The present study was conducted to investigate factors affecting within-litter variation of piglet birth weight and the incidence of runt piglets. In total, 8433 piglets were included in the study. They had been born from 624 Landrace x Yorkshire sows raised on ten farms in the north of Vietnam. A linear mixed effect model (LMEM) and a generalized linear mixed model (GLMM) were used to determine the associations between the risk factors and within-litter variation in birth weight and number of runt piglets, respectively. The within-litter standard deviation (SD) of birth weight and its coefficient of variation were 0.27 ± 0.10 kg and 19.8 ± 8.0%, respectively. Litter size was positively associated with within-litter variation in birth weight, whereas the mean birth weight was negatively associated with litter size. The incidence of runt piglets (birth weight <1.11 kg) was 21.3%. Increases in litter size and decreases in litter weight were associated with the incidence of runt piglets. Mean and SD of birth weight within litter were the most significant risk factors for runt piglets. The GLMM, which contained the mean and SD of birth weight, explained 36% variation of the incidence of runt piglets. The results of the present study suggested that increased mean birth weight and litter weight would be beneficial approaches for reducing within-litter variation in piglet birth weight and incidence of runt piglets, which may subsequently increase perinatal and preweaning survival.
"Experientia docet" - Experience is the best teacher