Lactation length and first-farrowing or weaning to service intervals affect the subsequent litter size of sows in a commercial farm in southeastern mexico

Background. Studies in temperate regions report the effect of lactation length (LL) and farrowing- service (IFS) and weaning-to-first service intervals (IWS) on the reproductive efficiency of sows in commercial farms. However, research about this topic under tropical conditions is scarce. Objective. To investigate the relationship of LL, IWS and IFS on subsequent number of piglets born alive (SPBA), and the effect of LL on number of parity per sow per year (NFY) and number of piglets born alive per sow per year (PBAY) in a commercial farm in the tropics of Mexico. Methodology. Data from 9663 litters were used. The statistical model for SPBA, NFY and PBAY included the fixed effects of farrowing year (2013, 2014), farrowing season (rainy, north and dry), farrowing number (1, 2, 3, 4, 5, 6), simple interaction of year by farrowing season, and the linear and quadratic effects of LL, IWS and IFS for SPBA, and the linear and quadratic effect of LL for NFY and PBAY. Results. The factors evaluated were significant for all variables of interest. Linear effect (P < 0.05) of LL, IWS and IFS was found only on SLNV. The predictive equation for SLNV was Y= 10.8551+0.02242*LLL+0.01515*IDS. The equation for SPBA with IFS was Y= 10.9939 + 0.01604*IFS. In addition, a negative linear and quadratic effect (P < 0.05) of LL on NFY, and a negative linear effect (P < 0.05) on SPBA were found. The predictive equation for NFY was Y= 2.7432-0.001689*LL-0.00032*LL2 and for PBAY was Y= 32.2414-0.1444*LL. Implications. The effect of LL, IWS and IFS on sow productivity is fundamental for decision making and adapting management, techniques and technologies to production systems. Conclusion. Under the conditions of the present study, increasing LL and IWS increased sow SPBA. However, increasing LL reduced NFY and PBAY.