摘要
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.
摘要译文
进行了2×2阶级研究，以评估牛奶津贴和物理形式对荷斯坦乳制牛犊的生长性能，瘤胃发酵和血液代谢物的影响。总共48个小腿[40.4±1.55千克体重（bw），n = 12次，每次治疗：6个男性和6个女性]被随机分配给4种治疗中的1个：（1）犊牛喂养低牛奶津贴和精细地（FG）启动饲料[低FG; 1.47±2.12毫米的几何平均粒度（GMLP）]，（2）牛犊喂养低牛奶余量和纹理（TS）起动饲料[低TS，包括蒸汽碎片（玉米和大麦），用颗粒补充剂，GMLP 4.15±1.77 mm]，（3）犊牛美联储高牛奶津贴和FG启动器进料（高FG）; （4）犊牛喂养高牛奶津贴和TS启动器饲料（高TS）。将起始饮食与7％的切碎的苜蓿干草混合，作为饮食干物质（DM）的比例。在任何治疗中没有观察到牛奶拒绝，并且使用逐渐断奶程序，通过研究的WK 8从牛奶中断奶牛犊。我们观察到牛奶津贴和物理形式的饲料摄入，平均每日增益，饲料效率，BW和结构生长之间的互动。牛犊喂养高牛奶余量具有较低的入射进料摄入，但与喂食低津贴的那些相比，饲料效率更高，总体BW。在治疗中，DM摄入量和平均每日收益在不同之处。无论是起动器进料的物理形式，臀部高度，心周长，瘤胃醋酸盐的摩尔比例，醋酸盐比，血浆胆固醇和高密度脂蛋白都大，但瘤胃总挥发性脂肪酸，摩尔比例的丙酸盐与喂食低津贴的那些相比，牛犊喂养高牛奶余量的浆液中较低的血浆β-羟基丁酸酯。无论牛奶津贴，喂养FG启动器饲料的小牛是否与喂食TS启动剂饮食的小牛相比具有更高的血尿尿素氮浓度。总之，当牛犊喂养高牛奶余量时，可以使用两种形式的起始饲料，没有对其性能的负面影响。
A.Jafari[1];A.Azarfar[1];G.R.Ghorbani[2];M.Mirzaei[3];M.A.Khan[4];H.Omidi-Mirzaei[5];A.Pakdel[6];M.H.Ghaffari[7]. Effects of physical forms of starter and milk allowance on growth performance, ruminal fermentation, and blood metabolites of Holstein dairy calves[J]. Journal of Dairy Science, 2020,103(12): 11300-11313