Milk production and fatty acid profile of milkfat by dairy cows fed a winter oats (Avena sativa L.) pasture only or a total mixed ration

Abstract

Milk production and milk fatty acid (FA) composition were determined in 12 Holstein dairy cows in mid-lactation fed winter oats pasture only (WOP) or total mixed ration (TMR) in a single crossover design. The WOP treatment cows received a high quality winter oats (Avena sativa L.) pasture rotationally grazed, while the TMR treatment cows were fed a corn silage-based TMR feed ad libitum once daily. Milk production tended to be lower (14.9 versus 16.3 kg day-1; P = 0.15), and milkfat (32.2 versus 35.5 gkg-1; P < 0.01), and total protein (35.8 versus 37.8 g kg-1; P < 0.01) concentration were significantly lower for the WOP fed cows than for the TMR fed cows. The cows fed WOP lost live-weight and body condition score, but the cows fed TMR gained liveweight. Cows fed WOP had a lower saturated:unsaturated FA ratio (1.85 versus 2.22; P < 0.02). The cis-9 trans-11 CLA content was 2.6-fold higher (1.41 versus 0.55% of total FA; P < 0.01) for the WOP cows. These results indicated that the nutritive value of the milk could be improved by feeding cows on high quality pasture; however, milk production was lower for grazing dairy cows. © 2005 Taylor & Francis Group, LLC.