Conjugated linoleic acid content in adipose tissue of calves suckling beef cows supplemented with raw or extruded soybeans on pasture

¹ Département des sciences animales, Université Laval, Québec, Québec, Canada, G1V 0A6
² Organic Dairy Research Centre, Alfred Campus, University of Guelph, Alfred, Ontario, Canada, K0B 1A0
³ Agriculture and Agri-Food Canada, Kapuskasing, Ontario, Canada, P5N 2Y3

^* To whom correspondence should be addressed. E-mail: Yvan.Chouinard{at}san.ulaval.ca.

	Abstract

The concentration of CLA in adipose tissue can be increased in ruminants by feeding pasture and extruded soybeans. The objective of this study was to evaluate maternal supplementation of raw (RS) or extruded (ES) soybeans on the concentrations of CLA in milk fat of cows and s.c. adipose tissue of suckling calves. Thirty-two spring-calving cows (BW 624 ± 76 kg; BCS 3.5 ± 0.4; mean ± SD) and calves (BW 127 ± 15 kg) were separated into 2 groups. Cows were distributed in order to have 8 calves of each gender in both groups. When animals were turned out to pasture, dams received 2 kg/d of either RS or ES. Dietary treatments had no effect on average milk intake (P = 0.22) and pasture forage intake (P = 0.13) for calves over the course of the grazing season. As a result, no effect of treatments was observed on ADG (P = 0.26). At weaning, milk fat content of CLA reached 15.4 and 24.2 mg/g total fatty acids for cows fed RS and ES, respectively (P = 0.02). The CLA concentrations in adipose tissue were 16.9 and 25.0 mg/g of total fatty acids for calves suckling dams fed RS and ES, respectively (P < 0.001). Overall, results demonstrated supplementing grazing cows with ES increased CLA content in milk and adipose tissue of suckling calves.

Key Words: conjugated linoleic acid, extruded soybeans, nursing beef cows, pasture, subcutaneous adipose tissue, suckling calves