Influence of precalving feed allowance on periparturient metabolic and hormonal responses and milk production in grazing dairy cows.
Influence of precalving feed allowance on periparturient metabolic and hormonal responses and milk production in grazing dairy cows.
复制标题
产犊前饲料供给量对放牧奶牛围产期代谢和激素反应以及产奶量的影响。
作者：
J. Roche;E. Kolver;J. Kay
将52头经产奶牛分成4个处理，每头奶牛在27+/-9.6d产前分别消耗5.4、8.2、10.0或11.0 kg干物质。这相当于体重的1.3%、1.9%、2.4%和2.6%(体重；不包括胎儿体重)。产犊后，所有奶牛都在牧场上随意饲喂。分别于产犊前17d、产犊当天、产犊后第1、2、3、4、7、14、28、35天采血。结果表明，近期放牧奶牛需要1.05兆焦耳/千克体重(0.75)，先前对能量需求的估计被低估了。随着牧草摄入量的增加，血糖、胰岛素样生长因子-1和瘦素的血浆浓度呈二次曲线上升。这与产仔前血浆生长激素浓度呈线性下降以及非酯化脂肪酸和β-羟丁酸浓度随干物质摄入量(DMI)的增加呈二次曲线下降有关。产仔后这些代谢物的血浆浓度没有表现出产仔前喂养的持久影响。产奶前营养对产奶量的影响很小，除乳脂外，仅限于产奶后第1周。产奶量随着产犊前DMI和产犊体况评分的增加而增加，直到产后第3周，以后处理效果不明显。这些结果表明，放牧奶牛在产犊前最后一个月的饲喂水平对奶牛的代谢和激素状态以及哺乳前5周的产奶量影响很小。
Fifty-two multiparous dairy cows were allocated to 4 treatments consuming 5.4, 8.2, 10.0, or 11.0 kg/d of pasture dry matter per cow for 27 +/- 9.6 d precalving. This equated to 1.3, 1.9, 2.4, and 2.6% of body weight (BW; not including the conceptus weight). Following calving, all cows were fed ad libitum on pasture. Blood was sampled 17 d precalving, on day of calving, and on d 1, 2, 3, 4, 7, 14, 28, and 35 postcalving. Results suggest that the near-term grazing dairy cow requires 1.05 MJ of ME/kg of BW(0.75) and that previous estimates of energy requirements were underestimated. Precalving plasma concentrations of glucose, insulin-like growth factor-1, and leptin increased quadratically with increasing pasture intake. This was associated with precalving plasma concentrations of growth hormone that declined linearly, and concentrations of nonesterified fatty acids and beta-hydroxybutyrate that declined quadratically with increasing dry matter intake (DMI). Postcalving plasma concentrations of these metabolites showed no lasting effect of precalving feeding. The effect of precalving nutrition on milk production was small, and other than milk fat, was confined to wk 1 postcalving. Milk fat yield increased with increasing precalving DMI and calving body condition score until wk 3 post-calving, after which treatment effects were not evident. These results indicate that the level of feeding in grazing dairy cows during the last month before calving has only small effects on cow metabolic and hormonal status, and on milk production in the first 5 wk of lactation.