Effect of Genotype, Gender, and Feed Restriction on Slaughter Results and Meat Quality of Broiler Chickens

Slaughter results and meat quality were evaluated in 768 broilers according to genotype (standard breast yield vs. high breast yield), gender, and feeding systems (ad libitum vs. feed restriction from 13 to 21 d of age). Standard-yield chickens had higher carcass weights (2358 g vs. 2319 g; P < 0.001) and hind legs proportion (31.1% vs. 30.6%; P < 0.01), and lower dressing out percentage (73.6% vs. 74.0%; P < 0.01) compared to high-yield birds, besides lower meat L* index (45.3 vs. 46.2; P < 0.05), higher final pH (5.89 vs. 5.85; P < 0.05) and thawing losses (10.5% vs. 9.43%; P < 0.05). Males showed higher carcass weight (+24%), dressing percentage (+0.7%), and hind leg yield (+4%) (P < 0.001) than females. Restricted birds had lower carcass weight (-2%; P < 0.001) and dressing percentage (‑0.3%) (P < 0.05) than those always fed ad libitum. As what concerns meat quality, gender and feeding system affected only meat final pH, lower in ad libitum group than in restricted one and in females than males. In conclusions, slaughter results and carcass traits changed especially with genotype and gender, coherently with slaughter weight whereas meat quality was mostly affected by genotype

Effect of Genotype, Gender, and Feed Restriction on Slaughter Results and Meat Quality of Broiler Chickens

Slaughter results and meat quality were evaluated in 768 broilers according to genotype (standard breast yield vs. high breast yield), gender, and feeding systems (ad libitum vs. feed restriction from 13 to 21 d of age). Standard-yield chickens had higher carcass weights (2358 g vs. 2319 g; P < 0.001) and hind legs proportion (31.1% vs. 30.6%; P < 0.01), and lower dressing out percentage (73.6% vs. 74.0%; P < 0.01) compared to high-yield birds, besides lower meat L* index (45.3 vs. 46.2; P < 0.05), higher final pH (5.89 vs. 5.85; P < 0.05) and thawing losses (10.5% vs. 9.43%; P < 0.05). Males showed higher carcass weight (+24%), dressing percentage (+0.7%), and hind leg yield (+4%) (P < 0.001) than females. Restricted birds had lower carcass weight (-2%; P < 0.001) and dressing percentage (‑0.3%) (P < 0.05) than those always fed ad libitum. As what concerns meat quality, gender and feeding system affected only meat final pH, lower in ad libitum group than in restricted one and in females than males. In conclusions, slaughter results and carcass traits changed especially with genotype and gender, coherently with slaughter weight whereas meat quality was mostly affected by genotype

Effects of floor type, stocking density, slaughter age and gender on productive and qualitative traits of rabbits reared in collective pens

At 34 d of age, 376 crossbred rabbits of both sexes were housed in 16 open-top collective pens (1.68 m2) according to a 2 72 72 factorial arrangement with two types of pen floor (wooden v. plastic slatted), two stocking densities (12 v. 16 animals/m2), and two slaughter ages (76 v. 83 d). The rabbits were examined for growth performance, slaughter results, and meat quality. The effect of gender was also examined. The percentage of rabbits with wounds due to aggression varied with stocking density (8.2% v. 26.2% for 12 v. 16 animals/m2; P 64 0.001), slaughter age (15.0% v. 22.0% at 76 v. 83 d; P 64 0.10), and gender (11.3% v. 25.8% for females v. males; P 64 0.001). Rearing rabbits on a plastic rather than a wooden slatted floor promoted slaughter weight (2795 g v. 2567 g; P 64 0.001), dressing percentage (61.4% v. 60.9%; P 64 0.01), dissectible fat (2.4% v. 2.0%; P 64 0.01), and hind leg muscle-to-bone ratio (5.81 v. 5.35; P 64 0.001). Increased stocking density impaired daily growth (38.5 g/d v. 35.9 g/d; P 64 0.05) and feed intake (140 g/d v. 134 g/d; P 64 0.01) during the second period (55 d to slaughter) and decreased slaughter weight (2725 g v. 2637 g; P 64 0.01). At the older slaughter age, the feed conversion ratio was impaired (2.98 v. 3.18; P 64 0.001); the slaughter weight (2574 g v. 2788 g; P 64 0.001), dissectible fat (2.0% v. 2.4%; P 64 0.01), and hind leg muscle to bone ratio (5.41 v. 5.75; P 64 0.01) increased; meat thawing losses, cooking losses, and shear force decreased (P 64 0.05). The main differences between the females and males were found in the slaughter for transport losses (2.6% v. 2.2%; P 64 0.01) and l. lumborum proportions (13.0% v. 12.4%; P 64 0.01). In conclusion, the growth performance of pen-housed rabbits was largely determined by the type of floor and less affected by stocking density. The meat quality depended on ontogenetic factors, such as slaughter age and gender, and not on housing conditions. The differences in the percentages of wounded animals due to experimental factors deserve further investigation from the perspective of animal welfare issues

