Journal of Food, Agriculture and Environment

The effect of grazing management and camelina seed supplementation in the diet on milk performance and milk fatty acid composition of dairy ewes

Author(s):

Daniel Mierlita^*, Stelian Daraban, Florin Lup, Anca Chereji

Recieved Date: 2011-07-10, Accepted Date: 2011-10-06

Abstract:

The objective of this study was to investigate the effects of ewes’ feeding system (grazing vs. part-time grazing) in combination or not with camelina seed (Camelina sativa L.) as dietary supplement on milk yield parameters, and especially on the fatty acid (FA) profile of milk fat. Experimental diets were constituted by a 2 x 2 factorial arrangement of grazing time (grazing 12 h/d = G vs. grazing 6 h/d and diet supplementation with grass hay ad libitum = PG) and camelina seed (-CS = no camelina seed vs. +CS = 80 g/d camelina seed). No differences were noticed between the dietary groups in respect of milk yield or milk protein content. G diet ewes’ milk contained less total fat. Feeding + CS increased energy corrected milk (ECM), milk fat content and fat yield. FA profile in the milk fat of G diet ewes proved more beneficial to human health as a result of the higher concentrations of α-linolenic acid (C18:3) and cis-9, trans-11 CLA (conjugated linoleic acid isomer) and the lower content of saturated hypercholesterolemic FA. Camelina seed generated a higher concentration of monounsaturated FA, especially of C18:1, trans-11 (trans-vaccenic acid) in milk fat, and resulted in the increase in the concentration of C18:3 and cis-9, trans-11 CLA. Feeding a grazing diet combined with CS increased the proportion of C18:1, trans-11 FA, of C18:3 and of cis-9, trans-11 CLA in milk fat at the expense of saturated FA, being considered beneficial to human health. Ewes fed +CS combined with grazing diet (G/+CS) had the lowest proportion of C10:0, C14:0, C16:0 and C17:0 (feeding system x CS: P<0.10 to 0.05) in milk fat; conversely they had the highest proportion of C18:0, t11-C18:1, c9-C18:1, c9,t11-CLA and C18:3 in milk fat (feeding system x CS: P<0.05 to 0.001). The decrease in C12:0, C14:0 and C16:0 resulted in the decrease of milk fat atherogenic index of G diet ewes and of those whose diet was supplemented with camelina seed (+CS), compared to PG diet and -CS diet, respectively. The conclusion was that when the quality and availability of pasture does not limit milk yield, limiting grazing time adversely affects FA profile in milk, with no positive effect on milk yield.

Keywords:

Dairy ewes, milk fat, pasture, camelina seed, fatty acid composition

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Journal: Journal of Food, Agriculture and Environment
Year: 2011
Volume: 9
Issue: 3&4
Category: Agriculture
Pages: 368-373

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