Adeoye, A.A., Udoh, J.E. and Rotimi, E.A.

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The phenotypic expression of any trait in animals is determined by genetic and non- genetic factors. Records of 252 litters of Nigerian indigenous pigs sired by 48 boars and 83 sows at the Swine Unit of Obafemi Awolowo University Teaching and Research Farm between 1990 and 1998 (8 years) were collected and used to investigate the effect of parity and nongenetic factors on the litter traits. The pigs were kept under intensive and routine management. Data collected were on litter size at birth and weaning, litter weight at birth and weaning, pig weight at birth and weaning, sex ratio at birth and weaning and mortality at weaning were subjected to analysis of variance. The means values of the traits were: litter size at birth (5.78±2.07), litter size at weaning(5.51±2.02), litter weight at birth(6.15±2.36 kg), litter weight at weaning(25.14±11.13 kg), pig weight at birth(0.95±0.12kg), pig weight at weaning(4.17±1.33kg), sex ratio at birth(0.48±0.23), sex ratio at weaning (0.48±0.25) and mortality(4.58±1.70%).Parity had significant effect (p<0.05) on pig weight at weaning while the effect of parity was not significant(p>0.05) on other litter traits. The effect of season was significant (p<0.05) on litter size at weaning, pig weight at weaning and mortality. Year of birth did not have significant effect on most of the traits except on litter weight at birth and weaning as well as weight at weaning. The correlation coefficients among the traits ranged from -0.01 to 0.96. Parity and the non-genetic factors were not important source of variation on most of the litter traits considered in Nigerian indigenous pig. It could be recommended that parity, season and year of birth should be considered for those traits they have significant effect on for better production. Key words: Parity, mortality, non-genetic factors, litter traits, Nigerian indigenous pig