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Previous research has indicated that antemortem stress factors can influence the development of pale, soft, and exudative (PSE) meat in swine as well as in turkeys. Such antemortem factors can include environmental temperatures, relative humidity, preslaughter handling practices, and transportation. However, the effect of transportation on meat quality of turkeys has not been extensively studied. Eighty Nicholas male turkeys (21 wk of age) were divided into two groups and were either transported in coops on a flatbed trailer for 3 h immediately prior to processing or processed without transportation. Breast muscle samples were collected for pH (0, 2, 24 h), L* value (2, 24 h), drip loss, and cook loss. Additionally, breast fillets were marinated and cooked to determine marination uptake, retention, and cook loss. The breast muscles from transported turkeys had significantly higher muscle pH at 0, 2, and 24 h; significantly lower L* values at 2 and 24 h; significantly higher marination retention (i.e., lower drip loss after marination); and significantly lower cook loss in the marinated fillets compared with fillets of the nontransported turkeys. There were no significant differences in drip loss and cook loss of the nonmarinated fillets or the marination uptake percentage between the transported and nontransported turkeys. These results suggest that transporting turkeys immediately before processing does not induce PSE meat and may actually improve water-holding properties.

Pale, soft, exudative (PSE) turkey meat is a growing problem for industry and has been associated with rapid postmortem pH decline and loss of protein functionality, similar to PSE pork. This study was designed to estimate the incidence of PSE meat in a commercial plant and use response surface methodology to characterize the relationship between pH, lightness (L* value), and water-holding capacity (WHC). One hundred thirty-four turkey breast fillets were selected from the processing line so that 67 had normal color (lightness), and the other 67 were more pale than normal. Fillets were analyzed at time of deboning (1.5 h postmortem) and at 24 h postmortem for color (L* value), pH, drip loss, expressible moisture, and temperature. Additionally, L* values were measured on 2,995 turkey breasts from the processing line to determine the commercial incidence of PSE meat based on color. The pale fillets had significantly lower pH, greater L* value, and less WHC but equal temperature when compared with the fillets with normal color. The L* value and pH were correlated with WHC as measured by expressible moisture, but L* value seems to have more predictive value. By using the L* value range (>53) from the pale-selected fillets as an indication of paleness, approximately 40% of the 2,995 fillets would exhibit poor WHC. These results suggest that PSE meat can represent a significant portion of commercially processed turkey breast meat and that the L* value measurement could be used to sort turkey meat so that PSE type meat could be used in specialized formulations.

Previous research has indicated that seasonal-type heat stress (HS) can contribute to the development of pale, soft, exudative (PSE) meat in fast-growing turkeys and that halothane exposure may identify stress-susceptible animals. This study evaluated the ability of halothane screening to identify stress-susceptible birds prone to developing pale, exudative meat when reared to market age. Two lines of turkeys (n = 292), one selected for rapid overall growth (BODY) and the other for large breast muscle yield (BREAST), were exposed to 3% halothane for 5 min at 2 to 4 wk of age and were raised together until 16 wk of age. Approximately 10% of both BODY and BREAST birds were sensitive to halothane. Between 16 and 20 wk, all of the halothane sensitive (HAL+) and half of the halothane nonresponders (HAL-) were exposed to an HS environment of 30 to 36 C (night/day), whereas the other half of the HAL- birds were kept at an ambient temperature of 13 to 21 C (night/day). All birds were slaughtered at 20 wk of age, and samples were collected for pH, L* value, drip loss, cooking loss, and shear value. The BREAST strain had 5% greater breast percentage than the BODY strain, and there were no differences in ready-to-cook yields between any treatments. The HAL+ HS birds had significantly lower muscle pH (0 h) and significantly higher L* values at 2 h postmortem compared with HAL- HS birds in the BREAST strain; however, there was no difference in L* value at 24 h postmortem. The HAL- HS birds had significantly lower muscle pH (0 h and 2 h) and significantly higher L* values at 2 h postmortem compared with HAL- controls in the BODY strain. The HAL- HS BREAST birds had significantly higher drip loss than HAL- controls. No differences in shear value were found among any treatments. The incidence of PSE (2-h L* values >52) was significantly higher in HAL+ HS birds (34.7%) compared with HAL- HS birds (13.4%). These results suggest that halothane sensitivity early in life is associated with HS susceptibility and the development of pale meat when birds are slaughtered at market age. These results also suggest that halothane screening may be better at predicting the development of PSE meat during HS in the strain selected for large breast yield rather than rapid overall growth.

