Periódicos Brasileiros em Medicina Veterinária e Zootecnia

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

Tek, Hasan Basri

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 (< 30 mm) wasevaluated under four groups. Mares undergoing only reproductive examination were control group Group I (n = 18). Themares has less than 30 mm in diameter folicle applied oral altrenogest (0.044 mg / bw, for 10 days) were grouped according to the month of application: Group II [February; n = 16], Group III [March; n = 57] and Group IV [April; n = 15].Ultrasonographical examinations performed at the day of admission and repeated twice a week for 15 days. Naturel matingwas planned considering to uterine edema (> 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)...(AU)

Texto completo