Effect of Rumen Undegradable Protein Levels on Performance of Thai Native x Brahman Beef Cattle

Abstract

This experiment aimed to study the effects of rumen undegradable protein levels on productive performance of Thai Native-Brahman beef cattle. Four yearling Thai Native x Brahman beef cattle with an average Body Weight (BW) of 175.5±18.6 kg were used in a 4 x 4 Latin square arrangement. The treatments were levels of Rumen Undegradable Protein (RUP) in concentrate at 30, 35, 40 and 45%. Concentrates were formulated to contain 14% CP and were fed at 2.0% BW. The results showed that the DM intake, OM digestibility and TVFA increased linearly (p<0.05) while the level of RUP increased. Moreover, the ruminal NH₃-N (p<0.01) and BUN linearly decreased, whereas at 45% RUP the ruminal NH₃-N concentration increased (quadratically, p<0.01). The bacteria and protozoa populations also increased as the level of RUP increased. However, the bacteria and protozoa populations decreased quadratically (p<0.05) when the level of RUP changed from 40 to 45%. The N retention (g/d) tended to increase with increasing the level of RUP. However, the N retention tended to decrease at the level of 45% RUP. It could be concluded that RUP level at 40% in concentrate had positive effects on productive performances.