Journal
JOURNAL OF DAIRY SCIENCE
Volume 93, Issue 4, Pages 1677-1684Publisher
ELSEVIER SCIENCE INC
DOI: 10.3168/jds.2009-2681
Keywords
lactating dairy cow; alpha-linolenic acid; milk fatty acid; duodenal infusion
Funding
- Ministry of Agricultural Science and Technology [Nyhyzx07-036-01]
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Increasing the a-linolenic acid (LNA; 18:3 cis-9,cis-12,cis-15) content of milk fat might help promote consumers' health. The objective of this study was to determine the potential to alter the content of LNA in milk by duodenal infusion of a free fatty acid mixture rich in LNA. Four multiparous lactating Chinese Holstein cows fitted with duodenal carmulas were administered 2 treatments in a crossover design: an LNA-rich fatty acid infusion at varying concentrations (0, 40, 80, 120, and 160 g/d) versus a basal infusate control. Dry matter intake was not affected by LNA infusions. Milk production tended to decrease and was quadratically affected as LNA infusion increased, but 4% fat-corrected milk yield was not changed. Milk fat content tended to increase linearly with LNA infusion. Milk protein content was not changed by LNA infusion, whereas milk lactose content and yield were decreased quadratically as LNA infusion increased. Increasing the amount of LNA infused into the duodenum linearly increased concentrations of 18:3 cis-9,cis-12,cis-15 (0.61 to 25.4 g/100 g of total fatty acids) and 18:2 cis-9,cis-12 in milk fat. Increasing LNA decreased the percentages of 4:0, 14:0, and 16:0 fatty acids linearly. Increasing LNA also linearly decreased the percentages of 18:1 cis-9 and 18:2 6.9-9,trans-11 in milk fat. Milk fat content of 20:5 cis-5,cis-8,cis-11,cis-14,cis-17 was quadratically affected, whereas concentrations of 18:0, 18:1 trans-9, 18:1 trans-11, and 18:2 trans-10,cis-12 were not affected. Increasing the supply of 18:3 cis-9,cis-12,cis-15 to the small intestine linearly increased 18:3 cis-9,cis-12,cis-15 in milk fat and markedly altered milk fat composition.
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