This study assessed the correlation between blood progesterone levels and age in Pesisir cattle post-Cosynch therapy. Eighteen Pesisir cows were classified into three age categories: under 3 years (A1), 3 to 5 years (A2), and above 5 years (A3). Blood samples were obtained at various intervals throughout three estrous cycles following treatment and assessed by Enzyme-Linked Immunosorbent Assay to quantify blood progesterone concentrations. A chi-square test was conducted to evaluate differences among age groups. The findings indicated marked variations in progesterone levels throughout the estrous cycles, with the minimum concentrations noted on day 11 (A1: 3.08±1.37 ng/ml, A2: 5.63±2.30 ng/ml, A3: 5.39±0.59 ng/ml) and maximum levels recorded during the luteal phase (A1: 14.39±2.25 ng/ml, A2: 16.40±6.56 ng/ml, A3: 23.59±16.38 ng/ml). Older cows (A3) demonstrated elevated progesterone levels relative to younger cows, indicating improved luteal function. Nonetheless, despite synchronization, no pregnancies were observed in either group following artificial insemination. This may be ascribed to heightened progesterone levels during insemination, signifying an insufficient estrous synchronization response. The data indicate that progesterone levels are affected by age, with older cows exhibiting a more significant hormonal profile. The unsuccessful development of pregnancy underscores the necessity for enhanced optimization of estrous synchronization techniques to augment reproductive success in Pesisir cattle.
Keywords | Pesisir cattle, Progesterone levels, Cosynch procedure, Estrous synchronization