INFLUENCE OF PENNING TYPE AND FEEDING LEVEL ON SEXUAL-BEHAVIOR AND FEET AND LEG SOUNDNESS IN BOARS

Ninety-six Yorkshire males at 28 d of age were placed on a pre-test fe eding regimen (22% CP) of either ad libitum (A) access to feed or a re stricted (R, 85% of A) diet. All pigs were housed in groups of four un til approximately 30 kg body weight. The boars were then placed under test and assigned to a group pen (GP) containing eight boars or to ind ividual pens (IF) and fed a 16% CP diet at A or R levels. Feeding type s during pre-test and test phases were, therefore, ad libitum followed by ad libitum (AA), ad libitum: restricted (AR), restricted: ad libit um(RA), and restricted: restricted (RR) for each of the two (IF and GP ) housing types. All boars were weighed every 2 wk to determine the fe eding level and ADG. The pen floors were partly slatted with water nip ples in the slatted areas. Areas available for each boar were 1.63 and 2.15 m(2) in IP and GP, respectively. Sexual behavior, semen characte ristics, and feet and leg scores were recorded between 150 and 240 d o f age. The IP boars required longer (P < .05) contact with receptive g ilts before mating, made more (P < .01) ano-genital sniffings, and att empted more (P < .10) incorrect mounts than GP boars. The GP boars had a higher(P < .01) mating score, younger(P < .001) age at completion o f the mating test, and lower (P < .01) total sperm count and sperm con centration(P < .001) than IP boars. The AA boars exhibited less (P < . 10) chomping and salivation than boars on other feeding regimens. The AA and GP boars had higher total semen volumes and gel-free fractions. The GP-AA boars were lighter (P < .005) in body weight at first colle ction than their pen mates on restricted feed. A high correlation (r = .96, P < .01) was found between snout to body contacts and penile erec tion (sexual stimulation) and a very low correlation between body cont act and age (sexual experience). The GP boars had better feet and legs than the IP boars. The AA-IP boars had more (P < .05) problems with t urned-out legs and sloping pasterns than other groups of boars. Partia l isolation during the prepubertal period resulted in subnormal sexual behavior and locomotion difficulties. Therefore, group penning seems to be the best means for housing young boars.