Potential Use of Kasedbok (Neptunia javanica Miq.) on Feed Intake, Digestibility, Rumen Fermentation, and Microbial Populations in Thai Native Beef Cattle

SIMPLE SUMMARY: Kasedbok (Neptunia javanica Miq.) is a fodder tree legume that grows successfully in a range of tropical and subtropical regions. Kasedbok could be used as a protein source in beef cattle’s concentrate diet, which would lower the cost of feeding. We evaluated the effect of the Kasedbok levels in the diets on feed intake, digestibility, rumen fermentation, and the microbial population in beef cattle. The findings indicated that using up to 240 g/kg Kasedbok in concentrate diets does not affect feed utilization, rumen characteristics, or microbial population, lowering feed costs. ABSTRACT: This experiment was conducted to determine the influence of Kasedbok (Neptunia javanica Miq.) on the feed utilization, rumen fermentation, and microbial population in Thai Native beef cattle. Four animals with a mean body weight of 295 ± 15 kg were randomly arranged in a 4 × 4 Latin square design. There were four treatments, utilizing 0, 80, 160, and 240 g/kg Kasedbok in concentrate. Local feed resources, including cassava chips, rice bran, palm kernel meal, and soybean meal, were utilized to formulate the concentrate diets, which contained between 11.8 and 12.0% crude protein (CP). The trial was conducted for four periods of three weeks each. The first two weeks consisted of an adaptation period, while the final week was a sampling period. The findings of the current study reveal that feed intake, dry matter (DM), organic matter (OM), neutral detergent fiber (NDF), and acid detergent fiber (ADF) digestibility were similar between treatments. In addition, there was no effect of Kasedbok levels on rumen pH, blood urea nitrogen (BUN) concentration, or volatile fatty acid. However, increasing the inclusion level of Kasedbok linearly decreased CP digestibility and ammonia nitrogen (NH(3)-N) concentration (p = 0.04). In contrast, the population of fungal zoospores improved significantly (p = 0.03), while the bacterial and protozoal counts remained unchanged (p > 0.05). Furthermore, when the level of Kasedbok was increased from 0 to 80, 160, and 240 g/kg DM, the cost of concentrate decreased by 4.1, 7.8, and 10.6 USD/100 kg DM, respectively. The results of this experiment suggest that utilizing 240 g/kg of Kasedbok in a concentrated mixture will not affect feed utilization, rumen fermentation, improve microbial population, and reduce feed cost in Thai native beef cattle.