Effects of the feeding system on performance and myopathy occurrence in two broiler chicken genotypes

To evaluate whether performance and myopathy occurrence differed according to genotype (Cobb 500 vs. Ross 308) and feeding system (AL: ad libitum vs. ER: early restricted from 13 to 23 d of age, vs. LR: late restricted from 27 to 37 d; restriction rate: 80% of ad libitum), 828 day- old male chicks were assigned to 6 groups (2 x 3 arrangement), housed in 36 pens, and controlled for: individual live weight (weekly) and pen feed intake (daily) until slaughter (48 d); white striping and wooden breast occurrence at slaughter. Individual data were analysed by PROC MIXED of SAS (fixed effects: feeding system, genotype, and interaction; random effect: pen); pen feed intake and myopathy occurrence were analysed by PROC GLM and CATMOD, respectively. The feeding system affected performance: at the end of the first period (1-22 d), ER chickens showed lower weight gain (40.5 g/d vs. 47.8 g/d and 48.0 g/d), feed intake (50.8 g/d vs 61.0 g/d and 60.2 g/d) and weight (903 g vs 1056 g and 1059 g) than AL and LR broilers (P<0.001); at the end of the second period (23-48 d), ER chickens showed higher weight gain (98.3 g/d vs 93.6 g/d and 90.2 g/d) and feed intake (182 g/d vs. 177 g/d and 171 g/d) compared to AL and LR chickens (P<0.001). Final live weight was the highest in AL group, intermediate in ER group, and the lowest in the LR one (3482 g, 3454 g, and 3399 g; P<0.01). Feed conversion in the whole period did not change with the feeding system. At gross examination, white striping occurrence changed from 77.8% to 67.1%, and 81.7% in AL, ER and LR broilers (p<0.10). Differences between genotypes were evident from the first day and, at the end of the trial, weight gain (74.3 g/d vs 70.1 g/d), feed intake (126 g/d vs 114 g/d), feed conversion (1.69 vs 1.64), and live weight (3548 g vs. 3342 g) were higher in the Ross than in the Cobb chickens (P<0.001). At slaughter, the rate of white-striped breasts was similar (on average 75.5%), but the occurrence of severely white-striped breasts was higher in the Ross than in the Cobb chickens (25.9% vs. 7.41%; P<0.001). Wooden breast occurrence (on average 5.1%) did not change with the feeding system or the genotype. In conclusion, under our conditions, a late feed restriction did not permit to recover performance at the end of the trial nor to control white striping occurrence. Moreover, the genotype affected growth rate and white striping degree: the highest the growth rate, the highest the severity of white striping

comparison of breast muscle traits and meat quality characteristics in 2 commercial chicken hybrids

Abstract A trial was conducted to compare muscle traits and meat quality characteristics of the pectoralis muscle in 2 chicken commercial hybrids having standard (SBY) and high breast yield (HBY), respectively. A total of 2,124 one-day-old male chicks, equally divided into 2 experimental groups represented by strains (SBY and HBY), were grown using homogenous conditions and fed the same standard diets until reaching live weight of 4.2 kg at 53 and 55 d for the SBY and HBY groups, respectively. Thirty-six birds per each genotype were randomly selected, and their pectoralis major muscles were used to assess meat quality properties (color attributes, pH, drip loss, cook loss, Allo-Kramer shear values after cooking, moisture, proteins, total lipids, and ashes) as well as histological traits (cross-sectional area, frequency of abnormal fibers, and intramuscular fat infiltration). As expected, HBY genotype had higher breast yield (31.0 vs. 30.0%; P ≤ 0.05). Histological evaluations showed that HBY pectoralis muscles had higher cross-sectional fiber area coupled with a dramatically higher (P ≤ 0.001) incidence of abnormal fibers and more abundant infiltration of intramuscular fat. Moreover, histopathological anomalous features such as central nuclei, proliferation of endomysial and perimysial collagen, inflammatory infiltrate, and necrosis of the fibers were also observed. As for meat quality, SBY hybrid showed lower ultimate pH values (5.97 vs. 6.07; P ≤ 0.01), whereas overall color parameters were not affected by genotype. Breast meat from the HBY genotype also exhibited significantly lower ability to retain liquid during refrigerated storage (drip loss, 2.46 vs. 2.06%; P ≤ 0.05) and cooking (26.2 vs. 21.1%; P ≤ 0.05) as well as higher shear-force values (2.59 vs. 2.11 kg/g; P ≤ 0.001). Finally, with regard to chemical composition, significant differences (P ≤ 0.05) were detected in protein (22.8 vs. 23.5%) and lipid (1.65 vs. 1.82%) contents, which were significantly lower in the HBY hybrid, whereas moisture content tended (P = 0.07) to be inferior in the SBY hybrid

