Effect of under- and overfeeding on sheep and goat milk and plasma enzymes activities related to oxidation.

Twenty-four dairy sheep and goats, respectively, were assigned each to three homogenous subgroups per animal species and fed the same diet in quantities which met 70% (underfeeding), 100% (control) and 130% (overfeeding) of their energy and crude protein requirements. The results showed that the underfed sheep in comparison with the control had significantly lower glutathione reductase (GR), superoxide dismutase (SOD), catalase and glutathione peroxidase (GPX) activities and total antioxidant capacity (measured with Ferric Reducing Ability of Plasma [FRAP] assay) in their blood plasma. A significant increase in the glutathione transferase (GST) and GPX activities, malondialdehyde content and total antioxidant capacity (measured with 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) [ABTS] assay) in the blood plasma of underfed goats compared with controls was observed, while the opposite happened for the GR and SOD activities. The underfeeding in both animal species caused a significant increase in the protein carbonyls (PC) content of their blood plasma. The overfeeding, compared with the control, caused a significant decline in the GPX activity and total antioxidant capacity (measured with FRAP) in the blood plasma of sheep while the opposite happened for the GPX and GST activities in the case of goats. The overfed animals, of both species, compared with the respective controls, had higher PC content in their blood plasma. The feeding level had no noticeable impact on the antioxidants' enzymes activities of milk in both animal species. Moreover, the underfeeding in the blood plasma and the overfeeding in milk of both animal species resulted into a significant increase in the PC content. Finally, only in sheep milk, the underfeeding, compared with the respective control, and overfeeding reduced significantly the total antioxidant capacity (measured with ABTS). The feeding level caused oxidative stress in both organism and milk but the response was different in animal species and needs further investigation.

Effect of soya bean and fish oil inclusion in diets on milk and plasma enzymes from sheep and goat related to oxidation.

This study investigated the effects of dietary inclusion of soya bean oil combined with fish oil (SFO) on the activities of a) superoxide dismutase (SOD), glutathione reductase (GR), catalase (CAT) and glutathione transferase (GST) in blood plasma and b) SOD, GR, CAT and lactoperoxidase (LPO) in the milk of sheep and goats. Furthermore, the oxidative stress indicators for measuring total antioxidant activity and free radical scavenging activity [ferric reducing ability of plasma (FRAP) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assays] and oxidative stress biomarkers [malondialdehyde (MDA) and protein carbonyl (PC)] were also determined in the blood plasma and milk of the animals. For this purpose, twelve dairy sheep and twelve dairy goats were assigned each to two homogenous subgroups. Treatments in both animal species involved a control diet without added oil and a diet supplemented with 5% soya bean oil and 1% fish oil. The results showed that the inclusion of SFO in the diets of sheep and goats increased significantly the activities of CAT and GR in their blood plasma. The same effect was observed for the activities of GST and FRAP in the blood plasma of goats. Moreover, the fact that the goats had significantly higher average daily PUFA intake (3.62 g/kg BW0.75 ) compared to sheep (2.51 g/kg BW0.75 ) resulted in an enhancement in the MDA content in their plasma. A significant increase in CAT activity in the milk in both animal species fed with SFO diets was also found. Finally, due to the higher apparent transfer rate of n-3 FA from the diet to the milk in sheep, the PC concentrations were found to be enhanced in their plasma and milk. In conclusion, the impact of dietary SFO supplementation on the oxidative status of body and/or on the milk of small ruminants depends not only on the daily PUFA intake, but also on the amount of n-3 FA that reach their milk.

A comparative study of the fatty acid and terpene profiles of ovine and caprine milk from Greek mountain sheep breeds and a local goat breed raised under a semi-extensive production system.

The objective of this study was to compare the fatty acid and terpene profile of ovine and caprine milk from animals raised under a semi-extensive production system in commercial farms located in Northwest Greece. Regarding fatty acid profile, ovine milk had a higher percentage of conjugated linoleic acid (CLAcis-9, trans-11) as well as higher percentages of both n-6 and n-3 fatty acids in relation to caprine milk. Terpene profile analysis showed a high frequency of appearance for α-pinene, d-limonene, ß-pinene in both types of milk. ß-Caryophyllene was detected in the majority of the examined ovine and caprine milk samples suggesting that its presence could be used as a potential biomarker of grass feeding. The relative frequency of appearance was higher in caprine milk for the majority of identified terpenes. Ovine milk had better nutritional value in comparison to caprine milk that had an enriched terpene profile than ovine milk.