Effects of body condition score at parturition and postpartum supplemental fat on adipose tissue lipogenic activity of lactating beef cows1

Abstract

Three-year-old Angus x Gelbvieh beef cows nutritionally managed to achieve a BCS of 4 +/- 0.07 (479.3 +/- 36.3 kg of initial BW) or 6 +/- 0.07 (579.6 +/- 53.1 kg of initial BW) at parturition were used in a 2-yr experiment (n = 36/yr) to determine the effects of BCS at parturition and postpartum lipid supplementation on cow adipose tissue lipogenesis. Beginning 3 d postpartum, cows within each BCS were randomly assigned to be fed hay and a low-fat control supplement or supplements with either cracked high-linoleate safflower seeds or cracked high-oleate safflower seeds until d 60 of lactation. Diets were formulated to be isonitrogenous and isocaloric, and safflower seed diets provided 5% DMI as fat. Adipose tissue biopsies were collected near the tail-head region of cows on d 30 and 60 of lactation. Dietary treatment did not affect (P > or = 0.43) adipose tissue lipogenesis. Body condition score at parturition did not affect acetate incorporation into lipid (P = 0.53) or activity of acetyl CoA carboxylase (P = 0.77) or fatty acid synthase (P = 0.18). Lipoprotein lipase activity and palmitate incorporation into triacyl-glycerol tended to be greater (P = 0.06), and palmitate esterification into total acylglycerols was greater (P = 0.01) in cows with a BCS of 4 at parturition. Mean activity of acetyl-CoA carboxylase (P < 0.001), lipoprotein lipase (P = 0.01), and rate of palmitate incorporation into monoacylglycerol (P = 0.02), diacylglycerol (P = 0.001), triacylglycerol (P = 0.003), and total acylglycerols (P = 0.002) were greater at d 30 than d 60, suggesting a greater proclivity for fatty acid biosynthesis and esterification by adipose tissue at d 30 of lactation. Although dietary lipid supplementation did not affect adipose tissue lipogenesis, results suggest that cows with a BCS of 4 at parturition have a greater propensity to deliver exogenously derived fatty acids to the adipocyte surface and incorporate preformed fatty acids into acylglycerols as stored adipocyte lipid. Additionally, cows in early lactation seemed to be able to synthesize and incorporate more fatty acids into stored lipid than cows during peak lactation.

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

“…In adipose tissue the lack of effect of cow BCS on abundance of ACC mRNA was consistent with our previous observation of no difference in ACC activity in adipose tissue of BCS 4 cows compared to BCS 6 cows at the same time points postpartum (Lake et al, 2006b). It is generally accepted that mammary gland ACC activity is up-regulated and adipose tissue ACC activity is down-regulated during lactation.…”

“…Thus, low BCS at parturition could be associated with adaptive mechanisms to insure maintenance of minimal lipogenic potential in adipose tissue by allowing less ACC repression during lactation. Increases in the amount of ACC-P was observed by day 60 of lactation indicating increased amounts of inactive enzyme compared to day 30, which was consistent with our previous observation of approximately 46% lower ACC activity by day 60 of lactation in beef cows (Lake et al, 2006b). Regulation of ACC includes citrate activation, as well as phosphorylation inactivation (Munday, 2002) through protein kinase-A and AMP-activated protein-kinase (Minokoshi et al, 2002).…”

“…Abundance of ACC-P tended to be lower in adipose tissue of BCS 4 cows compared with BCS 6 cows suggesting BCS 4 cows either had greater ACC activity or activity was suppressed to a lesser extent during lactation compared with BCS 6 cows. However, Lake et al (2006b) reported no difference in ACC activity in adipose tissue of BCS 4 and 6 cows during lactation. Thus, low BCS at parturition could be associated with adaptive mechanisms to insure maintenance of minimal lipogenic potential in adipose tissue by allowing less ACC repression during lactation.…”

Effects of postpartum dietary fat and body condition score at parturition on plasma, adipose tissue, and milk fatty acid composition of lactating beef cows1

“…Although this dietary management strategy did not seem to alter nutrient partitioning (Lake et al, 2005), we suspected that greater percentages of 18:2n-6 in adipose tissue samples from linoleate cows with BCS of 4 were attributable to increased proportions of membrane lipids associated with connective tissue in those samples. The greater percentage of 18:0 in adipose tissue of BCS 4 cows was consistent with increased lipogenic enzyme activity (Lake et al, 2006b), decreased mobilization of body lipids (Lake et al, 2006a), and maintenance of BCS (Lake et al, 2005) in cows with BCS of 4 at parturition.…”

“…BCS of 4 at parturition maintained BCS (Lake et al, 2005) and had the metabolic proclivity to increase adipose tissue lipid accretion (Lake et al, 2006b) during the first 60 d of lactation. We hypothesized that the aforementioned nutrient partitioning effects of dietary lipids and BCS are associated with changes in fatty acid composition of tissues involved with nutrient partitioning.…”