|Van Vleck, Lloyd|
Submitted to: Midwestern Section of the American Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 11/16/2006
Publication Date: 7/20/2007
Citation: Wang, Y., Wise, T.H., Rohrer, G.A., Hanford, K.J., Van Vleck, L.D. 2007. Logistic regression analysis to predict weaning-to-estrous interval in first-litter gilts [abstract]. Journal of Animal Science. 85 (Supplement 2):62. (Abstract #46) Interpretive Summary:
Technical Abstract: Delayed return to estrus after weaning is a significant problem for swine producers. In this study, we investigated the relationships between weaning-to-estrous interval (WEI) and body weight (BW), back fat (BF), plasma leptin (L), glucose (G), albumin (A), urea nitrogen (PUN) concentrations and litter traits to identify physiological traits associated with WEI. Data were collected from 845 gilts prior to farrowing (f, 110 d gestation), at weaning (w) and at first estrus (e) after weaning. A composite population of 1/4 Duroc (D), 1/4 Landrace (Lc), 1/2 white cross (W) was developed by mating W females to either D or Lc boars. The lines were crossed and subsequently inter se mated. Records collected in 2002 were from D or Lc sired gilts. All other records (2003-2005) were on DLcW composite gilts. Statistical analyses were performed using combined data with year as a fixed effect. Estimates of correlations showed that WEI was positively associated with BWe, Le, BWe-BWw and Le-Lw, and was negatively associated with Ge, Ae, Ge-Gw and Ae-Aw (P < 0.05). At f, w and e, BW and BF were positively associated with L (P < 0.05). With WEI classified as ideal (1-7 d, I), acceptable (8-14 d, A) or late/no estrus (> 14 d, N), stepwise logistic regression was used to generate models with reduced sets of traits to discriminate between pairs of populations: I vs. A+N (M1) and I vs. A (M2). Because the goal was to predict WEI, only farrowing and weaning traits were included. With M1, yr 2002, yr 2004, BWw, BFw, Aw, Lw-Lf and number of pigs weaned in litter were positively associated with I, while yr 2003, BWf, PUNf and number of pigs fostered off (NF) were negatively associated. With M2, BFf, Lw, BFw-BFf, Aw-Af, NF and number of pigs alive at birth had positive associations with I, while BFw and Lf had negative associations. The results suggest physiological traits associated with WEI may be useful in predicting WEI of gilts.