Ferraretto L F, Gencoglu H, Hackbart K S, Nascimento A B, Dalla Costa F, Bender R W, Guenther J N, Shaver R D, Wiltbank M C
Department of Dairy Science, University of Wisconsin-Madison, 1675 Observatory Dr., Madison 53706.
Department of Dairy Science, University of Wisconsin-Madison, 1675 Observatory Dr., Madison 53706; Department of Animal Nutrition and Nutritional Diseases, Faculty of Veterinary Medicine, University of Uludag, Bursa, Turkey 16059.
J Dairy Sci. 2014 Feb;97(2):754-63. doi: 10.3168/jds.2013-6925. Epub 2013 Dec 18.
The objective of this trial was to evaluate the effects of feed restriction (FR) on serum glucose, nonesterified fatty acids, progesterone (P4), insulin, and milk production in dairy cows. Eight multiparous Holstein cows, 114 ± 14 d pregnant and 685 ± 39 kg of body weight, were randomly assigned to a replicated 4 × 4 Latin square design with 14-d periods. During the first 8 d of each period, cows in all treatments were fed for ad libitum feed intake. Beginning on d 9 of each period, cows received 1 of 4 treatments: ad libitum (AL), 25% feed restriction (25 FR), 50% feed restriction (50 FR), and 50% of TMR replaced with wheat straw (50 ST). Daily feed allowance was divided into 3 equal portions allocated every 8h with jugular blood samples collected immediately before each feeding through d 14. In addition, on d 12 of each period, blood samples were collected before and at 60, 120, 180, 240, 300, 360, 420, and 480 min after morning feeding. The conventional total mixed ration and total mixed ration with straw averaged 15.1 and 10.8%, 32.1 and 50.5%, and 26.8 and 17.0% for concentrations of crude protein, neutral detergent fiber, and starch, respectively. Cows that were feed and energy restricted had reduced dry matter intake, net energy for lactation intake, circulating glucose concentrations, and milk production, but greater body weight and body condition score losses than AL cows. Circulating concentrations of insulin were lower for cows fed 50 FR (8.27 μIU/mL) and 50 ST (6.24 μIU/mL) compared with cows fed AL (16.65 μIU/mL) and 25 FR (11.16 μIU/mL). Furthermore, the greatest plasma nonesterified fatty acids concentration was observed for 50 ST (647.7 μ Eq/L), followed by 50 FR (357.5 μEq/L), 25 FR (225.3 μEq/L), and AL (156.3 μEq/L). In addition, serum P4 concentration was lower for cows fed AL than cows fed 50 ST and 25 FR. Thus, FR reduced circulating glucose and insulin but increased P4 concentration, changes that may be positive in reproductive management programs.
本试验的目的是评估限饲（FR）对奶牛血清葡萄糖、非酯化脂肪酸、孕酮（P4）、胰岛素和产奶量的影响。八头经产荷斯坦奶牛，怀孕114±14天，体重685±39千克，被随机分配到一个重复的4×4拉丁方设计中，试验期为14天。在每个试验期的前8天，所有处理组的奶牛都自由采食。从每个试验期的第9天开始，奶牛接受4种处理之一：自由采食（AL）、25%限饲（25 FR）、50%限饲（50 FR）以及用麦秸替代50%的全混合日粮（50 ST）。每日饲料供应量分为3等份，每8小时投喂一次，在第14天之前，每次投喂前立即采集颈静脉血样。此外，在每个试验期的第12天，在早晨喂食前以及喂食后60、120、180、240、300、360、420和480分钟采集血样。常规全混合日粮和含秸秆的全混合日粮的粗蛋白、中性洗涤纤维和淀粉浓度分别平均为15.1%和10.8%、32.1%和50.5%、26.8%和17.0%。限饲和限能的奶牛干物质摄入量、泌乳净能摄入量、循环葡萄糖浓度和产奶量降低，但与自由采食组奶牛相比，体重和体况评分损失更大。与自由采食组（16.65 μIU/mL）和25%限饲组（11.16 μIU/mL）的奶牛相比，50%限饲组（8.27 μIU/mL）和50 ST组（6.24 μIU/mL）的奶牛循环胰岛素浓度较低。此外，50 ST组（647.7 μEq/L）的血浆非酯化脂肪酸浓度最高，其次是50%限饲组（357.5 μEq/L）、25%限饲组（225.3 μEq/L）和自由采食组（156.3 μEq/L）。另外，自由采食组奶牛的血清P4浓度低于50 ST组和25%限饲组奶牛。因此，限饲降低了循环葡萄糖和胰岛素水平，但提高了P4浓度，这些变化在繁殖管理方案中可能是有益的。
