title: Milk conjugated linoleic acid response to fish oil and sunflower oil supplementation to dairy cows managed under two feeding systems.
abstract: Earlier research showed that conjugated linoleic acid (CLA) content in milk fat is highest when cows' diets are supplemented with a blend of fish oil (FO) and linoleic acid-rich oils. The objective of this study was to compare the effect of FO and sunflower oil (SFO) supplementation on milk cis-9, trans-11 CLA when dairy cows managed on pasture or in confinement. Fourteen Holstein cows were assigned into 2 treatment groups: cows grazed on alfalfa-grass pasture (PAS) or were fed corn silage-alfalfa hay mix ad libitum (LOT). Both groups were supplemented with a 8.2 kg/d grain supplement containing 640 g of FO and SFO (1:3 wt/ wt). Grain supplement was fed in 2 equal portions after each milking, for a period of 3 wk. Milk samples were collected during the last 3 d of the experimental period. Milk yield was greater with the LOT diet (23.1 kg/ d) compared with the PAS diet (19.4 kg/d). Milk fat percentages (2.51 and 2.95 for the LOT and PAS, respectively) and yields (0.57 and 0.51 kg/d) were similar for the 2 diets. Milk protein percentages were not affected by diets (3.34 and 3.35 for the LOT and PAS diets, respectively), but protein yields were lower for the PAS diet (0.61 kg/d) compared with the LOT diet (0.75 kg/ d). Treatment diets had no effect on milk trans C18:1 concentrations [10.64 and 9.82 g/100 g of total fatty acids (FA) for the LOT and PAS, respectively] or yields (60.65 and 64.01 g/d), but did affect isomers distributions. Concentration (g/100 g of total FA) of vaccenic acid was lower with the LOT diet (2.15) compared with the PAS diet (4.52), whereas concentration of trans-10 C18:1 was greater with the LOT diet (4.99) compared with the PAS diet (1.69). Milk cis-9, trans-11 CLA concentration was greater with the PAS diet (1.52) compared with the LOT diet (0.84). In conclusion, the increase in milk cis-9, trans-11 CLA content was greater when pasture-based diets were supplemented with FO and SFO. The lower cis-9, trans-11 CLA concentration in milk from the confinement-fed cows resulted from trans-10 C18:1 replacing vaccenic acid as the predominant trans C18:1 isomer.
authors: Department of Animal Science, Food and Nutrition, Southern Illinois University, Carbondale 62901, USA. aabugha@siu.edu
authors: A A
authors: AA
authors: AbuGhazaleh
authors: D O
authors: DO
authors: Felton
authors: S A
authors: SA
authors: Ibrahim
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000818:Animals; D002417:Cattle / Q000378:metabolism*; D003612:Dairying / Q000379:methods; D004032:Diet / Q000662:veterinary; D004041:Dietary Fats / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D019587:Dietary Supplements; D004435:Eating / Q000502:physiology; D005223:Fats / Q000737:chemistry; D005248:Feeding Methods / Q000662:veterinary; D005260:Female; D005395:Fish Oils / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D007774:Lactation / Q000378:metabolism; D044243:Linoleic Acids, Conjugated / Q000378:metabolism*; D008892:Milk / Q000737:chemistry* / Q000201:enzymology / Q000378:metabolism; D010938:Plant Oils / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D011897:Random Allocation; D013230:Stearoyl-CoA Desaturase / Q000378:metabolism; D000074242:Sunflower Oil
chemical_list: D004041:Dietary Fats; D005223:Fats; D005395:Fish Oils; D044243:Linoleic Acids, Conjugated; D010938:Plant Oils; D000074242:Sunflower Oil; D013230:Stearoyl-CoA Desaturase