EFFECT OF VARYING LEVELS OF DIETARY RUMEN UNDEGRADABLE PROTEIN ON DRY MATTER INTAKE, NUTRIENT DIGESTIBILITY AND GROWTH PERFORMANCE OF CROSSBRED CATTLE HEIFERS

Abstract

Thirty six crossbred dairy cattle heifers (average weight 200±4 kg) were used in completely randomized design to examine effect of varying levels of ruminally undegradable protein on nutrient intake, nutrient digestibility, nitrogen (N) balance, blood metabolites, blood chemistry and growth performance. Heifers were divided into four groups. Four iso-nitrogenous and iso-caloric diets (RUP25, RUP35, RUP45 and RUP55) were formulated. The RUP25 diet was formulated to contain RUP 25% of CP. The RUP35, RUP45 and RUP55 diets supplied RUP 35, 45 and 55% of CP, respectively. This experiment lasted for 70 days. The heifers fed ad libitum. The intake of dry matter (DM), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) increased (P<0.05) with increasing level of dietary RUP. Digestibility of DM, NDF and ADF was greater (P<0.05) in heifers fed RUP25 diet than those fed RUP35, RUP45 and RUP55 diets. A linear increase (P< 0.05) in N balance was noted in heifers fed increasing level of dietary RUP. Urinary N excretion, blood urea N (BUN) and creatinine decreased (P< 0.05) linearly in heifers with increasing level of dietary RUP. Blood pH, blood glucose and blood chemistry remained unaltered across all treatments. In conclusion, N retention can be enhanced, weigh gain can be increased and FCR can be improved by increasing RUP in the diet of growing crossbred cattle heifers and RUP55 diet is optimum regarding DM intake, N retention, weight gain and FCR. The information developed in this study can help in cost effective dairy production through attaining early puberty in heifers.