Grings E E, Staigmiller R B, Short R E, Bellows R A, MacNeil M D
USDA-ARS, Fort Keogh Livestock and Range Research Laboratory, Miles City, MT 59301, USA.
J Anim Sci. 1999 Apr;77(4):810-5. doi: 10.2527/1999.774810x.
A study was conducted to evaluate the influence of nutrition and sire breed on age at puberty and first lactation milk yield in crossbred beef heifers. After weaning, 208 heifers sired by Hereford, Limousin, or Piedmontese bulls were assigned to either a control (CG) or stair-step gain (SSG) dietary regimen plus a mineral supplement with or without Cu, Zn, and Mn top-dressed onto the feed. Heifers on the SSG regimen were fed a diet intended to supply energy to support gains at a rate of 120% of the CG diet for 55 d and then were switched to a diet formulated to produce an ADG at 70% of the rate of the CG diet for 84 d. They then switched back to the 120% diet for the last 30 d before breeding. Total weight gain and overall rate of gain did not differ among dietary treatments. Hereford- and Limousin-sired heifers gained at similar rates, and Piedmontese-sired heifers gained an average of .10 kg/d slower than the other two sire breed groups. During one period, Piedmontese-sired heifers on the CG diet gained .19 kg/d faster ( P < . 01) when supplemented with mineral than when not. During that same period, there was no influence of mineral supplementation on weight gains for Hereford- or Piedmontese-sired heifers on the high SSG diet, but Limousin-sired heifers tended (P = .07) to gain faster (1.00 vs .85 kg/d) when supplemented with Cu, Zn, and Mn than when not. Piedmontese-sired heifers reached puberty at the earliest age (P = .03), followed by Hereford- and then Limousin-sired heifers. There were no treatment effects on milk yield at an average of 70 d of lactation. However, at approximately 120 d of lactation, Piedmontese-sired heifers were producing less milk (P < .05) than Limousin- but not Hereford-sired heifers. Hereford-sired heifers had lower (P < .05) plasma Cu concentrations than Piedmontese-sired heifers. There were no treatment effects on plasma Zn concentrations. Heifers sired by bulls of breeds that differ in potential muscularity differed in growth, reproduction, milk yield, and plasma mineral concentrations, but dietary treatments resulted in little to no differences in these variables.
开展了一项研究，以评估营养和父本品种对杂交肉牛小母牛初情期年龄和首次泌乳产奶量的影响。断奶后，将由赫里福德牛、利木赞牛或皮埃蒙特牛公牛所生的208头小母牛分配到对照（CG）或阶梯式增重（SSG）饮食方案中，并添加或不添加在饲料上额外添加铜、锌和锰的矿物质补充剂。采用SSG方案的小母牛先喂食一种旨在提供能量以支持增重的日粮，其速度为CG日粮的120%，持续55天，然后改为一种配方日粮，以使平均日增重（ADG）达到CG日粮速度的70%，持续84天。然后，在配种前的最后30天，它们又换回120%的日粮。不同饮食处理之间的总增重和总体增重速度没有差异。由赫里福德牛和利木赞牛所生的小母牛增重速度相似，而由皮埃蒙特牛所生的小母牛平均每天比其他两个父本品种组慢0.10千克。在一个时期内，采用CG日粮的皮埃蒙特牛所生小母牛在补充矿物质时比不补充时增重快0.19千克/天（P < 0.01）。在同一时期，对于采用高SSG日粮的赫里福德牛或皮埃蒙特牛所生小母牛，矿物质补充对其体重增加没有影响，但对于利木赞牛所生小母牛，补充铜、锌和锰时比不补充时增重有加快的趋势（P = 0.07）（分别为1.00千克/天和0.85千克/天）。由皮埃蒙特牛所生的小母牛最早达到初情期（P = 0.03），其次是赫里福德牛所生的小母牛，最后是利木赞牛所生的小母牛。在平均70天的泌乳期，不同处理对产奶量没有影响。然而，在大约120天的泌乳期，皮埃蒙特牛所生的小母牛产奶量比利木赞牛所生的小母牛少（P < 0.05），但比赫里福德牛所生的小母牛产奶量无显著差异。赫里福德牛所生小母牛的血浆铜浓度低于皮埃蒙特牛所生小母牛（P < 0.05）。不同处理对血浆锌浓度没有影响。由潜在肌肉发达程度不同的品种的公牛所生的小母牛在生长、繁殖、产奶量和血浆矿物质浓度方面存在差异，但饮食处理在这些变量上几乎没有差异或没有差异。
