Abstract Efficient production by dairy cows depends on optimal protein nutrition. Canola meal (CM) and dried corn distillers’ grains (DDGS) have been primary protein meals on Western USA dairies for >10 years, but a lower relative price of soybean meal (SBM) has created interest in how best to include it in diets containing CM and DDGS. Pens of ∼315 multiparous early lactation cows were fed rations with 145 g/kg CM and 0 g/kg SBM or 65 g/kg CM and 65 g/kg SBM of dry matter (DM). A methionine (Met) diet (SBM+M) was created by addition of ruminally protected Met to deliver ∼4.6 g of absorbable Met/cow/day. Body condition (BCS) was scored, and milk yields recorded for 5 months after treatment assignment at 13.2 ± 0.11 days in milk (DIM). Blood serum was collected for progesterone (P4), E2 and amino acid (AA) analyses, 24 h prior to 1st and 2nd artificial insemination (AI). The DM intake was unaffected by treatment, but milk yield and components had treatment*DIM interactions which indicated CM cows outperformed SBM cows at earlier DIM. The SBM+M cows produced more milk and milk protein than SBM cows, but at earlier DIM, while SBM+M cows produced more milk fat than SBM cows at later DIM. Rumen microbial protein (MCP) outflow was lower when SBM replaced CM, and MCP was lower in later lactation (i.e., 109 versus 51 DIM). Cows culled for clinical mastitis, lameness and physical injury were not treatment impacted. No aspect of 1st or 2nd AI pregnancy was treatment impacted with an overall 1st AI pregnancy rate of 52/100 cows. The E2 levels in serum collected 24 h prior to 1st AI were unimpacted by treatment or subsequent pregnancy outcome. However, E2 levels were lower in cows open at 32 days post 2nd AI compared to those pregnant. Substituting SBM for CM reduced performance in spite of no apparent Met limitation, with a likelihood that it was metabolizable protein which limited, primarily due to lower MCP outflow. Addition of Met to the SBM diet resulted in improvements, especially to milk protein content and yield, but not to the levels of the cows fed the CM ration. If phyto-estrogens in SBM interfered with E2 and P4 metabolism, it did not occur at a level which impacted pregnancy outcomes, suggesting it is of little concern to dairy farmers when fed to early lactation dairy cows, at least at this feeding level.

中文翻译：

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用豆粕替代双低菜粕（含和不含瘤胃保护蛋氨酸）对早期泌乳经产荷斯坦奶牛 160 天的生产、繁殖和健康的影响

摘要 奶牛的高效生产取决于最佳的蛋白质营养。双低菜粕 (CM) 和干玉米酒糟 (DDGS) 一直是美国西部乳品厂的主要蛋白质膳食超过 10 年，但豆粕 (SBM) 的相对较低的价格引起了人们对如何最好地将其纳入饮食的兴趣含有 CM 和 DDGS。约 315 头经产早期泌乳牛的围栏饲喂 145 g/kg CM 和 0 g/kg SBM 或 65 g/kg CM 和 65 g/kg SBM 干物质 (DM) 的日粮。蛋氨酸 (Met) 日粮 (SBM+M) 是通过添加瘤胃保护的 Met 产生的，以提供约 4.6 g 可吸收 Met/牛/天。对身体状况 (BCS) 进行评分，并在 13.2 ± 0.11 天的牛奶 (DIM) 治疗分配后记录 5 个月的产奶量。收集血清用于孕酮 (P4)、E2 和氨基酸 (AA) 分析，第 1 次和第 2 次人工授精 (AI) 前 24 小时。DM 摄入量不受处理的影响，但产奶量和成分具有处理*DIM 相互作用，这表明 CM 奶牛在早期 DIM 的表现优于 SBM 奶牛。SBM+M 奶牛比 SBM 奶牛生产更多的牛奶和乳蛋白，但在早期 DIM，而 SBM+M 奶牛在后期 DIM 比 SBM 奶牛生产更多的乳脂。当 SBM 代替 CM 时，瘤胃微生物蛋白 (MCP) 流出量较低，并且在泌乳后期 MCP 较低（即 109 与 51 DIM）。因临床乳腺炎、跛行和身体受伤而被扑杀的奶牛未受到治疗影响。第 1 次或第 2 次人工授精妊娠的任何方面均未受到治疗影响，总体第 1 次人工授精妊娠率为 52/100 头奶牛。在第一次 AI 前 24 小时收集的血清 E2 水平不受治疗或后续妊娠结果的影响。然而，与怀孕的奶牛相比，在第 2 次 AI 后 32 天开放的奶牛的 E2 水平较低。尽管没有明显的 Met 限制，但用 SBM 代替 CM 降低了性能，可能是可代谢的蛋白质受到限制，主要是由于较低的 MCP 流出。在 SBM 日粮中添加 Met 会导致改善，尤其是牛奶蛋白质含量和产量，但不会改善喂食 CM 日粮的奶牛的水平。如果 SBM 中的植物雌激素干扰 E2 和 P4 代谢，它不会在影响妊娠结果的水平上发生，这表明当饲喂早期泌乳奶牛时，奶农几乎不会担心，至少在这个饲养水平上。可能是可代谢的蛋白质受到限制，主要是由于较低的 MCP 流出。在 SBM 日粮中添加 Met 会导致改善，尤其是牛奶蛋白质含量和产量，但不会改善喂食 CM 日粮的奶牛的水平。如果 SBM 中的植物雌激素干扰 E2 和 P4 代谢，它不会在影响妊娠结果的水平上发生，这表明当饲喂早期泌乳奶牛时，奶农几乎不会担心，至少在这个饲养水平上。可能是可代谢的蛋白质受到限制，主要是由于较低的 MCP 流出。在 SBM 日粮中添加 Met 会导致改善，尤其是牛奶蛋白质含量和产量，但不会改善喂食 CM 日粮的奶牛的水平。如果 SBM 中的植物雌激素干扰 E2 和 P4 代谢，它不会在影响妊娠结果的水平上发生，这表明当饲喂早期泌乳奶牛时，奶农几乎不会担心，至少在这个饲养水平上。