Increasing Dietary Energy with Starch and Soluble Fibre and Reducing ADF at Different Protein Levels for Growing Rabbits

The effect of increasing dietary energy by increasing both starch (14% to 20%) and soluble fibre (9.6% to 11.6%) and decreasing ADF content (21% to 13%) at two crude protein levels (14% and 15%) was assessed on health, growth performance, caecal fermentative activity, gut mucosa traits, and carcass and meat quality of growing rabbits reared from 34 to 76 days of age. At weaning, 306 rabbits were divided into six groups and fed ad libitum six diets formulated according to a bi-factorial arrangement with 3 (starch+soluble fibre)/ADF ratio (L=1.2; M=1.8; H=2.8) x 2 protein levels. The contemporary increase of dietary starch and soluble fibre and the reduction of ADF linearly increased the digestibility of dry matter, energy and all nutrients, decreased feed intake and improved feed conversion (3.65 to 2.76 in rabbits fed diets L and H; P<0.001); it increased morbidity (P=0.09) but did not affect mortality due to epizootic rabbit enteropathy; at caecum, VFA production raised (52.1 to 61.9 mmol/L) and pH (5.90 to 5.67) and N ammonia lowered (4.85 to 1.93 mmol/L); the villi/crypts ratio (4.42 vs. 3.81 and 3.95 in rabbits fed diets L, M and H) decreased in a non linear mode. The decrease of the protein level did not affect growth performance, but nearly halved mortality (28.9% vs. 16.3%; P=0.01) and increased caecal pH (5.70 to 5.87; P=0.05). Weak effects of the dietary treatments were measured on carcass traits and meat quality

Effect of feed restriction and feeding plans on performance, slaughter traits and body composition of growing rabbits

