Effect of milking frequency and α-tocopherol plus selenium supplementation on sheep milk lipid composition and oxidative stability

Abstract

The aim of this research was to study the effect of milking frequency [once-daily milking (ODM) vs. twice-daily milking (TDM)] and antioxidant (AOX) supplementation on fatty acid (FA) profile and oxidative stability in sheep milk. Sixteen Assaf ewes were used; 8 did not receive any vitamin-mineral supplement (control), and the other 8 received an oral dose of 1,000 IU of α-tocopherol and 0.4 mg of Se daily. The experiment consisted of 2 consecutive periods; the first was 3 wk with TDM of both mammary glands. The second period was 8 wk and consisted of ODM of one mammary gland and TDM of the other gland. All ewes were fed ad libitum the same total mixed ration from lambing and throughout the experiment. There were no differences in plasma or milk Se concentrations between control and AOX ewes. However, plasma and milk α-tocopherol concentrations and AOX capacity were increased in ewes receiving the AOX supplement. Milk FA profile was practically unaffected after 21 d of AOX supplementation. However, after 77 d, AOX supplementation increased the relative percentage of C16:0 and cis-9 C18:1 and reduced the proportions of some saturated FA with less than 16 carbons and cis-9 C12:1. Antioxidant supplementation had no effect on the proportions of conjugated linoleic acid or total polyunsaturated FA (PUFA) but decreased the proportion of trans-7,cis-9 C18:2 and increased that of n-6 C20:3. Once-daily milking did not affect α-tocopherol, Se, or fat resistance to oxidation in milk. Total monounsaturated FA, cis-9 C16:1, and several cis and trans isomers of C18:1 were increased and total saturated FA were decreased in milk from ODM glands. Compared with TDM, ODM increased the proportions of cis-9,cis-12 C18:2 and several isomers of C18:2 and reduced those of cis-9,cis-12,cis-15 C18:3 and some PUFA of 20 and 22 carbons, but total proportion of PUFA was unaffected. Once-daily milking and AOX supplementation modified milk FA profile, but the effects of ODM could be considered of little biological relevance for consumer health. Supplementing ewes with α-tocopherol plus Se could be considered an effective strategy to improve plasma AOX status and reduce milk fat oxidation without substantial changes in the milk FA profile.

Fatty Acid Composition of Dairy Milk: A Case Study Comparing Once- and Twice-a-Day Milking of Pasture-Fed Cows at Different Stages of Lactation

“…Additionally, the BCS of cows milked OAD was higher than the BCS of cows milked TAD. The changes in the milk and its composition in the present study are consistent with Delamaire and Guinard-Flament [24] as well as Pulido et al [25].…”

“…The lower proportion of SFA in cows milked OAD, compared to cows milked TAD, is consistent with the findings of Dutreuil et al [31], Ferlay et al [32] and Pulido et al [25]. The higher proportion of UFA in milk from cows milked OAD, compared to cows milked TAD agrees with Dutreuil et al [31].…”

Sesame Meal, Vitamin E and Selenium Influence Goats’ Antioxidant Status

“…No effect on the oxidative stability of cows' milk has been observed when the animals' diets were supplemented with Se [10,11]. On the other hand, dietary supplementation with 1000 IU VitE and 0.4 mg Se/day simultaneously improved the plasma antioxidant status and reduced the milk fat oxidation of ewes, as found recently by Pulido et al [6], indicating a synergistic role between these compounds (Se and VitE).…”

“…Their content in milk is closely related with the type and the origin of the animals' feedstuffs [3,4], but because-in most cases-the basal diet doesn't fulfill the animals' Se and VitE requirements, their synthetic or organic (in the case of Se) forms are usually incorporated in their rations. Both Se and VitE are the most well established dietary supplements, and a number of studies have determined their impact on the oxidative status and oxidative stability of milk by using supplementary doses exceeding the animals' nutritional requirements [5,6]. More specifically, the oxidative deterioration of stored milk was avoided when red clover-fed cows were supplemented with 1182 mg VitE/animal daily [7].…”

Effect of Milking Vacuum and the Supplementation of Vitamin E and Se in Milk Quantity, Quality, and Hygiene of Mammary gland in Mountainous Greek Sheep

“…It is well known that vitamin E and selenium affect the activity of leukocytes [17][18][19] due to the micronutrients' involvement in biological roles. Vitamin E and Se act as antioxidants and protect lipid membranes from reactive oxygen species and lipid hydroperoxides, thus improving the immune system responses [20,21]. Sheep frequently lack these two nutrients [22,23] and deficiencies of either vitamin E or Se have been associated with increased incidence and severity of intramammary infections, increases in clinical mastitis cases, and higher SCC [21,24,25].…”