Effect of forage:concentrate ratio on the quality of ewe's milk, especially on milk fat globules characteristics and fatty acids composition

Abstract

The aim of this study was to evaluate the milk quality of Massese ewes receiving diets with different forage:concentrate ratios (FC ratio), specially on milk fat globules characteristics and fatty acids composition. The diet is one of the main environmental factors that influence the lipidic content of milk. A trial was carried out on twenty ewes, which had been subdivided into two homogeneous groups and kept indoors at 25 days post partum. The experiment lasted 60 days, from 40 to 100 days post partum and the animals were fed two diets that differed in terms of the FC ratio: 60:40 and 40:60, as fed. The results obtained in this study showed that a greater proportion of forage, compared with an higher percentage of concentrate, led to an increase in the percentage of fat (+8.66%) and to a decrease in the percentage of milk fat globules with a size between 2 and 5 microm (-17.32%). However, the average diameter was not affected. There was also a decrease in the percentages of some medium chain fatty acids (C12:0, C14:0; -14.89% and -4.03 respectively) and an increase in mono and polyunsaturated ones such as trans11-C18:1 (+31.71%), total CLA (+22%), EPA (+18.18%) and DHA (+66.67%). In conclusion, a greater proportion of forage seem to improve the milk fatty acid profile by the increase of some fatty acid identified has being beneficial for human health.

Sustainable Intensification? Increased Production Diminishes Omega-3 Content of Sheep Milk

“…In contrast, the fatty acids that ought to be reduced in the diet (particularly myristic and lauric acid) and the ratio of n-6/n-3 appeared to be closely associated with the supplementary feeding of both "hays" and "concentrate feeds", with the latter clearly being the most influential of all the factors considered. Again, this confirms indications from univariate analyses and previous studies [22,24,27].…”

“…The 21% increase and 9% increase, respectively, in the concentration of saturated lauric and (especially) myristic acid in milk from SI farms are also of concern, since these, along with palmitic acid, are the main SFAs linked to inflammation and increased cardiovascular risk, with the strongest connection being for myristic acid [12]. Such composition differences, along with the fact that ewes in the EX flocks produced 37% less milk, confirm previous studies that have reported that while higher conserved forage and concentrate feeds in dairy diets do increase productivity, they also have negative effects on milk's nutritional quality, especially in terms of FA profiles [24,27]. It ought to be noted here, however, that there were no differences in CLA or protein contents, the SCC, or CFUs, and there was only a small difference in the lactose content between milk from semi-intensive and extensive systems.…”

Eicosapentaenoic and docosahexaenoic acids as inflammation-modulating and lipid homeostasis influencing nutraceuticals: A review

“…Similarly, EPA and DHA content in the ewe's milk was increased by 18% and 67% respectively, by changing forage/ concentrate ratio from 40/60 to 60/40 (Martini, Liponi, & Salari, 2010). Grass feeding can increase also DHA content in beef (Scollan et al, 2006).…”

Amiata Donkeys: Fat Globule Characteristics, Milk Gross Composition and Fatty Acids

“…Each milk sample was thus characterised by a different percentage of MFGs, for each diameter size class. Subsequently, the ten classes were grouped, as reported in Martini et al (2010a), into three sizes of fat globules: small globules with a <2 µm diameter, medium-sized globules with a diameter from 2 to 5 µm, and large globules with a >5 µm diameter.…”