Impact of Photoperiod Length and Treatment with Exogenous Melatonin during Pregnancy on Chemical Composition of Sheep’s Milk

Abstract

The aim of the study was to determine the effect of photoperiod and exogenous melatonin on milk yield and chemical composition of sheep’s milk. Sheep (n = 60) were randomly divided into three groups: lambing in February (Group 1—n = 20), lambing in June (Group 2—n = 20), and lambing in June and treated with subcutaneous melatonin implants (Group 3—n = 20). Milk yield was higher for Group 1 and Group 2 than for Group 3 (p < 0.01). The milk of ewes of Groups 2 and 3 had a significantly (p < 0.01) higher content of dry matter, protein, and fat. Group 3 sheep’s milk contained significantly more (p < 0.01) of SFA (Saturated Fatty Acids). The highest content of MUFA (Monounsaturated Fatty Acids) and PUFA (Polyunsaturated Fatty Acids) was found in the samples collected from Group 1, the lowest was in the milk of Group 3 animals. The highest (p < 0.01) CLA, content was identified in the milk of Group 1, while the lowest was recorded for the milk obtained from sheep treated with exogenous melatonin (Group 3). The experiment carried out has shown that day length and treatment with exogenous melatonin modulate the chemical composition of milk.

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

“…According to others, higher fat content was found in colostrum of ewes treated with melatonin in their third month of pregnancy but no alteration was found in protein content [ 49 ]. Molik et al [ 50 ] have shown that melatonin treatment increases protein and fat content of milk, which is in agreement with our results.…”

A novel signaling transduction pathway of melatonin on lactose synthesis in cows via melatonin receptor 1 (MT1) and prolactin receptor (PRLR)

“…It has been reported that continuously feeding rumen bypass melatonin to the cows not only significantly reduced mastitis but also the lactose content in milk ( Yao et al, 2020 ). Auldist et al reported that subcutaneous implantation of melatonin in cows lowered their milk lactose ( Auldist et al, 2007 ) and similar results were observed in dairy goats and sheep ( Molik, Błasiak & Pustkowiak, 2020 ; Yang et al, 2020 ). Although melatonin supplementation with reduced milk lactose content in cows or other species has been frequently reported, the underlining mechanism(s) are currently unknown.…”

The role of sheep’s milk bioactive substances in the prevention of metabolic and viral diseases

“…A study by Dahiya and Puniya (2018) in mice with diet-induced obesity showed that supplementation with CLA-enriched skim milk exerted "anti-obesity" effects. Sheep's milk has the highest concentration of CLA isomers compared to the milk of other ruminants (Molik et al, 2020). Due to the highest content of CLA isomers in sheep's milk and its products, they can be used as food ingredients supporting weight control and preventing obesity.…”

“…A diet rich in CLA isomers, most of which are found in sheep's milk (Molik et al, 2020), may prevent cancer. The trans(t)-10, cis(c)-12-CLA isomer exerts "antitumour", "anti-obesity" and "antidiabetic" effects, while c-9, t-11-CLA has mainly "antitumour" properties.…”