A study of some factors affecting reproductive performance in female pigs in Kenya

Abstract

The objective of the pig industry is to produce a large number of healthy piglets efficiently and economically. Thus the sow is the productive unit of industry. The reproductive processes of the sow include estrous cycles, ova production, copulation, pregnancy maintenance, parturition and lactation. At the end of the gestation period, the sow should produce a satisfactory number of morphologically and functionally normal piglets and nurture them to weaning age with minimum losses. Malfunction or failure of any or a number of these reproductive processes would affect the' reproductive performance of the sow. Investigations on reproductive performance and problems in swine have been made in different parts of the world. Very little has been done on this subject in Kenya. This work was done to gatfler data on reproductive performance in female pigs in Kenya. Particular reference was given to the ability of the sow to produce ova (ovulatory rate), litter size, prevalence of anatomical abnormalities of the reproductive organs, prevalence of brucpllosis, leptospirosis and other bacterial agents which exist as conensals in the genital tract of pigs but may cause reproductive problems. Data for Litter size were collected from nine piggeries around Nairobi. All or some of the 1,092 uterine specimens collected from the two bacon factories in Kenya were studied for ovulatory rate, prevalence of anatomical abnormalities; cystic ovarian follicles, presence of bacterial agents and embryonic mortality. In addition to these, attempts were made to detect antibodies against ~la and Leptospira using 500 blood samples. The serum agglutination and Rose Bengal plate tests were used in the case of Brucella and the microagglutination test in the case of Leptospira. *' The mean litter size was 10.4 ± 2.0 and mean ~ number weaned was 8.6 ± 2.5 piglets per litter. 17.1% of the piglets born died during the preweaning period but the causes of death were not easily obtainable. The mean ovulatory rates were 11.4 ± 2.5~ anq 9.2 for gilts and sows respectively. Cystic ovarian follicles were observed in 2.7% of the specimens. A 25% embryonic loss was observed in the gravid uterine specimens. About 65% of the fetuses were in the anterior presentation. Malformations of the reproductive organs were found in 27.9% of the animals. Escherichia coli, Streptococci, Staphylococci and corynebacteria were the bacteria isolated from the reproductive tracts. Antibody titres against Brucella and Leptospira were low. Two herds were positive for brucellosis anq one for leptospirosis. Results from the abattoir specimens and litter size data from farms indicates that the ovulatory * ± - Stau.tiard deviation (S.D.)

rate of gilts: embryonic mortality; litter size; piglet mortality: and incidence of malformations of the reproductive organs were similar to those recorded in other countries. The incidence of cystic ovarian follicles was very low compared to results from other countries. It was concluded from this work that all these factors had no adverse effect on the reproductive performance of female pigs in Kenya. Antibody titres against Brucella and Lept,ospira were low. It was therefore concluded that infection with these organisms may be rare in female pigs in Kenya. Further research on other reproductive parameters such as age at first service, weaning-to-service interval, returns to service and number of litters per sow per year is required to gauge overall reproductive performance of female pigs in Kenya. Continuous research is necessary in order to detect reproductive failures when they occur so that they can be corrected.