Relationships among nutritional regimen, metabolic disorders, reproduction, and production in dairy cows during the transition period

Negative energy balance (NEB) during the first weeks postpartum is associated with infertility in dairy cows. A meta-analysis approach was used to investigate the association between prepartum energy feeding regimen, productive parameters, health, and reproductive performance. Days to conception (DTC) was used as the dependent variable to assess reproductive performance. The database was developed from 7 experiments completed in our group from 1993 to 2010. Individual data for 408 cows (354 multiparous and 54 primiparous) were included in the analysis. The net energy for lactation (NEL) intake was determined from each cow's average dry matter intake (DMI) and calculated dietary NE L density. Treatments were applied prepartum and were classified as either controlled energy (CE) or high energy (DMI) diets fed during the far-off (FO) or close-up (CU) dry periods. Cow was the experimental unit. All analyses were carried out using SAS 9.2 (SAS Institute, Inc.). The Cox proportional hazard model revealed a significant difference in DTC between HE and CE during the CU period (median = 167 and 157 d; hazard ratio (HR) = 0.696). Cows fed HE diets during the last 4 wk prepartum lost more body condition score (BCS) in the first 6 wk postpartum than those fed CE (--0.43 and --0.30, respectively). Cows with 3 or more lactations lost more BCS than cows with one or two lactations (--0.42 and --0.33, respectively). Cows fed CE during the FO period had lower nonesterified fatty acids (NEFA) concentrations in wk 1, 2, and 3 of lactation compared with cows fed HE. Higher NEFA concentration in wk 1 postpartum was associated with a greater probability of diseases (n = 251; OR = 1.176). Cows on the CE regimen during the FO period had greater plasma glucose concentrations during wk 1 and 3 after calving than cows fed the HE regimen. Higher plasma glucose (HG) concentration compared with lower glucose (LG) in wk 3 (HG, n = 154; LG, n = 206) and wk 4 (HG, n = 71; LG, n = 254) after calving was associated with greater HR for DTC (wk 3: median = 151 and 171 d for HG and LG, HR = 1.334; wk 4: median = 148 and 167 d, HR = 1.394). In the first 2 wk after calving, cows that received HE in the FO period had higher concentrations of total lipids and triglyceride and greater ratio of triglyceride to glycogen in liver than did CE.;There was no statistical difference for milk production in the first 4 wk postpartum between cows fed CE or HE prepartum. Cows fed HE during CU had greater milk fat concentration than cows fed CE on wk 2, 3, and 4. Cows fed HE during CU had higher protein concentration during wk 3 and 4 then cows fed CE. Cows that were fed HE during CU lost more body weight (BW) either as absolute value (kg) or as percentage loss during the first 6 wk postpartum (38.5 vs 19.7 kg, SEM 8.9, P = 0.01 and 5.6 vs 2.9 %, SEM 1.2, respectively). In addition, cows that were fed HE during the dry period had more odds of experiencing displaced abomasum or ketosis when compared to cows that received CE.;Lastly, principal component (PC) analysis was conducted on 8 variables: glucose wk 3 (GLU3), glucose wk 4 (GLU4 ), beta-hydroxybutyrate wk 1 (BHBA1), insulin wk 2 (INS2), nonesterified fatty acids wk --1 (NEFA-1), energy-corrected milk wk 4 (ECM4), fat corrected milk wk 4 (FCM4), and milk urea nitrogen wk 5 (MUN5). For linear regression analysis from PC, animals were classified in two groups based on first and fourth quartile values for DTC as high (slow; ≥ 174 d) or low (fast; < 87 d). Overall, prepartum nutrition was shown to have great impact on metabolic, production, and reproductive parameters of dairy cattle. (Abstract shortened by UMI.).