Effect of grinding size of barley and dehydrated alfalfa on performance and body composition of does during their early reproductive cycles

This work aimed to test the effect of grinding size of barley and dehydrated alfalfa on reproductive traits of rabbit does and to evaluate doe body composition with bioelectrical impedance technique in the early breeding cycles. Two dietary treatments were arranged with both barley and alfalfa coarsely ground at 4.5 mm (CC diet) or finely at 1.5 mm (FF diet). At first insemination, 42 nulliparous females were randomly assigned to each of these diets. Differences in grinding size resulted in a larger geometric mean particle size for the CC diet than for the FF diet (868 vs. 667 μm). Similar daily feed intakes in lactation were found among parturitions for rabbit does fed the CC diet (414 g, on average) whereas it increased from the first to the second parturition for rabbit does fed the FF diet (334 vs. 465 g, P = 0.027). Neither reproductive results nor body composition were affected by dietary treatments. Parity order affected reproductive performance. The lowest rates of fertility (86 vs. 98%, P < 0.001) and the longest parturition intervals (59 vs. 43 days, P = 0.008) were recorded at the second and third parturitions. Consequently, in these two cycles numerical productivity was lower than in the fourth parity (53 vs. 78 kits weaned per doe per year, P < 0.001). Mortality, because of mastitis, reached the highest rate after the first parturition (12%, P = 0.001) but decreased in the subsequent cycles. For rabbit does on both diets and in the first two cycles, fat content decreased from day 29 of gestation to day 21 of lactation (16.1 vs. 10.8%, P < 0.01) as well as energy content (1140 vs. 917 kJ/100 g, P < 0.01) while water percentage increased (58.1 vs. 65.3%, P < 0.003). Ash content also increased (2.99 vs. 3.17%, P < 0.004) in this period, especially in the second cycle (from 3.05 to 3.19%, P < 0.001). Protein content also increased in lactating does but significant differences were already detected on day 11 after parturition (from 17.5 to 18.3%, P < 0.008). From day 21 of lactation to the following parturition, rabbit does recovered their body reserves which decreased (P < 0.001) again after the subsequent parturition. The bioelectrical impedance technique showed that rabbit does mobilized their fatty and energetic reserves during the first 21 days of lactation and that body contents of ash and protein increased when females were simultaneously pregnant and lactating.