Department of Animal Science, Faculty of Agriculture, Lorestan University, PO Box 465, Khorramabad, 68151-44316, Iran.
Department of Animal Science, Faculty of Agriculture, Lorestan University, PO Box 465, Khorramabad, 68151-44316, Iran.
J Dairy Sci. 2020 Dec;103(12):11300-11313. doi: 10.3168/jds.2020-18252. Epub 2020 Oct 23.
A 2 × 2 factorial study was conducted to evaluate the effects of milk allowance and physical forms of starter on growth performance, ruminal fermentation, and blood metabolites of Holstein dairy calves. A total of 48 calves [40.4 ± 1.55 kg of body weight (BW), n = 12 per treatment: 6 males and 6 females] were randomly assigned to 1 of the 4 treatments: (1) calves fed low milk allowance and finely ground (FG) starter feed [low-FG; 1.47 ± 2.12-mm geometric mean particle size (GMLP)], (2) calves fed low milk allowance and textured (TS) starter feed [low-TS, includes steam-flaked grains (corn and barley) with a pelleted supplement, GMLP 4.15 ± 1.77 mm], (3) calves fed high milk allowance and FG starter feed (high-FG); and (4) calves fed high milk allowance and TS starter feed (high-TS). The starter diets were blended with 7% of chopped alfalfa hay as a proportion of diet dry matter (DM). No milk refusal was observed in any treatments, and calves on both treatments were weaned from milk by wk 8 of the study using a gradual weaning procedure. We observed no interaction between milk allowance and physical forms of starter on feed intake, average daily gain, feed efficiency, BW, and structural growth. Calves fed high milk allowance had lower starter feed intake but greater feed efficiency and overall BW compared with those fed low allowance. Total DM intake and average daily gain were not different among treatments. Regardless of the physical form of starter feed, hip height, heart girth, the molar proportion of ruminal acetate, acetate to propionate ratio, plasma cholesterol, and high-density lipoprotein were greater, but ruminal total volatile fatty acids, the molar proportion of propionate, and plasma β-hydroxybutyrate were lower in calves fed high milk allowance compared with those fed low allowance. Regardless of the milk allowance, calves fed the FG starter feeds had greater blood urea nitrogen concentrations compared with calves fed the TS starter diets. In conclusion, both forms of the starter feeds can be used when calves are fed high milk allowance with no negative effect on their performance.
一项 2×2 析因试验研究了牛奶供给量和开食料物理形态对荷斯坦奶牛犊牛生长性能、瘤胃发酵和血液代谢物的影响。共有 48 头犊牛[体重 40.4±1.55kg，n=12 头/处理：6 公 6 母]随机分为 4 个处理组之一：（1）低牛奶供给量和细磨（FG）开食料[低-FG；几何平均粒度（GMLP）为 1.47±2.12mm]；（2）低牛奶供给量和纹理（TS）开食料[低-TS，包括蒸汽压片谷物（玉米和大麦）和颗粒补充料，GMLP 为 4.15±1.77mm]；（3）高牛奶供给量和 FG 开食料（高-FG）；（4）高牛奶供给量和 TS 开食料（高-TS）。开食料与 7%切碎的苜蓿干草混合，占日粮干物质（DM）的比例。在任何处理中都没有观察到拒食现象，并且在研究的第 8 周通过逐渐断奶程序从牛奶中断奶。我们没有观察到牛奶供给量和开食料物理形态之间的相互作用对采食量、平均日增重、饲料效率、BW 和结构生长有影响。高牛奶供给量组的犊牛开食料采食量较低，但饲料效率和整体 BW 较高。处理间总 DM 采食量和平均日增重没有差异。无论开食料物理形态如何，高牛奶供给量组的髋高、胸围、瘤胃乙酸摩尔比例、乙酸丙酸比、血浆胆固醇和高密度脂蛋白较高，但瘤胃总挥发性脂肪酸、丙酸摩尔比例和血浆 β-羟丁酸较低。与低牛奶供给量组相比，高牛奶供给量组的犊牛血液尿素氮浓度更高，而 FG 开食料组的犊牛血液尿素氮浓度更高。总之，当犊牛高牛奶供给量时，可以使用这两种形式的开食料，对其性能没有负面影响。
