The guinea pig as a model for the study of the effects of milk on growth and development

Study of the effects of enteral nutrition on neonatal growth and development has been hindered by the lack of a suitable model. A model has been developed to measure the effects of an artificial milk formula on the growth of the newborn guinea pig. The composition of milk expressed from lactating guinea pigs 2 to 13 days postpartum was analysed for its protein, lactose, fat and metabolizable energy contents. Changes in osmolality, water and electrolyte contents were determined. An isotope (3H2O) dilution method was used to measure daily milk intakes of naturally suckled animals. An artificial formula, based on cow's milk (CMF), isocaloric with natural guinea pig milk was designed and synthesized. Neonatal guinea pigs were reared either naturally or on CMF from birth to 8 days. Comparable growth and milk intakes were achieved by the two feeding groups. No adverse effects of CMF were noted. The study represents the development of an effective means of raising a laboratory animal during the suckling period on an artificial milk formula. The model may be used to measure the impact of enteral nutrition on the ontogeny of the gut, and on neonatal growth and development, in a precocial species which more closely resembles man than the altricial species, such as rat and mouse, generally used for this purpose.