Reinhardt C D, Brandt R T, Eck T P, Titgemeyer E C
Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506, USA.
J Anim Sci. 1998 Jul;76(7):1778-88. doi: 10.2527/1998.7671778x.
We conducted two trials to examine the effects of restricted vs full feeding and of grain processing method on feedlot performance, digestion, and mastication efficiency by Holstein steers in different growing-finishing systems. In Trial 1, 272 Holstein steers (177 +/- 9.98 kg) were blocked by weight and assigned to growing phase diets based on corn silage (SIL), steam-flaked corn that was either limit-fed (SFLF) or full-fed (SFFF), or whole corn that was limit-fed (WCLF) or full-fed (WCFF). Limit-fed steers were fed at levels predicted to allow daily gain of 1 kg/d. On d 112, all steers were switched to WCFF or SFFF diets until the mean BW of each treatment group was 545 kg. Overall, steers fed WCLF and SFLF during the growing phase and finished on SF were 8.1 and 6.6% more efficient at converting dietary ME to gain (P = .02 and .04, respectively) than steers in the SFFF group. In Trial 2, three ruminally and duodenally cannulated Holstein steers were fed whole (WC) and rolled corn (RC) diets at FF and LF intake in an incomplete replicated 2 x 2 switchback design. Ad libitum access to feed resulted in higher (P = .02) ruminal starch digestibility than did limit-feeding, and calves had higher total tract DM (P = .05) and starch (P = .03) digestion at the heavier BW. Limit-feeding whole corn resulted in increased particle size of masticate (P = .06) compared with full-feeding whole corn. Because of apparent differences in mastication efficiency between limit-fed and full-fed calves, grain processing method during periods of restriction and compensatory growth may be important considerations for managing growth in systems that incorporate limit-feeding.
我们进行了两项试验，以研究在不同育肥系统中，限饲与全量饲喂以及谷物加工方法对荷斯坦公牛育肥性能、消化和咀嚼效率的影响。在试验1中，272头荷斯坦公牛（体重177±9.98千克）按体重进行分组，并根据玉米青贮料（SIL）、限量饲喂（SFLF）或全量饲喂（SFFF）的蒸汽压片玉米、限量饲喂（WCLF）或全量饲喂（WCFF）的整粒玉米分配到生长阶段日粮中。限饲的公牛按照预计能实现日增重1千克/天的水平进行饲喂。在第112天，所有公牛都换成WCFF或SFFF日粮，直至每个处理组的平均体重达到545千克。总体而言，在生长阶段饲喂WCLF和SFLF并在SF日粮上育肥的公牛，在将日粮代谢能转化为增重方面，比SFFF组的公牛分别高出8.1%和6.6%（P值分别为0.02和0.04）。在试验2中，三头安装了瘤胃和十二指肠瘘管的荷斯坦公牛，采用不完全重复的2×2折返设计，分别以全量采食（FF）和限量采食（LF）的方式饲喂整粒玉米（WC）和碾压玉米（RC）日粮。自由采食饲料的瘤胃淀粉消化率高于限量饲喂（P = 0.02），体重较重时，犊牛的全消化道干物质（P = 0.05）和淀粉（P = 0.03）消化率更高。与全量饲喂整粒玉米相比，限量饲喂整粒玉米会使咀嚼物的颗粒尺寸增大（P = 0.06）。由于限饲和全量饲喂的犊牛在咀嚼效率上存在明显差异，在采用限饲的养殖系统中，限制期和补偿生长期间的谷物加工方法可能是管理生长的重要考虑因素。
