Effects of body condition score at parturition and postpartum supplemental fat on metabolite and hormone concentrations of beef cows and their suckling calves1

Abstract

To determine the effects of BCS at parturition and postpartum lipid supplementation on blood metabolite and hormone concentrations, 3-yr-old Angus x Gelbvieh beef cows, which were nutritionally managed to achieve a BCS of 4 +/- 0.07 (479.3 +/- 36.3 kg of BW) or 6 +/- 0.07 (579.6 +/- 53.1 kg of BW) at parturition, were used in a 2-yr experiment (n = 36/yr). Beginning at 3 d postpartum, cows within each BCS were assigned randomly to be fed hay and a low-fat control supplement or lipid supplements with either cracked high-linoleate or high-oleate safflower seeds until d 61 of lactation. The diets were formulated to be isonitrogenous and isocaloric, and the safflower seed supplements were formulated to achieve 5% DMI as fat. On d 31 and 61 of lactation, blood samples were collected preprandially and then hourly postprandially (at 0, 1, 2, 3, and 4 h). Serum insulin (P = 0.27) and glucose (P = 0.64) were not affected by BCS at parturition. The mean concentrations of plasma NEFA (P = 0.08) and beta-hydroxybutyrate (P = 0.08) tended to be greater, and serum IGF-I was greater (P < 0.001) in BCS 6 than BCS 4 cows. Conversely, serum GH was greater (P = 0.003) for BCS 4 cows, indicating that regulation of IGF by GH may have been uncoupled in BCS 4 cows. The postpartum diet did not affect NEFA (P = 0.94), glucose (P = 0.15), IGF-I (P = 0.33), or GH (P = 0.62) concentrations. Oleate-supplemented cows had greater (P = 0.03) serum insulin concentrations, whereas control cows had greater (P = 0.01) plasma beta-hydroxybutyrate concentrations. Concentrations of NEFA (P = 0.05) and glucose (P < 0.001) were greater, and beta-hydroxybutyrate tended (P = 0.07), to be greater at d 3, whereas serum IGF-I was greater (P = 0.003) at d 6 of lactation. Similar concentrations of NEFA, glucose, GH, and IGF-I indicate that the nutritional status of beef cows during early lactation was not influenced by lipid supplementation. However, perturbations of the somatotropic axis in BCS 4 cows indicate that the influence of energy balance and BCS of the cow at parturition on postpartum performance should be considered when making managerial decisions.

Body condition score and day of lactation regulate fatty acid metabolism in milk somatic cells and adipose tissue of beef cows

“…Typical for cows in lactation, fatty acid mobilization occurs at greater rates in cows with greater body fat. Consistent with the lower HSL mRNA in the BCS 4 cow adipose tissue, we previously reported lower circulating NEFA in BCS 4 cows compared to BCS 6 cows (Lake et al, 2006a).…”

“…This was consistent with results reported by Ramos et al (1999) where peak lactation was characterized by increased LPL mRNA abundance in mammary tissue. The increased abundance of mammary LPL transcripts observed from day 30 to day 60 of lactation could have occurred in response to other changes observed in these cows during the same time period, such as decreased plasma NEFA (Lake et al, 2006a). Perhaps the mammary gland responded to the reduction in fatty acid supply by increasing LPL mRNA transcription in an effort to increase mammary gland efficiency for fatty acid extraction from all sources; adding credence to this suggestion was the observation of similar levels of daily milk fat production and yield by beef cows in a previous study from our laboratory (Lake et al, 2005).…”

“…c SEM (n = 18 for BCS; n = 36 for day of lactation). measure to increase mammary fatty acid biosynthesis given the decreased endogenous supply of NEFA, as we previously reported for BCS 4 cows in lactation (Lake et al, 2006a). The role of FAS in lipogenesis involves the multistep elongation of newly synthesized fatty acids ultimately producing palmitic acid as the primary end product.…”

“…Our data for HSL mRNA abundance in beef cow adipose tissue strongly indicates that the process of energy partitioning back to adipose tissue storage begins with changes in mRNA abundance by day 60 of lactation. Moreover, we previously reported a decrease in circulating NEFA from day 30 to day 60 of lactation (Lake et al, 2006a).…”

“…Thus, repression of adipose tissue lipoprotein lipase (LPL) and acetyl-CoA carboxylase (ACC) genes (Travers et al, 1997), with simultaneous up-regulation of the hormone sensitive lipase (HSL) gene (Martin-Hidalgo et al, 1994) would provide the mammary gland with endogenous energy supplies to meet the metabolic demands of lactation. Our laboratory has examined the effects of dietary supplemental fat on body condition score (BCS; 1 = emaciated and 9 = obese; Wagner et al, 1988) and energy partitioning during early lactation in beef cows (Bottger et al, 2002;Lake et al, 2005Lake et al, , 2006aScholljegerdes et al, 2009). Generally, dietary oil supplementation affected tissue fatty acid profile, but effects on biochemical events were not always evident.…”