Factors influencing litter size and birthweight in the newborn long-haired guinea pigs (Cavia aperea f. porcellus)

Abstract

As a result of domestication, many different guinea pig breeds occurred, differing in appearance. The available literature lacks information on the subject of reproductive traits in long-haired guinea pigs. The study indicates that the number of pups born per litter, season of the year as well as mother's age at the time of delivery statistically significantly affect birthweight of pups (P < 0.001). Obtained results confirm that long-haired guinea pigs reproduce throughout the year. The average litter size was 2.7 ± 1.03 pups (the range of 1–6). Most frequently triplets were born, which constituted 44% of all live born litters, and the least frequently sextuplets, which in the studied samples were born only once. The average birthweight was 98.45 ± 22.42 g (ranging between 42 and 150 g). It was proved that the body weight of singletons and twins was similar and statistically did not differ significantly. However, body weight of triplets statistically differed significantly (P < 0.05) compared to singletons and twins, as well as pups from larger litters. Calculated correlation coefficient (R = −0.501; P < 0.001) indicates that the increased number of pups is accompanied by the decrease in the body weight of newborns. It was observed that the largest newborns in terms of birthweight (104.47 ± 23.83 g) were born by females at 18–24 months of age. The pups born by mothers of this age group statistically differ significantly (P < 0.05) from the offspring born by females from other groups. Mortality in pups was 27%, from which stillbirths constituted over 80%, and the rest of pups died during 28-day rearing.