Studies of management effects on fertility of purebred and crossbred exotic gilts in two breeding farms at Nsukka, Nigeria
Sixty healthy gilts comprising 15 Landrace (LR), Large White (LW) and LW x Hampshire (HS) breeds respectively, were selected from Federal Government (FG) breeding center at Okpuje near Nsukka and University of Nigeria Nsukka (UNN) farms. They were bred through 4 years (1993 to 1996) during which management effects on fertility were assessed. Gilts were mated on obsenration of third cyclic oestrus and at subsequent postweaning oestrus. Fertility was assessed from vital reproductive traits due to dams and offsprings. All gilts had successful first and second parity breeding. Thereafter there were increasing cases of abortion and anoestrus particularly among purebred groups in FG farms. Generally, 8 (53.3%), 6 (40.0%), 10 (66.7%) and 13 (86.7%) out of 15 dams in respective groups could attain fifth parity within four years. Both groups exhibited long breeding intervals (ranging from 192-268 days). Purebred LW and LR offspring had slightly lower mean litter size of 8.5 ± 1.8 and 8.8 ± 1.5 compared with 9.5 ± 0.9 and 9.7 ± 1.4 (P<0.05) for LW x LR and LW x HS crossbred counterparts respectively. Birth end weaning weights and daily weight gain were similarly lower for purebred than crossbred offsprings. Attendant mortality rates of 13.1 % and 15.7% for the former were significantly higher than 9.8% and 10.1 % (<0.05) obtained for the latter offsprings respectively. The FG farm was more understocked, underutilized and undermanaged than the UNN farm probably because of inconsistencies arising from administrative bureaucracy. Consequently constraints are identified for improvement through efficient resources inputs, staff incentives and application of modem strategic management techniques re-commended for tropical environment. Further research into stocking Hamphsire crossbred pigs in the tropics is suggested, in view of its favourable performance.
Keywords: Exotic pigs, management, fertility, production, tropics.