Influence of rabbit sire genetic origin, season of birth and parity order on doe and litter performance in an organic production system

Seasonal Variations in Production Performance, Health Status, and Gut Microbiota of Meat Rabbit Reared in Semi-Confined Conditions

In this study, we investigated the variations in production performance, health status, and gut microbiota of meat rabbits raised in the semi-confined barn during summer and winter. Compared to summer, rabbits reared in winter possessed significantly higher slaughter weight and carcass weight. Rabbits fed in the summer were more vulnerable to different stressors, which led to increased protein levels of HSP90, IL-1α, IL-1β, IL-2, and concentrations of MDA, but declined GSH and SOD activities. Additionally, significant differences in gut microbial communities were observed. Compared to the winter, rabbits fed in the summer had significantly lower and higher alpha and beta diversity. Both Firmicutes and Verrucomicrobiota were the dominant phyla, and they accounted for greater proportions in the winter than in the summer. At lower microbial taxa levels, several seasonal differentially enriched microbes were identified, such as Akkermansia muciniphila, the Oscillospiraceae NK4A214 group, the Christensenellaceae R-7 group, Alistipes, and Muribaculaceae. Functional capacities linked to microbial proliferation, nutrient metabolism, and environmental adaptive responses exhibited significantly different abundances between summer and winter. Moreover, strong interactions among different indicators were presented. Based on our findings, we not only proposed several potential strategies to ameliorate the undesirable effects of seasonal changes on the productivity and health of meat rabbits but also underscored the directions for future mechanistic studies of adaptation physiology.

Genetic and Phenotypic Parameters of Rabbit Individual Body Weight in the Preweaning Period

The preweaning weight of kits has been related to their mortality during the suckling period. Selecting rabbit kits for individual body weight in the first days of life could be interesting; however, better knowledge of body weight's heritability during the preweaning period is necessary to determine the opportune moment for selection. A total of 1696 growth records of kits from 81 females of the ITLEV2006 synthetic line were analysed in order to estimate the genetic and non-genetic parameters for individual body weight at birth as well as at 5, 7, 14, 21, 28, and 35 days of age. The estimates of heritability (h2) for individual weight were between low (0.11 at birth, 0.16 at 5 days, and 0.17 at 7 days) and moderate (0.21, 0.21, 0.24, and 0.21 at 14, 21, 28, and 35 days, respectively). Weight at birth showed a strong and positive genetic correlation with weight at 5 days (+0.79) and 7 days of age (+0.78), but the correlation was low for the rest of the weight measurements (+0.41, +0.49, +0.54, and +0.54 with weight at 14, 21, 28, and 35 days, respectively). Weight at 5 days and 7 days displayed strong and positive genetic correlations with the rest of the weight measurements (higher than +0.83). The values of the common litter effect (c2) were high, and they increased with age from 0.43 at birth to 0.66 at 35 days of age. The values of the maternal permanent effect (p2) were low compared to those of the common litter effect (c2), varying between 0.04 and 0.11. In conclusion, opting to select for body weight at 5 or 7 days of age would yield a greater response compared to selecting for birth weight. This approach would indirectly increase the kits' weight at birth and at weaning, thereby reducing preweaning losses.

Effect of mastitis incidence on litter size, litter weight, and milk composition of rabbit does

This study aimed to examine the effect of mastitis incidence on the litter size, litter birth weight, and milk composition of Hycole does on a commercial rabbit farm during their third and fourth parity. At third parity does were assigned to the "No mastitis" (n = 30) and "Mastitis" (n = 28) groups on the basis of visible abscesses in the mammary gland area. The microbiological analysis revealed the presence of different pathogenic bacteria. At third parity, "Mastitis" females had fewer kits than the "No mastitis" group, and the average birth weight was lower. On day 2 of the third lactation, "Mastitis" does produced significantly less milk daily compared with the "No mastitis" group. A significant effect on the incidence of mastitis on the litter size and litter weight during the growth of kits up to the 35th day was also observed. The effect of the incidence of mastitis on milk chemical composition was limited. At the fourth parity, the litter characteristics and daily milk yield were leveled in "Mastitis" and "No mastitis" females. To conclude, our study showed that mastitis negatively affects litter size, birth weight, and daily milk yield in the current parity. However, early detection and proper treatment allowed to obtain good reproductive results and healthy kits in the next parity.