Partial replacement of corn by soybean hulls in high-grain diets for feedlot sheep

Abstract: The objective of this work was to evaluate the partial replacement of corn grains by soybean hulls, in high-grain diets, and its effect on the feeding behavior and ruminal fermentation parameters of feedlot sheep. Eight rumen-cannulated crossbred sheep were assigned to four treatment groups composed of a control, to fed a diet of 50% corn silage and 50% concentrate, and to three groups fed high-grain diets, as follows: 85% corn (Diet85), 75% corn plus 10% soybean hulls (Diet75), and 65% corn plus 20% soybean hulls (Diet65). High-grain diets reduced rumination time and provided a higher degradation of feed dry matter, a higher-propionic acid concentration, a lower-acetic acid concentration, a lower methane and carbon dioxide gas production, and a lower ruminal pH value. Diet65, with 20% soybean hulls, promoted an increase in the acetic acid proportion, with a reduction in the CO2:CH4 ratio. At the end of in vitro incubation, the pH value was higher for the control diet, and it was lower for Diet85. The inclusion of soybean hulls does not change methane production and dry matter degradation, and it can be used to substitute up to 20% of corn grain in high-grain diets.摘要：本研究旨在评估高精料日粮中以大豆皮部分替代玉米籽粒的效果，并探究其对圈养育肥绵羊采食行为与瘤胃发酵参数的影响。本研究选用8只安装瘤胃瘘管的杂交肉羊，随机分为4个处理组：对照组饲喂由50%玉米青贮与50%精料组成的日粮，其余3组饲喂高精料日粮，具体分组如下：85%玉米组（日粮85）、75%玉米+10%大豆皮组（日粮75）、65%玉米+20%大豆皮组（日粮65）。结果表明，高精料日粮可缩短绵羊反刍时间，提升饲料干物质降解率，提高丙酸浓度、降低乙酸浓度，减少甲烷与二氧化碳气体生成量，同时降低瘤胃pH值。其中添加20%大豆皮的日粮65可提升乙酸占比，并降低CO₂:CH₄比值。体外发酵培养结束后，对照组日粮的pH值最高，日粮85的pH值最低。添加大豆皮不会改变甲烷生成量与干物质降解率，因此可在高精料日粮中替代最高20%的玉米籽粒。