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

Survey of skin pigmentation of yellow-skinned broiler chickens

ABSTRACT The appearance of whole carcass and skin-on cut-up products is an important attribute that deeply affects the consumer's choice. Skin pigmentation is affected mainly by genetics, concentration and dietary source of pigments, health status of the birds, and scalding-plucking conditions during slaughtering, although other factors might play an important role. Retailers request batches of broiler chicken carcasses characterized by uniform skin pigmentation to be sold as whole carcass or parts. The aim of this study was to evaluate the variability of skin color of yellow-skinned broilers reared under intensive conditions. For the study, a total of 2,300 medium size broiler chickens (2,300 to 2,500 g of live weight) from 23 flocks (100 birds/flock; n = 12 flocks of males and n = 11 flocks of females; n = 12 flocks of Ross 508 and n = 11 flocks of Ross 308) were randomly selected in a single slaughterhouse. The color measurements were carried out on both breast and thigh pterylae as well as on shank skin adopting the L* a* b* system and using a Minolta colorimeter CR 300. The overall range in measured yellowness (b*) was fairly large for all skin color measurement positions. For breast, a mean value of 22.77 (SD = 5.12) was observed, with values ranging from 7.45 to 39.12. Average values of thigh and shank were 20.23 (SD = 5.02; range 1.99 to 37.82) and 53.99 (SD = 8.13; range 24.22 to 78.65), respectively. A higher skin yellowness was observed in females in all body parts as well as in Ross 308. Yellowness values of breast and thigh were significantly correlated (r = 0.85;

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

Dimensionless Correlations for Natural Convection Heat Transfer from a Pair of Vertical Staggered Plates Suspended in Free Air

Buoyancy-induced convection from a pair of staggered heated vertical plates suspended in free air is studied numerically with the main scope to investigate the basic heat and momentum transfer features and to determine in what measure any independent variable affects the thermal performance of each plate and both plates. A computational code based on the SIMPLE-C algorithm for pressure-velocity coupling is used to solve the system of the governing conservation equations of mass, momentum and energy. Numerical simulations are carried out for different values of the Rayleigh number based on the plate length, as well as of the horizontal separation distance between the plates and their vertical alignment, which are both normalized by the plate length. It is observed that an optimal separation distance between the plates for the maximum heat transfer rate related to the Rayleigh number and the vertical alignment of the plates does exist. Based on the results obtained, suitable dimensionless heat transfer correlations are developed for each plate and for the entire system

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

On toric geometry and K-stability of Fano varieties

We present some applications of the deformation theory of toric Fano varieties to K-(semi/poly)stability of Fano varieties. First, we present two examples of K-polystable toric Fano $3$-fold with obstructed deformations. In one case, the K-moduli spaces and stacks are reducible near the closed point associated to the toric Fano $3$-fold, while in the other they are non-reduced near the closed point associated to the toric Fano $3$-fold. Second, we use openness of K-semistability to show that the general members of two deformation families of smooth Fano $3$-folds are K-semistable by building degenerations to K-polystable toric Fano $3$-folds.Comment: 27 page