Influence of partial and complete caponization on chicken meat quality

Caponization is a surgical technique ad- opted to alter the sexual maturation of male chickens with the aim of improving the quality characteristics of carcass and meat. Under commercial conditions within each flock, about 10% of the birds usually result with incomplete caponization and are called slips. A trial was conducted to compare quality traits of breast and thigh meat from capons (n = 12), slips (n = 12), and cocks (unoperated birds; n = 12) (Hubbard × Golden Comet) reared together and processed at 180 d old un- der commercial conditions. Capons exhibited the high- est (P < 0.01) values of breast and thigh meat lightness and yellowness as well as the lowest values of redness (P < 0.01) compared with cocks and slips. These varia- tions in meat color were related to a lower concentra- tion of heme pigments in both breast and thigh meat from capons. Capons and slips presented lower Allo- Kramer shear values of cooked breast meat (P < 0.05) in comparison with cocks. As for chemical composition, capons showed a higher content of total lipid, choles- terol, and ash both in breast and thigh meat. Total saturated, monounsaturated, and polyunsaturated fatty acids were not strongly affected by caponization. However, capons exhibited a significantly higher (P < 0.01) content of linoleic and linolenic acids as well as a lower content of arachidonic, eicosapentaenoic, do- cosapentaenoic, and docosahexaenoic acids in respect to slips and cocks. Overall, this study indicated that caponization can affect the main meat quality traits with special regards to appearance (color), texture, and composition. Finally, it was found that slips present in- termediate meat quality characteristics between capons and cocks

Effect of EU electrical stunning conditions on breast meat quality of broiler chickens

Electrical stunning is still the main method used worldwide in commercial poultry plants. The stunning procedures in water bath affect both bird welfare and meat quality attributes. The European Union (EU) Council Regulation 1099/2009 on the protection of the animal at the time of killing established the minimum current flow through individual bird at a specified frequency to assure an effective stun that must last until the bird death. The aim of this study was to compare the effect of the application of different stunning current flows on the incidence of hemorrhages (classified as 1=no lesion, 2=moderate and 3=severe lesion) and some quality traits (pHu, color, drip and cooking losses, and shear force) of chicken breast meat. A total of 12 flocks of broiler chickens, each equally divided into light, medium and heavy-size, were submitted either to the stunning condition usually adopted before the entry into force of the current EU Regulation (90 mA/bird, 400 Hz) (OLD) or to that enforced by it (150 mA/bird, 400 Hz) (NEW). Overall, the incidence of severe hemorrhages dramatically increased in NEW group in comparison with OLD one (55 vs. 27%; P<0.001) and particularly in heavy-size birds (72 vs. 25%; P<0.001). In general, meat quality attributes were not affected by the stunning conditions with the exception of drip loss that resulted lower in NEW than OLD birds (1.01 vs. 1.27; P<0.001). In conclusion, the adoption of a higher current flow, as suggested by the EU regulation to protect animal at the time of killing, increases the incidence of breast hemorrhages while maintaining meat quality traits with possible beneficial effect on water holding capacity of fresh meat

Effect of free range production system on chicken carcass and meat quality traits