This experiment was conducted to evaluate the effects of electrical stimulation (ES) on muscle metabolism and breast meat quality in turkeys. Thirty-six turkey hens were either ES at the neck in a saline bath (570 V, 450 mA, AC, 60 Hz, 2 s on 1 s off for 10 pulses) or used as unstimulated controls. One breast fillet from all carcasses was harvested at 2 h postmortem. The opposite fillet was harvested from the ES carcasses at 8 h postmortem and from the unstimulated controls at either 8 or 24 h postmortem. All fillets were sampled at time of deboning for expressible moisture, pH, R-value, gravimetric fragmentation index (GFI), and sarcomere length. The remainder of the fillet and the samples for GFI and sarcomere length were aged on ice until 24 h postmortem. After aging, fillets were analyzed for cook loss and shear value. Color was measured at time of deboning and at 24 h postmortem. Electrical stimulation accelerated rigor mortis development as indicated by significantly lower pH values and higher R-values at 2 h postmortem when compared to control fillets. The pH and R-values of the 2-h ES treatment were not significantly different from the 8-h ES, 8-h controls, or the 24-h controls. Fillets from carcasses that were ES and deboned at 2 h had significantly longer sarcomeres than the 2-h controls; however, there were no significant differences between the 2-h ES and the 8-h ES treatments, 8-h controls, or the 24-h controls. Although ES accelerated muscle metabolism at 2 h postmortem, it had no effect on shear value, expressible moisture, cook loss, GFI, L*, or a* color values. These results suggest that this postmortem ES system would not benefit turkey processors.

White striping is the white striation occasionally observed parallel to the direction of muscle fibers in broiler breast fillets and thighs at the processing plant. Broiler breast fillets can be categorized as normal (NORM), moderate (MOD), or severe (SEV) based on the degree of white striping. Histologically, SEV fillets are characterized by the highest degree of degeneration of muscle fibers along with fibrosis and lipidosis when compared with NORM. The present study was undertaken to compare the hematologic and serologic profiles of broilers with NORM and SEV degrees of white striping to get more information on the systemic changes associated with the condition. Day-old male broiler chicks of a commercial strain were grown on the same diet in 6 replicate pens (n = 32 birds/pen). Blood samples (5 mL) were collected from the wing vein of each bird on the day before processing for analyzing hematologic and serologic profiles. At 63 d, the birds were weighed and processed in a commercial inline processing system. Weight of the butterfly fillets, liver, and abdominal fat pad were recorded. Left-side fillets were scored to obtain the degree of white striping for each bird. Representative samples for NORM (n = 24) and SEV (n = 17) categories were selected to compare the hematologic and serologic profiles. The SEV birds had greater (P0.05) live, fillet, and liver weights, as well as fillet yield, compared with the NORM birds, but the abdominal fat yield was less (P0.05) in SEV birds. The NORM and SEV birds did not show any differences in various hematological parameters, including the differential leukocyte count. Conversely, SEV birds had elevated (P0.05) serum levels of creatine kinase, alanine transaminase, aspartate aminotransferase, and lactate dehydrogenase. These results suggest that there is no systemic infectious or inflammatory condition associated with a SEV degree of white striping. The elevated serum enzyme levels confirm the muscle damage associated with the degenerative myopathy in SEV birds.

