Effect of grouping weaned piglets by weight classes: evidence from Zimbabwe

Abstract

A study was carried out to determine the effect of sorting pigs in different weight classes on post weaning performance at a small scale pig farm in Zimbabwe. Twenty four purebred large white piglets were used for the study. After weaning at 4 weeks, piglets were each placed into four groups with 6 piglets each, 4.0­5.9 kg (low weight), 6.0­7.9 kg (moderate weight), 8.0–9.4 kg (heavy weight) and piglets greater than 9.5 kg extremely heavy weight). Two piglets, a male and a female were randomly chosen from each of these groups to form a group comprising of piglets of mixed weights. Data on the average daily gain (ADG), live weight gain (LWG) and feed conversion ratio (FCR) was collected from week six until slaughter (week 18). Analysis of variance using the Restricted Maximum Likelihood (REML) method was performed with type of group nested within the different weight classes.The results showed that heavier weight pigs at weaning had better post weaning performance as compared to low weight pigs. However mixing different weight pigs affected FCR only with piglets in the mixed group having a better FCR than those in the uniform groups. In terms of LWG, there were no significant differences observed between uniform and mixed weight groups for the piglets greater than 6 kg at weaning. This study showed that raising piglets in mixed weight groups will have a negative effect on performance on low weight pigs (less than 6 kg at weaning). Farmers are therefore advised to raise such piglets in uniform weight classes.