The aim of this study was to evaluate effects of milk replacer (MR) feeding rate and processing of corn in calf starter (CS) on growth performance, nutrient digestibility, and rumen and fecal fibrolytic bacteria in dairy calves. Holstein male calves (n = 48, 2-3 d of age) were randomly assigned to 1 of 4 treatments with a 2 × 2 factorial arrangement of MR level of 0.749 kg of MR/d (LO) or up to 1.498 kg of MR/d (HI); and whole corn or flaked corn in textured CS. Calves were weaned by reducing MR offered by 50% during wk 6. Intakes of MR and CS were recorded daily, whereas body weight (BW) was measured weekly. Rumen fluid and fecal matter were collected at wk 5 and 8 to quantify fibrolytic bacteria and nutrient digestibility. Data were analyzed as a completely randomized design using mixed model ANOVA. Repeated measures were used as appropriate. Calves fed HI had greater average daily gain than calves fed LO at wk 2, 3, 4, and 5, yet at wk 7 calves fed HI had lower average daily gain compared with calves fed LO. Starter intake was greater for calves fed LO compared with HI at wk 4, 5, 6, and 7. During wk 5 and 8, calves fed LO had increased ADF and NDF digestibility compared with calves fed HI. During wk 5, dry matter and organic matter digestibility were lower for LO-fed calves compared with HI-fed calves, but during wk 8 the opposite was observed, with HI-fed calves having lower dry matter and organic matter digestibility than LO-fed calves. At wk 5, Clostridium cluster IV and Butyrivibrio fibrisolvens proportions in rumen fluid tended to be higher and Clostridium cluster IV, Fecalibacterium sp., and Prevotella sp. proportions in fecal matter were higher in calves fed LO compared with HI. From wk 8 to 16, dry matter intake was unaffected by treatment; however, energy efficiency was greater in calves fed LO, causing LO calves to have higher BW gain during this period. Greater starter digestibility was observed for calves fed LO versus HI in concert with increased fibrolytic bacteria proportions (wk 5) in fecal and rumen samples, which resulted in greater postweaning BW gain and similar BW and frame measurements by 16 wk of age. Overall the results show that rate of MR feeding has a larger effect than the processing of corn in CS on performance, fiber digestibility, and rumen and fecal fibrolytic bacterial communities.

中文翻译：

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饲喂代乳粉的量和发酵剂中玉米的加工对乳牛犊生长性能，养分消化率以及瘤胃和粪便溶纤菌的影响。

这项研究的目的是评估代乳料（MR）的饲喂率和小牛用起子（CS）中玉米的加工对奶牛犊生长性能，养分消化率以及瘤胃和粪中溶纤菌的影响。荷斯坦雄性犊牛（n = 48，年龄2-3 d）被随机分配到4种处理方法中的一种，其2×2析因排列的MR水平为0.749 kg MR / d（LO）或最高1.498 kg MR / d（HI）; 以及整粒CS中的整个玉米或片状玉米。通过在第6周减少MR降低50％来使小牛断奶，每天记录MR和CS的摄入量，而每周测量体重（BW）。在第5周和第8周收集瘤胃液和粪便，以量化纤溶细菌和营养物质的消化率。使用混合模型ANOVA将数据分析为完全随机设计。适当地使用重复的措施。在第2周，第3周，第4周和第5周时，喂饲HI的犊牛的平均日增重比喂喂LO的犊牛要高，但第7周的喂饲HI的犊牛的日均增重比喂LO的犊牛低。与第4周，第5周，第6周，第7周和第7周相比，饲喂LO的犊牛的摄食量要比HI高。在第5周和第8周，与饲喂HI的犊牛相比，饲喂LO的牛的ADF和NDF消化率增加。在第5周，LO饲喂的犊牛的干物质和有机物消化率低于HI饲喂的牛犊，但是在第8周，观察到相反的情况，HI饲喂的犊牛的干物质和有机物消化率低于LO饲喂小牛。在第5周，瘤胃液中的梭状芽孢杆菌群集IV和纤维状丁酸梭菌的比例往往更高，梭状芽孢杆菌群集IV，Fecalibacterium sp。和Prevotella sp。与HI相比，喂LO的犊牛粪便中的比例更高。从8周到16周，干物质的摄入不受治疗的影响；但是，犊牛饲喂的LO的能量效率更高，导致LO犊在此期间具有更高的BW增益。与粪便和瘤胃样品中的溶纤细菌比例增加（wk 5）相一致，LO和HI饲喂的犊牛观察到更高的起始消化率，这导致断奶后BW增高，并且在16 wk龄时具有类似的BW和构架测量值。总体而言，结果表明，在CS中，MR饲喂的速率对玉米的生产性能，纤维消化率以及瘤胃和粪便的纤溶细菌群落的影响要比玉米加工的影响大。导致LO小牛在此期间具有较高的BW增益。与粪便和瘤胃样品中的溶纤细菌比例增加（wk 5）相一致，LO和HI饲喂的犊牛观察到更高的起始消化率，这导致断奶后BW增高，并且在16 wk龄时具有类似的BW和构架测量值。总体而言，结果表明，在CS中，MR饲喂的速率对玉米的生产性能，纤维消化率以及瘤胃和粪便的纤溶细菌群落的影响要比玉米加工的影响大。导致LO小牛在此期间具有更高的BW增益。与粪便和瘤胃样品中的溶纤细菌比例增加（wk 5）相一致，LO和HI饲喂的犊牛观察到更高的起始消化率，这导致断奶后BW增高，并且在16 wk龄时具有类似的BW和构架测量值。总体而言，结果表明，在CS中，MR饲喂的速率对玉米的生产性能，纤维消化率以及瘤胃和粪便的纤溶细菌群落的影响要比玉米加工的影响大。