Pasture-flock-raised poultry are becoming an increasingly popular product, but only limited options are currently available for maintaining gut health. For these producers, prebiotics are an attractive option because they are generally recognized as safe (GRAS) and can be mixed into the feed and thus do not require adjustments to production protocols. However, if prebiotic treatments reduce production performance, they would not be useful to producers. Thus, the objective of this study was to measure performance of pasture-raised broilers fed 1 of 3 prebiotic treatments. For these trials, 2 breeds of birds were used: Naked Neck slow-growing breeds and Cornish White Rock cross fast-growing breeds. The experimental design was replicated for each breed. A total of 340 birds were split into 4 groups, each group fed one feed additive: 1) galactoligosaccharides (2% wt/wt), 2) fructooligosaccharides (1% wt/wt), 3) plum fibers (1% wt/wt), or 4) no additives. During the 8-wk rearing period, 10 birds from each group were collected and euthanized to take small intestine samples. Histological preparations were made from the small intestine tissue, and 4 measurements of villi height and crypt depth from each cross section were taken. Throughout the study, mortality was monitored and BW measurements were taken at 2-wk intervals. For the Cornish White Rock cross, the group receiving the feed supplemented with fructooligosaccharides had higher (P0.05) 8-wk BW than those fed Plum; control and birds fed galactoligosaccharides were intermediate. For the Naked Neck breed, the group receiving the plum fibers had the highest final BW. It appears that all 3 feed supplements offered some protective effect for alterations in villi length and crypt depth due to feed withdrawal, but only for the Naked Neck breed. The data indicate the 3 prebiotics utilized in this study could be used without risk of decreasing production performance, but only for Naked Neck breeds.

White striping could be a potential reason for the rejection of raw breast fillets in the market. The condition is characterized grossly by the white striations occurring on the fillets showing myopathic changes on microscopic examination. Early research has shown similar lesions in the case of nutritional muscular dystrophy, which is a condition caused mainly by the deficiency of vitamin E in the diet. The present study was intended to evaluate the effect of different levels of dietary vitamin E ( dl -α-tocopherol acetate) on the incidence of normal, moderate, and severe degrees of white striping, by modern description, on broiler breast fillets. Basal diets adequate for starter (0 to 18 d), grower (19 to 32 d), and finisher (33 to 49 d) age periods supplemented with 15, 50, 100, 200, and 400 IU of vitamin E/kg of feed were used in the study. Each of the 5 diet treatments were fed to 8 pens (53 birds each) of male broilers from a commercial strain. At 49 d, 5 birds were randomly selected from each pen (n = 40 birds/diet treatment) and were processed. Live weight, ready-to-cook weight, weight of the fillets, wings, tenders, legs, and the racks were obtained. The fillets were scored for the 3 degrees of white striping. There were no significant differences among the diet treatments with respect to the weight and carcass yield parameters. Furthermore, the diet treatments did not show any significant effect on the occurrence of normal, moderate, and severe degrees of white striping. However, fillet weight was the only parameter that had a significant effect on the occurrence of white striping. Higher degrees of white striping were seen associated with heavier fillets, which is in accordance with previous studies. Different levels of vitamin E levels used in the present study did not show any significant effect on the occurrence of 3 degrees of white striping. These results suggest that dietary vitamin E level is not associated with the modern condition of white striping in broiler breast meat.

