Effect of ambient temperature on the productive and carcass traits of growing rabbits divergently selected for body fat content

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.

Influence of tomato processing by-product extract as dietary supplementation on growth performance, carcass characteristics and antioxidant status of growing rabbits under high ambient temperature

This study evaluated the effects of dietary supplementation of tomato processing by-product extract (TPBE) on growth performance, carcass characteristics and antioxidant status of growing rabbits under high ambient temperature. A total of eighty weaned New Zealand White (NZW) male rabbits (6-weeks-old; initial body weight, 730.28 ± 36.05 g) were randomly assigned to 4 groups. The first group was the control without supplementation; while the other groups were fed diets supplemented with 100, 200 and 250 mg TPBE/kg. The results showed that TPBE contained 211.85 mg/100g as total phenols and total flavones of 303.36 mg/100g. Rabbits fed a 250 mg TPBE-supplemented diet showed the heaviest body weight, the lowest feed intake and the best feed conversion ratio. TPBE diets reduced mortality percentage. Dietary supplementation of 250 mg TPBE had the highest dressing percentage. Plasma total protein, globulin, catalase and glutathione peroxidase of rabbits fed diets supplemented with 200 and 250 mg TPBE were high. Plasma total cholesterol, triglycerides, plasma hydrogen peroxide and malondialdehyde concentrations were decreased with dietary levels of TPBE. Rabbits fed 250 mg TPBE had higher T-AOC than the other groups. TPBE supplemented diets improved net revenue and economic efficiency. Conclusively, TPBE is containing appreciable content of polyphenols and flavonoids and the dietary supplementation of TPBE (250 mg/kg diet) had a positive impact on growth performance, reducing mortality and enhancing the antioxidant status of rabbits reared under high ambient temperature.

Ramifications of Heat Stress on Rabbit Production and Role of Nutraceuticals in Alleviating Its Negative Impacts: An Updated Review

Heat stress has become a widespread concern worldwide, which is a major environmental stress that causes substantial economic loss in the rabbit industry. Compared to other agricultural animals, rabbits are more sensitive to heat stress as they have fewer sweat glands and a thicker coat of fur, increasing the heat dissipation complexity. Thus, heat stress hurts rabbits' productivity, meat quality, reproductive performance, antioxidative properties, immune responsiveness, intestinal histomorphology, and microbiome. Nutraceuticals include vitamins, minerals, antioxidants, organic acids, fatty acids, probiotics, prebiotics, synbiotics, enzymes, and medicinal plants due to the possible impacts on maintaining common biological situations, strengthening immune response, and preventing illness, which ultimately led to an increase in productivity. Nutraceuticals have recently attracted a lot of attention to alleviate the adverse impacts of heat stress in rabbit farms. The objective of the current review is to provide acquaintance with the recent findings about the impact of heat stress on rabbit productivity and the advantages of dietary supplementation of nutraceuticals in mitigating it.

Improving productivity in rabbits by using some natural feed additives under hot environmental conditions - A review

Heat stress is a major challenge to animal production in tropical and subtropical climates. Rabbits suffer from heat stress more than farm animals because they have few sweat glands, and their bodies are covered with thick fur. Intensive farming relies on antibiotics as antimicrobials or growth promoters to increase animals' productivity and health. However, the European Union and many countries have banned or restricted the use of antibiotics in animal feed for human health concerns. Several studies have found that replacing antibiotics in rabbit feed with natural plants or feed additives increases productivity and improves immune capacity, especially under heat stress conditions. Growth performance, immune response, gut microflora, and carcass yield may be increased in rabbits fed a diet supplemented with some natural plants and/or propolis. In this review article, we discuss and summarize the effects of some herbs and plant extracts as alternative feed additives on rabbit productivity, especially for those raised under hot ambient temperatures.

Genetic parameters of growth traits and carcass weight of New Zealand white rabbits in a tropical dry forest area

Objective:

The objective of this study was to estimate the heritability (h²), repeatability (r), and correlations (r_ŷiyi) in some traits of zootechnical interest in a population of New Zealand white rabbits of a tropical dry forest area.

Materials and Methods:

Three mating groups were formed, each one of 1 male and 70 females. The traits evaluated were litter size at birth (LB), born alive (BA), born dead (BD), litter weight born alive (LW), litter weight at weaning (LWW), weaning weight (WW), slaughter weight (SW), and carcass weight (CW). Weaning took place at 42 days, and the fattening phase lasted 60 ± 3 days. A descriptive statistical study was carried out on the study variables. Paternal heritability was estimated (hf2) and maternal (hm2), repeatability, rabbit index IC, and Pearson’s correlations (r_ŷiyi) between traits. The descriptive statistics showed high variation for the BD traits.

Results:

The values of the productivity found were similar to those presented in studies around the world. h² presented magnitudes between low and medium. hf2 ranged between 0.09 and 0.42 and between 0.11 and 0.45 for hm2. In general, the values of hm2 were higher than the values of hf2. The r values for the traits LB, BA, LW, LWW, and SW presented low magnitude, while it was medium for WW and CW. From the values of r, IC was calculated for each of the rabbits, allowing their categorization, which will be used in future selection plans. r_ŷiyi among the variables ranged from −0.01 to 0.860. They were generally positive and mostly not significant (p > 0.05); they took a magnitude from low to moderate, except for the correlation between LB and BA.

Conclusion:

The production of rabbits under tropical conditions is similar to other reports. The genetic parameters evaluated were medium-to-low, indicating a robust non-additive gene and/or environmental effect.