Estimation of deviations from predicted lactation feed intake and the effect on reproductive performance

Abstract

The objectives of this study were to quantify significant negative deviations (DEV) from predicted daily lactation feed intake values and to estimate their effect on reproductive performance and subsequent intake in purebred and F1 sows. Daily lactation feed intake (LFI) records from day 1 to 22 of lactation from purebred Yorkshire (n=1587 parity records), purebred Landrace (n=2197 parity records), and reciprocal cross F1 (n=6932 parity records) females were used to predict daily LFI values. The mixed model included fixed effects of breed, season, parity group (1, 2, 3 and ≥4), day of lactation, and interactions of day with breed and parity group, and a covariate of litter size after cross-fostering. Random effects included litter, contemporary group (herd–year–month), dam, and sire nested within breed. Deviations from predicted LFI values were quantified using an internally studentized residual (SR). A SR≤−1.71, equivalent to observed LFI at least 1.9kg less than predicted, was considered a DEV. Zero DEV occurred in 60% of lactation records, while 18% of lactation records had 1 DEV, and 22% of lactation records had ≥2 DEV. Thirty-four percent of negative deviations occurred during the summer months (June, July, August) which was more frequent when compared to the spring (26%), fall (23%), and winter (17%) months. Adjusted 21-day litter weaning weight (LW21) decreased as the number of DEV increased within a single lactation period, and wean-to-first service interval (WTSI) increased when at least 3 DEV occurred within a single lactation. An increase in DEV during early lactation did not affect LW21 or WTSI (P>0.05), though an increase in number of DEV after day 5 of lactation was associated with lower LW21 and longer WTSI. Odds of a negative deviation from predicted LFI occurring on any given day of lactation were estimated as odds ratios. If a DEV occurred the prior day, a DEV was 8.7 and 39.5 times more likely to occur than if a DEV had not occurred for purebred and F1 sows, respectively. In F1 sows, a DEV was 3.1 (P<0.01) times more likely to occur after day 5 of lactation when a DEV occurred on day 1 to 5 of lactation. Negative deviations from predicted LFI values decreased reproductive performance and had a larger effect on performance when they occurred during late lactation.