Volume 91, Issue 2, February (2004), pp. 271-278 © The Author 2004
doi:10.1079/BJN20031050

Medline/PubMed Citation | Related Articles in PubMed | Download to Citation Matcher  

Supplementation of grazing dairy cows with rumen-protected tuna oil enriches milk fat with n-3 fatty acids without affecting milk production or sensory characteristics

Soressa M. Kitessa¹, Suresh K. Gulati², Gillian C. Simos³, John R. Ashes⁴, Trevor W. Scott⁵, Eva Fleck⁶, Peter C. Wynn†^3
1CSIRO Livestock Industries, Underwood Ave, Floreat Park, Wembley, WA 6913, Australia
²Faculty of Veterinary Science B19, University of Sydney, NSW 2006, Australia
³Department of Animal Science, University of Sydney, NSW 2006, Australia
⁴Australian Consumer Association, Sydney, Australia
⁵Rumentek Industries, Parkside, South Australia, 5001
⁶CSIRO Molecular Science, North Ryde, Sydney, Australia

 (Received 28 August 2003–Revised 23 October 2003–Accepted 28 October 2003)

The present study was conducted to determine the pattern of incorporation of dietary EPA and docosahexaenoic acid (DHA) into milk, and to evaluate consequent changes in milk fat composition and sensory characteristics. Fourteen multiparous cows in early lactation were divided into two groups and were offered supplements for 10 d. While individual stalls after each morning milking, one group was offered a mixture of rumen-protected tuna oil (RPTO)–soyabean supplement (2 kg; 30:70, w/w; +RPTO) and the second group was offered the basal ration without RPTO (−RPTO). Both groups grazed together on a spring pasture after supplementation. Feeding supplemental RPTO increased the concentrations of EPA and DHA in milk fat from undetectable levels in −RPTO cows to 6·9 and 10·1 g/kg milk fat respectively. Total n-3 PUFA concentration in milk fat was increased three- to fourfold by tuna-oil supplementation (8·4 to 32·0 g/kg milk fat). There were no significant effects on milk production (35·4 v. 33·9 l/d), milk protein (28·2 v. 30·1 g/kg) or milk fat (36·2 v. 40·4 g/kg for −RPTO and +RPTO respectively). The concentration of total saturated fatty acids in milk fat was significantly reduced (568 v. 520 g/kg total fatty acids) and there was a 17 % reduction in the atherosclerotic index of milk after tuna-oil supplementation. Untrained consumer panellists (n 61) rated milk from both groups of cows similarly for taste and smell. We conclude that it is possible to enrich milk with n-3 PUFA without deleterious effects on yield, milk composition or sensory characteristics.

Keywords:
Grazing, Tuna oil, Eicosapentaenoic acid, Docosahexaenoic acid, Dairy cows

Abbreviations:
DHA, docosahexaenoic acid, ME, metabolisable energy, RPTO, rumen-protected tuna oil