Miller P S, Reis B L, Calvert C C, DePeters E J, Baldwin R L
Department of Animal Science, University of California, Davis 95616.
J Dairy Sci. 1991 Nov;74(11):3800-6. doi: 10.3168/jds.S0022-0302(91)78572-X.
Twenty-one multiparous lactating dairy cows with previous 305-d milk production records varying from 5900 to 13,600 kg were used to investigate effects of bST administration and stage of lactation on nutrient plasma arterial concentrations and arterial-venous differences across the mammary glands (uptake). On d 71 and continuing until d 126 of lactation, cows were injected with 40 mg of sometribove (bST group) or bicarbonate buffer (placebo group). Arterial and venous blood plasma samples were collected over a 12-h period on d 35, 70, 105, and 126 of lactation. Plasma concentration of glucose was 7% higher in midlactation compared with early lactation cows. Plasma concentration of acetate decreased from 2.11 to 1.87 mM in placebo versus bST-treated cows. Plasma arterial concentration and uptake of D-beta-hydroxybutyrate were .52 and .18 mM higher, respectively, in early versus midlactation cows. Concentration and uptake of NEFA were elevated in both early lactation and bST-treated cows. Triacylglyceride concentrations were 24 and 19% lower in early lactation and bST-treated cows compared with midlactation cows receiving placebo. Likewise, uptake of triacylglyceride was reduced in early lactation and with bST treatment compared with midlactation. The mediation of nutrient delivery and uptake by the mammary gland appears to be markedly similar between early lactation and bST-treated cows, suggesting a similarity between these physiological states and the homeostatic and homeorhetic mechanisms regulating nutrient partitioning in the lactating dairy cow. In early compared with midlactation cows receiving placebo, uptakes of D-beta-hydroxybutyrate and NEFA were reduced, and triacylglyceride uptake increased.
选用21头经产泌乳奶牛，其之前305天的产奶量记录在5900至13600千克之间，用于研究注射牛生长激素（bST）和泌乳阶段对血浆动脉营养物质浓度以及乳腺动静脉差异（摄取量）的影响。在泌乳第71天直至第126天，给奶牛注射40毫克的重组牛生长激素（bST组）或碳酸氢盐缓冲液（安慰剂组）。在泌乳第35、70、105和126天的12小时内采集动脉和静脉血浆样本。与泌乳早期的奶牛相比，泌乳中期奶牛的血浆葡萄糖浓度高7%。安慰剂组奶牛的血浆乙酸盐浓度从2.11毫摩尔降至1.87毫摩尔，而bST处理组奶牛则不然。与泌乳中期奶牛相比，泌乳早期奶牛的血浆动脉D-β-羟基丁酸盐浓度和摄取量分别高0.52毫摩尔和0.18毫摩尔。泌乳早期奶牛和bST处理组奶牛的非酯化脂肪酸浓度和摄取量均升高。与接受安慰剂的泌乳中期奶牛相比，泌乳早期奶牛和bST处理组奶牛的甘油三酯浓度分别低24%和19%。同样，与泌乳中期相比，泌乳早期奶牛和bST处理组奶牛的甘油三酯摄取量减少。泌乳早期奶牛和bST处理组奶牛在乳腺营养物质输送和摄取的调节方面似乎明显相似，这表明这些生理状态以及调节泌乳奶牛营养分配的稳态和同稳态机制之间具有相似性。与接受安慰剂的泌乳中期奶牛相比，泌乳早期奶牛的D-β-羟基丁酸盐和非酯化脂肪酸摄取量减少，甘油三酯摄取量增加。
