Productive performance and blood parameters of bulls fed diets containing babassu mesocarp bran and whole or ground corn

The objective of the present study was to evaluate the effects of corn milling and the inclusion of babassu mesocarp bran (BMB) on productive performance, digestibility of dietary nutrients, and blood parameters of dairy crossbred (Holstein-Gyr) bulls finished in confinement. Twenty-four bulls were fed four different experimental diets, containing two levels of inclusion of BMB (0 and 41.24%) and corn supplied in two different forms (ground and whole), for 98 days (77 days of data collection and 21 days of adaptation). The intakes and digestibility coefficients of the dry matter (DM) and nutrients were determined. There were no significant interaction effects of the BMB inclusion level and the form of corn used on the performance and digestibility variables. The intakes of DM, crude protein (CP), and neutral detergent fibre (NDF) increased with the inclusion of BMB in the diets. However, the inclusion of BMB in the diets decreased the ether extract intake, the NDF apparent digestibility, and the feed efficiency of DM and CP. Dry matter and NDF intakes also increased with the use of ground corn in the diet, which promoted an increase in the intake of total digestible nutrients (TDN), digestibility of non-fibrous carbohydrates, and average daily gain. However, the supply of ground corn reduced the feed efficiency of TDN. The remaining measured variables did not vary with the tested diets. The levels of plasma protein and albumin remained normal, but glucose concentrations were always high, irrespective of the tested diet. The form of corn supplied and the level of BMB inclusion had a significant interaction effect on the levels of triglycerides, urea, aspartate aminotransferase, and alkaline phosphatase. Babassu mesocarp bran can be included up to 41.24% in the diet of confined bulls without a negative effect on the animal weight gain. Corn should be supplied ground because this form improves the performance of crossbred bulls

本研究旨在评估玉米粉碎方式及巴巴苏中果皮麸皮（babassu mesocarp bran, BMB）添加水平对舍饲荷斯坦-吉尔奶用杂交公牛（Holstein-Gyr）生产性能、日粮养分消化率及血液指标的影响。试验选用24头公牛，饲喂四种不同试验日粮，分别设置两种BMB添加水平（0%与41.24%），并采用两种玉米供给形式（粉碎与整粒），试验期共计98天，其中21天为适应期，77天为数据收集期。本研究测定了干物质（dry matter, DM）及各类养分的采食量与消化系数。结果显示，BMB添加水平与玉米供给形式对生产性能及消化率指标无显著交互效应。日粮中添加BMB可提升干物质、粗蛋白（crude protein, CP）及中性洗涤纤维（neutral detergent fibre, NDF）的采食量，但会降低乙醚提取物采食量、NDF表观消化率以及干物质与粗蛋白的饲料转化率。日粮采用粉碎玉米可提升干物质与中性洗涤纤维采食量，同时提高总可消化养分（total digestible nutrients, TDN）摄入量、非纤维碳水化合物消化率及平均日增重，但会降低总可消化养分的饲料转化率。其余测定指标不受试验日粮的影响。血浆蛋白与白蛋白水平维持正常范围，但无论饲喂何种试验日粮，葡萄糖浓度始终偏高。玉米供给形式与BMB添加水平对甘油三酯、尿素、天冬氨酸氨基转移酶及碱性磷酸酶水平存在显著交互效应。综上，舍饲荷斯坦-吉尔奶用杂交公牛日粮中巴巴苏中果皮麸皮的添加量可达41.24%，不会对动物增重产生负面影响；建议采用粉碎形式供给玉米，以提升杂交公牛的生产性能。