Sensibilidade e especificidade do perfil estral para o diagnóstico de ovulação em fêmeas suínas

Abstract

The objective of this study was to evaluate the sensitivity and the specificity of the estimation of ovulation (ESTOV) in female swine based on estrus profile using estrus detection by back pressure in the presence of a boar (BPB) in comparison with real time ultrasound diagnosis. Starting at weaning, 198 females were submitted to BPB 3 times a daily (6:30, 14:30 and 22:30 h) and to ultrasound exam twice daily (6:30 and 14:30 h). In the estrus profile, the beginning of the estrus was characterized by the first positive response to BPB and the end of the estrus was characterized by the first negative response to BPB. Ovulation time (OT) was determined by ultrasound diagnosis by the absence of pre-ovulatory follicles or when the number of follicles at the moment of diagnosis was inferior to that observed in the previous exam, as long as those findings were confirmed in the next exam. Estrus duration (ED) was categorized in 3 groups, to make possible to estimate the frequency of female ovulating before, during or after the third part of the estrus, considering both ESTOV and OT. Sensitivity and specificity were estimated for ESTOV considering the OT as reference. The mean weaning-to-estrus interval (WEI) was 86,6 ± 30,7 h, mean ED was 62,6 ± 18,1 h and mean estrus-toovulation interval (EOI) was 47,4 ± 14,8 h. The initial and final time of ovulation did not differ between categories of WEI (< 72 h, 72 – 96 h e > 96 h), but the weaning-toovulation interval was longer as the WEI was longer (P < 0,0001). Mean ESTOV was 49,5 ± 3,6 h. Considering real time ultrasound diagnosis as reference, 20,4% of the ESTOV would have occurred before ovulation and 27,9% would have occurred after ovulation, corresponding to 48,3% of imprecise estimations. Considering the frequency of ovulation occurring before or during the third part of estrus, the sensitivity and specificity of ESTOV in comparison with OT were equal to 84,3% and 35,3%, respectively. Sensitivity and specificity were equal to 83,8% and 56,7% when considering ovulations occurring during or after the third part of estrus. Additionally, when considering ovulations occurring or not during the third part of estrus, sensitivity and specificity were equal to 66,3% and 56,7%, respectively. Thus, potentially high losses can occur if breeding systems are exclusively based on estrus profile because this method is inaccurate to estimate ovulation, as indicated by its low sensitivity and specificity when compared with real time ultrasound diagnosis.