ABSTRACT

A study was carried out to evaluate reciprocal, maternal, sex-linked and heterotic effects on growth and reproductive traits in pigs. This study was conducted between September 2009 and November 2011. With three breeds of pigs — Large White (LW), Landrace (LR) and West African Indigenous (WAI), a modified diallel cross was carried out. This generated 72 piglets. Data were generated from these litters from 0 to 140 days of age and used to estimate the mean cross, parity and sex effects at birth, weaning up to 140 days of age. At pre-weaning period (0 — 63 days), cross 4 (LRXLW) gave a significantly (P<0.05) higher body weight (BW) than the other crosses while at post-weaning (70 — 140 days), crosses 3, 4 and 6 were significantly higher (P<0.05) in BW than the rest. Parity 2 gave significantly (P<0.05) higher BW than parity I while there was no significant (P>0.05) sex effect from birth to 140 days of age. There was also a significant Cross x Sex interaction at ages 0, 14, 70, 77, 98, 133 and 140 days while at 98 days of age, there were significant Cross x Parity, Cross x Sex, Parity x Sex and Cross x Parity x Sex effects. The Linear Body Measurements (LBMs) showed significant cross effect (P<0.05) for all traits — Ear length (EL), Tail length (TL), Heart Girth (HG), Height at Withers (HW), Head circumference (HC), Snout circumference (SC), Snout length (SL) and Body length (BL) at different ages, while there was significant effect of parity (P<0.05) for BL, SL, SC, HW, HG and EL. There was no significant effect (P>0.05) of sex on LBMs. The cross 2 (LWxWAI) had the highest mortality (41.67%) among the crosses, while parity 2 (28.79%) had higher mortality than parity 1, and females had more mortality than males. The reciprocal cross LRxLW performed significantly better (P<0.05) than the main cross at 2-9, 12 and 14— 18 weeks of age for BW. Maternal effect was also significant (P<0.05) at 4 — 9, 14, 17 and 18 weeks of age. Sex-linked effect was also significant (P<0.05) at weeks 2 and 12. The reciprocal, maternal and sex-linked effects on BW between the LW and WAI breed crosses favoured the reciprocal cross (WAIxLW) with significant reciprocal effects (P<0.05) at 0 — 5 weeks only, significant maternal effects at 0 — 4 weeks of age and significant (P<0.05) sex-linked effect at week 5. Also, the reciprocal, maternal and sex-linked effects on BW between the LR and WAT breed crosses, favoured the main cross (LRxWAI) with significant reciprocal effects (P<0.05) at 2 — 9 and 11-20 weeks of age, significant maternal effects at 2 — 20 weeks of age and no significant sex-linked effect. For the various LBMs, different crosses and their reciprocals showed significant reciprocal, maternal and sex-linked effects (P<0.05) at different ages. There was no positive heterosis among the various crosses except LRxLW and LRxWAI crosses, which exhibited positive heterosis at 8 weeks of age, while others exhibited negative heterosis and high percentage heterosis. In addition, the LBMs exhibited varied levels of positive and negative heterosis based on the main and reciprocal crosses. It is therefore recommended that in a cross breeding programme involving these three breeds of swine — LW, LR and WAI breeds, the cross involving LR males and LW females will give the best performance in terms of growth and reproductive traits measured, followed by the cross involving WAI males on LW females, and lastly using LR males on WAI females.