Influence of backfat thickness, body weight and body condition score of sows during gestation and lactation on the vitality of pre-weaned piglets and litter performance

The number of weaned piglets per sow per year is an important parameter for the productivity of sows in pig production. This number depends on several parameters of which in many cases the sow has a central role. To improve the sow’s reproduction it is important to keep the sow’s body condition optimal. However, clear recommendations towards sow body condition and feeding levels, and knowledge about the exact influence on piglet vitality are scarce. Literature regarding these subjects mainly originates from the 1980’s and is probably not in line with recent housing conditions, reproductive performance of the sow, and genetics. Therefore research was carried out in order to investigate the exact influence of 3 parameters of sow body condition (body weight, backfat thickness and body condition score) on a number of piglet vitality parameters: average birth weight, litter size, stillbirth ratio, weight gain during lactation, and litter size and average weight at weaning. Research was carried out on 286 Topigs 20 sows and litters on two farms; one in Germany and one in the Netherlands. Sow body weight, body weight and body condition score was measured and assessed at day 108 of gestation and at weaning. Data on piglet vitality measures were gathered at moment of birth and weaning. The main objective of this research was to find correlations between sow factors and vitality of piglets. Possible relations between sow factors (backfat thickness, body weight, body condition score, and backfat and weight losses) and piglet vitality (litter size, average birth weight, ratio live born: stillborn and weight gain during the lactation period were investigated. A linear increase in body weight during the first 5 parities was seen on both farms, and it could be concluded that body weight is highly dependent on the parity number. Therefore, body weight can be used as tool to evaluate the body condition and development of the sow. Body condition score is a subjective method and shows large variations between assessors. No relation was found in body condition score at the different moments in the reproductive cycle of the sow, and due to large variations between sows the body condition score is not an accurate tool to assess sow body condition. More objective methods should be used to assess the sow’s condition. Between the two trial farms of this study large differences were seen between the sow’s body condition and the reproductive performance. On the one farm, backfat thickness and body weight increased with parity, while in the other farm backfat levels remained relative constant, with only a small increase with parity. This shows the importance of using a good tool for condition evaluation. Backfat thickness measurements are recently the most objective method to asses sow body condition, as the farm with increasing levels used the body condition score, and the other farm measured backfat thickness to evaluate sow body condition. Changes on the first farm would have been recognized earlier with an objective tool. It should be investigated whether adapting feeding schedule to the individual sow will decrease variation between sows and optimize the reproduction of the sow. Also more information is necessary on the optimal condition of the sow per breed and parity number, as recent literature mentions many different recommendations and backfat thickness depends on the type of breed. When correct nutrient and energy levels are feed, dependent on housing conditions, breed type and reproductive performance, the exact growth coefficient per breed can be determined. Sow breeding farms then can evaluate their feeding schedule based on the body weight and backfat thickness of their sows.