Ultrasonographic characterization of the ovaries and the uterus in prepubertal and pubertal gilts.

In two experiments (EXP), 44 and 52 crossbred gilts (mean age+/-S.D. and weight+/-S.D.: 204+/-22 and 203+/-9 days, 114+/-13 and 127+/-12 kg, respectively, in EXP 1 and 2) from four farms were examined by means of transcutaneous ultrasonography (US) to define the characteristics of the ovaries and the uterus (echotexture, size) and to investigate the appropriateness of US to determine sexual maturity. Gilts were judged as prepubertal [PRE; follicles 2-5 mm (F2-5) only] or pubertal [PUB; F7-8, corpora lutea (CL), corpora haemorrhagica (CH)] at the first (PUB-1; EXP 1) or a subsequent estrous cycle [PUB-2; additionally corpora albicantia (CA); EXP 1] by US, and results were verified by postmortem examination (EXP 1), or progesterone analysis and detection of estrous signs (EXP 2). Accuracy of US was 100% for PRE and PUB (both EXP) and 77.3% for PUB-1 and PUB-2 (EXP 1). PRE and PUB with CL/CH had uteri of homogeneous, PUB with F7-8 of heterogeneous echotexture. The size was expressed as the mean sectional area (SAsono) of 2-5 cross-sections of the uterine horns (calculated by multiplication of 1/2 the maximum x the minimum dimension of the cross-sections x pi). SAsono corresponded with the sectional area of postmortem dissected transverse uterine segments relatively with r=0.92 (P<0.0001; EXP 1). Mean SAsono (both EXP) and mean uterine weight (EXP 1) were PRE<PUB (all P<0.0001). SAsono and UW showed a high correlation (UW=287x SAsono-66; r=0.92; P<0.0001; EXP 1). In conclusion, the diagnosis of sexual maturity is facilitated in prepubertal and pubertal gilts based on the characteristics of the ultrasonographic appearance of the ovaries and the size of the uteri.