Phase-feeding (PF) has been effective in maintaining broiler growth while reducing production cost, but the effect on different broiler strains grown in a small-bird production scenario has not been assessed. The objective of this study was to evaluate 3 commercial broiler strains typically used in a small-bird production scenario to assess the effect of various debone times and PF on yield and meat quality. Birds (n = 1,080) were fed either diets with average industry nutrient levels or diets with phased levels of amino acids. In total, 540 birds were commercially processed at 40 and 42 d of age. Breast fillets were harvested at 2, 4, and 6 h postmortem (PM). Muscle pH was measured at the time of debone and fillet dimensions, instrumental color (L*, a*, and b*), and pH were measured at 24 h PM. Fillets were cooked to 76°C and cook loss was calculated, followed by Meullenet-Owens Razor shear (MORS) analysis. Phase-feeding, strain, and sex had little effect on fillet yield, but deboning at 2 h PM resulted in a higher fillet yield compared with that of later debone times. Strain, sex, and debone hour had significant effects on fillet dimensions, with strain A producing longer and wider fillets than strains B and C. Males had larger fillets than females (longer and wider), whereas deboning early resulted in significantly thicker fillets compared with those of later deboning. There were no differences in fillet dimensions due to PF, however, uniformity was improved. The PF treatment did not affect pH, color, cook loss, or MORS energy. Deboning at 2 h PM resulted in higher MORS energy, indicating decreased tenderness in 2 of the strains, whereas in one strain, tenderness was not affect by debone time. Results of this study suggest PF does not adversely affect yield or meat quality of broilers in small-bird programs but strain, sex, and debone time can affect quality. Results also suggest that strain can effect tenderness of breast fillets when deboned prerigor.

The relationship between textural perception of poultry meat and the masticatory activity and chewing behavior of 7 subjects were investigated. A total of 90 broilers were slaughtered at 7 wk of age and deboned at either 1.25, 4, or 24 h postmortem (PM). Sensory analysis on cooked meat was conducted by 7 trained meat descriptive panelists. Panelists were asked to evaluate initial hardness, hardness of mass, cohesiveness of mass, and number of chews related to meat tenderness. Tenderness of cooked meat was also predicted instrumentally by both the Meullenet–Owens razor shear (MORS) and Blunt–Meullenet–Owens razor shear (BMORS). Masticatory muscle (anterior-temporalis and masseter) activities during chewing were measured by electromyography (EMG) and 19 parameters were used to characterize muscle activity during mastication. Jaw movement velocity and trajectory to characterize the chewing behavior was also recorded by electrognathography (EGN) during mastication. Significant differences among fillets deboned at various times PM were found in all sensory attributes. Significant differences in sensory attributes, muscle activities, and jaw movements among subjects were also observed. It was found that poultry meat texture was better predicted by muscle activity parameters (EMG) than by chewing behavior (EGN). Overall, EMG parameters calculated from mid and late chewing cycles were better predictors of poultry texture perception than initial cycles, indicating that comminuting of poultry meat is an important aspect of its texture perception.

The impact of postharvest aging on the tenderness, color, water holding capacity, and appearance of broiler breast fillets after deboning was investigated. A total of 360 broilers were processed and deboned at either 1.5-, 3-, or 6-h postmortem (PM) and aged at 4 ± 1 °C for up to 6 d. Tenderness was predicted by the Meullenet–Owens razor shear. Drip loss, cook loss, color, and muscle-shape profiles were also evaluated during the 6-d aging duration. Deboned fillets were in the tenderness range corresponding to “neither tough nor tender” for the first 2 d of aging and changed into “slightly tender” after 3 d of aging according to the instrument-tenderness perception equivalent scale. Tenderization due to postdeboning aging seemed to be more pronounced for fillets deboned in a prerigor state (that is, 1.5- and 3-h PM). Over the aging period, tenderness improved by 6.9 and 7.4 percentage points for the 1.5- and 3-h PM treatments, respectively, while those fillets deboned in a postrigor state (6-h PM) exhibited no significant difference in tenderness. Drip and cook loss of fillets consistently increased over the aging period. The color of fillets tended to become less red and more yellow during aging although there was no significant difference in L*. Overall, the tenderizing effects of deboned broiler breast fillets during the storage of 6 d were minimal but seemed to be affected by fillet height and length as determined through analysis of covariance (ANCOVA) and K-means clustering analysis. Thicker and tougher fillets were more susceptible to the tenderizing effects during postdeboning aging.