[EN] Two feeding systems (L, ad libitum vs. R, feed restriction) were combined with 3 feeding plans (MM, MH, HH) to evaluate the effects on performance, slaughter results, body composition and nitrogen balance of 300 commercial crossbred rabbits kept individually from weaning to slaughter (34-70 d of age). The R rabbits were fed from 80% (first days on trial) to 100% (end of 3rd wk) of ad libitum intake, whereafter R rabbits had free access to feed. The 3 feeding plans were: MM plan, M diet with moderate digestible energy (DE) content, 10.6 MJ/kg, throughout the trial; HH plan, H diet with high DE content, 11.1 MJ/kg, throughout the trial; MH plan, M diet for the first 3 wk and H diet for the last 2 wk. Feed restriction did not affect nutrient digestibility, growth rate on the whole trial and slaughter results, but improved feed conversion (2.96 vs. 2.89 in L and R rabbits, respectively; P<0.01) and reduced N excretion (2.16 vs. 2.07 g excreted N/d, in L and R rabbits; P<0.05). At the end of the first period (55 d), R rabbits showed lower empty body protein, lipid, and gross energy gains than L rabbits, but differences disappeared within the end of the trial. The HH plan improved feed conversion (2.97 vs. 2.89 for MM vs. HH; P<0.05), but increased excreted N (2.03 vs. 2.17 g/d; P<0.001) in comparison with the MM plan due to the higher digestible protein/DE ratio of H diet, whereas the MH plan showed intermediate results. In conclusion, a moderate feed restriction during post weaning improved feed conversion and reduced N excretion without negative effects on growth or slaughter results. Moreover, N excretion was confirmed to depend largely on dietary nitrogen content.This study was funded by the Ministero dell’Istruzione dell’Università e della Ricerca (Project COD.60A08–7188/12).Birolo, M.; Trocino, A.; Tazzoli, M.; Xiccato, G. (2017). Effect of feed restriction and feeding plans on performance, slaughter traits and body composition of growing rabbits. World Rabbit Science. 25(2):113-122. https://doi.org/10.4995/wrs.2017.6748SWORD113122252Blas, C. de, & Mateos, G. G. (s. f.). Feed formulation. Nutrition of the rabbit, 222-232. doi:10.1079/9781845936693.0222Di Meo C., Bovera F., Marono S., Vella N., Nizza A. 2007. Effect of feed restriction on performance and feed digestibility in rabbits. It. J. Anim. Sci., 6: 765-767.ERM/AB–DLO. 1999. Establishment of Criteria for the assessment of the nitrogen content of animal manures, European Commission, Final Report, Luxembourg.Fernández Carmona J., Pascual J.J., Cervera C. 2000. The use of fats in rabbit diets. In: Proc. 7th World Rabbit Congress, 5-7 July, 2000, Valencia, Spain. World Rabbit Sci., 8, suppl. 1, vol. C, 29-59.Gidenne T., Aubert C., Drouilhet L., Garreau H. 2013a. Feed efficiency in rabbit breeding: technico-economical and environmental impacts. In: Proc. 15èmes Journ. Rech. Cunicole, 26-27 November, 2013, Le Mans, France, 1-13.Marlier D., Dewree R., Delleur V., Licois D., Lassence C., Poulipoulis A., Vindevogel H. 2003. A review of the major causes of digestive disorders in the European rabbit. Ann. Med. Vet., 147: 385-392.Mertens D.R. 2002. Gravimetric determination of amylase-treated neutral detergent fiber in feeds with refluxing in beakers or crucibles: collaborative study. J. AOAC Int., 85: 1217-1240.XICCATO, G. (2010). FEEDING AND MEAT QUALITY IN RABBITS: A REVIEW. World Rabbit Science, 7(2). doi:10.4995/wrs.1999.383Xiccato G., Cinetto M., Dalle Zotte A. 1992. Effetto del livello nutritivo e della categoria di conigli sulla digeribilità degli alimenti e sul bilancio azotato. Zoot. Nutr. Anim., 18: 35-43.Xiccato G., Trocino A., Sartori A., Queaque P.I. 2003. Effect of weaning diet and weaning age on growth, body composition and caecal fermentation of young rabbits. Anim. Sci., 77: 101-111. https://doi.org/10.1017/S135772980005370

Behaviour and reactivity of female and male rabbits housed in collective pens: effects of floor type and stocking density at different ages

[EN] At 33 d of age, 376 crossbred rabbits of both genders were housed in sex-mixed groups in 16 open-top collective pens (1.68 m2) in a factorial arrangement, with 2 types of flooring (wooden slats vs. plastic grid, W vs. P) and 2 stocking densities (12 vs. 16 animals/m2). Behavioural recordings (time budget), reactivity towards unknown humans (tonic immobility and human approach tests) and environment (open-field and novel object tests) and hair and faeces sampling for corticosterone analysis were performed during the 8th wk of age and at a pre-slaughter age (during the 11-12th wk of age). The effects of age and gender were also taken into account. Rabbits housed in W pens rested more in the crouched position (41.4 vs. 35.5% of the observed time) (P<0.001) and showed lower allogrooming (P=0.05), running (P<0.01) and biting pen elements (P=0.01) than those housed in P pens. The percentage of rabbits that interacted with humans during the human approach test (24.0 vs. 48.1% of rabbits in the pen; P<0.01) and number of rabbit-object contacts during the novel object test (on av. 50.4 vs. 87.2; P<0.001) were lower for rabbits in W pens compared to those in P pens. During the open-field test, the percentage of rabbits that spontaneously entered the arena was lower for rabbits from W pens than for those from P pens (60.0 vs. 72.5%; P<0.05). Finally, the hair corticosterone level was higher in the former than in the latter rabbits (on av. 14.0 vs. 12.5 ng/g; P<0.05). As the stocking density increased, only the time spent resting increased (66.7 to 69.1% observed time; P<0.01), and the percentage of rabbits that spontaneously entered the arena during the open-field test decreased (73.8 to 58.8%; P<0.01). When age increased, the rabbits were less active at the reactivity tests and interacted less with an unknown object or person. Differences according to gender were weak. In conclusion, the wooden slatted floor challenged the welfare of growing rabbits as it constrained their movement, conditioned their reactivity towards a new environment, and increased their stress level, whereas the increase in stocking density did not impair rabbit welfare.This work was supported by the Seventh Framework Programme of the European Commission [grant number 600376, CUP C91J13001170006]. The authors wish to thank Dr. Andrea Zuffellato (AIA S.p.A., Italy) for his technical support and assistance.Trocino, A.; Filiou, E.; Zomeño, C.; Birolo, M.; Bertotto, D.; Xiccato, G. (2018). Behaviour and reactivity of female and male rabbits housed in collective pens: effects of floor type and stocking density at different ages. World Rabbit Science. 26(2):135-147. https://doi.org/10.4995/wrs.2018.7747SWORD13514726

