The luteal regression and the follicular dynamic were evaluated during the natural luteal regression period (n=14) or after induction of luteolysis by the administration of 500 g of cloprostenol (n=13), using a portable ultrasound device. Luteolysis induction increased luteal regression over 24 (0.89±0.13×0.24±0.17cm²/day; P<0.05) and 48 hours period (0.78±0.15×0.36±0.07cm²/day; P<0.05), but the reduction of progesterone concentration was similar (P>0.05). There was no difference (P>0.05) in follicular dynamic between the two groups. Cows in which the largest follicle during luteolysis was the ovulatory follicle presented shorter periods of follicular growth (3.71±0.56×5.26±0.34 days; P<0.05) and luteolysis to estrous intervals (85.71±14.68×121.33±8.34 hours; P<0.05). This study shows that functional (but not morphological) regression of corpus luteum and follicular dynamics after spontaneous or induced luteolysis are similar in Gir cattle.
Cattle; Gir; follicular dynamic; luteolysis