Toledo Mateus Z, Stangaferro Matias L, Caputo Oliveira Rafael, Monteiro Pedro L J, Gennari Rodrigo S, Luchini Daniel, Shaver Randy D, Giordano Julio O, Wiltbank Milo C
Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison 53706.
Department of Animal Science, Cornell University, Ithaca, NY 14853.
J Dairy Sci. 2023 Mar;106(3):2137-2152. doi: 10.3168/jds.2022-21950. Epub 2023 Jan 27.
Study objectives were to evaluate the effects of feeding rumen-protected Met (RPM) in pre- and postpartum total mixed rations (TMR) on health disorders and the interactions of health disorders with lactation and reproductive performance. Multiparous Holstein cows [470; 235 cows at University of Wisconsin (UW) and 235 cows at Cornell University (CU)] were enrolled at approximately 4 wk before parturition and housed in close-up dry cow (n = 6) and replicated lactation pens (n = 16). Pens were randomly assigned to treatment diets (pre- and postpartum, respectively): (1) control (CON): basal diet = 2.30% and 2.09% Met as % of metabolizable protein (MP) (UW) or 2.22% and 2.19% Met as % of MP (CU); (2) RPM: basal diet fed with RPM with 2.83% and 2.58% Met (Smartamine M, Adisseo Inc.; 12 g prepartum and 27 g postpartum), as % of MP (UW) or 2.85% and 2.65% Met (Smartamine M; 13 g prepartum and 28 g postpartum), as % of MP (CU). Total serum Ca was evaluated at the time of parturition and on d 3 ± 1 postpartum. Daily rumination was monitored from 7 d before parturition until 28 d postpartum. Health disorders were recorded during the experimental period until the time of first pregnancy diagnosis (32 d after timed artificial insemination; 112 ± 3 d in milk). Uterine health was evaluated on d 35 ± 3 postpartum. Time to pregnancy and herd exit were evaluated up to 350 d in milk. Treatment had no effect on the incidence of most health disorders and did not alter daily rumination. Cows fed RPM had reduced subclinical hypocalcemia (13.6 vs. 22%; UW only) on day of parturition relative to CON. Percentage of cows culled (13.1 vs. 19.3%) and hazard of herd exit due to culling [hazard ratio = 0.65, 95% confidence interval (CI): 0.42-1.02] tended to be reduced for cows fed RPM compared with CON. Moreover, cows fed RPM had greater milk protein concentration and protein yield overall, although retrospective analysis indicated that RPM only significantly increased protein yield in the group of cows with one or more health disorders (1.47 vs. 1.40 kg/d), not in cows without health disorders (1.49 vs. 1.46 kg/d) compared with CON. Overall, treatment had no effect on pregnancy per timed artificial insemination; however, among cows with health disorders, those fed RPM had reduced time to pregnancy compared with CON (hazard ratio = 0.71, 95% CI: 0.53-0.96). Thus, except for subclinical hypocalcemia on the day of parturition, feeding RPM in pre- and postpartum TMR did not reduce the incidence of health disorders, but our retrospective analysis indicated that it lessened the negative effects of health disorders on milk protein production and time to pregnancy.
研究目的是评估在产前和产后全混合日粮（TMR）中添加瘤胃保护性蛋氨酸（RPM）对健康问题的影响，以及健康问题与泌乳和繁殖性能之间的相互作用。多胎荷斯坦奶牛[共470头；威斯康星大学（UW）235头，康奈尔大学（CU）235头]在分娩前约4周入组，分别饲养在围产干奶牛舍（n = 6）和重复的泌乳牛栏（n = 16）中。牛栏被随机分配到处理日粮（分别为产前和产后）：（1）对照组（CON）：基础日粮中蛋氨酸含量分别为可代谢蛋白质（MP）的2.30%和2.09%（UW）或2.22%和2.19%（CU）；（2）RPM组：基础日粮添加RPM，蛋氨酸含量分别为MP的2.83%和2.58%（Smartamine M，安迪苏公司；产前12克，产后27克）（UW）或2.85%和2.65%（Smartamine M；产前13克，产后28克）（CU）。在分娩时和产后第3±1天评估血清总钙含量。从分娩前7天到产后28天监测每日反刍时间。在实验期内记录健康问题，直至首次妊娠诊断时（定时人工授精后32天；产奶112±3天）。在产后第35±3天评估子宫健康状况。评估产奶350天内的妊娠时间和牛群淘汰时间。处理对大多数健康问题的发生率没有影响，也未改变每日反刍时间。与对照组相比，饲喂RPM的奶牛在分娩当天亚临床低钙血症发生率降低（仅UW组：13.6%对22%）。饲喂RPM的奶牛被淘汰的百分比（13.1%对19.3%）以及因淘汰导致牛群离开的风险[风险比 = 0.65，95%置信区间（CI）：0.42 - 1.02]相对于对照组有降低趋势。此外，饲喂RPM的奶牛总体上乳蛋白浓度和蛋白产量更高，尽管回顾性分析表明，与对照组相比，RPM仅显著提高了有一个或多个健康问题的奶牛组的蛋白产量（1.47对1.40千克/天），而对无健康问题的奶牛组（1.49对1.46千克/天）没有显著影响。总体而言，处理对定时人工授精后的妊娠率没有影响；然而，在有健康问题的奶牛中，饲喂RPM的奶牛与对照组相比妊娠时间缩短（风险比 = 0.71，95%CI：0.53 - 0.96）。因此，除了分娩当天的亚临床低钙血症外，在产前和产后TMR中添加RPM并没有降低健康问题的发生率，但我们的回顾性分析表明，它减轻了健康问题对乳蛋白生产和妊娠时间的负面影响。
