Comparison of performance and metabolism from late pregnancy to early lactation in dairy cows with elevated v. normal body condition at dry-off

Abstract

Excessive mobilization of body reserves during the transition from pregnancy to lactation imposes a risk for metabolic diseases on dairy cows. We aimed to establish an experimental model for high v. normal mobilization and herein characterized performance, metabolic and endocrine changes from 7 weeks antepartum (a.p.) to 12 weeks postpartum (p.p.). Fifteen weeks a.p., 38 pregnant multiparous Holstein cows were allocated to two groups that were fed differently to reach either high or normal body condition scores (HBCS: 7.2 NEL MJ/kg dry matter (DM); NBCS: 6.8 NEL MJ/kg DM) at dry-off. Allocation was also based on differences in body condition score (BCS) in the previous and the ongoing lactation that was further promoted by feeding to reach the targeted BCS and back fat thickness (BFT) at dry-off (HBCS: >3.75 and >1.4 cm; NBCS: <3.5 and <1.2 cm). Thereafter, both groups were fed identical diets. Blood samples were drawn weekly from 7 weeks a.p. to 12 weeks p.p. to assess the serum concentrations of metabolites and hormones. The HBCS cows had greater BCS, BFT and BW than the NBCS cows throughout the study and lost more than twice as much BFT during the first 7 weeks p.p. compared with NCBS. Milk yield and composition were not different between groups, except that lactose concentrations were greater in NBSC than in HBCS. Feed intake was also greater in NBCS, and NBCS also reached a positive energy balance earlier than HBCS. The greater reduction in body mass in HBCS was accompanied by greater concentrations of non-esterified fatty acids, and β-hydroxybutyrate in serum after calving than in NBCS, indicating increased lipomobilization and ketogenesis. The mean concentrations of insulin across all time-points were greater in HBCS than in NBCS. In both groups, insulin and IGF-1 concentrations were lower p.p than in a.p. Greater free thyroxine (fT4) concentrations and a lower free 3-3′-5-triiodothyronine (fT3)/fT4 ratio were observed in HBCS than in NBCS a.p., whereas p.p. fT3/fT4 ratio followed a reverse pattern. The variables indicative for oxidative status had characteristic time courses; group differences were limited to greater plasma ferric reducing ability values in NBSC. The results demonstrate that the combination of pre-selection according to BCS and differential feeding before dry-off to promote the difference was successful in obtaining cows that differ in the intensity of mobilizing body reserves. The HBCS cows were metabolically challenged due to intense mobilization of body fat, associated with reduced early lactation dry matter intake and compromised antioxidative capacity.

Mammalian target of rapamycin signaling and ubiquitin-proteasome–related gene expression in skeletal muscle of dairy cows with high or normal body condition score around calving

“…Moreover, the lower serum concentrations of Ala in HBCS cows during the p.p. period may be related to a greater demand for gluconeogenic AA for the liver (Chibisa et al, 2008) that is likely coupled with a reduced supply of ruminal propionate to the liver as a result of decreased DMI after calving (Schuh et al, 2019). In support of this, the quantitative data on liver metabolism of AA have shown an increased contribution of Ala to the immediate postpartum increment in the liver release of glucose likely through its role in the inter-organ transfer of nitrogen from catabolized AA (Larsen and Kristensen, 2013).…”

“…A more detailed description of variables characterizing body condition as well as animal performance was reported previously (Schuh et al, 2019). In brief, BCS, BFT, and BW (Supplemental Figure S1) were greater in HBCS than in NBCS cows at enrolment (15 wk a.p.…”

“…The basic set-up of the trial with the performance results as well as the data of "classical" variables, i.e. NEFA, BHB, insulin, glucose, leptin, IGF-1, oxidative and thyroid hormone status, assessed in blood serum were already described by Schuh et al (2019). In brief, 38 multiparous German Holstein cows (average parity: 2.9 ± 0.30, mean ± SEM) were allocated 15 wk before their anticipated calving date to either NBCS (n = 19) or HBCS (n = 19) group.…”

“…until week 12 p.p. as previously described (Schuh et al, 2019). Total mixed rations (TMR), as well as the concentrate feed, were sampled every 2 weeks and stored at -20 °C until analysis.…”

“…To address these issues, we used an experimental model in dairy cows for high versus normal mobilization around calving by feeding different diets (energy levels) before dry-off and based on pre-selection [as quantified by body condition score (BCS) and backfat thickness (BFT)] in the previous and the ongoing lactation (Schuh et al, 2019). We hypothesized that cows calving with high BCS are metabolically challenged during early lactation due to a more severe NEB and intense mobilization of body fat that may also affect the regulation of specific signaling components related to protein synthesis and protein degradation.…”