1Department of Animal Science, Faculty of Agriculture and Natural Resources,Arak University,38 156-8-8349,Arak,Iran.
2Facultad de Medicina Veterinaria y Zootecnia,Universidad Autónoma del Estado de México,México.
Animal. 2017 Aug;11(8):1295-1302. doi: 10.1017/S1751731116002810. Epub 2017 Jan 18.
Chemical and physical treatments of barley grain increase ruminally resistant starch and can improve the rumen fermentation pattern. The objective of the present study was to evaluate the effects of chemical (addition of citric acid, CA) and physical (grinding to two different particle sizes, PS) treatment of barley grain on performance, rumen fermentation, microbial protein yield in the rumen and selected blood metabolites in growing calves. In all, 28 male Holstein calves (172±5.1 kg initial BW) were used in a complete randomised design with a factorial arrangement of 2 barley grain particle sizes×2 levels of citric acid. The diets were as follows: (i) small PS (average 1200 µm) barley grain soaked in water (no CA addition); (ii) small PS barley grain soaked in a CA solution (adding 20 g CA/kg barley); (iii) large PS (average 2400 µm) barley grain soaked in water (no citric acid addition) and (iv) large PS barley grain soaked in a citric acid solution (adding 20 g CA/kg barley). Barley grain was then incorporated at 35% in a total mixed ration and fed to the calves for 11 weeks. Feeding small PS barley decreased feed intake (P=0.02) and average daily weight gain (P=0.01). The addition of CA to barley grain did not affect intake but increased weight gain (P0.05). However, the molar proportion of propionate was increased (P=0.03) when barley was more finely ground, and that of acetate was increased (P=0.04) when CA was added to barley grain. The ruminal concentration of ammonia nitrogen was increased (P<0.01) and microbial nitrogen synthesis in the rumen tended to decrease by adding CA to barley. Treating barley grain with citric acid increased fibre digestibility of total mixed rations, attenuated the decrease in ruminal pH, and improved weight gain and feed efficiency in male Holstein growing calves fed a high-cereal diet (550 g cereal grain/kg diet).
化学和物理处理大麦可增加瘤胃抗性淀粉，并改善瘤胃发酵模式。本研究旨在评估化学（添加柠檬酸，CA）和物理（粉碎至两种不同粒径，PS）处理大麦对生长牛生产性能、瘤胃发酵、瘤胃微生物蛋白产量和一些血液代谢物的影响。选用 28 头荷斯坦公牛犊（172±5.1kg 初始体重），采用完全随机设计，2 个大麦粒径×2 个 CA 水平的因子设计。日粮如下：（i）小 PS（平均粒径 1200μm）大麦浸泡在水中（不添加 CA）；（ii）小 PS 大麦浸泡在 CA 溶液中（添加 20g CA/kg 大麦）；（iii）大 PS（平均粒径 2400μm）大麦浸泡在水中（不添加柠檬酸）；（iv）大 PS 大麦浸泡在柠檬酸溶液中（添加 20g CA/kg 大麦）。然后，将大麦以 35%的比例掺入全混合日粮中，供犊牛连续采食 11 周。与小 PS 大麦相比，小 PS 大麦降低了采食量（P=0.02）和平均日增重（P=0.01）。向大麦中添加 CA 不影响采食量，但增加了增重（P>0.05）。然而，当大麦粉碎得更细时，丙酸的摩尔比例增加（P=0.03），当 CA 添加到大麦中时，乙酸的摩尔比例增加（P=0.04）。瘤胃氨氮浓度增加（P<0.01），添加 CA 降低了瘤胃微生物氮合成，导致瘤胃 pH 下降。用柠檬酸处理大麦提高了全混合日粮的纤维消化率，减轻了瘤胃 pH 的下降，提高了高谷物日粮（550g 谷物/kg 日粮）条件下生长公牛犊的增重和饲料效率。
