Due to their importance for the control of meat quality in broiler chickens, the present study aimed at identifying the factors associated with the occurrence of myopathies and characterizing the meat properties when affected by myopathies. To this aim, a total of 768 broiler chickens were reared until slaughter (46 d) to evaluate the effect of genotype, gender, and feeding regime (ad libitum vs. restricted rate, 80% from 13 to 21 d of age) on performance and meat quality. Standard broilers were heavier (3,270 vs. 3,139 g; P<0.001) and showed lower feed conversion (1.56 vs. 1.61; P<0.001) than the high-yield broilers. Males showed higher final live weight (3,492 vs. 2,845 g) and lower feed conversion (1.54 vs. 1.63) than females (P<0.001). Feed restriction decreased final live weight (3,194 vs. 3,142 g; P<0.01) and feed conversion (1.60 vs. 1.57; P<0.01) compared to ad libitum feeding. At gross examination, feed restriction tended to increase white-striped breasts (69.5 vs. 79.5%; P<0.10), whereas females showed less wooden breasts than males (8.0 vs. 16.3%; P<0.05). White-striped fillets had higher pHu (5.87 vs. 5.83), and lower a* (-0.81 vs. -0.59) and b* color indexes (13.7 vs. 14.5) (P<0.05), whereas wooden breast fillets exhibited higher cooking losses (25.6 vs. 22.1%) and AK-shear force (4.23 vs. 2.84 kg/g) compared with normal fillets (P<0.001). At histological examination, 3.1% of pectoralis major were normal, 26.6% mildly degenerated, 45.3% moderately degenerated, and 25.0% severely degenerated. In conclusion, genotype had a moderate effect on growth without modifying myopathy occurrence. In contrast, gender and feed restriction affected performance, meat quality, and breast abnormalities.

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In this review, the methods used to measure fibre and soluble fibre fractions are briefly presented and the effects of the soluble fibre content in diets for growing rabbits reviewed by a meta-analysis of studies available in literature, with the aim of elucidating the relationships with other dietary nutrients. Soluble fibre was assumed as the difference between total dietary fibre (TDF) and neutral detergent fibre (NDF), as it is simple to obtain and has been measured in numerous studies. Dietary soluble fibre content affects the digestive utilisation of soluble and insoluble fibre fractions and its increase is associated with reduced mortality in growing rabbits affected by epizootic rabbit enteropathy. This effect could be attributed to the high fermentability of soluble fibre, the consequent changes in the intestinal microbiota and an enhanced gut barrier function just after weaning. A supply of 12-14% of soluble fibre (as-fed) is recommended in diets for post-weaning and growing rabbits containing around 30% NDF and 18% acid detergent fibre. The positive effects of increasing dietary soluble fibre are linked to the use of sugar beet pulp as primary source of soluble fibre and should be confirmed with other sources of soluble fibre.

Research on rabbit welfare has been fragmentary and to date has been performed by only a few European teams who have often neglected the productive and commercial aims of rabbit rearing. With European Project COST Action 848 (Multi-facetted research in rabbits: a model to develop healthy and safe production in respect with animal welfare), rabbit welfare began to be considered in European research projects with the focus mainly on ethology, welfare evaluation methods, doe-litter relationships, man-animal relationships, and reproducing and fattening housing systems. As regards legislation, since 1996 the Standing Committee for the protection of animals kept for farming purposes established in the European Council by the Convention on the Protection of farm animals (ETS 87/1976) has been preparing specific recommendations to ensure improved welfare of domestic rabbits kept for commercial purposes, which should provide the basis for future European and national regulations. The European Commission asked the European Food and Safety Authority (EFSA) for its opinion on "The impact of the current housing and husbandry systems on the health and welfare of farmed domestic rabbits". The present paper provides a critical review of the existing literature on rabbit welfare with special emphasis on housing conditions.

BackgroundThe present work aimed at evaluating the effect of the dietary replacement of soybean oil (S) by two types of insect fats extracted from black soldier fly larvae (H, Hermetia illucens L.) and yellow mealworm larvae (T, Tenebrio molitor L.) on growth performance, nutrient digestibility, blood parameters, intestinal morphology and health of growing rabbits.MethodsAt weaning, 200 crossbred rabbits (36 days old) were allotted to five dietary treatments (40 rabbits/group): a control diet (C) containing 1.5% of soybean oil and four experimental diets where soybean oil was partially (50%) or totally (100%) substituted by H (H50 and H100) or T (T50 and T100) fats. Total tract digestibility was evaluated on 12 rabbits per treatment. The growth trial lasted 41 d and, at slaughtering (78 days old), blood samples were collected from 15 rabbits per treatment, morphometric analyses were performed on duodenum, jejunum and ileum mucosa, and samples of liver, spleen and kidney were submitted to histological evaluation.ResultsNo difference was observed between the control and the experimental groups fed insect fats in terms of performance, morbidity, mortality and blood variables. The addition of H and T fats did not influence apparent digestibility coefficients of dry matter, protein, ether extract, fibre fractions and gross energy. Gut morphometric indices and organ histopathology were not affected by dietary inclusion of H and T fats.ConclusionsH and T fats are suitable sources of lipid in rabbit diets to replace soybean oil without any detrimental effect on growth performance, apparent digestibility, gut mucosa traits and health.Electronic supplementary materialThe online version of this article (10.1186/s40104-018-0309-2) contains supplementary material, which is available to authorized users.