Nutritional evaluation of different sources of nitrogen on digestible nutrient intake, nitrogen balance and production of rumen metabolites in growing Yankasa sheep
Emirates Journal of Food and Agriculture
Animal Production Program, Abubakar Tafawa Balewa University, PMB 0248, Bauchi, Nigeria; Department of Biological Sciences, School of The Environment and Society, Singleton Park SA2 8PP, Swansea University, United Kingdom
A study was conducted to evaluate digestible nutrient intake, nitrogen balance and rumen metabolites in twenty growing Yankasa rams fed urea and /or sundried broiler litter (SDBL) as a partial or complete replacement for cotton seed cake (CSC) in diets for 90 days. The diets were: 1(CSC; control), 2(urea), 3(urea/SDBL), 4(CSC/urea) and 5(CSC/SDBL). The results indicated difference (P<0.05) in DM intake across diets, with animals fed CSC, urea and CSC/urea having the highest values (543.1, 523.4 and 483.6 g/day respectively), while those fed urea/SDBL and CSC/SDBL ((459.5 and 424.3g/day respectively) had the lowest feed intake. Mean digestible CP intake differed (P<0.001)across the diets and the values were higher for rams fed CSC and urea (75.7 and 72.7g/day) and lowest for those on CSC/SDBL (49.0g/day). However, mean digestible ADF intake was similar among the diets. A positive nitrogen balance was observed for all animals across the treatments, with significant (P<0.05) differences between treatments ranging from 4.3g/day for rams fed CSC/SDBL to 7.5g/day for those on urea. pH decreased with time after feeding. At 3 hrs post feeding, pH was highest (P<0.01) for rams fed CSC/SDBL and CSC/urea (6.9) and lowest for those on urea alone (6.1) and CSC (6.2). There was a gradual increase in the concentrations of both rumen ammonia-N (RAN) and total volatile fatty acids (VFA) after feeding. Rams fed urea and urea/SDBL (37.5 and 34.2mg/100ml respectively) had the highest (P<0.001) RAN concentration 3 hrs after feeding, while those on the other diets recorded the lowest. On the other hand, rams fed CSC/SDBL (13.1mmol/100ml) had the highest (P<0.001) VFA concentrations while those on urea the lowest (10.5mmol/100ml). It was concluded from this study that diets containing urea and CSC/urea fed to Yankasa sheep gave results comparable to those fed cotton seed cake (control), which are better than for those fed sundried broiler litterbased diets in terms of digestible nutrients intake, positive nitrogen balance and production of adequate rumen ammonia-N. However, rams fed CSC/SDBL had a better concentration of total volatile fatty acids of rumen fluid after feeding.