Use of Cross-Fostering to Enhance Growth of Pigs That Are Predicted to Grow Poorly Based on Plasma α-1 Acid Glycoprotein Concentration

Porcine α-1 acid glycoprotein (AGP) in newborn pigs can be used to predict growth rate through weaning and is a marker for growth impairment. This study examined whether nutritional support can improve the growth rate of piglets identified as having poor growth potential. Cross-fostering (CF) and CF plus a milk supplement (CF + MS) were used to attempt to improve the growth performance of pigs. Blood was collected at d1 post-parturition for measurement of plasma AGP for all pigs in 28 litters contributing to the experiment. Piglets with the highest plasma AGP level were weight and sex matched to a littermate with a low plasma AGP concentration and four pairs of these weight and sex matched pigs were grouped into four foster litters per treatment (control, CF, CF + MS). The control group was assembled by pairing littermates remaining in donor litters. Pigs stayed on treatment until weaning at 21 days of age. At 35 days of age, dual energy X-ray absorptiometry (DXA) was performed on CF and CF + MS pigs to evaluate carcass composition. Control pairs differed in weaning weight, with pigs with higher plasma AGP at 1 day of age having smaller weaning weights than their littermates of similar birth weight (P < 0.05). However, CF eliminated the difference in weaning weight between the slow growing pigs and their birth weight matched littermates. CF + MS produced a similar effect as CF (P > 0.05). At 35 days of age, body weights were still similar between CF littermates and between CF + MS littermates (P > 0.05). DXA analysis demonstrated that body composition was similar between CF or CF + MS treated pigs and their littermates. These data demonstrate that CF can be used to correct the growth impairment in pigs predicted using plasma AGP as the marker. CF + MS can do the same, but at greater expense.

Russet Sparrows spot alien chicks from their nests

Background： In coevolutionary interactions between brood parasites and their hosts, host parents are under strong selection to evolve defenses against parasitism. Egg rejection is an efficient and common defense against parasitism, although some apparently suitable hosts do not reject cuckoo eggs.Methods： Sparrows Ploceidae are widespread throughout the Old World, and they have a suitable diet for rearing cuckoos, but still they are rarely exploited by brood parasites. To solve such puzzle, we conducted artificial parasitism and cross-fostering experiments in Russet Sparrow （Posset cinnomomeus）.Results： The present study showed that Russet Sparrows have no egg recognition ability, but recognize their own nestlings and eject alien chicks or starve them to death. They may use visual cues in chick recognition, although they accept sister species Tree Sparrow （Posset montonus）.Conclusions： By rejecting nestlings of foreign species, Russet Sparrows have succeeded to escape from the brood parasitism by cuckoos and other parasites. Our studies shed light on the puzzle why some species are not utilized by cuckoo parasites as hosts,