Erratum to: Rumen-protected conjugated linoleic acid supplementation to dairy cows in late pregnancy and early lactation: effects on milk composition, milk yield, blood metabolites and gene expression in liver

Eight multiparous Holstein cows in mid lactation (average days in milking of 160 ± 40) were used in a replicated 4 by 4 Latin square design, each experimental period lasting 3 weeks, to determine the effects of whole cottonseed (WCS) treatment and dietary crude protein (CP) concentration on the profile of milk fatty acids. Each 3-week experimental period consisted of 2 weeks for ration adaptation followed by 1 week for data collection. The experimental diets consisted of: (1) Control (without WCS), 16% CP; (2) 20% WCS, 16% CP; (3) 20% WCS, 13% CP; and (4) 20% crushed WCS, 13% CP. Minerals and vitamin supplements were the same in all experimental diets. The WCS treatment led to increased DM intake, fat-corrected milk yield, fat concentration, proportion of long-chain fatty acids, unsaturated fatty acids and ratio of unsaturated to saturated fatty acids (P < 0.05). Decreased concentration of dietary CP from 16 to 13% (diet 2 compared with diet 3) led to a decrease in both milk yield and milk composition (P < 0.05). WCS crushed in diets with 13% CP (diet 4 compared with diet 3) increased (P < 0.05) the concentration of conjugated linoleic acid in milk fat. The results demonstrated that adding WCS to the diet of lactating cows improves both milk yield and milk fatty acid profile, particularly the proportion of conjugated linoleic acid.

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Lactation response of cows to different levels of ruminally inert conjugated linoleic acids under commercial conditions

Canadian Journal of Animal Science ◽

10.4141/a04-073 ◽

2005 ◽

Vol 85 (2) ◽

pp. 231-242 ◽

Cited By ~ 11

Author(s):

Rachel Gervais ◽

Richard Spratt ◽

Martin Léonard ◽

P. Yvan Chouinard

Keyword(s):

Linoleic Acid ◽

Dairy Cows ◽

Conjugated Linoleic Acid ◽

Milk Production ◽

Milk Fat ◽

Metabolic Profile ◽

Milk Composition ◽

Dietary Lipids ◽

Calcium Salts ◽

Lactating Cows

Dietary conjugated linoleic acid (CLA) supplements have been shown to reduce milk fat synthesis in dairy cows. A rumen-inert source of CLA is required for commercial feed applications. The conversion of dietary lipids to a calcium salt is considered as a method to counter the extensive hydrogenation of dietary lipids that occurs in the rumen. Our objective was to determine whether feeding calcium salts of CLA under commercial conditions would affect milk production, milk composition and blood metabolic profile. A total of 240 dairy cows from eight farms were blocked according to the calving date, and randomly assigned to four treatments providing CLA at 0, 8, 16 and 32 g d-1. Milk production was recorded and milk was sampled on day 0, 7, 14, 28 and 42 of the feeding period. Blood samples were taken on day 42 from early-lactating cows (< 157 d in milk) to determine the metabolic profile. Milk fat yield was decreased 11, 20 and 28%, and milk fat concentration was reduced 13, 22 and 28% (linear; P < 0.001) when cows received 8, 16 and 32 g d-1 of CLA, respectively. Milk yield, milk protein and blood metabolic parameters were not affected by experimental treatments. Calcium salts of CLA can be used as an effective tool to manage milk fat content on commercial dairy farms. Key words: Conjugated linoleic acid, milk fat, ruminally inert fat

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