Theilgaard P, Ingvartsen K L, Løvendahl P
Danish Institute of Agricultural Sciences, PO Box 50, DK-8830 Tjele, Denmark.
J Anim Sci. 2007 Feb;85(2):388-94. doi: 10.2527/jas.2006-447. Epub 2006 Oct 13.
This study analyzed genetic and phenotypic variation in plasma GH during lactation in first parity dairy cows. The heritability and repeatability were examined using an algorithm for separation of basal and peak concentrations and different power transformations. Blood samples were obtained 17 times during first parity in 85 Holstein, 67 Red Dane, and 62 Jersey cows and assayed for GH. Each breed comprised 2 genetic groups; thus, a total of 6 genetic groups were defined. Across genetic groups, cows were assigned to 1 of 2 total mixed rations with a low or a normal energy concentration. The separation algorithm identified only 4.0% of the plasma GH concentrations as peaks. After excluding peak concentrations, the repeatability of GH during lactation was improved. A log-transformation was found appropriate for GH. The log-transformed GH concentrations for lactating dairy cows had a heritability ranging between 0.14 in early lactation to 0.08 in mid and late lactation. The repeatability was 0.24 in early lactation and increased to between 0.58 and 0.61 in mid and late lactation. We conclude that for GH concentrations in lactating cows that are sampled infrequently, the exclusion of peak values to obtain a basal GH concentration was not effective in clarifying phenotypic or genetic effects.
本研究分析了头胎奶牛泌乳期血浆生长激素（GH）的遗传和表型变异。使用一种用于分离基础浓度和峰值浓度的算法以及不同的幂变换来检查遗传力和重复性。在85头荷斯坦奶牛、67头红丹麦奶牛和62头泽西奶牛的头胎期间采集了17次血样，并对GH进行了检测。每个品种包括2个遗传组；因此，总共定义了6个遗传组。在各个遗传组中，奶牛被分配到2种总混合日粮中的1种，日粮能量浓度低或正常。分离算法仅将4.0%的血浆GH浓度识别为峰值。排除峰值浓度后，泌乳期GH的重复性得到改善。发现对数变换适用于GH。泌乳奶牛经对数变换后的GH浓度遗传力在泌乳早期为0.14，在泌乳中期和晚期为0.08。重复性在泌乳早期为0.24，在泌乳中期和晚期增加到0.58至0.61之间。我们得出结论，对于不频繁采样的泌乳奶牛的GH浓度，排除峰值以获得基础GH浓度在阐明表型或遗传效应方面无效。
