Casas E, Keele J W, Fahrenkrug S C, Smith T P, Cundiff L V, Stone R T
Roman L. Hruska U.S. Meat Animal Research Center, ARS, USDA, Clay Center, NE 68933, USA.
J Anim Sci. 1999 Jul;77(7):1686-92. doi: 10.2527/1999.7771686x.
The Piedmontese breed has a high frequency of double-muscling. Animals tested in this breed are homozygous for a guanine to adenine transition in exon 3 (C313Y) of the myostatin (MSTN) gene. This transition seems to be responsible for the double-muscling phenotype. The objective of this study was to compare effects of alternative MSTN genotypes on proportion of assisted calving and weights at birth, weaning, and 1 yr of age. Reciprocal backcross and F2 calves out of Piedmontese-Angus (PA) and Piedmontese-Hereford (PH) dams born in 1995 (n = 82), 1996 (n = 75), and 1997 (n = 144) were evaluated for birth (BWT, kg), adjusted weaning (W200, kg), and yearling (W365, kg) weights and calving difficulty expressed as a proportion of assisted calving (CD). The number of copies of C313Y was assessed in each calf. Data were analyzed with a model that included effects of year, sex, subclasses of proportion Piedmontese (.25, .5, .75) by number of C313Y copies (0 = +/+, 1 = mh/+, 2 = mh/mh), and age of dam as covariate. For BWT, heterozygous mh/+ animals were 3.2 +/- .8 kg heavier than +/+ animals. Homozygous mh/mh animals increased .19 +/- .06 in proportion of CD compared with mh/+ animals. Differences between homozygous animals (mh/mh - +/+) were 5.2 +/- 1 kg for BWT and .21 +/- .06 for CD. Heterozygous mh/+ animals were 9.1 +/- 4 kg heavier at W200 than homozygous +/+ animals. Homozygous +/+ and heterozygous animals were 20 +/- 8 and 24.5 +/- 8 kg, respectively, heavier at W365 than mh/mh animals. Differences between mh/+ and the mean of mh/mh and +/+ genotypes for W200 and W365 were 8.8 +/- 3 and 18 +/- 5 kg, respectively, suggesting dominance effects on postnatal growth. Production of heterozygous animals, to take advantage of the positive impact of one copy of C313Y on carcass traits, may be a viable option when the value of increased retail product yield is greater than the increased cost associated with calving difficulty.
皮埃蒙特牛品种具有较高的双肌频率。在该品种中进行检测的动物，其肌肉生长抑制素（MSTN）基因外显子3（C313Y）中存在从鸟嘌呤到腺嘌呤的转换，且为纯合子。这种转换似乎是造成双肌表型的原因。本研究的目的是比较肌肉生长抑制素（MSTN）不同基因型对助产比例以及出生重、断奶重和1岁龄体重的影响。对1995年（n = 82）、1996年（n = 75）和1997年（n = 144）出生的皮埃蒙特 - 安格斯（PA）和皮埃蒙特 - 赫里福德（PH）母本所生的正反交回交和F2代犊牛，评估其出生体重（BWT，kg）、校正断奶体重（W200，kg）、周岁体重（W365，kg）以及以助产比例表示的产犊难度（CD）。测定每头犊牛C313Y的拷贝数。数据采用包含年份、性别、皮埃蒙特牛比例亚类（0.25、0.5、0.75）×C313Y拷贝数（0 = +/+，1 = mh/+，2 = mh/mh）以及母本年龄作为协变量的模型进行分析。对于出生体重，杂合子mh/+动物比+/+动物重3.2±0.8 kg。与mh/+动物相比，纯合子mh/mh动物的助产比例增加了0.19±0.06。纯合子动物（mh/mh - +/+）之间的出生体重差异为5.2±1 kg，助产比例差异为0.21±0.06。杂合子mh/+动物的校正断奶体重（W200）比纯合子+/+动物重9.1±4 kg。纯合子+/+和杂合子动物的周岁体重（W365）分别比mh/mh动物重20±8 kg和24.5±8 kg。mh/+与mh/mh和+/+基因型均值在校正断奶体重（W200）和周岁体重（W365）上的差异分别为8.8±3 kg和18±5 kg，表明对出生后生长存在显性效应。当零售产品产量增加的价值大于与产犊难度增加相关的成本时，生产杂合子动物以利用C313Y一个拷贝对胴体性状的积极影响可能是一个可行的选择。
