本研究的目的是确定与产前MI相关的因素,使用不同类别的预测因子评估线性模型的性能,以估计产前MI,并探讨不同水平的产前dmi对过渡代谢和泌乳性能的影响。通过相对于产卵从d-35到98的自动饲料箱测量未产母牛(n=100)和存胎母牛(n=173)的个体采食量。照明和身体活动由可穿戴传感器监测。在d-21、-10、-3、0、3、7、10、14和21测量血液代谢物。在整个研究中评估体重(BW)和身体状况评分(BCS)。计算每头牛的平均产前dmi作为BW百分比(DMIpBW),并用作线性模型的因变量。奇偶校验,产前BCS和BW,以前哺乳期(M305)和干奶期(MYDO)的产奶量,和干旱期的长度与DMIpBW相关,并解释了所有奶牛41%的变异,49%的奶牛。当在预测模型中添加有关产前反流和血液代谢产物的数据时,对DMIpBW的估计得到了改善。在后者中,调整后的R-Sq增加到47%至61%之间的值,和选定的模型在5倍交叉验证分析中表现一致。为了评估DMIpBW对过渡代谢和性能的影响,奶牛在产次范围内排名,并被分类为低(LFI),中等(MFI),或高饲料摄入量(HFI)。平均BMI为BW的1.44、1.70和1.91±0.01%,分别。未分娩母牛的体重没有差异,但所有3组胎牛不同(LFI=892,MFI=849,HFI=798±8kg)。在所有群体中,BCS>3.5的奶牛的比例不同,平均为67.4、55.1和36.5±6%,分别。对于胎牛来说,M305和MYDO在所有组之间有所不同,平均为9,808、10,457和11,182±233kg,18.1、23.1和26.2±1kg/d,分别。产牛后,与其他2组相比,LFI(LFI=20.9,MFI=21.9,HFI=22.1±0.2kg/d)和产奶量(LFI=36.7,MFI=38.2,HFI=38.3±0.4kg/d)较低。产后EBAL在所有组之间存在差异,LFI平均为-2.79、-1.63和-0.66±0.3Mcal/d,MFI,HFI,分别。在过渡期内,LFI奶牛的血清NEFA浓度较高,BHB,Cl(仅适用于术前),和AST(仅产后),降低血清胆固醇浓度,P,GLDH,GGT(仅适用于术前),AST(仅适用于术前),尿素(仅存根),和SOD活性(仅存根)。总之,低水平的产前dmi与更胖和更重的奶牛有关,以前泌乳的产奶量较低,能量代谢的重要调整,以及随后泌乳中的STI和产奶量的适度损失。此外,将产前反刍动物活动和目标血液代谢产物纳入预测模型改善了产前MI的估计值.
The objectives of this study were to identify factors associated with prepartum DMI, evaluate the performance of linear models to estimate prepartum DMI using different classes of predictors, and investigate the consequences of different levels of prepartum DMI on transition metabolism and lactation performance. Individual feed intake of nulliparous (n = 100) and parous cows (n = 173) was measured by automatic feeding bins from d -35 to 98 relative to calving. Rumination and physical activities were monitored by wearable sensors. Blood metabolites were measured on d -21, -10, -3, 0, 3, 7, 10, 14, and 21. Body weight (BW) and body condition score (BCS) were assessed throughout the study. The average prepartum DMI as percentage of BW (DMIpBW) was calculated for each cow and used as dependent variable of linear models. Parity, prepartum BCS and BW, milk production in the previous lactation (M305) and at dry-off (MYDO), and length of the dry period were associated with DMIpBW and explained 41% of the variation in all cows, and 49% in parous cows. Estimations of DMIpBW were improved when data on prepartum rumination and blood metabolites were added in the predictive models. In the latter, the adjusted R-Sq increased to values between 47 and 61%, and selected models performed consistently in a 5-fold cross-validation analysis. To evaluate the implications of DMIpBW to transition metabolism and performance, cows were ranked within parity and classified into terciles as low (LFI), moderate (MFI), or high feed intake (HFI). The mean DMI was 1.44, 1.70, and 1.91 ± 0.01% of BW, respectively. No differences in BW were observed in nulliparous cows, but all 3 groups of parous cows differed (LFI = 892, MFI = 849, HFI = 798 ± 8 kg). The proportion of cows with BCS > 3.5 at enrollment differed among all groups, and averaged 67.4, 55.1, and 36.5 ± 6%, respectively. For parous cows, M305 and MYDO differed among all groups and averaged 9,808, 10,457, and 11,182 ± 233 kg, and 18.1, 23.1, and 26.2 ± 1 kg/d, respectively. After calving, DMI (LFI = 20.9, MFI = 21.9, and HFI = 22.1 ± 0.2 kg/d) and milk yield (LFI = 36.7, MFI = 38.2, and HFI = 38.3 ± 0.4 kg/d) was lower in LFI cows compared with the other 2 groups. Postpartum EBAL differed among all groups and averaged -2.79, -1.63, and -0.66 ± 0.3 Mcal/d for LFI, MFI, and HFI, respectively. During the transition period, LFI cows had higher serum concentrations of NEFA, BHB, Cl (prepartum only), and AST (postpartum only), and lower serum concentrations of cholesterol, P, GLDH, GGT (prepartum only), AST (prepartum only), urea (parous only), and SOD activity (parous only). In conclusion, a low level of prepartum DMI was associated with fatter and heavier cows, lower milk production in previous lactation, important adjustments in energy metabolism, and moderate losses in DMI and milk yield in the subsequent lactation. Moreover, the inclusion of prepartum rumination activity and target blood metabolites into predictive models improved the estimations of prepartum DMI.