Novel insight into the control of litter size in pigs, using placental efficiency as a selection tool.

Abstract

Chinese Meishan pigs produce three to five more pigs per litter than less-prolific U.S. or European pig breeds as a result of a markedly decreased placental size and an increased pig weight: placental weight ratio (placental efficiency). We hypothesized that as a result of their intense selection for prolificacy, the Chinese had indirectly selected for a smaller, more efficient placenta in the Meishan breed. The goals of this study were to determine whether 1) significant variation in placental size and efficiency existed within our population of purebred Yorkshire pigs and 2) selection of pigs (boars and gilts) based on clear differences in placental size and efficiency would affect litter size. There was significant (approximately threefold) variation in placental efficiency in our herd of Yorkshire pigs, and marked (approximately twofold) variation existed within individual litters. We then selected pigs (boars and gilts) that had either a higher (A Group) or lower (B Group) than average placental efficiency. Although the birth weights of selected A Group pigs were similar to those of the B Group pigs, they had markedly smaller placentae. Males from each group (A or B) were bred to the females of the same group, and farrowing data were collected from parities 1 and 2. In both parities, A Group females farrowed more live pigs per litter than did B Group females (12.5 +/- .7 vs 9.6 +/- .5, P < .05). Although A Group pigs were on average approximately 20% lighter than B group pigs (1.2 +/- .1 vs 1.5 +/- .1 kg, P < .05), their placentae were approximately 40% lighter (250 +/- 10 vs 347 +/- 15 g, P < .01), resulting in a marked increase in placental efficiency. The results of this study suggest that selection on placental size and efficiency may provide a valuable tool for optimizing litter size in commercially important pig breeds.

Dietary l-arginine supplementation enhances placental growth and reproductive performance in sows

“…Importantly, the size and functional capacity of the placenta, and uteroplacental transfer of materials between mother and fetus, were the major factors to affect embryonic/fetal growth and development (Bazer et al 1969;Gude et al 2004;Wu et al 2006Wu et al , 2010. Previous reports have shown that placental efficiency affects litter size and that placental size is highly correlated with fetal weight after day 60 of gestation in swine (Biensen et al 1998;Wilson et al 1999). Another interesting and novel finding of the present work is that dietary arginine supplementation enhanced placental weight per sow (Table 2), indicating an increase in total placental growth.…”

A Review of Gene Expression in Porcine Endometrial Lymphocytes, Endothelium and Trophoblast During Pregnancy Success and Failure

“…the ratio of fetal weight to placental weight). Significant improvement has not occurred [11,12]. Nutritional studies (improved diet balance or vitamin supplementation) also failed to show consistent beneficial effects [13,14].…”

Polymorphisms ofosteopontingene and their association with placental efficiency and prolificacy in goats

“…However, placental growth and development of its functional ability are important because they are the means by which the foetus receives metabolic substrates for growth. So selection on placental size and efficiency may provide a valuable tool for optimizing litter size in commercial livestock, such as swine and sheep (Wilson et al 1999;Mesa et al 2012). In our study, there is no significant difference on placental efficiency among three goat breeds with different prolificacy.…”