Effect of timing of relocation of replacement gilts from group pens to individual stalls before breeding on fertility and well-being

Variation in gilt fertility is associated with increased replacement and reduced longevity. Stress before breeding is hypothesized to be involved in reduced fertility. This study tested the timing of gilt relocation from pens to individual stalls before breeding on fertility and well-being. The experiment was performed in replicates on a commercial research farm. After detection of first estrus, gilts (n = 563) were assigned to treatment for relocation into stalls 3 wk (REL3wk), 2 wk (REL2wk), or 1 wk (REL1wk) before breeding at second estrus. Subsets of gilts from each treatment (n = 60) were selected for assessment of follicles at second estrus. Data included interestrus interval, number of services, conception, farrowing, total born, and wean to service interval. Piglet birth weight was obtained on subsets of litters (n = 42/treatment). Measures of well-being included BW, backfat, BCS, lesions, and lameness from wk 1 after first estrus until wk 16. Gilt BW at wk 5 (158.4 kg) was not affected (P > 0.10) by treatment. Measures of BCS, lameness, and lesions at breeding and throughout gestation did not differ (P > 0.10). Treatment did not affect (P > 0.10) gilts expressing a normal interestrus interval of 18 to 24 d (83.4%) but did influence (P < 0.05) the proportion expressing shorter (P < 0.001) and longer (P < 0.001) intervals. Gilts in REL3wk had a shorter (P < 0.001) interestrus interval (20.7 d) than those in REL2wk and REL1wk (22.6 d). Gilts with shorter intervals (n = 24) had fewer total born while gilts expressing longer cycles (n = 65) had reduced farrowing rates. The number of services (1.9) and number of follicles (19.7) at breeding were not affected (P > 0.10) by relocation. There was no effect of treatment on farrowing rate (85.2%), born alive (12.6), or any litter birth weight measures (P > 0.10). The percentage of sows bred within 7 d after weaning (94.4%) was also not affected by treatment (P > 0.10). These results suggest that the timing of relocation before breeding had no effect on well-being or on the majority of gilts with normal estrous cycles and their subsequent fertility. However, a smaller proportion of the gilts exhibited shorter and longer interestrus intervals in response to relocation 1 or 3 wk before breeding. In cases where gilt fertility may be less than optimal, producers that relocate gilts from pens to stalls before breeding should evaluate interestrus interval as a response criterion.