Energy homeostasis in rabbit does during pregnancy and pseudopregnancy

This study was conducted to evaluate the changing concentrations of metabolic hormones and metabolites in pregnant (P) and pseudopregnant (PP) rabbit does. Twenty-five New Zealand White rabbit does were submitted to artificial insemination (AI) and then classified as P (n = 15) or PP (n = 10). Blood samples were collected weekly until day 32 post AI. During pregnancy, leptin concentrations were greater on Days 14 and 21 (P< 0.05), while insulin was greater on days 21 and 32 post AI (P< 0.05) compared to PP does. The triiodothyronine/thyroxine (T3/T4) ratio was greater in the first and last week (P< 0.001); whereas, cortisol concentrations were greater in the last week of pregnancy and after parturition (P< 0.01) compared with that of PP does. Non-esterified fatty acids (NEFA) concentrations increased from day 7 until day 32 post AI (P< 0.05). Glucose concentrations were unchanged throughout pregnancy although concentrations were positively associated with litter size. These results indicate concentrations of hormones and metabolites change during pregnancy to ensure energy requirements are met for both the foetuses and the maternal tissues. Physiological hyperleptinemia, hyperinsulinemia, and changes in cortisol as well as thyroid hormones indicate there is an adaptation of metabolic functions induced by pregnancy. These adaptations could be mediated by gonadal steroids because changes mainly occur in the second half of pregnancy when the profile of the sex hormones differs between P and PP does.