Growth performance of segregated early-weaned versus conventionally weaned pigs through finishing
Steven D. Drum, DVM, MS; Roger D. Walker, PhD; William E. Marsh, PhD;Martha M. Mellencamp, PhD; Vickie L. King, PhD
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Objective: To measure growth performance differences between segregatedearly-weaned (SEW) and conventionally weaned (CW) littermates to slaughter,and to investigate the effects of immunostimulation from vaccination onSEW pigs compared to CW pigs.
Methods: One hundred ninety-two pigs from 24 litters were systematicallyassigned to either a segregated early-weaning treatment (SEW) or a conventional-weaningtreatment (CW). All pigs were weighed at birth and injected intramuscularly(IM) with 0.5 mL oxytetracycline at 200 mg per mL, and on day 10 with 1.0mL oxytetracycline at 200 mg per mL. SEW pigs were weaned at 10 days ofage and moved to an offsite nursery. CW pigs were cross-fostered to maintainlitter sizes, weaned at 24 days of age, and moved to a similar onsite nursery.Pigs in both the SEW and CW pens were allocated either to a vaccinationtreatment (VAC) or a control treatment (CON). VAC pigs were given four injectionsof commercially prepared inactivated, adjuvented cattle vaccines on days37 and 51; CON pigs received sterile saline injections on the same days.Pigs were weighed and feed disappearance recorded on a weekly basis throughthe nursery phase (day 56). On day 56, pigs were moved to a research finishingfacility where SEW and CW pigs were housed in separate but identical finishingfacilities. All feed disappearance throughout the finishing phase was recordedand pigs were weighed on days 100, 129, and at slaughter.
Results: At the end of the nursery phase, SEW pigs were heavierthan CW pigs (P<.0001). During the last 4 weeks of the nurseryphase, SEW pigs had a higher average daily gain (ADG) than CW pigs (P<.0001).However, ADG was lower in SEW pigs compared to CW pigs during the weeksof vaccination (P<.0001), and a higher feed:gain (F:G) ratio wasobserved during the first week of vaccination (P=.0022). In the finisher,we observed no effect of vaccination (P>.43) or weaning treatmenton ADG. Feed:gain ratios for the last 4 weeks of the nursery were lowerin SEW pigs than in CW pigs (P<.05), and there were no differencesin F:G in the finisher (P>.40). There was no detectable differencein adjusted days-to-109 kg for SEW and CW males (P=.9893), whileCW females had lower adjusted days-to-109 kg than SEW (P=.0067).
Implications: Our data indicate that SEW pigs weigh more at theend of the nursery phase, but did not maintain that advantage through finishing.Vaccination momentarily slows growth of SEW nursery pigs, but the effectdisappears in finishing.