Abstract

LOPEZ ORDAZ, Rufino et al. Relationship between 9-cis, 11-trans and 10-trans, 12-cis conjugated linoleic acid isomers and milk yield in Holstein-Friesian cows. Review. Rev. mex. de cienc. pecuarias [online]. 2013, vol.4, n.3, pp.339-360. ISSN 2448-6698.

The purpose of the present review was to explore the mechanisms of addition of 9-cis, 11-trans and 10-trans, 12-cis conjugated linoleic acid (ALC) isomers to dairy cow diets and their relationship to milk yield. Both isomers are formed by isomerization of linoleic acid by the rumen bacteria Butyrivibrio fibrisolvens. They can also be produced by desaturation of vaccenic acid (11-trans 18:1) in the small intestine and liver of dairy cows. In humans, consumption of these isomers is associated to hypocholesterolemic, antiatherogenic functions, stimulating the immune system, providing protection against certain types of cancer, as an antioxidant and stimulating drops in body weight too. In contrast, dairy cows fed with both isomers show an increase in milk yield associated to reduced milkfat content. Isomer 9-cis, 11-trans is responsible for increases in milk yield; whereas 10-trans, 12-cis is related to a drop in milk fat. Energy partition has a big impact on reducing postpartum negative energy balance. This is associated to an increase in cow reproductive activity and condition. Milk fat depression owing to either conjugated linoleic acid isomers or milk fat depressing diets can be explained through presence of fat synthesis inhibitors. In conclusion, addition of both isomers to dairy cow diets during lactation do not affect DMI, body weight and condition and protein yield. Quite the reverse, addition of both isomers to dairy cow diets during lactation increases milk yield and diminishes milk fat content.

Keywords : Conjugated linoleic acid; trans isomers; Butyrivibrio fibrisolvens.

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