The effect of Spirulina supplementation in ewes’ oxidative status and milk quality

Abstract

Spirulina (SP) is an edible blue-green algae rich in bioactive compounds such as vitamins, minerals, antioxidants, and γ-linolenic acid. However, its impact on the oxidative status of ewes’ organism and milk, as well as on milk’s quality has not been extensively studied. Forty-eight dairy Chios ewes were divided into four homogenous groups (n = 12) and were fed individually. The concentrate of the control group (CON) had no SP, while in the concentrates of the treated groups, SP was added to obtain a daily supply of 5 (SP5), 10 (SP10), and 15 (SP15) g per animal. The milk yield and chemical composition were not affected by the addition of SP. Τhe proportion of short-chain fatty acids was increased in the milk of SP5 and SP10 ewes while those of medium-chain fatty acids were reduced in the milk of SP10 compared with the CON animals. The SP addition enhanced the proportion of polyunsaturated fatty acids and reduced the thrombogenicity index in milk, while its highest level tended to decrease the milk’s atherogenicity index. A rise in the activity of superoxide dismutase (SOD) in the blood plasma of SP-fed ewes was found. The same was observed for the activities of catalase (CAT), glutathione peroxidase (GSH-Px), and glutathione transferase in the blood plasma of SP10, SP15, and SP5 fed ewes respectively. On the contrary, the protein carbonyls content (PC) in ewes’ s blood plasma declined by the dietary supplementation of SP. The oxidative stability of ewes’ milk improved by the dietary addition of SP as indicated by the rise in the activities of SOD, CAT, and GSH-Px and the total antioxidant capacity (measured by FRAP and ABTS assays) as well. Finally, the highest level of SP caused the sharpest drop in PC content of milk. In conclusion, the dietary supplementation with 15 g SP/ewe/day showed the potential to improve the ewes’ oxidative status of their organism and milk.