Tjardes K E, Buskirk D D, Allen M S, Tempelman R J, Bourquin L D, Rust S R
Department of Animal Science, Michigan State University, East Lansing 48824-1225, USA.
J Anim Sci. 2002 Mar;80(3):841-6. doi: 10.2527/2002.803841x.
Twelve Angus (237 +/- 13 kg) and twelve Holstein (235 +/- 15 kg) steers were used to determine whether corn silage-based diets with different NDF levels influence DMI to a similar extent in Angus and Holstein steers and as body weight of the steers increase. Steers were randomly assigned to individual slatted-floor pens and used in a crossover design consisting of six 14-d periods. Experimental diets contained corn silage from a normal hybrid (low-fiber; LF) and its male-sterile counterpart (high-fiber; HF) and were alternated each period. The LF and HF diets contained 33.8 and 50.8% NDF, respectively. The HF diet decreased (P < 0.01) overall steer mean DMI 14.0% relative to LF, with mean differences increasing as steers increased in BW (P < 0.01). Feeding the HF diet also reduced ADG by an average of 13.8% relative to the LF diet (P < 0.01). Holstein steers consumed 14.4% more DM and gained 14.3% faster (P < 0.01) than Angus steers. There was a fiber level x breed-type interaction (P = 0.08) for efficiency of gain. Angus steers receiving the HF diet had greater efficiency of gain than Angus steers consuming the LF diet; however, Holstein steers consuming the LF diet had greater efficiency of gain than those receiving the HF diet. The HF treatment reduced total-tract digestibility of DM and GE by 4.6 and 4.5%, respectively (P < 0.01), and decreased DE intake by 20.5% (P < 0.01) but increased apparent totaltract digestibility of NDF and ADF (9.4 and 8.4%, respectively; P < 0.01). Holstein steers had similar digestibility of DM and GE (P > 0.10) but had greater DE intake (P < 0.01) compared to Angus steers. There were fiber level x breed-type interactions for total-tract digestibility of NDF and ADF (P < 0.06). The difference in DM digestibility was negatively associated with the difference in DMI (r2 = 0.23; P < 0.01) for LF minus HF within Angus steers, but not within Holstein steers (P = 0.42). Total-tract digestibility of NDF and ADF was 4.1 and 3.4% lower for the HF diet but was only 1.1 and 0.6% lower for the LF diet when fed to Holstein compared to Angus steers. Results from this trial demonstrate that high-NDF corn silage-based diets reduced intake of both Angus and Holstein steers, and this reduction in DMI continued as steers increased in BW from 235 to 330 kg. Breed differences were also noted for digestible energy intake as influenced by fiber level.
选用12头安格斯牛（体重237±13千克）和12头荷斯坦牛（体重235±15千克）来确定不同中性洗涤纤维（NDF）水平的玉米青贮日粮对安格斯牛和荷斯坦牛干物质采食量（DMI）的影响程度是否相似，以及随着牛体重增加情况如何。将牛随机分配到个体板条地面栏舍，并采用交叉设计，包括六个14天的周期。实验日粮包含来自普通杂交种的玉米青贮（低纤维；LF）及其雄性不育对应品种（高纤维；HF），且每个周期交替使用。LF和HF日粮的NDF含量分别为33.8%和50.8%。与LF日粮相比，HF日粮使总体牛的平均DMI降低了14.0%（P<0.01），且随着牛体重增加，平均差异增大（P<0.01）。饲喂HF日粮相对于LF日粮还使平均日增重（ADG）平均降低了13.8%（P<0.01）。荷斯坦牛比安格斯牛多消耗14.4%的干物质，增重速度快14.3%（P<0.01）。在增重效率方面存在纤维水平×品种类型的交互作用（P = 0.08）。采食HF日粮的安格斯牛比采食LF日粮的安格斯牛有更高的增重效率；然而，采食LF日粮的荷斯坦牛比采食HF日粮的荷斯坦牛有更高的增重效率。HF处理使干物质和总能的全消化道消化率分别降低了4.6%和4.5%（P<0.01），使消化能摄入量降低了20.5%（P<0.01），但提高了中性洗涤纤维和酸性洗涤纤维的表观全消化道消化率（分别提高了9.4%和8.4%；P<0.01）。荷斯坦牛的干物质和总能消化率相似（P>0.10），但与安格斯牛相比，其消化能摄入量更高（P<0.01）。在中性洗涤纤维和酸性洗涤纤维的全消化道消化率方面存在纤维水平×品种类型的交互作用（P<0.06）。在安格斯牛中，LF减去HF的干物质消化率差异与DMI差异呈负相关（r2 = 0.23；P<0.01），但在荷斯坦牛中并非如此（P = 0.42）。与安格斯牛相比，饲喂HF日粮时，中性洗涤纤维和酸性洗涤纤维的全消化道消化率分别低4.1%和3.4%，而饲喂LF日粮时仅低1.1%和0.6%。该试验结果表明，高NDF玉米青贮日粮降低了安格斯牛和荷斯坦牛的采食量，并且随着牛体重从235千克增加到330千克，DMI的这种降低持续存在。在纤维水平影响下，可消化能量摄入量也存在品种差异。