There is a growing consumer interest towards poultry products coming from unconventional housing systems with outdoor access. A study was conducted to characterize carcass traits and chemico-physical properties of chickens labelled free-range (according to the EC Directive 1538/91) if compared with conventional ones. Free range female (FR-F) and male (FR-M) chickens were separately raised for 56 and 70 d, respectively, in order to obtain currently marketed product categories. They belonged to medium growing Isa strain and had continuous daytime access to open-air area from 28 d to slaughter age and indoors stocking density did not exceed 27.5 kg/sqm. Conventional female (C-F) and male (C-M) chickens belonged to a fast growing hybrid (Ross 708) and were separately raised for 39 and 50 d, respectively, under intensive conditions in a poultry house under controlled environmental conditions at a stocking density of 30-32 kg/sqm. Females (FR-F and C-F) and male (FR-M and C-M) birds were slaughtered into 2 separate sessions. After slaughtering, 20 carcasses for each group (FR-F, 1.2 kg; FR-M, 1.9 kg; C-F, 1.2 kg; C-M, 2.3 kg) were randomly selected for evaluating carcass cut-up yields and fifteen of them were used to assess quality properties of both breast and leg meat (skin and meat colour, ultimate pH, drip and cooking losses, AK-shear force). C birds had dramatic higher carcass and breast meat yield, whereas FR had higher wing and leg yields (P &lt;0.001). Both meat and skin of breast and leg coming from FR birds were lighter and less red and more yellow (P &lt;0.001). Even if no difference were found in ultimate pH, FR birds exhibited higher water-holding capacity (lower drip and cooking losses) in both breast and leg meat (P &lt;0.01). Finally, although shear force did not differ in breast meat, leg from FR birds were tougher (P &lt;0.001). Overall these data indicate that noticeable quality trait differences exist between free range and conventional labelled poultry products

Effect of different arginine-to-lysine ratios in broiler chicken diets on the occurrence of breast myopathies and meat quality attributes

This study was carried out to evaluate the effect of different digestible arginine-to-lysine (dig Arg:Lys) ratio in broiler diets on the occurrence of breast myopathies, productivity, and meat quality traits. A total of 1,755 1-day-old Ross 308 male chicks was randomly divided in 3 experimental groups (9 replications/group): CON, fed a 4 feeding-phases commercial diet (dig Arg:Lys ratio = 1.05, 1.05, 1.06, 1.07, respectively in starter, grower I, grower II and finisher phase), and ARG2 and ARG3 groups fed CON diet supplemented respectively with 20 and 30% higher levels of crystalline L-arginine (dig Arg:Lys ratio = 1.25, 1.25, 1.26, 1.27 and 1.35, 1.35, 1.36, 1.37, respectively). Productive performance was recorded throughout the rearing cycle. At processing (43 d), breasts (n = 150/group) were randomly collected to evaluate the incidence and severity of white striping (WS), wooden breast (WB), and spaghetti meat (SM) defects (3- points scale).Meat quality traits, such as color, pH, drip and cook losses, marinade performances, and proximate composition were determined on 12 fillets/group. Although productive performance and meat quality traits resulted not significantly affected, the occurrence of some breast myopathies was modified by the dietary treatments. ARG2 and ARG3 exhibited a significantly higher percentage of breast without WS compared to CON (28 and 41 vs. 17%, respectively; P < 0.001). ARG3 reported the lowest percentage of breasts with severe WS (11 vs. 27 and 31%, respectively for ARG3, ARG2, and CON; P < 0.001) and the highest of those showing no SM abnormality (81 vs. 69 and 65%, respectively for ARG3, ARG2, and CON; P < 0.01). Furthermore, a numerical reduction of breasts with severe WB was observed in ARG3 (12 vs. 25 and 19%, respectively for ARG3, ARG2, and CON; P = 0.12). In conclusion, the dietary supplementation of arginine to increase the dig Arg:Lys ratio by about 30% in respect to the current recommendations for broiler chickens has positive implications on the occurrence of some breast meat abnormalities

The Influence of the Season and Market Class of Broiler Chickens on Breast Meat Quality Traits

