Songsak Chumpawadee, Kritapon Sommart, Thevin Vongpralab, and Virote Pattarajinda

pp. 59 - 70

Abstract

The objective of this research was to determine the effect of synchronizing the rate of degradation of dietary energy and nitrogen release on growth performance in Brahman beef cattle. Fifteen Brahman cattle, 1.5 years old, with an average initial body weight of 184.8±11.1 kg were assigned to one of three treatments
according to a randomized complete block design. Dietary treatments contained 3 levels of synchrony index (0.39, 0.56 and 0.74) that were derived from laboratory chemical composition analysis and degradation kinetics using nylon bag technique. Diets were fed at the rate of 2.5% BW by separate concentrate and
roughage. Average daily gain increased linearly (P<0.05) with increase levels of synchrony index in the diets. The digestibility of dry matter, organic matter and neutral detergent fiber increased linearly (P<0.01). The digestibility of acid detergent fiber increased linearly (P<0.05). Ruminal total volatile fatty acids concentration increased linearly (P<0.05) at 6 h post feeding. Higher concentration and fluctuation of ruminal ammonia nitrogen and blood urea nitrogen were observed in animals that received lower synchrony index in their diets. Rumen microbial population tended to increase with diets having higher levels of synchrony index. The results indicated that synchronized rate of dietary energy and nitrogen degradation improved
ruminal fermentation and digestibility, thus this increased the growth rate in Brahman cattle fed with ricestraw- based diets.