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

• Published in: Journal of animal science 2007-03, Vol.85 (3), p.717-730
• Main Authors: Lake, S.L, Weston, T.R, Scholljegerdes, E.J, Murrieta, C.M, Alexander, B.M, Rule, D.C, Moss, G.E, Hess, B.W
• Format: Article
• Language: English
• Subjects: adipose tissue; Adipose Tissue - drug effects; Adipose Tissue - physiology; Animal Feed; Animal Nutritional Physiological Phenomena; Animal productions; Animals; beef cows; Biological and medical sciences; blood chemistry; body condition; body weight; Carthamus tinctorius; Cattle - blood; Cattle - metabolism; Diet - veterinary; dietary fat; Dietary Fats - pharmacology; Dietary Supplements; fatty acid composition; Fatty Acids - analysis; Fatty Acids - blood; feed supplements; Female; Fundamental and applied biological sciences. Psychology; lactation; Lactation - physiology; linoleic acid; Linoleic Acid - analysis; Linoleic Acid - pharmacology; lipid metabolism; mammary glands; medium chain fatty acids; Milk - chemistry; milk fat; oleic acid; Oleic Acid - analysis; Oleic Acid - pharmacology; parturition; Parturition - physiology; postpartum period; Pregnancy; Seeds - chemistry; Terrestrial animal productions; Vertebrates
• ISSN: 0021-8812; 1525-3163
• DOI: 10.2527/jas.2006-353

Two experiments were conducted with lactating Angus x Gelbvieh beef cows to determine the effects of postpartum lipid supplementation, BCS at parturition, and day of lactation on fatty acid profiles in plasma, adipose tissue, and milk. In Exp. 1, 36 pri-miparous cows (488 ± 10 kg of initial BW; 5.5 ± 0.02 initial BCS) were given ad libitum access to hay and assigned randomly to a low-fat (control) supplement or supplements with cracked, high-linoleate safflower seeds (linoleate) or cracked, high-oleate safflower seeds (oleate) from d 3 to 90 of lactation. Diets were formulated to be isonitrogenous and isocaloric; safflower seed diets provided 5% of DMI as fat. Plasma and milk samples were collected on d 30, 60, and 90 of lactation. Adipose tissue biopsies were collected near the tail-head region of cows on d 45 and 90 of lactation. In Exp. 2, 3-yr-old cows achieving a BCS of 4 ± 0.07 (479 ± 36 kg of BW) or 6 ± 0.07 (580 ± 53 kg of BW) at parturition were used in a 2-yr experiment (n = 36/yr). Beginning 3 d postpartum through d 61 of lactation, cows were fed diets similar to those of Exp. 1. Adipose tissue and milk samples were collected on d 30 and 60, and plasma was collected on d 31 and 61 of lactation. Responses to postpartum dietary treatment were comparable in both experiments. Cows fed linoleate and oleate had greater (P < 0.001) total fatty acid concentrations in plasma than cows fed control. Except for 15:1, milk fatty acids with