The effect of altrenogest treatment timing and artificial lighting on hastening of ovulation in barren mares

ABSTRACT

Background: The mares are seasonally polyestrous animals that regular ovulatory cycles of mares occur together withincreasing day length. Exposure of mares to an artificial photoperiod is the most common and predictable technique thatit is used to develop follicular activity early in the year. Follicle activity is minimal in mares during two winter months ofJanuary and February in Northern Hemisphere. The main objective of this study was to investigate efficacy of artificiallighting and timing of altrenogest treatment for hastening the ovulation in Thoroughbred mares.Materials, Methods & Results: One hundred and six Thoroughbred mares had different follicle sizes ( 35 mm folicle size), and pregnancies were determined at 14, 28 and 50th daypostovulation. Statisticaly, mean and standard deviations and general linear model procedure was performed on Minitab 17,and Anova was used to analysis of variance. The averages of the major variations were compared with the Tukey’s multiplecomparison test. The factors effecting to pregnancy rate was analyzed by Chi-square test. Correlations were comparedwith the Pearson correlation test. The effect of initial months on the size of follicle diameter was found to be significant(P = 0.037). Artificial lighting had no effect on the initial follicle diameter (P = 0.919). The initial follicle diameter (P =0.001)...