摘要
Ruminal parameters, rumen development, nutrient digestibilities, and N utilization were estimated in Holstein calves fed starch from different sources. Ground corn, ground barley, ground wheat, and crimped oats were used to formulate 4 isostarch (25% of starter dry matter) pelleted diets. These diets were randomly allocated to calves (16 calves per treatment, 8 female and 8 male) and fed ad libitum along with mixed grass hay throughout the experiment. Ruminal contents and blood were sampled at d 35, 50, and 70 of age to estimate ruminal parameters and plasma β-hydroxybutyrate, respectively. At d 70, twenty-four male calves (6/treatment) were randomly selected, euthanized, and forestomach weight, papillae length (PL), papillae width (PW), rumen wall thickness (RWT), and papillae concentration were measured. At d 63, twenty-four female calves (6/treatment) were randomly selected and moved to metabolism stalls to estimate total tract apparent nutrient digestibilities and N utilization. Female calves were given 2 wk for adaptation to experimental facilities and then total collections of feces and urine were made from d 77 to 84 of age. Ruminal pH at d 35 of age was higher in calves fed corn and oat diets than in those fed barley and wheat diets. Ruminal pH at d 50 and 70 of age was the lowest in calves on barley diets followed by those on oat and wheat diets and then by those on the corn diet. Ruminal total volatile fatty acid concentrations at d 35 of age were greatest in calves fed corn or wheat diets followed by those fed barley and oat diets. Calves on corn and wheat diets maintained greater ruminal volatile fatty acids concentrations at d 50 and 70 of age. Ruminal ammonia, acetate, propionate, butyrate, and blood β-hydroxybutyrate concentrations were also greater in calves on the corn and wheat diets. Full and empty weights of forestomach, PL, PW, RWT, and papillae concentrations were greater in calves on corn and wheat diets. Daily average intake of nutrients (dry matter, crude protein, neutral detergent fiber, starch, Ca, and P) was greater in calves fed corn and wheat diets than in those fed barley and oat diets. Starch source did not influence the total tract apparent digestibilities of nutrients in calves. Daily N retention (g/d) was greatest on the corn diet followed by the wheat diet and then the barley and oat diets. In conclusion, calves on a corn diet have greater ruminal capacity to accommodate feed bulk. More physically and metabolically functional rumens in calves on corn and wheat diets probably resulted in greater feed consumption and N retention.
摘要译文
在来自不同来源的荷斯坦犊牛饲喂淀粉中估计瘤胃参数，瘤胃发育，营养物质消化率和氮利用率。磨碎的玉米，大麦，磨碎的小麦，并且使用卷曲的燕麦配制4个isostarch（25％的起始干物质）颗粒饲料。这些饮食随机分配到小牛（每次处理16小牛，在整个实验过程中随意喂食8只雌性和8只雄性并随意喂食干草。瘤胃内容物和血液在第35,50天取样，和70岁的人分别估计瘤胃参数和血浆β-羟丁酸。在第70天，随机选择24只雄性小牛（6只/处理），实施安乐死，并确定前胃重量，测量乳头长度（PL），乳头宽度（PW），瘤胃壁厚度（RWT）和乳头浓度。在第63天，随机选择24只雌性小牛（6只/处理）并移至新陈代谢停滞区以估计总肠道表观营养素消化率和氮利用率。给雌性小牛喂食2周以适应实验设施，然后从77至84岁时制备粪便和尿液的总收集物。饲喂玉米和燕麦日粮的犊牛在35岁时的瘤胃pH值高于饲喂大麦和小麦日粮的犊牛。在50和70岁时的瘤胃pH值在大麦日粮中最低，其次是燕麦和小麦日粮，然后是玉米日粮。在饲喂玉米或小麦日粮的犊牛中，在35岁时的瘤胃总挥发性脂肪酸浓度最高，其次是喂食大麦和燕麦日粮。玉米和小麦日粮中的犊牛在50和70岁时保持较高的瘤胃挥发性脂肪酸浓度。瘤胃氨，乙酸盐，丙酸盐，丁酸盐，玉米和小麦日粮中犊牛的血β-羟丁酸浓度也较高。充实和空重的前胃，PL，PW，RWT，玉米和小麦日粮中犊牛的乳头和乳头浓度更高。每日平均摄入的营养素（干物质，粗蛋白，中性洗涤纤维，淀粉，钙，喂养玉米和小麦日粮的犊牛和P）比饲喂大麦和燕麦日粮的小牛更大。淀粉来源不影响小牛营养物质的总消化道表观消化率。玉米日粮中的每日N保留量（g / d）最大，然后是小麦日粮，然后是大麦和燕麦日粮。结论，玉米日粮中的小牛有更大的瘤胃容量来适应饲料量。玉米和小麦日粮中犊牛的物理和代谢功能更高的瘤胃可能导致更高的饲料消耗和氮保留。
M.A.Khan[*][1];H.J.Lee[*];W.S.Lee[*];H.S.Kim[*];S.B.Kim[*];S.B.Park[*];K.S.Baek[*];J.K.Ha[†];Y.J.Choi[†];. Starch Source Evaluation in Calf Starter: II. Ruminal Parameters, Rumen Development, Nutrient Digestibilities, and Nitrogen Utilization in Holstein Calves[J]. Journal of Dairy Science, 2008,91(3): 1140-1149