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Abstract :

Extruded linseed (EL), rich in α-linolenic acid, is a feed used in dairy cattle nutrition in order to modify milk fatty acid profile in a way to potentially improve human health. However, effects of EL on dairy cow performance are little documented. The objective was to assess the effects of EL supplementation on animal performance, then to estimate the economic consequences at a farm level. A meta-analysis (21 experimental trials) allowed us to characterize the variability of animal responses related to the quantity of EL and the basal diet composition. A cohort study performed on 1204 herds and 194056 cows displayed an association between quantity of EL and milk yield (+ 0.4 à +1,3 kg/d), and milk contents (-0,03 to -0,20 g/kg MPC and -0,1 to -0,9 g/kg MFC). Other beneficial associations were highlighted: a decrease in number of days open and a better probability to cure of intra-mammary infections. Finally, we demonstrated that a farmer willing to modify the fatty acid composition of the milk to improve human health face higher feed costs but can be rewarded by better animal performance that increase profitability of the farm.

Key words :

Dairy cow, Extruded linseed, Animal performance, Epidemiology, Meta-analysis