CHLORELLA VULGARIS MICROALGAE AS A SUSTAINABLE FEED INGREDIENT EFFECTS ON MEAT QUALITY AND MYOPATHY OCCURRENCE IN BROILER CHICKENS

CHLORELLA VULGARIS MICROALGAE AS A SUSTAINABLE FEED INGREDIENT: EFFECTS ON MEAT QUALITY AND MYOPATHY OCCURRENCE IN BROILER CHICKENS is a conference paper presented at the 69th International Congress of Meat Science and Technology (ICoMST) held in Padova (Italy) from the 20th to the 25th of August 2023. The present study found that dietary Chlorella vulgaris microalgae are a useful strategy to manipulate breast meat color, while higher inclusion rates in diets improve the n-3 fatty acids content in breast meat. The impact of C. vulgaris on myopathies in broilers is not evident, but some differences in the gross examination in WB rate between birds fed the control diet and the diet with 6% m highlight the need for further investigation

Effect of light restriction on productive results and behavior of broiler chickens

The study aimed to evaluate the effect of light restriction (18L:6D vs. 14L:10D), genotype (A vs. B), and sex on performance, behavior, and meat quality, and the occurrence of wooden breast (WB) and white striping (WS) in broiler chickens. To this purpose 800 one-day-old chickens of two genotypes, half males and half females, were reared from hatching until slaughtering at 45 d of age in 32 collective pens (25 chickens per pen). Light restriction reduced growth rate and final live weight (LW), but improved feed conversion ratio (FCR) (P < 0.01) and reduced inactive behaviors of chickens (P < 0.001). Light restriction also reduced WS occurrence in breasts (89.5% to 64.6%; P < 0.001) and reduced meat shear force (2.64 to 2.20 kg/g; P < 0.05) and ether extract content (2.29% to 1.87%; P < 0.05). Regarding genotype, compared to genotype B, chickens of genotype A were heavier (3242 g vs. 3124 g; P < 0.01) with higher cold carcass weight and Pectoralis major muscle yield (12.9% vs. 12.0%; P < 0.001) and a higher FCR (1.63 vs. 1.61; P < 0.01). Finally, females had lower final LW (2852 g vs. 3513 g) and higher FCR (1.64 vs. 1.59) than males (P < 0.001), but a higher proportion of breast and P. major (P < 0.001), lower cooking losses (P < 0.001) and shear force (P < 0.01), and higher protein content (21.6% vs. 20.7%; P < 0.001). In conclusion, light restriction depressed growth, but was effective in decreasing WS occurrence and improved feed conversion. The decrease in inactive behaviors (sitting/laying) of light-restricted chickens can be positively considered in view of animal welfare

Dietary inclusion of Chlorella vulgaris and heat-stress in broiler chickens: effects on growth performance and product quality of broiler chickens

This work, in the form of an abstract, on the effect of dietary inclusion of Chlorella vulgaris and heat-stress in broiler chickens on growth performance and product quality of broiler chickens was presented at the XIXth European Symposium on the Quality of Eggs and Egg Products XXVth European Symposium on the Quality of Poultry Meat - Abstract Book

Effect of genotype, gender and feed restriction on growth, meat quality and the occurrence of white striping and wooden breast in broiler chickens

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 17 ( 120.81 vs. 120.59) and b 17 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