Abstract
The objective was to determine the effects of supplementation of protected conjugated linoleic acid (CLA), CLA-20 comprising 10% each of cis-9, trans-11 and trans-10, cis-12, on milk production and fatty acid profiles in plasma and milk in lactating dairy cows. Five mid-lactation, multiparous crossbred Holstein Friesian cows with average 402±20 kg BW were used in a 5x5 Latin square design for 21-d periods. Cows were given a total mixed ration (TMR) and supplemented with CLA-20 at 0, 20, 40, 80 and 160 g/d. The results showed that dry matter intake depression occurred in cows supplemented with CLA-20 at 160 g/d. Milk production slightly increased when CLA-20 supplementation was at 20, 40 and 80 g/d. However, 3.5% fat-corrected milk (FCM) was not affected by CLA-20 supplementation. Increased levels of CLA-20 supplementation resulted in a significantly decreased percentage of milk fat. Plasma concentrations of fatty acid were not altered by the amounts of CLA-20 supplementation except for the concentration of trans10, cis-12 CLA. For all dietary treatments, percentages of fatty acids (C4:0, C6:0, C8:0, C13:0, C14:0 C14:1 C15:0 C15:1 C16:0, C16:1, C18:1n9t, C18:2n6t, C18:2n6c, C20:0, C18:3n6, C18:3n3, C20:1 and C20:3n6) in milk fat were similar. Concentrations of C10:0, C11:0, C12:0 and C18:1n9c were decreased cubically and C18:0 was elevated linearly (p<0.01) according to the increased amounts of CLA-20 supplemented. The linear increase was observed for cis-9, trans-ll CLA (0.62, 1.17, 1.94, 1.87 and 1.82% of total fatty acid), trans-10, cis-12 CLA (0.01, 0.63, 0.67, 0.93 and 0.95% of total fatty acid) and total CLA (0.80, 2.25, 3.16, 3.97 and 3.94% of total fatty acid) in milk fat from 0 to 160 g/d of CLA-20 supplement. In conclusion, concentration of cis-9, trans-ll CLA in milk fat was concomitantly elevated at an increasing rate with the increased amounts of CLA-20. Based on the results in this study, supplementation of CLA-20 at 80 g/d optimally enhanced total CLA in milk fat.
Highlights
Most biologically active isomer of conjugated linoleic acid (CLA) is cis-9, trans-11, which is accounted for more than 80% of the isomers of CLA in milk fat (Chin et al, 1992)
The cis-9, trans-11 CLA is an important component of milk fat and beneficial to human health due to its anti-carcinogenic properties
Research has focused on methods of altering CLA content of milk fat
Summary
Most biologically active isomer of conjugated linoleic acid (CLA) is cis-9, trans-11, which is accounted for more than 80% of the isomers of CLA in milk fat (Chin et al, 1992). The cis-9, trans-11 CLA is an important component of milk fat and beneficial to human health due to its anti-carcinogenic properties. Research has focused on methods of altering CLA content of milk fat. In corporation of commercial sources of CLA into dairy cattle rations is one potential means of increasing CLA content of milk (Hanson et al, 1998). Rumen microorganisms can biohydrogenate unsaturated fatty acids; The objective of this study was to determine.
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