São Paulo State University, Department of Animal Production, Botucatu, Brazil.
Theriogenology. 2011 Jan 1;75(1):131-7. doi: 10.1016/j.theriogenology.2010.07.018. Epub 2010 Sep 27.
The objective was to evaluate serum concentrations of nonesterified fatty acids (NEFA), cortisol, insulin, and progesterone (P4) of dairy cows maintaining or mobilizing body weight (BW). Eleven non-lactating, non-pregnant, and ovariectomized Gir × Holstein cows were stratified by BW and body condition score (BCS), and randomly assigned to: 1) BW loss (six cows; LOSS) and 2) BW maintenance (five cows; MAINT). Treatments were achieved through a grazing schedule using three pastures. From Days -7 to 1 of the study, all cows were maintained in Pasture A (12 kg of dry matter/cow daily). From Days 2 to 30, LOSS cows were maintained in Pasture B (less than 1.0 kg of dry matter/cow daily), whereas MAINT cows were maintained in Pasture C (12 kg of dry matter/cow daily). However, from Days 3 to 30 of the study, cows from both treatments were regrouped daily into Pasture A from 0600 to 1200 h to allow LOSS cows to consume, on average, 4.5 kg/d of forage dry matter. On Day -66 of the study, all cows received an intravaginal drug releasing device containing 1.9 g of P4 (replaced every 14 d and removed on Day 3). Cow BW and BCS were assessed on Day 0 and 30 and blood samples were collected daily from Days 0 to 30 at 0600 and 1200 h. Changes in BW and BCS were greater (P ≤ 0.05) in LOSS cows compared to MAINT cows. Within samples collected at 0600 h, serum NEFA concentrations were often greater (P < 0.05) in LOSS cows compared to MAINT after Day 14. Serum P4 concentrations were greater (P < 0.05) on Days 21 and 22, and tended (P < 0.10) to be greater on Days 16, 23, and 24 of the study in LOSS cows compared to MAINT. In conclusion, BW loss was associated with increased circulating concentrations of P4 in non-lactating ovariectomized dairy cows; this was mainly attributed to fat mobilization and consequent release of P4 stored in adipose tissues.
目的是评估维持或动员体重（BW）的奶牛的血清非酯化脂肪酸（NEFA）、皮质醇、胰岛素和孕酮（P4）浓度。11 头非泌乳、非妊娠和卵巢切除术的 Gir×Holstein 奶牛按 BW 和体况评分（BCS）分层，并随机分为：1）BW 损失（六头奶牛；LOSS）和 2）BW 维持（五头奶牛；MAINT）。通过使用三个牧场的放牧计划来实现治疗。从研究的第-7 天到第 1 天，所有奶牛都在牧场 A（每头牛每天 12 公斤干物质）中维持。从第 2 天到第 30 天，LOSS 奶牛在牧场 B（每天每头牛不到 1.0 公斤干物质）中维持，而 MAINT 奶牛在牧场 C（每头牛每天 12 公斤干物质）中维持。然而，从研究的第 3 天到第 30 天，来自两种处理的奶牛每天从 0600 到 1200 小时重新分组到牧场 A，以使 LOSS 奶牛平均每天消耗 4.5 公斤干物质饲料。在研究的第-66 天，所有奶牛都接受了含有 1.9 克 P4 的阴道内药物释放装置（每 14 天更换一次，第 3 天取出）。在第 0 天和第 30 天评估奶牛 BW 和 BCS，并在第 0 天到第 30 天的每天 0600 和 1200 小时采集血样。与 MAINT 奶牛相比，LOSS 奶牛的 BW 和 BCS 变化更大（P≤0.05）。在 0600 小时采集的样本中，与 MAINT 相比，LOSS 奶牛在第 14 天后经常具有更高的血清 NEFA 浓度（P<0.05）。在研究的第 21 天和第 22 天，血清 P4 浓度更高（P<0.05），在第 16 天、第 23 天和第 24 天，LOSS 奶牛的血清 P4 浓度也有升高的趋势（P<0.10）。综上所述，BW 损失与非泌乳卵巢切除奶牛循环中 P4 浓度升高有关；这主要归因于脂肪动员和随后释放储存在脂肪组织中的 P4。
