Tveit B, Lingaas F, Svendsen M, Sjaastad O V
Department of Animal Science, Agricultural University of Norway, As.
J Dairy Sci. 1992 Sep;75(9):2421-32. doi: 10.3168/jds.S0022-0302(92)78003-5.
Plasma acetoacetate concentration in the 1st mo of lactation and its relation to BW change, milk yield, DMI, and BW postpartum were studied in 361 first lactation cows during 6 yr. The cows were fed concentrate at 6 and 3 kg/d. Calvings took place from August to December. Single observations for all cows were fitted by a multitrait animal model that accounted for all genetic relationships. Heritability for acetoacetate was .11 with a genetic correlation of .87 for milk yield, -.65 for weight change, and -.13 for BW postpartum. Acetoacetate was higher at 3 kg/d of concentrate than at 6 kg/d, and calving after 3 to 4 mo of indoor feeding was related to higher acetoacetate than was calving shortly after the pasture season. Acetoacetate was related to weight loss postpartum, but at a different degree in different years. In some years, compounds of the silage caused strongly elevated plasma concentrations of acetoacetate after feeding. Experiments were performed to compare hay with silages of different qualities. Rumen concentration of different amines 3 h postfeeding was taken as an index of the amine load of the cow. The concentration of several amines in rumen fluid were high after feeding ketogenic silage.
在6年时间里，对361头头胎泌乳奶牛的血浆乙酰乙酸浓度及其与体重变化、产奶量、干物质采食量和产后体重的关系进行了研究。奶牛分别按每天6千克和3千克的量饲喂精饲料。产犊时间为8月至12月。所有奶牛的单次观测数据采用多性状动物模型进行拟合，该模型考虑了所有遗传关系。乙酰乙酸的遗传力为0.11，与产奶量的遗传相关系数为0.87，与体重变化的遗传相关系数为-0.65，与产后体重的遗传相关系数为-0.13。精饲料喂量为每天3千克时的乙酰乙酸浓度高于每天6千克时的浓度，在室内饲养3至4个月后产犊的奶牛，其乙酰乙酸浓度高于在放牧季节后不久产犊的奶牛。乙酰乙酸与产后体重减轻有关，但在不同年份程度不同。在某些年份，饲喂青贮饲料后，青贮饲料中的成分会使血浆乙酰乙酸浓度大幅升高。进行了实验以比较干草与不同质量的青贮饲料。将采食后3小时瘤胃中不同胺类的浓度作为奶牛胺负荷的指标。饲喂生酮青贮饲料后，瘤胃液中几种胺类的浓度较高。
