Luteal development, function and regression were studied in Gir cattle. Morphologic characteristics of corpora lutea were evaluated during the estrous cycle (n=15), using a portable ultrasound device. Luteal activity was evaluated by serum progesterone. The corpus luteum was first identified at 3.28±0.19 days after ovulation. There was a day effect on corpus luteum cross-section area (P<0.0001), on luteal tissue cross-section area (P<0.0001) and on progesterone levels (P<0.0001). Maximum corpus luteum cross-section area occurred between days 7 and 16 of the estrous cycle. During this period, mean corpus luteum area was 3.21±0.05cm², mean luteal cavity area was 0.42±0.04cm², luteal tissue was 3.06±0.05cm², and mean progesterone concentration was 4.61±0.17ng/ml. Luteal growth rate between first detection and day 7 was 0.42±0.05cm²/day, and regression rate between days 16 and 21 was -0.36±0.04cm²/day. Corpora lutea characteristics in Gir cattle were similar to those observed in other cattle breeds.
Cattle; Gir; Corpus luteum; progesterone
