Modifying Milk Fatty Acid Profile by Feeding Linseed in Dairy Cows

Twenty four crossbred dairy cows in 2^nd-4^th lactation were divided into four groups of six animals each to study the effect of feeding linseed and linseed oil on milk fatty acid profile. Cows were fed on isonitrogenous and iso-caloric ration consisting of conventional concentrate mixture, berseem fodder (Trifolium alexandrinum) and wheat (Triticum aestivum) straw. The concentrate mixture in treatment T₁ consisted of ground nut cake 40%, wheat 30%, barley 27%, mineral mixture 2% and common salt 1%. In treatment T₂, GNC was replaced with 31.5% deoiled GNC and ground linseed (Linum usitatissimum) @ 8.5%. In T₃, deoiled GNC @ 35% and Ca salt of linseed oil @ 3.5% was added whereas in group T₄, deoiled GNC @ 35% and linseed oil @ 3% was added. To maintain similar level of fat in all the treatment groups, slight adjustments were made with respect to the quantity of barley (27, 27, 28.5 and 29% in T₁, T₂, T₃ and T₄, respectively). Dry matter intake and digestibility of nutrients did not vary among treatments. Daily average milk yield and 4% FCM yield was similar in all the groups. Milk yield ranged from 12.40 (T₃) to 13.38 kg/d (T₂). The levels of milk protein, fat, lactose, milk urea nitrogen, cholesterol, total solids and total ash were also similar in different groups. Total long chain fatty acids and poly unsaturated fatty acids (PUFA) concentration was higher (P<0.05) in T₃ than in T₁, T₂ and T₄. Total PUFA yield (g/100 g fat) increased by 137.34% in cows fed bypass fat as compared to control group (T₁). The concentration of linoleic acid (C18: 2) and linolenic acid (C18: 3) in milk fat was lowest in cows fed GNC (T₁) which increased (P<0.05) by 103.6 and 233%, respectively in cows fed crushed linseed (T₂) and calcium salt of linseed oil (T₃). Total conjugated linolenic acid yield improved by 32% in T₃ and 75% in cows fed ground linseed (T₂) over T₁. The results of the present study indicated that milk fatty acid profile may be improved for better human health by feeding linseed fat as reflected by higher concentration of PUFA including conjugated linoleic acid.