Premium
t 10, c 12‐18:2‐Induced Milk Fat Depression is Less Pronounced in Cows Fed High‐Concentrate Diets
Author(s) -
Glasser Frédéric,
Ferlay Anne,
Doreau Michel,
Loor Juan J.,
Chilliard Yves
Publication year - 2010
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/s11745-010-3460-x
Subject(s) - conjugated linoleic acid , rumen , lipogenesis , zoology , dry matter , chemistry , fatty acid , linseed oil , latin square , total mixed ration , lactation , food science , biology , adipose tissue , ice calving , biochemistry , linoleic acid , fermentation , pregnancy , genetics
In intensively reared dairy cows, milk fat secretion is reduced in response to high‐concentrate diets and it is often referred to as the “milk fat depression” (MFD) syndrome. Some trans fatty acid (FA) isomers produced in the rumen of the cows, including t 10, c 12‐18:2, are known for their inhibitory effect on mammary lipogenesis. To study whether this effect depends on the basal diet, duodenal infusions of t 10, c 12‐18:2 were performed on cows fed four different diets (a factorial arrangement of forage:concentrate ratio and linseed oil supplementation). The overall response obtained with t 10, c 12‐18:2 infusion was consistent with previous studies: a decrease in milk fat content and yield without significant variations in milk yield. Mean transfer efficiency of infused t 10, c 12‐18:2 was 19.6%. However, the decrease in milk fat and FA yields (both de novo synthesis and preformed long‐chain FA) was less pronounced in cows fed high‐concentrate diets (−27% of the initial level), compared with cows fed low‐concentrate diets (−42% of initial level). This difference was independent of dietary oil supplementation and milk FA yield before infusion. Results pertaining to effects of dietary forage:concentrate ratio were confirmed by statistical meta‐analysis of data from previously published t 10, c 12‐18:2 infusion experiments. This study shows that in cows fed MFD diets the mammary gland becomes more resistant to or experiences a lower response potential to further inhibition of lipogenesis and/or delta‐9 desaturation of FA.