The problems caused by a high disposal of sows are reflected in the productivity and profitability of the herd, since they affect in a negative way the reproductive and economic performance of pig farms, all over the world. One of the main reasons forsows disposal is the presence of ovarian cysts (luteinized cyst, cystic corpus luteum and follicular cyst), which can be originated from neuroendocrine malfunction, and they are considered as the increased size of a graffian follicle that has not ruptured, and may be multiple and on both ovaries, sometimes due to insufficient luteinizing hormone or ovulation failure (1). Moreover, they maybe present as a result of stressful conditions provoked either by physical or emotional stress which are perceivedby the central nervous system influencing the productivity of a sow fay preventing her to get pregnant and producing a non-infectious infertility (2). Those ovarian cysts can also cause anoestrus and follicular atresia, which bring as a consequence a drop in conception rates, an irregular oestral cycle and aggressive behaviour in affected sows (2). Previous studies carried out by Toriumi, et al. (1996), showed that the development of luteal ovarian cysts are associate mainly to a deficiency of luteinizing hormone (LH) than to an intrinsic abnormality of the ovary. The cystic corpus luteum is produced for a high concentration of LH, in contrast, the follicular cyst is caused by low LH and high follicle-stimulating hormone (FSH) levels (5). Another reason for sow disposal is the presence of endometritis which is considered as the inflammation of the endometrium. This disturbance can cause embryonic mortality and termination of the pregnancy, and consequently an important reduction in parturition rate with a marked effect on productivity (2). In this study, due to the high percentage of cysts found in sows sent to slaughter for low productivity, as well as for the economic losses observed, it was decided to develop a methodology for macroscopic and microscopic evaluation of the reproductive tract of such animals, making emphasis on the uteri and ovaries.
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