Wooden Breast, White Striping and Spaghetti Meat: Chemical Composition, Technological Quality, Microbiological Profile and Sensory Attributes of Broiler Breasts

Poultry meat is consumed worldwide and its production is expected to increase in the up‑coming years. Genetic selection in poultry focused on growth rate, feed conversion, and breast yield, resulting in the occurrence of white striping and wooden breast abnormalities and, most recently, spaghetti meat. These myopathies affect the quality traits of raw meat, including pH, color, water holding capacity, and cooking loss, which limit its further processing and decrease consumer acceptance. Additionally, the effects of myopathies on the chemical composition, i.e., reduced protein and essential amino acid content and increased fat contents, impair to some extent the nutritional value of the mea

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

Nutritional and Feeding Strategies for Controlling Breast Muscle Myopathy Occurrence in Broiler Chickens: A Survey of the Published Literature

Myopathies of the breast muscle in broiler chickens are a great concern of modern poultry production because of the economic losses associated with the waste of unfit meat, the effects on meat nutritional quality for food and on meat technological quality for processing, and last, but not less important, the effects on animal welfare and health. Largely spread in fast‑growing genotypes, these muscle defects have a low hereditability for which genetic selection for their control seems to be a weak strategy or, at least, a weak long‑term strategy. On the other hand, several investigations have been performed on the physiological mechanisms triggering the onset and the evolution of myopathies, and different non‑genetic strategies have been proposed to control their in vivo occurrence. Thus, the present paper aimed to analyse the scientific literature investigating the effects of feeding and nutritional strategies on the occurrence of myopathies to find out the most tested strategies, the most promising ones and, in perspective, strengths and weakness of the same strategies

Digestible fibre to starch ratio and protein level in diets for growing rabbits

To evaluate the effect of digestible fibre (DF) to starch ratio (0.8, 1.5, and 2.8) and protein level (15% and 16%) on health status, digestive physiology, growth performance, and carcass traits, 246 rabbits weaned at 33 d were fed until slaughter (75 d) six diets formulated according to a bi-factorial arrangement (3 DF to starch ratios by 2 protein levels). Growth performance and carcass quality at slaughter were not af- fected by treatments. Increasing DF to starch ratio did not modify dry matter digestibility (62.0% on average), while increased (P<0.001) DF digestibility (52.3 to 68.1%), stimulated caecal fermentation (total VFA: 56.0 vs 67.8 and 67.2 mmol/l; P=0.02) and changed VFA molar proportions. Increasing dietary protein increased digestibility of dry matter (P=0.02), crude protein (P<0.001) and digestible fibre (P<0.001) and increased cae- cal VFA production (P<0.01). The highest mortality (17.1% vs 1.5% average mortality of the other groups, P<0.001) was found in rabbits fed the diet with the lowest DF to starch ratio and the highest protein level

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

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

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