Effects of Sunflower Oil Supplementation in Cassava Hay Based-Diets for Lactating Dairy Cows (Report‪)‬

ABSTRACT : Twenty-four, lactating dairy cows were randomly assigned according to a Rrandomized complete block design (RCBD) to investigate the effect of sunflower oil supplementation (SFOS) with cassava hay based-diets on feed intake, digestibility of nutrients, rumen fermentation efficiency and milk production. The treatments were as follows: T1 = Control, using commercial concentrate as a supplement (CON); T2 = Concentrate with cassava hay (CHSO-0); T3 = Concentrate with cassava hay and 2.5% sunflower oil (CHSO-2.5); T4 = Concentrate with cassava hay and 5% sunflower oil (CHSO-5). The cows were offered concentrate feed at a ratio of concentrate to milk production of 1:2 and urea-treated rice straw was fed ad libitum. The results revealed that feed intake, digestibility of nutrients and ruminal pH were similar among all treatments, while ruminal N[H.sub.3]-N was lower (p0.05) with SFOS. Blood urea-N (BUN) and milk urea-N (MUN) were not significantly affected by SFOS. The ruminal concentrations of volatile fatty acids were significantly different among the treatments. Sunflower oil supplementation significantly increased concentrations of unsaturated fatty acids, and ratio of unsaturated to saturated fatty acids in the milk, particularly the conjugated fatty acids, was significantly enhanced. Furthermore, production costs of treatments with sunflower oil supplementation were lower than for the control. Based on this study, SFOS in cassava hay based-diets improves rumen ecology, milk yield and milk quality, especially in terms of conjugated linoleic acids. (Key Words : Sunflower Oil, Cassava Hay, Conjugated Linoleic Acid (CLA), Rumen Fermentation, Urea-treated Rice Straw, Dairy Cows, Ruminant) INTRODUCTION