ANALYSIS OF LITTER PERFORMANCE DATA FROM THE EXPERIMENTAL STATION RELLIEHAUSEN FOR CONSTRUCTION OF LITTER QUALITY CRITERIA .1. INFLUENCE OFFIXED EFFECTS OF BREED COMBINATION, PARITY NUMBER AND BIRTH-WEIGHT

Title of the paper: Analysis of litter performance data from the exper imental station Relliehausen for construction of litter quality criter ia. I. Influence of fixed effects of breed combination, parity number and birth weight. In an analysis of 2286 litter- and 21738 piglet data from the experimental herd Relliehausen of Gottingen University in th e years 1983-1994 the fixed effects of saison, breed combination, pari ty number and birth weight of piglets were highly significant for trai ts of litter size, mean litter weight and variability of piglet weight s within litters as well as for individual piglet weights and growth r ates up to final slaughter weight. Between parity numbers first and mo re than fifths litters were significantly inferior to the others in si ze and uniformity of litters. Among breed combinations purebred and si ngle cross litters ranged significantly below multiple cross litters i n litter size and variability of piglet weights. Between single cross and criss cross sows no significant differences were found in these tr aits. Piglet weight is of significant importance to losses in the suck ling and rearing period up to 28 kg. It also affects the growth rates of pigs during rearing and fattening up to final weight. Piglets born to light (< 1 kg) are significantly inferior to piglets with normal an d heavy (> 2 kg) birth weights in these traits. The utilization of the se findings in the construction of practical criteria for litter quali ty will be presented in the second contribution.