Bar-Peled U, Aharoni Y, Robinzon B, Bruckental I, Lehrer R, Maltz E, Knight C, Kali J, Folman Y, Voet H, Gacitua H, Tagari H
Department of Animal Science, Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot, Israel.
J Dairy Sci. 1998 May;81(5):1420-7. doi: 10.3168/jds.S0022-0302(98)75706-6.
Groups of 9 or 10 cows were assigned to one of three treatments 1) machine-milking three times daily, 2) machine-milking six times daily, and 3) suckling three times daily in addition to machine-milking three times daily. Treatments were conducted during the first 6 wk postpartum. During wk 5, digestibility of the diet was estimated by the indigestible neutral detergent fiber method. During wk 6, milk yield and dry matter intake (DMI) were recorded daily, and plasma concentrations of glucose, nonesterified fatty acids, urea, protein, growth hormone, insulin, insulin-like growth factor I, oxytocin, and prolactin were determined. Milk yields were 38.5, 46.8, and 52.7 kg/d, and DMI were 18.1, 21.2, and 17.2, for cows on treatments 1, 2, and 3, respectively. Plasma glucose concentrations decreased, and plasma nonesterified fatty acid concentrations increased, for cows on treatments 2 and 3 compared with cows on treatment 1. Digestibility of dry matter was 57.5, 60.5, and 60.6%; of organic matter was 62.6, 64.6, and 66.8%; and of crude protein was 59.3, 62.7, and 64.6% for cows on treatments 1, 2, and 3, respectively. Concentrations of all assayed hormones, except insulin, increased moderately for cows on treatment 2 compared with cows on treatment 1 and increased dramatically for cows on treatment 3. Insulin concentrations followed the opposite trend. The DMI were positively related to milk yields and negatively related to oxytocin concentrations. Digestibility was negatively related to plasma glucose concentrations in a nonlinear pattern. The possible involvement of hormones in improvement of digestibility is discussed.
将9头或10头奶牛分为三组，分别接受以下三种处理之一：1）每日机器挤奶3次；2）每日机器挤奶6次；3）除每日机器挤奶3次外，每日人工哺乳3次。处理在产后的前6周进行。在第5周，通过不可消化中性洗涤纤维法估算日粮的消化率。在第6周，每天记录产奶量和干物质摄入量（DMI），并测定血浆中葡萄糖、非酯化脂肪酸、尿素、蛋白质、生长激素、胰岛素、胰岛素样生长因子I、催产素和催乳素的浓度。处理1、2、3组奶牛的产奶量分别为38.5、46.8和52.7千克/天，DMI分别为18.1、21.2和17.2。与处理1组奶牛相比，处理2组和3组奶牛的血浆葡萄糖浓度降低，血浆非酯化脂肪酸浓度升高。处理1、2、3组奶牛的干物质消化率分别为57.5%、60.5%和60.6%；有机物消化率分别为62.6%、64.6%和66.8%；粗蛋白消化率分别为59.3%、62.7%和64.6%。与处理1组奶牛相比，处理2组奶牛除胰岛素外的所有检测激素浓度均适度升高，处理3组奶牛的激素浓度则大幅升高。胰岛素浓度呈现相反趋势。DMI与产奶量呈正相关，与催产素浓度呈负相关。消化率与血浆葡萄糖浓度呈非线性负相关。文中讨论了激素在提高消化率方面可能的作用。
