RESUMO
In order to determine whether seasonal variations may influence the estrous cycle length (ECL), corpus luteum size (CLS), maximum area of CL (MACL), day of cycle with maximum area of CL (DCMACL), and pre-ovulatory follicles size (PFS), ten Criollo Limonero heifers were subjected to daily ultrasound ovary scanning throughout their estrous cycles during three seasons: hot-dry (HD), hot-humid (HH), and wind-rain (WR). The effect of season on ECL, MACL, DCMACL, and PFS was analyzed with an ANOVA (PROC GLM, SAS), whereas, for the effect of season on CLS, an ANOVA with repeated measures (PROC MIXED, SAS) was used. Results showed no effect (P > 0.05) of season on ECL, MACL, and DCMACL. However, size of PFS was larger (P < 0.02) during the WR season and the CLS tended (P < 0.09) to be lower during the HH. In conclusion, the relative stability of ECL, MACL, DCMACL, PFS, and CLS measures suggests no major seasonal variations which could imply adaptation capability of Criollo Limonero cattle to the tropical environment.
