Impact of pre-breeding feeding practices on rabbit mammary gland development at mid-pregnancy

Abstract

Optimizing rabbit does preparation during early life to improve reproductive performance is a major challenge for breeders. Does selected for reproduction have nutritional needs, which may not be supplied with the common practice of feed restriction during rearing in commercial rabbit production. Nutrition during early life was already known to influence metabolism, reproduction and mammary gland development later in life, in particular during pregnancy. The aim of this study was to analyze four different restriction feeding strategies during post-weaning and over the pubertal periods (high or moderate restriction feeding applied from 5 to 9 weeks of age and/or restricted or ad libitum over the following 3 weeks constituting the pubertal period). Unlike food intake, which remains regular, mean body weight gain was inversely proportional to the dietary restriction applied over the considered periods. The feeding strategies in place for the four groups have no effect on the reproductive parameters of the females, as opposed to certain metabolic parameters such as cholesterolemia, that vary with dietary intake. Furthermore, restriction programs have impacted mammary tissular structures at mid-pregnancy. The expression of lipid metabolism enzymes (Fatty acid synthase N and Stearoyl co-A desaturase) is also modified in mammary epithelial cells by the dietary strategies implemented. Moreover, milk gene expression, used as differentiation markers, indicates a better mammary epithelial development regarding further lactation, in the case of the less restrictive strategies during early life period, especially the higher feeding allowance. Our results highlight the importance of investigating feeding conditions of young female rabbits and nutrition in early life rearing, in order to provide specific recommendations for optimizing lactation and thus preventing neonatal mortality of the offspring.