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We followed the evolution of hematocrit and of plasma Na, K, Cl, total protein, creatinine, Pi, alkaline phosphatases, triglycerides, cholesterol, glucose and GPT. The amount of feed given to the rabbit does was restricted to 75 percent of the quantity eaten ad libitum, in similar conditions to those of intensive breeding. This had a slight effect on the values obtained for plasmatic components in healthy rabbits. This was not dependent on the timing of blood collection, nor on the physiological state of the animal. The changes in biochemical composition of the plasma due to pregnancy in healthy rabbit does are: a fall in total plasma protein and cholesterol levels, alkaline phosphatases activity, hematocrit, and a rise followed by a marked fall in plasma triglycerides level. During lactation, these levels return progressively to the values obtained in non-pregnant, non-lactating rabbits.

We analysed the working life of purebred New Zealand, and Californian rabbit breeding does kept in identical conditions. Our study notes the health of the does as well as various factors affecting the survival rate of baby rabbits until weaning. After the first six months of rearing the productivity and the health of the two breeds were very different. The Californian females came through their first two gestations and lactations very well but more than half of them showed signs of respiratory ailments, and many had to be eliminated. Their first two litters were characterised by a low number of baby rabbits weaned as well as a large number of whole litters dead before weaning. The females of the New Zealand breed were in good health but then died suddenly at the end of gestation or in the middle of lactation; the surviving females raised practically their whole litter until weaning. The loss of animals is numerically fairly similar in the two breeds but takes on different farms. This comparative study of the elimination of the does, of their mortality, or of that of the baby rabbits during lactation leads us to the hypothesis that these three phenomena are probably different manifestations of the same pathological phenomena occurring early on, probably from the first gestation onwards.

One of the most important limiting factors of rabbit production is reproductive pathology. This pathology has two aspects: livestock reduction (elimination and death of rabbit does) and mortality of young rabbits before weaning. We studied alterations of hematocrit and of plasma Na, K, Ca, Mg, Pi, total proteins, prolactin, during gestation and lactation of primiparous rabbit does. In females which were going to die the first results showed a fall in plasma NaK, Ca concentrations and a rise in plasma Mg. We think that these alterations are only consequences of anterior metabolic alterations and are indicators or secondary causes of the animal's proximate death. We noticed a deep fall in plasma prolactin concentration before death; its signification is discussed. In the females which did not wean their whole litter, average prolacting levels during gestation and at the beginning of lactation were lower than in females weaning their whole litter. These first results would confirm the hypothesis that youngs' mortality is a pathology linked with dams' state.