The Effect of Subcutaneously Administered Crystal's Oily Solution on Estrus and Conception Rates in Ewes

Abstract

The study aims to evaluate the effects of subcutaneously (SC) injected oily solution of melatonin crystal at different doses in 2-3 years, healthy, multiparous sheep during the anoestrus period on serum melatonin and prolactin levels, estrus occurrence, mating, conception, and pregnancy rates. The study group consists of 350 ewes. The ewes were divided into 5 groups: MEL10 (n=70, 10mg melatonin), MEL20 (n=70, 20mg melatonin), MEL40 (n=70, 40mg melatonin), placebo (n=70), and control (n=70) groups. The melatonin groups received SC injections of the oily melatonin solution 11 days before ram introduction. The placebo group received only the oily solution. The control group did not receive any treatment. Blood samples were collected from all groups before the melatonin injection and on the 11th day after the injection. The data showed that the melatonin level in the blood samples collected before and after the injection increased in the MEL10 (P:0.045) and MEL20 (P:0.0359) groups. Additionally, the prolactin level decreased in the second blood sample collected from all groups (P>0.05). Regarding reproductive parameters, the estrus rate in the MEL10, MEL20, MEL40, placebo, and control groups was 75.71%, 58.57%, 54.28%, 51.42%, and 52.85%, respectively. The mating rate was 61.42%, 57.14%, 52.85%, 48.57%, and 50% in the same groups, and the pregnancy rate was 60%, 52.85%, 42.85%, 41.42%, and 38.57%, respectively. The conception rate was determined as 97%, 92%, 81%, 85%, and 77% in the MEL10, MEL20, MEL40, placebo, and control groups, respectively. In conclusion, subcutaneous injection of melatonin at appropriate doses to sheep can indirectly simulate the breeding season, and stimulate heat. Additionally, it can increase pregnancy and conception rates. This method can considered a potential alternative to melatonin implants or different synchronization methods in the future.