The effects of breed and housing system on the production and reproduction of weaner piglets in an outdoor pig unit

[摘要] Outdoor pigfarming is a concept which (within the 20th century) had its origin(revival) in the early 1950s in England. Today approximately 15% of all breedingsows in England are kept out of doors while in South Africa probably less than0,3% of sows (recorded), are kept out of doors.The rationale for outdoor pig farming was motivated from four angles of incidence:firstly an economic viewpoint, secondly the animal's adaptability to theenvironment, thirdly an ethological viewpoint and finally the new politicaldispensation - specifically the prospective small-farmer.The ultimate aim of this study was to identify the most suitable genotype andfarrowing house of outdoor pigfarming based on the reproduction information ofthe sow's litters. The effect of genotype was significant (P = 0.0695) only for thetrait litter size at birth, implying no significant poorer performance from the othergenotypes in terms of relative reproductive efficiency. The three linear models,obtained by ANOV A procedures using SAS, which were specified for thereproductive traits litter size at birth, mortality and weaning mass, could explainvery little of the variation for the three traits and Rl values of 0,05, 0,086 and 0,45were calculated for the three traits respectively. However, the effect of parity washighly significant (P = 0.0001) for all three traits.The effect of house was non-significant (P = 0.3314) for number of piglets bornalive, but significant for mortality (P = 0.0548) and highly significant for weaningmass (P = 0.0056). The inferiority of farrowing house 5 was undoubtedly revealedin this study.The importance of sufficient clean and fresh straw which will not only stimulate thesow's natural nesting activities, but will also form a buffer and heating mechanismfor the young piglets, was clearly shown, given the significant (P = 0.0548) effectof house on mortality rate, and the highly significant (P = 0.0056) effect of houseon weaning mass.In retrospect the reproduction performance of the outdoor breeding sow is measuredagainst the norms applicable to the modern sow, however, the outdoor sow has toreproduce while competing with all the elements of nature (Falconer's paradox).The effect of parity was highly significant (P = 0.0001) for all three traits.This study, especially Tables 4,4; 4.8 and 4.11, showed that three distinctive(significant) phases could be identified during a sow's reproductive lifetime (Figures4.1; 4.3 and 4.4). The commencing phase (Ist and 2nd litter) where number ofpiglets born alive, mortality and weaning masses are at its lowest. The optimisingphase (3rd to 5th litter) when numbers of piglets born alive, and weaning massreach their optimum while mortality rate reaches the intermediate stage. Thediminishing phase (from the 6th litter onwards) where the number of piglets bornalive are less than the optimising phase and more than the commencing phase, andmortality rate reaches its peak and weaning mass declines significantly.

[发布机构] University of the Free State