Westhoff T A, Overton T R, Tikofsky J N, Van Amburgh M E, Ryan C M, Mann S
Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.
Department of Animal Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY 14853.
J Dairy Sci. 2024 Dec;107(12):10882-10899. doi: 10.3168/jds.2024-25026. Epub 2024 Sep 27.
The objective of this study was to investigate the effect of increasing MP supply in the prepartum, postpartum, or both diets on intake, performance, and metabolic indicators. Multiparous Holstein cows (n = 96) were assigned to 1 of 4 treatment groups at 28 d before expected calving following a randomized block design. Prepartum diets were formulated to contain either a control (CON; 85 g of MP/kg DM) or high (HI; 113 g of MP/kg DM) level of estimated MP. From calving to 21 DIM, diets were formulated to contain either a CON (104 g of MP/kg DM) or HI (131 g of MP/kg DM) level of estimated MP. To control the potential confounding effect of Met and Lys supply, diets were formulated to supply an equal amount at 1.24 and 3.84 g/Mcal of ME in both prepartum diets and 1.15 and 3.16 g/Mcal of ME in both postpartum diets, respectively. The combination of a pre- and postpartum diet resulted in 4 treatment groups: (1) CON-CON (CC; n = 23), (2) CON-HI (CH; n = 24), (3) HI-CON (HC; n = 22), and (4) HI-HI (HH; n = 23). A common lactation diet (113 g of MP/kg DM) was fed from 22 DIM to the end of the observation period at 42 DIM. Milk yield and DMI were collected daily, and plasma metabolic indicators (BHB, fatty acids [NEFA], PUN, and glucose) were determined twice weekly from -28 to 28 d relative to calving and once weekly from 29 to 42 DIM. Samples with BHB ≥1.2 mmol/L between 3 and 10 DIM were considered hyperketonemia events. Milk composition was determined weekly. Milk yield during 1 to 21 DIM was greater in HH (44.7 ± 1.0 kg/d) compared with CC (39.2 ± 1.0 kg/d) and HC (38.0 ± 1.0 kg/d) and milk yield in CH (42.4 ± 0.9 kg/d) was greater than HC, respectively. From 22 to 42 DIM, milk yield was greater in CH (53.3 ± 1.0 kg/d) and HH (54.1 ± 1.0 kg/d) compared with CC (49.6 ± 1.0 kg/d) and HC (49.3 ± 1.0 kg/d). Dry matter intake (% of BW) and concentrations of milk protein, fat, and total solids were not affected by treatment. Prepartum concentrations of PUN were greater in HI compared with CON. From 1 to 21 DIM, PUN concentrations were greater in CH and HH compared with CC and HC. From 1 to 21 DIM, concentrations of glucose were lower in HH compared with HC, and BHB were greater in CH and HH compared with HC. Concentrations of NEFA, as well as the number of hyperketonemia events did not differ by treatment during this time. From 22 to 42 DIM, concentrations of NEFA were greater in HH compared with HC and concentrations of BHB were greater in CH and HH compared with HC. Overall, feeding CH or HH increased lactation performance without altering intake or hyperketonemia events. Results from this study support formulating a fresh diet to reduce the negative MP balance during early lactation.
本研究的目的是调查在产前、产后或两种日粮中增加代谢蛋白（MP）供应对采食量、生产性能和代谢指标的影响。经产荷斯坦奶牛（n = 96）在预计产犊前28天按照随机区组设计被分配到4个处理组中的1组。产前日粮被配制为含有对照（CON；85 g MP/kg干物质）或高（HI；113 g MP/kg干物质）水平的估计MP。从产犊到产后21天，日粮被配制为含有对照（104 g MP/kg干物质）或HI（131 g MP/kg干物质）水平的估计MP。为了控制蛋氨酸（Met）和赖氨酸（Lys）供应的潜在混杂效应，日粮被配制为分别在产前日粮中按每兆卡代谢能（ME）1.24和3.84 g供应等量的Met和Lys，在产后日粮中按每兆卡ME 1.15和3.16 g供应等量的Met和Lys。产前和产后日粮的组合产生了4个处理组：（1）CON-CON（CC；n = 23），（2）CON-HI（CH；n = 24），（3）HI-CON（HC；n = 22），和（4）HI-HI（HH；n = 23）。从产后22天到42天的观察期结束时，饲喂一种通用的泌乳日粮（113 g MP/kg干物质）。每天记录产奶量和干物质采食量（DMI），并在相对于产犊的 -28至28天每周测定两次血浆代谢指标（β-羟丁酸（BHB）、脂肪酸（非酯化脂肪酸，NEFA）、血浆尿素氮（PUN）和葡萄糖），在产后29至42天每周测定一次。在产后3至10天BHB≥1.2 mmol/L的样本被视为酮血症事件。每周测定牛奶成分。与CC（39.2±1.0 kg/d）和HC（38.0±1.0 kg/d）相比，HH在产后1至21天的产奶量（44.7±1.0 kg/d）更高，CH（42.4±0.9 kg/d）的产奶量高于HC。从产后22至42天，与CC（49.6±1.0 kg/d）和HC（49.3±1.0 kg/d）相比，CH（53.3±1.0 kg/d）和HH（54.1±1.0 kg/d）的产奶量更高。干物质采食量（占体重的百分比）以及牛奶蛋白、脂肪和总固体的浓度不受处理影响。产前HI组的PUN浓度高于CON组。从产后1至21天，CH和HH组的PUN浓度高于CC和HC组。从产后1至21天，HH组的葡萄糖浓度低于HC组，CH和HH组的BHB浓度高于HC组。在此期间，NEFA浓度以及酮血症事件的数量在各处理组间没有差异。从产后22至42天，HH组的NEFA浓度高于HC组，CH和HH组的BHB浓度高于HC组。总体而言，饲喂CH或HH提高了泌乳性能，而不改变采食量或酮血症事件。本研究结果支持配制新的日粮以减少泌乳早期的负MP平衡。
