The effects of breed and housing system on the production and reproduction of weaner piglets in an outdoor pig unit
Visser, Daniël Pieter
MetadataShow full item record
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 breeding sows in England are kept out of doors while in South Africa probably less than 0,3% 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 the environment, thirdly an ethological viewpoint and finally the new political dispensation - specifically the prospective small-farmer. The ultimate aim of this study was to identify the most suitable genotype and farrowing house of outdoor pigfarming based on the reproduction information of the sow's litters. The effect of genotype was significant (P = 0.0695) only for the trait litter size at birth, implying no significant poorer performance from the other genotypes in terms of relative reproductive efficiency. The three linear models, obtained by ANOV A procedures using SAS, which were specified for the reproductive traits litter size at birth, mortality and weaning mass, could explain very little of the variation for the three traits and Rl values of 0,05, 0,086 and 0,45 were calculated for the three traits respectively. However, the effect of parity was highly significant (P = 0.0001) for all three traits. The effect of house was non-significant (P = 0.3314) for number of piglets born alive, but significant for mortality (P = 0.0548) and highly significant for weaning mass (P = 0.0056). The inferiority of farrowing house 5 was undoubtedly revealed in this study. The importance of sufficient clean and fresh straw which will not only stimulate the sow's natural nesting activities, but will also form a buffer and heating mechanism for the young piglets, was clearly shown, given the significant (P = 0.0548) effect of house on mortality rate, and the highly significant (P = 0.0056) effect of house on weaning mass. In retrospect the reproduction performance of the outdoor breeding sow is measured against the norms applicable to the modern sow, however, the outdoor sow has to reproduce 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 (Figures 4.1; 4.3 and 4.4). The commencing phase (Ist and 2nd litter) where number of piglets born alive, mortality and weaning masses are at its lowest. The optimising phase (3rd to 5th litter) when numbers of piglets born alive, and weaning mass reach their optimum while mortality rate reaches the intermediate stage. The diminishing phase (from the 6th litter onwards) where the number of piglets born alive are less than the optimising phase and more than the commencing phase, and mortality rate reaches its peak and weaning mass declines significantly.