Murphy M G, Rath M, O'Callaghan D, Austin F H, Roche J F
Department of Animal Husbandry and Production, University College Dublin, Ireland.
J Dairy Sci. 1991 Jul;74(7):2165-71. doi: 10.3168/jds.S0022-0302(91)78389-6.
This experiment was conducted to evaluate the effect of bST on average daily gain, onset of puberty, first lactation milk yield, and reproductive efficiency in Friesian heifers. Heifers (n = 16 per treatment) were allocated to either: 1) control (1.5 ml of vehicle) or 2) bST (15 mg of bST in 1.5 ml of vehicle) using a randomized complete block design. Subcutaneous injections of bST were administered once daily from 7 mo of age for 120 d or until heifers reached puberty. Heifers were weighed every 2 wk, and blood samples were collected twice weekly after heifers reached 200 kg. Progesterone concentrations were used to determine onset of puberty. Heifers were bred between 16 and 18 mo of age and, following parturition, milk yield and composition were recorded twice weekly and once every 2 wk, respectively. Heifers assigned to bST treatment had an average daily gain (kg) of .8 compared with .7 in control heifers. Number of days from birth to onset of puberty for bST-treated heifers was 401 compared with 381 for control heifers. Treatment with bST had no effect on milk yield, milk composition, or reproductive efficiency during the first lactation. These data demonstrate that daily administration of bST to Friesian heifers from 7 to 11 mo of age does not affect average daily gain, onset of puberty, reproductive efficiency, or first lactation milk yield of heifers.
本试验旨在评估牛生长激素（bST）对弗里斯兰小母牛平均日增重、青春期开始时间、首次产奶量以及繁殖效率的影响。小母牛（每组16头）采用随机完全区组设计，分为两组：1）对照组（注射1.5毫升赋形剂）；2）bST组（1.5毫升赋形剂中含15毫克bST）。从7月龄开始，每天皮下注射bST，持续120天，或直至小母牛达到青春期。每2周称一次小母牛体重，小母牛体重达到200千克后，每周采集两次血样。用孕酮浓度来确定青春期开始时间。小母牛在16至18月龄时配种，分娩后，每周分别记录两次产奶量和成分，每2周记录一次产奶成分。bST处理组小母牛的平均日增重为0.8千克，而对照组小母牛为0.7千克。bST处理的小母牛从出生到青春期开始的天数为401天，而对照组小母牛为381天。bST处理对首次产奶期的产奶量、奶成分或繁殖效率没有影响。这些数据表明，7至11月龄的弗里斯兰小母牛每日注射bST不会影响其平均日增重、青春期开始时间、繁殖效率或首次产奶量。
