Zhang Jing, Lang Jiaojiao, Bu Lijun, Liu Yapeng, Huo Wenjie, Pei Caixia, Liu Qiang
College of Animal Science, Shanxi Agricultural University, Taigu 030801, Shanxi, China.
Anim Nutr. 2025 Apr 7;21:267-278. doi: 10.1016/j.aninu.2024.10.010. eCollection 2025 Jun.
Arginine (Arg) can potentially increase milk yields in early lactating dairy cows by stimulating the development of mammary gland and the biosynthesis of milk proteins and fatty acids (FA); however, the underlying mechanism is still unclear. The hypothesis that rumen-protected Arg addition would increase milk, milk fat, and milk protein yields was tested, aiming to dlucidate the possible mechanism. Forty-eight multiparous Chinese Holstein dairy cows (milk yield 34.9 ± 1.27 kg/d, body weight 658 ± 12.7 kg, and days in lactation [DIL] 16.4 ± 2.56) were selected on the principle of proximity and blocked by DIL and milk yield, and divided into one of four groups in a randomized block design: control (without RPArg), low RPArg (LRPArg; 20 g/d Arg), medium RPArg (MRPArg; 40 g/d Arg), and high RPArg (HRPArg; 60 g/d Arg), 4 replicates per group and 3 cows per replicate and the experiment duration was 95 days, including a 10-d covariate period, a 15-d adaptation period, and a 70-d sampling period. The production of actual milk, energy-corrected milk, fat-corrected milk, milk fat, and milk protein linearly increased ( < 0.05) with RPArg provision. The yields of de novo FA and mixed FA in the milk linearly increased ( < 0.01), but that of preformed FA linearly decreased ( = 0.007). Supplementation with RPArg linearly increased the daily production of Arg, Asp, Cys, Glu, His, Met, Phe, Ser, Thr, and Trp ( < 0.05). With RPArg provision, serum contents of glucose, albumin, total protein, and nitric oxide linearly increased ( < 0.05); the levels of estradiol, prolactin, and insulin-like growth factor 1 quadratically increased ( < 0.01); and that of blood urea nitrogen quadratically decreased ( = 0.023). Furthermore, supplementation with 40 g/d Arg from RPArg promoted the expression of proteins implicated in mammary gland proliferation, FA synthesis, and milk protein synthesis. Thus, RPArg addition enhanced milk production, FA synthesis, and milk protein synthesis by promoting the expression of proteins involved in mammary gland development, FA synthesis, and milk protein synthesis.
精氨酸（Arg）可能通过刺激乳腺发育以及乳蛋白和脂肪酸（FA）的生物合成来提高初产奶牛的产奶量；然而，其潜在机制仍不清楚。本试验验证了添加瘤胃保护性精氨酸会增加牛奶、乳脂和乳蛋白产量的假设，旨在阐明其可能的机制。按照相近原则选取48头经产中国荷斯坦奶牛（产奶量34.9±1.27 kg/d，体重658±12.7 kg，泌乳天数[DIL]16.4±2.56），并按DIL和产奶量进行分组，采用随机区组设计分为四组：对照组（不添加瘤胃保护性精氨酸）、低剂量瘤胃保护性精氨酸组（LRPArg；20 g/d精氨酸）、中剂量瘤胃保护性精氨酸组（MRPArg；40 g/d精氨酸）和高剂量瘤胃保护性精氨酸组（HRPArg；60 g/d精氨酸），每组4个重复，每个重复3头奶牛，试验期为95天，包括10天的协变量期、15天的适应期和70天的采样期。随着瘤胃保护性精氨酸的添加，实际牛奶、能量校正奶、脂肪校正奶、乳脂和乳蛋白的产量呈线性增加（P<0.05）。牛奶中新生脂肪酸和混合脂肪酸的产量呈线性增加（P<0.01），但预制脂肪酸的产量呈线性下降（P = 0.007）。添加瘤胃保护性精氨酸可使精氨酸、天冬氨酸、半胱氨酸、谷氨酸、组氨酸、蛋氨酸、苯丙氨酸、丝氨酸、苏氨酸和色氨酸日产量呈线性增加（P<0.05）。随着瘤胃保护性精氨酸的添加，血清葡萄糖、白蛋白、总蛋白和一氧化氮含量呈线性增加（P<0.05）；雌二醇、催乳素和胰岛素样生长因子1水平呈二次曲线增加（P<0.01）；血尿素氮水平呈二次曲线下降（P = 0.023）。此外，从瘤胃保护性精氨酸中添加40 g/d精氨酸可促进参与乳腺增殖、脂肪酸合成和乳蛋白合成的蛋白质表达。因此，添加瘤胃保护性精氨酸通过促进参与乳腺发育、脂肪酸合成和乳蛋白合成的蛋白质表达，提高了产奶量、脂肪酸合成和乳蛋白合成。
