Influence of different dietary rumen degradable protein concentrations on nutrient intake, nutrient digestibility, nitrogen balance, blood urea nitrogen and milk yield of lactating Beetal goats

Abstract

In this study, we investigated the effect of different dietary RDP concentrations on nutrient intake, nutrient digestibility, nitrogen balance, blood urea nitrogen (BUN) and milk yield of lactating Beetal goats. Thirty five lactating Beetal goats were randomly divided into five groups (seven goats per group) in a randomized complete block design. Five isocaloric and isonitrogenous diets were formulated to contain 30, 40, 50, 60 and 70% RDP of dietary protein represented as 30RDP, 40RDP, 50RDP, 60RDP and 70RDP, respectively. Feed intake was recorded, nutrient digestibilities (DM, CP, ADF and NDF) were determined and blood samples were taken at 3, 6, 9 and 12 h post feeding, and examined for BUN. In addition, milk produced by each goat was recorded. The results showed that increasing RDP level in the diet has a linear effect (dose-dependently) on nutrient digestibilites, nutrient intake and milk yield. Dry matter (DM), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) intake were higher (P < 0.05) in goats fed 70RDP diet than those fed 30RDP diet. Nutrients digestibilities (DM, CP, NDF and ADF) were significantly higher (P < 0.05) in goats fed 60RDP diet than those fed 30RDP. Goats fed 70RDP diet produced higher milk yield/d than those fed 30RDP diet. These results revealed that Beetal goats fed 70RDP showed increased nutrient intake and digestibility and proved to be the best in terms of economics as compared to 60RDP, 50RDP, 40RDP and 30RDP diets.