Authors : W. Brown , A.A. AbuGhazaleh and S. Ibrahim
Abstract: The objective of this study was to determine the effect of supplementing grazing dairy cows� diet with Fish Oil (FO) and Linseed Oil (LSO) on milk Conjugated Linoleic Acid (CLA). Sixteen Holstein cows (170�19 DIM) were divided into 2 groups (n = 8 per treatment) and fed a basal diet (7.2 kg d 1; DM basis) consisting of corn, soybean meal, molasses, vitamin/mineral premix plus 800 g saturated animal fat (CONT) or a basal diet plus 200 g FO and 600 g LSO (FOLSO). All cows grazed together on Sudan grass pasture for ad libitum and fed the treatment diets for 3 weeks. Cows were milked twice a day and milk samples were collected during the last 3 days of the trial. Milk production (24.89 and 22.45 kg d 1), milk protein percentages (2.76 and 2.82) and milk protein yield (0.68 and 0.64 kg d 1) for the CONT and FOLSO diets, respectively, were not affected (p>0.05) by treatment diets. Milk fat percentages (3.90 and 2.86) and milk fat yields (0.97 and 0.64 kg d 1) were lower (p< 0.05) with the FOLSO diet compared with the CONT diet. The concentration and yield of milk cis-9 trans-11 CLA were higher (p< 0.05) with the FOLSO diet (2.56% of total FA and 16.44 g d 1, respectively) than the CONT diet (0.66% of total FA and 6.44 g d 1, respectively). The concentrations of milk trans C18:1 and Vaacenic Acid (VA) were higher (p< 0.05) with the FOLSO diet (36.99 and 7.48% of total FA, respectively) than the CONT diet (28.8 and 2.27% of total FA, respectively). In conclusion, supplementing grazing cows� diet with FO and LSO increased milk cis-9 trans-11 CLA content but reduced milk fat content and yield.
W. Brown , A.A. AbuGhazaleh and S. Ibrahim , 2007. Conjugated Linoleic Acid in Milk Fat of Grazing Dairy Cows Fed Fish Oil and Linseed Oil . Research Journal of Dairy Sciences, 1: 6-12.