Nutritional status of grazing Lowline Angus crossbred supplemented with fermented cassava starch residue.

This study aimed to compare growth performance of Lowline Angus crossbred with Thai native cattle under a grazing system with supplementation of fermented cassava starch residue. Three Ruzi grass sub-fields were used for twenty heads of beef cattle for a 7-month experiment from February to August 2017. Yeast, molasses, and urea-fermented cassava starch residue was offered at 1.50% BW of animal. Blood metabolite and fecal composition were determined for health and nutritional stage assessment. The temperature-humidity index was highest (75.6-84.6) in April. Overall growth rate of beef cattle was not significantly different among breeds except in the first month when the native had greater weight gain than the crossbred. Average daily gain was 353 and 345 g for Thai native and its crossbred with Lowline Angus, respectively. Blood triglyceride concentration sampled at 7 months of the native was higher than that of the crossbred; in contrast, blood cholesterol of the crossbred tended to be higher than that of the native. Other blood metabolites including glucose, cholesterol, urea nitrogen, creatinine, total protein, albumin, and globulin were comparable between breeds. The native and the crossbred were similar in fecal composition, ruminal fermentation end-products (ammonia nitrogen and volatile fatty acids), and microbial population. Therefore, under grazing condition with low-quality feed supplementation, Thai native beef cattle and its Lowline Angus crossbred had similar growth rate, health, and nutritional status.