Effects of melatonin treatment on milk traits, reproductive performance and immune response in Sarda dairy sheep

Abstract

In ruminants, the role of melatonin in the control of reproductive seasonality is well reported, but it is still little known about its action on milk traits and on the immune system. The aim of this study was to assess the effect of melatonin on milk yield and composition, somatic cell count (SCC), some cytokine blood concentration and reproductive resumption in sheep. One hundred lactating sheep were allocated to two groups (of 50 sheep each), M (treated with melatonin) and C (controls), and exposed to the rams for 50 d. Time period in days from ram introduction to lambing (TRIL) and litter size were recorded. Every 15 d, from 1 March to 30 April, the individual daily milk yield was registered and milk composition and SCC, were analysed. The levels of Interleukin 2 and 6 (IL-2 and 6) and tumour necrosis factor-alpha (Tnf-a) were evaluated every 15 d. The highest fertility rate (p < .01) and the shortest TRIL (p < .05) was recorded in M group. Milk yield and composition were similar between groups. The somatic cells decreased continuously in the treated ewes (p < .01) and increased continuously in untreated ewes (p < .05). IL-2 and IL-6 increased in M group, although no statistical differences were found between groups. Melatonin administration improved reproductive efficiency, did not affect milk yield and composition and decreased somatic cells. This last effect could help to maintain healthy mammary gland and encourage farmers to reduce the use of drugs against mastitis. HIGHLIGHTSMelatonin is involved in different physiological processes, such as the control of reproductive seasonality, milk production and the immune response. Melatonin administration in Sarda sheep did not modify milk yield and composition, decreased SCC and advanced reproductive resumption in spring. Melatonin could be used to strengthen the sheep immune response in order to reduce the use of drugs for both therapeutic and preventive purposes against mastitis.

Effects of Short-Term Melatonin or Progestogen with Gonadotropic Treatments on Reproductive Performance, Hormonal Levels and Ovarian Activity of Ewes

“…Our results are consistent with the study of Lalliotis et al (1998), who incorporated melatonin implants into a MAP-based synchronization system during the anoestrous period. However, they are not in accordance with another study (Cosso et al 2021) that reported a lambing rate of 112%.…”

“…Similarly, the fertility of FGA+eCG (100%) and melatonin (50%) ewes were higher than the fertility after treatment with CIDR+eCG (60%) or melatonin + progesterone (11%) in Romney composite ewes reported by deNicolo et al (2008). Moreover, Cosso et al (2021) observed fertility of 92% in Sarda ewes treated with melatonin alone. The low fertility in melatonin treated sheep can be enhanced when used in conjunction with other techniques, such as ram effect exposure (Cognie 1990) or progestogenimpregnated intravaginal sponges (Henderson and Robinson 2000).…”

Administration of melatonin prior to modified synchronization protocol improves the productive and reproductive efficiency of Chinese crossbred buffaloes in low breeding season

“…In the current study, melatonin treatment did not influence milk volume. Similar results were reported by Cosso et al ( 60 ) that melatonin does not affect milk volume in sheep. The data indicated that melatonin does not affect milk fat, whereas recent reports claimed it reduced milk fat after melatonin treatment ( 61 , 62 ).…”

Association of Melatonin Administration in Pregnant Ewes with Growth, Redox Status and Immunity of Their Offspring

“…On the other hand, it could be assumed that melatonin treatment prioritises the presence of antioxidant peptides in the colostrum [ 47 ] over other proteins, including IgG, as was confirmed in MEL lambs by the lower levels of IgG and better redox status. According to previous studies, a decrease in IgG was shown three days after melatonin injection in lactating cows, with a concomitant decrease in somatic cell count in milk of cows [ 58 , 59 ] and ewes’ milk [ 60 ]. Contrary to the latter study and to the present one, others found a higher amount of IgG but no higher amounts of proteins in colostrum just after parturition in melatonin-treated ewes that lambed males compared to females [ 49 ].…”