Abstract
Eight Holstein cows with body weight 570 ± 43 kg and 60 ± 20 lactation days were distributed in a double Latin square design with four 21-day periods to determine the effects of feeding ground or whole flaxseed with or without monensin supplementation (0.02% on a dry matter basis) on fatty acid profile of butter stored for 15 and 45 days. Ground flaxseed supply, in comparison to whole flaxseed, reduced relative percentages of 16:0, cis7-16:1, 17:0, and cis10-17:1 but it increased those of cis9,trans11-18:2, cis3-18:3, and omega 3 fatty acids in butter fat, reducing relative percentage of medium-chain fatty acids and increasing the content of polyunsaturated fatty acids. Supplementation with monensin increased relative percentages of cis9,trans11-18:2 and tended to increase relative percentage of 17:0 and decrease that of saturated fatty acids in butter. Butter from cows fed diet with monensin presented lower relative percentages of cis 6-20:4. Relative percentages of cis 9-16:1, cis10-17:1, 18:0, trans11-18:1, cis9-18:1, cis3-18:3, cis6-20:4 in butter stored for 15 days were higher than those stored for 45 days and the relative percentages of cis3-20:5 tended to decrease with the increase of storage period. As a result, relative percentages of saturated fatty acids and medium-chain fatty acids increased with storage time, while those of monounsaturated and long-chain fatty acids decreased. Butter enriched with polyunsaturated fatty acids may have a shorter shelf life due to the negative effect of storage on fatty acid profile which may cause oxidation and rancidity.
Highlights
Some long chain polyunsaturated fatty acids (PUFA) are recognized for their potential effects on human health
In comparison to whole flaxseed, reduced relative percentages of 16:0, cis7-16:1, 17:0, and cis10-17:1 but it increased those of cis9,trans11-18:2, cis3-18:3, and omega 3 fatty acids in butter fat, reducing relative percentage of mediumchain fatty acids and increasing the content of polyunsaturated fatty acids
There were no interactions between flaxseed processing and monensin supplementation on butter concentrations of individual fatty acids except for trans1118:1 concentration that was twice higher (P
Summary
Some long chain polyunsaturated fatty acids (PUFA) are recognized for their potential effects on human health. Dietary feeding strategies may contribute to increase conjugated linoleic acid, omega-3, and other beneficial fatty acids in milk fat of dairy cows (Petit et al, 2004; Baer et al, 2001). Modifications in the profile of fatty acids may contribute to alter physical properties of milk fat such as improved butter spreadability (Enjalbert et al, 1997) as a result of higher and lower concentrations of cis-C18:1 and C16:0, respectively. Ruminal biohydrogenation of dietary polyunsaturated fatty acids may be high as it was shown by the low transfer of polyunsaturated fatty acids from whole flaxseed into milk (Petit et al, 2005). Means to decrease ruminal biohydrogenation would contribute to increase the transfer of polyunsaturated fatty acids from flaxseed in milk, which may modify the physical properties and fatty acid profile of butter
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