D. F. Jones
W. P. Weiss 1
The Ohio State University Department of Animal Sciences
A study was conducted to test the effect on production when fish oil replaced a proportion of tallow in the diet of Holstein cows. Four mid lactation Holstein cows were used in a 4x4 Latin square experiment. Cows were fed one of four diets consisting of 4.2% alfalfa hay, 35.1% alfalfa silage, 42.1% corn silage, and 18.6% pelleted concentrate. The diets contained 3% added fat (DM basis) as 100:0, 67:33, 50:50, or 33:67 tallow:fish oil. Each period consisted of 28 days, the first 21 days for diet adaptation and the last seven days for sampling milk, blood, and rumen fluid. Dry matter intake was not affected by treatment. Yields of milk, milk fat, milk protein, and milk protein percentage were not affected when fish oil replaced tallow in the diet. However, cows fed diets with fish oil tended to produce milk with lower milk fat percentage than cows not fed fish oil. Milk fatty acids 18:0 and cis 18:1 decreased; trans 18:1, 18:3 n-3, 20:4 n-6, and 20:5 n-3 increased; and 18:2 n-6, and 22:6 n-3 remained unchanged as fish oil was increased in the diet.
1For more information, contact at: The Ohio State University, Ohio Agricultural Research and Development Center, 314 Gerlaugh Hall, 1680 Madison Avenue, Wooster, OH 44691; 330-263-3622; e-mail: weiss.6@osu.edu