Tveit B, Svendsen M, Hove K
Department of Animal Science, Agricultural University of Norway.
J Dairy Sci. 1991 Oct;74(10):3561-7. doi: 10.3168/jds.S0022-0302(91)78548-2.
Minimum plasma calcium level around parturition and its relation to BW at parturition, milk yield, and weight change in mo 1 of lactation were studied in 334 first lactation Norwegian cows. Minimum plasma calcium level was reached 18 to 30 h postpartum. Single observations for all animals were fitted with a multitrait animal model including all genetic relationships. Heritabilities of the traits were calcium postpartum, .11; milk yield, .35; BW, .65; and weight change, .17 with standard errors about .10. Genetic correlations between calcium postpartum and the other traits were milk yield, -.49; BW, -.66; and weight change, .42 with standard errors about .25. Environmental factors with detectable effect on hypocalcemia were age at parturition and calving season. Regression of calcium postpartum on age was -2.66 x 10(-4) mmol/L per d. Calvings shortly after the pasture season were related to higher calcium postpartum than calvings after 3 to 4 mo with indoor feeding.
在334头初产挪威奶牛中，研究了分娩前后的最低血浆钙水平及其与分娩时体重、产奶量和泌乳第1个月体重变化的关系。产后18至30小时达到最低血浆钙水平。对所有动物的单次观测数据采用多性状动物模型进行拟合，该模型包含所有遗传关系。这些性状的遗传力分别为：产后钙水平，0.11；产奶量，0.35；体重，0.65；体重变化，0.17，标准误约为0.10。产后钙水平与其他性状之间的遗传相关性分别为：产奶量，-0.49；体重，-0.66；体重变化，0.42，标准误约为0.25。对低钙血症有显著影响的环境因素是分娩年龄和产犊季节。产后钙水平随年龄的回归系数为-2.66×10⁻⁴ mmol/L/天。与3至4个月后室内饲养产犊相比，牧草季节后不久产犊与产后较高的钙水平相关。
