Kamal M M, Van Eetvelde M, Depreester E, Hostens M, Vandaele L, Opsomer G
Department of Reproduction, Obstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
Department of Animal Sciences, Institute for Agricultural and Fishery Research (ILVO), Scheldeweg 68, 9090 Melle, Belgium.
J Dairy Sci. 2014 Sep;97(9):5448-58. doi: 10.3168/jds.2014-7898. Epub 2014 Jul 3.
The objective of the present study was to evaluate environmental and dam factors associated with birth size of Holstein calves. Data of 1,594 births from dairy herds in Belgium and Germany were analyzed in a retrospective cross-sectional study. Immediately after birth, the birth weight of the calves was measured. On the next day, the heart girth (HG), withers height, and diagonal length of the dams and calves were measured. Parity, body condition score, gestation length (GL), and age at calving were recorded for all dams. For the cows, days open, lactation length, length of the dry period, and calving interval were also calculated. The magnitude and shape of the lactation that took place during gestation was quantified using the MilkBot model based on monthly milk weights. Using the same procedure, cumulative milk production from conception to drying off (MGEST) was calculated. After descriptive analyses, mixed models were used to identify factors that are significantly associated with the birth weight (most consistent measure of size at birth) of the calves born to both heifers and cows. Of the variables offered to the offspring birth weight model in heifers (n=540), calf sex, season of calving, GL, HG, withers height, diagonal length, and age at calving were significant. The mean birth weight of the calves born to heifers was estimated to be 41.3±1.01kg. In comparison to calves born to old (25.5 to 37.3mo; n=99) heifers, the birth weight was estimated to be 2.75, 3.29, and 2.35kg heavier when the calves were born to very young (20.3 to <22mo; n=98), young (22 to <23.5mo; n=145), and standard aged (23.5 to <25.5mo; n=198) heifers, respectively. Of the variables offered to the offspring birth weight model in cows (n=1,054), calf sex, season of calving, GL, parity, dry period, and MGEST were significant. The mean birth weight of the calves born to cows was estimated to be 44.1±0.99kg. For cows having an identical HG, the birth weight of the calves was estimated to be 0.97 and 1.11kg higher in cows with low (1,400 to <5,400kg) and high (6,500 to <7,200) MGEST, respectively, compared with cows with very high (7,200 to 11,600kg) MGEST. The decisive effects of age at calving in heifers and of high milk production levels during gestation in cows on the birth weight of their calves may provide a basis for developing managerial interventions to improve long-term health and productivity of the offspring.
本研究的目的是评估与荷斯坦犊牛出生体重相关的环境因素和母体因素。在一项回顾性横断面研究中，分析了比利时和德国奶牛场1594例出生记录的数据。犊牛出生后立即测量其出生体重。次日，测量犊牛和母体的胸围（HG）、鬐甲高度和体斜长。记录所有母体的胎次、体况评分、妊娠期长度（GL）和产犊时年龄。对于母牛，还计算了空怀天数、泌乳期长度、干奶期长度和产犊间隔。使用基于每月产奶量的MilkBot模型对妊娠期泌乳的量和形状进行量化。采用相同程序，计算从受孕到干奶的累计产奶量（MGEST）。经过描述性分析后，使用混合模型确定与初产母牛和经产母牛所产犊牛出生体重（出生时体型最一致的指标）显著相关的因素。在初产母牛（n = 540）的后代出生体重模型中纳入的变量中，犊牛性别、产犊季节、GL、HG、鬐甲高度、体斜长和产犊时年龄具有显著意义。初产母牛所产犊牛的平均出生体重估计为41.3±1.01kg。与年龄较大（25.5至37.3月龄；n = 99）的初产母牛所产犊牛相比，年龄非常小（20.3至<22月龄；n = 98）、年轻（22至<23.5月龄；n = 145）和标准年龄（23.5至<25.5月龄；n = 198）的初产母牛所产犊牛的出生体重分别估计重2.75kg、3.29kg和2.35kg。在经产母牛（n = 1,054）的后代出生体重模型中纳入的变量中，犊牛性别、产犊季节、GL、胎次、干奶期和MGEST具有显著意义。经产母牛所产犊牛的平均出生体重估计为44.1±0.99kg。对于胸围相同的母牛，与MGEST非常高（7200至11600kg）的母牛相比，MGEST低（1400至<5400kg）和高（6500至<7200）的母牛所产犊牛的出生体重分别估计高0.97kg和1.11kg。初产母牛的产犊年龄和经产母牛妊娠期的高产奶量对其犊牛出生体重的决定性影响可能为制定管理干预措施以改善后代的长期健康和生产力提供依据。
