Effect of a supplement containing trans-10,cis-12 conjugated linoleic acid on the performance of dairy ewes fed 2 levels of metabolizable protein and at a restricted energy intake

• Published in: Journal of dairy science 2012-01, Vol.95 (1), p.109-116
• Main Authors: Weerasinghe, W.M.P.B., Wilkinson, R.G., Lock, A.L., de Veth, M.J., Bauman, D.E., Sinclair, L.A.
• Format: Article
• Language: English
• Subjects: Animal productions; Animals; Biological and medical sciences; conjugated linoleic acid; dairy protein; dairy sheep; Diet - veterinary; Dietary Proteins - metabolism; Dietary Proteins - pharmacology; Dietary Supplements; early lactation; Energy; energy intake; Energy Intake - physiology; ewes; Fatty Acids - analysis; Female; Food industries; Fundamental and applied biological sciences. Psychology; General aspects; Lactation - drug effects; lactose; Linoleic Acids, Conjugated - pharmacology; lipid content; Lipids - analysis; metabolizable energy; metabolizable protein; milk; Milk - chemistry; milk fat depression; milk fat percentage; Milk Proteins - analysis; milk yield; nutrients; sheep; Sheep - metabolism; Sheep - physiology; Terrestrial animal productions; urea; Urea - blood; Vertebrates
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.2011-4165

Trans-10,cis-12 conjugated linoleic acid (CLA) inhibits milk fat synthesis in dairy ewes, but the effects under varying dietary metabolizable protein (MP) levels when energy-limited diets are fed have not been examined. The objectives of the study were to evaluate the response of lactating dairy ewes to CLA supplementation when fed diets limited in metabolizable energy (ME) and with either a low or high MP content. Twelve multiparous ewes in early lactation were randomly allocated to 1 of 4 dietary treatments: a high MP (110% of daily MP requirement) or low MP (93% of daily MP requirement) diet unsupplemented or supplemented with a lipid-encapsulated CLA to provide 2.4g/d of trans-10,cis-12 CLA, in each of 4 periods of 25 d each in a 4×4 Latin square design. All diets were restricted to supply each ewe with 4.6 Mcal of ME/d (equivalent to 75% of ME requirement). Supplementation with CLA decreased milk fat percentage and yield by 33% and 24%, respectively, and increased milk, milk protein, and lactose yields by 16, 13, and 17%, respectively. Feeding the high MP diet increased the yields of milk, fat, protein, and lactose by 18, 15, 19, and 16%, respectively. Milk fat content of trans-10,cis-12 CLA (g/100g) was 0.09 and