CH) and leucaena leaf meal (LLM). Each feedstuff was weighed into duplicate nylon bags and incubated in each of the 2 rumen fistulated cows for 0, 2, 4, 8, 16, 24 and 48 h. Rumen feed residues from bags incubated for 16 h were used for estimation of lower gut digestibility by the technique of in vitro pepsin-pancreatin digestion. Ruminal ammonium nitrogen (NH< sub>3-N) concentrations did not differ between treatments or time with a mean of 5.5 mg%. Effective degradabilities of CSM, SBM, DBG, PSM, CH and LLM dry matter (DM) were 41.9, 56.1, 30.8, 47.0, 41.1 and 47.5%, respectively. Effective degradabilities of the CP in feedstuffs were 49.6, 59.2, 40.9, 33.5, 47.3 and 65.0% for the respective feedstuffs. The crude protein (CP) in vitro pepsin-pancreatin digestibilities as ranked from the highest to the lowest were SBM, CSM, LLM, CH, DBG, PSM, respectively. The intestinal and total tract digestion of feedstuffs in the current study were relatively lower than that obtained from previous literature. The results of this study indicated that SBM and LLM were highly degradable in the rumen, whereas CH, CSM and DBG were less degradable and resulted to higher rumen undegradable protein. SBM and LLM could be used to improve the rumen ecology, whereas CH, CSM and DBG could be used as rumen bypass protein for ruminant feeding in the tropics.