The association between environmental temperature, farrowing rate and sow litter size : a descriptive South African study

Abstract

The reproductive performance of pigs is the main determinant of the profit farmers make in pig production. There are many contributors to poor reproductive performance and in this study the influence of environmental temperature on farrowing rate and litter sizes has been described in the South African situation. Literature on the influence of season on reproductive performance ( seasonal infertility ), are somewhat conflicting. This is not surprising considering the variation between the situations of the studies performed, in terms of differing countries, management systems, nutrition, disease profiles, housing and genetics. Data were collected from four commercial breeding units with good records on a weekly basis from December 2010 to August 2012. These data included the number of sows inseminated/mated, number of sows farrowed and the number of piglets born alive, as well as the number of stillbirths. Note was also taken of whether environmental temperature control mechanisms were employed in the breeding house and dry sow houses. Temperature data from weather stations within 100km of the breeding units was obtained from the South African Weather Service. On all breeding units a decrease in farrowing rate following matings during severe average temperatures (>30°C) when compared to the farrowing rate following matings during mild average temperatures (<22°C) was observed. The most significant observation of this study was that the trend was for farrowing rates to decrease following inseminations/matings during times of high ambient temperatures (>30°C). Environmental temperature control did not negate this effect, but the breeding units employing the environmental temperature control did show higher average farrowing rates overall.

Reproduktiewe uitsette van sôe is die faktor wat bepaal hoeveel wins die varkboer maak. Daar is verskeie faktore wat bydra tot swak reproduktiewe prestasie van die kudde. Hierdie studie bestudeer die invloed van temperatuur op die jongingstempo en die werpselgrootte binne n Suid-Afrikaanse konteks. Literatuur oor die invloed van seisoen op reproduktiewe uitsette ( seisoenale onvrugbaarheid ) is ietwat teenstrydig. Dis nie verbasend nie wanneer mens in ag neem die variasie in die omstandighede van die verskillende studies in terme van verskillende lande, bestuur, voeding, siektes, behuising en genetika. Data was verkry vanaf vier kommersiële teeleenhede. Hierdie teeleenhede het goeie rekordhouding van weeklikse reproduktiewe uitsette tussen Desember 2010 en Augustus 2012. Die uitsette het ingesluit die hoeveelheid sôe ge-insemineer of gedek, die hoeveelheid sôe wat gejong het, die werpselgroottes en die hoeveelheid doodgebores. Dit was ook opgelet of daar meganismes van omgewingstemperatuur- beheer toegepas word in die dekkings-huis en die droë sôe huis. Temperatuur data was verkry van weerstasies binne 100km van die teeleenhede vanaf die Suid-Afrikaanse Weerdienste. Op al die teeleenhede was ekonomiese beduidende vermindering van die jongingstempo waargeneem met dekkings gedurende tye van hoë gemiddelde temperature (>30°C) in vergelyking met die jongingtempo wat gevolg het van dekkings gedurende matige temperature (<22°C). Die mees beduidende waarneming gedurende hierdie studie was die tendens vir die jongingstempo om te verminder met inseminasies of dekkings gedurende tye van hoë gemiddelde temperature (>30°C). Omgewings-temperatuur-beheer het nie hierdie tendens verander nie, maar die teeleenhede met omgewings-temperatuurbeheer het in die algemeen hoër gemiddelde jongingstempos gehad.