PENGARUH SISTEM PENGAWINAN (INSEMINASI BUATAN DAN ALAMI) DAN PARITAS INDUK BABI TERHADAP LITTER SIZE DI USAHA PETERNAKAN BABI PT. ADHI FARM, SOLO

The aims of this study was to determine the optimal litter size which produce from the mating system and the sow parity by noticing the litter size born alive, the age of weaning, litter size at weaning, mortality during the suckling period and litter size at weaning percentage. Fourty one farrowing and weaned sows are used in this research. The first factor is the mating system, included artificial insemination and natural service. The second factor is the parity of the sow (1 up to 5). The data collected were litter size born alive, the age of the weaning, the weaned litter size, mortality of the suckling period and litter size at weaning percentage.The result showed that the mating system had significant effect (P0.05) on the age of the weaning, the litter size at weaning, mortality during the sucling period and litter size at weaning percentage. The parity had significantly effect (P0.05) on the litter size born alive, mortality during the sucling period and litter size at weaning percentage. The interaction between the mating system and the parity was significantly effected (P

Secular Changes of Twinning Rates in Nordic Populations

In each species, natural selection has resulted in an optimal litter size, to ensure the largest average number of surviving offspring and the lowest maternal mortality. The terrestrial insectivores from which the primates evolved had large litters. It has been argued that in primates adaptation to an arboreal mode of life led to a reduction of litter size to a single offspring because of the difficulty of producting and caring for a large litter in a tree [6]. A recent critical survey of the literature indicates that twinning frequency in most nonhuman primates is lower than in man [20].There are clear ethnogeographic differences in the incidence of human twinning. Among peoples of Eastern Asia, multiple maternities are rare; in Japan for instance, the twinning rate is only 3-7 per mill, according both to the official statistics and hospital records. These low rates seem not to be caused by the facts that it is customary in Japan to have children very early in life or that twin births were at one time viewed with displeasure and concealed, or sometimes twins were even killed in some areas [21].In hospital series among some Negro tribes almost 10 times higher twinning frequencies than among Japanese have been reported e.g. the Yorubas in western Nigeria with values above 60 per mill [24]. However, where national birth statistics of Blacks are available, twinning is lower, e.g. in U.S.A. 13-15 per mill [1].

Optimal litter size: Does it cost more to raise a large litter in Caluromys philander?

Food intake of lactating Caluromys philander, a didelphid marsupial, was recorded from parturition until weaning of the pouch young. Variation in the average caloric value of daily food intake throughout lactation, in relation to litter size, showed no significant differences, but females increased food intake during late lactation, prior to weaning. Food intake was positively correlated with total litter mass at weaning. Moreover, there were significant differences in body mass and body length of offspring at first pouch exit (3 months) and at weaning (4 months): young born in small litters (1–3) were bigger than those born in large litters (6–7). Reproductive success is discussed on the assumption that pouch-young survival depends on food resources.