The use of fecal progesterone profile to determine ovarian function in gilts

Abstract

The objectives of the present study were to measure level of fecal progesterone (P4) metabolite in gilts in order to determine the ovarian function in relation to oestrous behaviour. In addition, correlation between plasma and fecal P4 metabolite were also analyzed. Five prepubertal crossbred gilts were included in the experiment. Laparoscopy was used to determine ovarian status in all gilts. Oestrus detection was performed daily and all gilts were allowed to have a direct boar daily. About 10 g of feces was collected either directly from rectum or immediately after defecation and then kept at –20 °C until analysed. Blood was collected from a jugular vein and immediately put into heparinized tube. Plasma was separated within 20 minute after collection and then kept at –20 °C until analysed. Both fecal and blood samples were collected every 7 days before the gilts showed signs of first oestrus. After first oestrus was observed the samples were collected every 3 days starting from day 1 (standing heat) until day 40. P4 metabolite in feces was extracted by using phosphate buffer solution. The measurement of P4 level in blood (plasma) and feces were performed by a solid-phase 125I-radioimmunoassay and its correlation was calculated by Spearman’s correlation. On average, fecal P4 metabolite was highest on day 13 after standing heat, whereas plasma P4 was highest on day 10 after standing heat. The maximum levels of P4 metabolite in feces varies among gilts from 143 to 2303 nmol/kg, whereas the minimum levels of P4 metabolite in feces varies from 0.45 to 5.7 nmol/kg. Level of plasma P4 and fecal P4 metabolite was positively correlated (r=0.73, P<0.001, n=65). The correlation coefficient within animal between plasma P4 and fecal P4 metabolite in 5 gilts were 0.63 (P<0.05), 0.64 (P<0.05), 0.92 (P<0.001), 0.81 (P<0.001) and 0.69 (P<0.01). The level P4 metabolite in feces was lower than 1.5 nmol/ml during prepubetal period. Levels of fecal P4 metabolite increased around day 7 after standing heat and remained in a high level (>20 nmol/kg) until day 16 after standing heat. In conclusions, levels of fecal P4 metabolite significantly correlated with P4 in plasma in all gilts and fecal progesterone profile can be a useful measurement to determine luteal function of ovaries in gilts.