Abstract The influence of the season and market class of broiler chickens on breast meat quality traits was determined on a total of 18 flocks reared and processed under commercial conditions. According to the Italian poultry production system the following classes of birds were considered: light size (1.2 kg of carcass weight; n = 90) and medium size (1.8 kg of carcass weight; n = 90), represented by females slaughtered at 40 and 52 d old, respectively, whereas heavy size were 57-d-old male broilers (2.4 kg of carcass weight; n = 90). After slaughter, 15 carcasses per flock (n = 270) were randomly collected during winter (n = 135) and summer (n = 135) seasons and used at 24 h postmortem to determine breast (pectoralis major) meat color (lightness, redness, and yellowness), pH, drip and cook loss, as well as Allo-Kramer (AK) shear values. Furthermore, pectoralis minor muscles were used to determine lipid, protein, moisture, and ash content. Finally, because the flocks included white- and yellow-skinned broilers, the color of the carcass skin was measured to assess the relationship between skin and raw breast meat color. With regard to the season, breast meat from birds slaughtered during summer exhibited a paler and less red color, lower pH, higher drip and cook losses, lower AK-shear, and a higher content of moisture and a lower content of protein and ash. In respect to medium and heavy birds, light broilers produced breast meat with higher values of redness, lower pH and cook loss, higher AK-shear values, and a higher content of moisture and ash. Finally, a positive correlation (r = +0.92; P ≤ 0.001) between skin and breast meat yellowness was found. These results indicate that during summer, broiler breast meat undergoes a depression of its functionality and quality. Moreover, the market class of birds also determined some differences in breast meat quality attributes

Effect of different levels of dietary zinc, manganese, and copper from organic or inorganic sources on performance, bacterial chondronecrosis, intramuscular collagen characteristics, and occurrence of meat quality defects of broiler chickens

The aim of the experiment was to assess the effects of two dietary levels of trace minerals (TM) zinc, manganese and copper either from organic (OTM) or inorganic (ITM) sources on broiler performance, carcass traits, intramuscular collagen (IMC) properties, occurrence of hock burns (HB), foot pad dermatitis (FPD), femoral and tibia head necrosis and breast muscle abnormalities (white striping, WS; wooden breast, WB; poor cohesion, PC). A total of 3,600 1-d-old male chicks were randomly assigned to one of four dietary treatments in a 2 x 2 factorial arrangement (9 replicates of 100 birds/dietary treatment). Birds were slaughtered at 31 (thinning) and 51 d of age. Body weight, daily weight gain (DWG), feed intake, feed conversion rate (FCR) and mortality were determined. A significant effect of the source of TM supplementation was found only in 51 d old chickens. Birds of OTM groups were heavier (P 0.05) by the different sources and doses of TM administrated

Relationship between pectoralis major muscle histology and quality traits of chicken meat

A trial was conducted to evaluate the influence of myodegeneration of pectoralis major muscle on quality traits and chemical composition of breast meat of heavy size male broilers. For this purpose, a total of 72 pectoralis major muscles were randomly collected from broilers farmed under homogeneous conditions and graded into three categories (mild, n= 22; moderate, n=33; and severe, n=17) based on the presence of abnormal fibers (giant fibers, fibers with hyaline degeneration and damaged and/or necrotic fibers) evaluated by histological and immunohistochemical analysis. Color, pH, drip and loss, Allo-Kramer shear values and chemical composition (moisture, proteins, total lipids, ashes and collagen) were determined on non-marinated breast meat, as well as purge loss and cook loss, total yield and Allo-Kramer shear values were measured on vacuum tumbled samples. Samples showing moderate myodegeneration had the highest mean cross-sectional area of the fibers, while samples with severe myodegeneration had myofibers of different diameter and without the characteristic polygonal shape, multifocal degeneration and necrosis, as well as infiltration of CD3-immunoreactive cells. Cooking losses of non-marinated meat were lower in mild group in respect to moderate and severe groups (21.4 vs. 24.7 and 24.7%; P<0.001). Breast muscles with severe damages, in comparison with mild degenerated samples, showed higher moisture (75.4 vs. 74.4%; P<0.05) and lower protein percentages (21.1 vs. 22.6%; P<0.001). The lipid percentage of severe degenerated samples was higher than that from moderate group (2.94 vs. 2.36; P<0.05), while collagen content was not modified by histological lesion levels. Marinated meat from mild group had higher uptake and total marinade yield after cooking. In conclusion, almost all breast fillets of heavy broiler chickens produced under intensive farming systems had histological lesions which reflected on chemical composition of meat and impaired water holding/binding capacities of the meat