World Rabbit Science

Evaluating animal models comprising additive genetic and maternal effects on growth traits in German Angora rabbit

2024-06-18T08:53:31+02:00

This investigation was carried out to estimate the genetic parameters for German Angora rabbits using most appropriate animal model comprising additive and maternal effects. The pedigree information and data on growth traits were collected from 5221 rabbits, which descended from 699 does and 294 bucks over a period of 21 yr (2001–2021) kept at Northern Temperate Regional Station, Garsa, Kullu (Himachal Pradesh), India. The average daily gain (ADG) and Kleiber ratio (KR) were calculated at different age intervals. Analyses were carried out by restricted maximum likelihood procedure fitting six animal models with various combinations of direct and maternal effects. The best model was evaluated on the basis of a likelihood ratio test. Analysis revealed that the model including both direct and maternal genetic effects along with permanent effect of the dam was most suitable for all traits except for body weight (BW) at 6th wk of age, ADG from 6th to 12th wk of age and KR associated to ADG from 12th to 18th wk of age. The direct heritability estimates from the best model were ranged from, 0.34±0.05 to 0.49±0.05 for BW; 0.19±0.04, to 0.46±0.06 for ADG and 0.21±0.04 to 0.41±0.05 for KR, respectively. Direct heritability estimates were overestimated when maternal effects were ignored. Maternal effects on BW declined from 0.49±0.04 at weaning to 0.06±0.03 at 12th wk of age and 0.09±0.04 at 18th wk of age. Correlations between direct and maternal effects ranged from −0.44±0.15 to−0.52±0.14 for body weights, indicating biological antagonism between these effects. Genetic correlations among various growth traits were positive and high, indicating scope for correlated response in later expressed traits. Analysis revealed that maternal additive influences were only important until weaning, whereas permanent environmental maternal influences were present in all growth traits considered in this study. The moderate estimates of heritability for growth traits and Kleiber ratio of rabbit in this study indicate that rates of genetic progress may be possible for these traits by selection under the standard management system.

Meta-analysis of genetic parameters for economic traits in rabbit using a random-effects model

2024-06-18T17:01:01+02:00

The genetic improvement of rabbits helps increase their productivity and, consequently, increase the supply of animal protein for human consumption. The aim of this study was to perform a meta-analysis of genetic parameters (heritability and genetic correlation) for litter size at birth, litter weight at birth, litter size at weaning, litter weight at weaning and slaughter weight in rabbits. The final dataset contained 147 estimates of heritability and 32 estimates of genetic correlation across 34 articles published between 1992 and 2022. A random-effects model was used and the heterogeneity of estimates was assessed using Q and I² statistics. Heritability estimates were of low magnitude for all traits, ranging from 0.09 to 0.18. The lowest heritability estimate was observed for litter size at weaning and the highest for slaughter weight. Most genetic correlations between traits were positive and moderate, ranging from 0.44 to 0.60. Significant heterogeneity among studies justified the use of random-effects models. The meta-analysis study provided reliable genetic parameter estimates and these results can support the development of rabbit breeding programmes..

Preslaughter feed withdrawal and sex influences on rabbit physiological response and meat quality

2024-04-22T10:39:12+02:00

Although preslaughter feed withdrawal is commonly used in the livestock industry to reduce the risk of viscera puncture during evisceration, the optimal feed withdrawal time (FWT) appears to be species dependent and is not yet well defined in rabbits. This study aimed to evaluate the impact of three preslaughter FWTs while considering the effect of sex on physiological response and meat quality of rabbits. Three FWTs (4, 11 and 18 h) were tested using 144 recently weaned Grimaud rabbits fed until they reached an average commercial slaughter live body weight of 2.5±0.2 kg. Rabbits were allocated into 24 cages, with six animals in each cage. Eight cages (four cages for females and four cages for males) were assigned to each of the three FWTs. Blood lactate concentrations measured at exsanguination did not raise concerns related to stress. Female rabbits subjected to 4 h FWT had a higher gastrointestinal tract weight compared to male rabbits and to other females subjected to 11 and 18 h FWT (P=0.04). Stomach content weights were lower after 18 h FWT compared to 4 and 11 h (P=0.002) for both sexes, while caecum weights were not affected by FWT. Caecum pH was higher after 11 and 18 h FWT compared to 4 h (P=0.02). Technological meat quality was not particularly affected by FWT, except for Longissimus lumborum drip loss which was lower for rabbits after 18 h FWT compared to 4 h FWT (P=0.005). With respect to microbiological meat quality, the end of shelf life was reached after 10 days for vacuum-packed hind legs from rabbits after 11 h FWT, as Escherichia coli cell counts for four out of the eight hind legs analysed were higher than 3 Log₁₀ colony-forming units (CFU)/10 g. For the other two FWT groups, the end of shelf life was reached after 15 d, at which point the cell counts for all hind legs were ≥3 Log₁₀ CFU/10 g for E. coli and ≥7 Log₁₀ CFU/g for total aerobic mesophilic and presumptive lactic acid bacteria (the maximum threshold concentrations according to current regulations). Our results demonstrate that when transport (30 min) and lairage (30 min) times are short (1 h in total), an 18-h preslaughter feed withdrawal for both male and female rabbits can allow the gut to empty properly with limited effect on meat quality.

Dietary inclusion of white lupine seeds and their byproducts in rabbits can contribute to EU agricultural sustainability: a review

2024-07-01T13:30:02+02:00

This review explores the potential of white lupin seeds (Lupinus albus) as a sustainable protein source for rabbit nutrition and examines their effects on growth performance, carcass traits, health status, milk yield, milk composition and nutrient availability. The dietary inclusion of white lupin seeds leads to comparable or superior growth, milk yield, milk composition, nutrient digestibility and digestive health of rabbits, as well as meat quality and carcass outcomes relative to traditionally used protein sources for feeding rabbits, such as soybean meal and sunflower meal. Studies also show that it is possible to use white lupin byproducts, such as the hull and bran, for rabbit diets, which can be convenient in terms of providing an adequate supply of lignocellulose and enhancing the sustainability of rabbit feed, promoting circular economy principles. The cultivation of white lupin can contribute to environmental sustainability by reducing greenhouse gas emissions and the use of synthetic fertiliser. Future research should focus on breeding improvements and comprehensive environmental assessments of white lupin seeds to maximise the benefits of white lupin for rabbit nutrition. These findings support the role of white lupin as a viable and eco-friendly alternative to traditional protein sources, such as soybean meal, which could support productivity and sustainability in rabbit farming.

Abstracts of the 48th Symposium on Cuniculture, ASESCU

2024-07-29T12:07:56+02:00

The 48^th Congress of the Spanish Association of Cuniculture (ASESCU) was held in Córdoba, Andalusia, Spain. The congress was organised by ASESCU in collaboration with the Faculty of Veterinary Medicine and the University of Córdoba. A total of four main lectures were delivered. One of these lectures discussed the current state of cuniculture in Andalusia, while another examined the evolution of the sector in Italy. Another lecture focused on state-of-the-art of alternatives to cages for rabbit housing, and the fourth lecture covered new rabbit lines developed for disease resistance. Additionally, two round tables were held, discussing the main challenges in the rabbit farming sector and new veterinary legislation. A total of 25 communications were presented on various topics, including nutrition, genetics, reproduction, housing and welfare, pathology and products. The event was attended by approximately 130 participants from various European and American countries. Below are the abstracts of the contributions.