Effects of flaxseed supplementation to lactating ewes on milk composition, cheese yield, and fatty acid composition of milk and cheese

Abstract

One hundred and twenty lactating ewes (Suffolk × East Friesian) were divided into four equal groups and randomly assigned to one of four isonitrogenous concentrates. The concentrates contained 0, 9, 18, and 26% flaxseed (DM basis) with ether extract content of 3.2, 5.4, 7.4, and 9.4%, respectively. Ewes were group fed concentrates (1 kg/animal/day) in two equal portions after morning and evening milking with free access to alfalfa hay. Results showed that feeding flaxseed at 18 and 26% level increased ( P < 0.05) milk fat and total solids, while no effect was observed on milk protein and lactose percentages. Cheese yield was 7.3% higher ( P < 0.5) from milk of ewes fed the 18% flaxseed concentrate than from milk of ewes fed the 0% flaxseed concentrate. Flaxseed supplementation linearly decreased ( P < 0.05) concentrations of short- and medium-chain and saturated fatty acids while increasing those of long-chain, mono- and poly-unsaturated fatty acids in milk fat. Effects of dietary treatments on fatty acid composition of cheeses were similar to those of milk. Concentrations of conjugated linoleic acid (CLA) and linolenic acid (C 18:3) in milk fat were increased linearly ( P < 0.05) with flaxseed supplementation. The concentration of CLA and C 18:3 in milk of ewes fed 26% flaxseed concentrates increased ( P < 0.05) by 73 and 43%, respectively. Similar increases were observed for the cheese. It was concluded that feeding flaxseed to lactating ewes improved fatty acid profiles in milk and cheese as well as cheese yield.