Accounting for lactation length and weaning-to-conception interval in genetic evaluations for litter size in swine.

Abstract

Effects of lactation length and weaning-to-conception interval on the subsequent litter size of purebred sows were estimated using an animal model. Data on 2,847 Landrace sows with 7,125 litters born between January 1989 and May 1997 and on 1,234 Yorkshire sows with 2,999 litters born between January 1990 and May 1997 were obtained from two Canadian selection herds. Sows having a lactation of less than 14 d (MMEW) were usually not mated until their second estrus, whereas sows weaned after at least 14 d of lactation (later weaning) were usually mated on their first estrus. Litter size included both number of pigs born alive and those stillborn. Linear, quadratic, and logarithmic effects of lactation length were tested. The effect of weaning-to-conception interval on litter size was modeled using an approach based on threshold variables and an approach using segmented polynomials. Results indicated linear and logarithmic effects of lactation length on subsequent litter size for Yorkshire and Landrace breeds, respectively. Litter size decreased as weaning-to-conception interval increased up to 7 and 10 d for Yorkshire and Landrace, respectively, then increased with further increases in weaning-to-conception interval up to 35 and 30 d for the two breeds, and then remained constant. The MMEW sows did not have lower subsequent litter sizes than later-weaned sows because the negative effect of a shorter lactation was offset by the positive effect of a longer weaning-to-conception interval. However, average time spent open per parity was longer for MMEW sows than for later-weaned sows. Both lactation length and weaning-to-conception interval should be considered in models for the genetic evaluation of litter size in purebred swine. Segmented polynomials can be used to predict litter size as a continuous function of weaning-to-conception interval or to derive weaning-to-conception interval adjustment factors for litter size.

Genetic parameters and trends for production and reproduction traits in Thai Landrace sows

“…Sterning et al (1990) and Tantasuparuk et al (2001) showed that sows with greater weight loss had longer weaning to estrus interval. Subsequent litter sizes decreased when weaning to estrus interval increased up to 10 days (Marois et al, 2000;Tummaruk et al, 2000). In this study, only 55% of first-parity sows were in estrus within 5 days after weaning, as compared to 73% and 78% of second-and third-parity sows.…”

Fixed part of the model for breeding value estimation in pigs based on litter size

“…Results obtained for systematic effect of duration of the period from weaning to breeding on the varation of the NBA in this investigation are in agreement with resultats obtained by Betka Logar (2000), Marios et al (2000), Petrovic Milica et al (2003), Urankar Janja et al (2004) and Lukovic (2006).…”

“…Similar conclusions relevant to the effect of this factor on the variation of the monitored trait were presented by Logar Betka (2000), Marios et al (2000), Urankar Janja (2004) and Lukovic (2006).…”

Relationship between lactation length and weaning service interval and subsequent sow productivity traits in an intensive swine production system

“…No obstante, la condición corporal después del destete juega un papel importante en el retorno al estro, y tiene un efecto perjudicial sobre el tamaño de la próxima camada. El IDS en una piara puede reducirse a través de mejores prácticas de manejo, mejoramiento genético, aunque su heredabilidad es baja (Cavalcante-Neto et al, 2008;Marois, Brisbane & Laforest, 2000).…”