Prerigor deboning and marination of broiler breast fillets are growing trends in the poultry industry. Marination can often enhance product attributes such as flavor, juiciness, and texture. The purpose of this study was to evaluate consumer acceptance of marinated broiler breast fillets deboned pre- (

The effectiveness of whey protein isolate (WPI) coatings incorporated with grape seed extract (GSE), nisin (N), malic acid (MA), and ethylenediamine tetraacetic acid (EDTA) and their combinations to inhibit the growth of Listeria monocytogenes, E. coli O157:H7, and Salmonella typhimurium were evaluated in a turkey frankfurter system through surface inoculation (approximately 10(6) CFU/g) of pathogens. The inoculated frankfurters were dipped into WPI film forming solutions both with and without the addition of antimicrobial agents (GSE, MA, or N and EDTA, or combinations). Samples were stored at 4 degrees C for 28 d. The L. monocytogenes population (5.5 log/g) decreased to 2.3 log/g after 28 d at 4 degrees C in the samples containing nisin (6000 IU/g) combined with GSE (0.5%) and MA (1.0%). The S. typhimurium population (6.0 log/g) was decreased to approximately 1 log cycles after 28 d at 4 degrees C in the samples coated with WPI containing a combination of N, MA, GSE, and EDTA. The E. coli O157:H7 population (6.15 log/g) was decreased by 4.6 log cycles after 28 d in samples containing WPI coating incorporated with N, MA, and EDTA. These findings demonstrated that the use of an edible film coating containing nisin, organic acids, and natural extracts is a promising means of controlling the growth and recontamination of L. monocytogenes, S. typhimurium, and E. coli O157:H7 in ready-to-eat poultry products.

Two experiments were conducted to assess the effect of genotype, production system, and nutrition on performance and livability of meat chickens for niche markets. Slow-growing (SG) and fast-growing genotypes (FG) were raised for 91 and 63 d, respectively, in experiment 1 (females) or 84 and 56 d, respectively, in experiment 2 (males). In each trial, SG were placed before FG to achieve a similar BW at processing. In experiment 1, each genotype was assigned to 8 pens of 20 birds each, with 4 pens within each genotype raised indoors in a conventional research facility or in a small facility with outdoor access. All birds were fed a low-nutrient diet. In experiment 2, genotype assignment to pens was as in experiment 1; however, 4 pens within each genotype were fed a low-nutrient diet or a conventional diet, and birds were raised indoors. Birds were gait-scored and commercially processed; legs were examined for tibial dyschon-droplasia lesions and scanned for bone mineral density. In experiment 1, FG gained more weight than SG (P0.05) even though they were placed later. Outdoor access increased feed intake, and feed efficiency was poorer (P0.05). Fast-growing genotypes had higher breast meat yield, whereas SG had higher wing and leg yields (P0.05). In experiment 2, the low-nutrient diet reduced (P0.05) gain of the SG; FG increased feed intake of the low-nutrient diet such that their gain was unaffected (P0.05). For FG, the low-nutrient diet resulted in a poorer (P0.05) feed efficiency. Although weight gain of the FG was maintained on the low-nutrient diet, breast yield was reduced (P0.05). Genotype affected bone health in both experiments, with SG having better gait scores and less tibial dyschondroplasia (P0.05). Outdoor access and the low-nutrient diet also resulted in better gait score (P0.05). These data indicate differences among genotypes and provide information about the efficiency and potential for alternative poultry systems.

Freezing is the most common and efficient way to maintain the quality of poultry products for long periods of time. However, tougher texture, discoloration, and drying have been reported as a result of long-term frozen storage. The impact of freezing on the tenderness, water-holding capacity, and color of broiler breast fillets was investigated for up to 8 mo. A total of 160 birds were deboned at either 2 or 6 h postmortem (PM). All deboned left fillets were frozen and stored at -18 degrees C for up to 8 mo, while the corresponding right fillets were assessed for texture approximately 24 h after deboning as a control measurement without any freezing treatment. Tenderness was measured by the Meullenet-Owens razor shear. Thaw loss, cooking loss, moisture content, color, and muscle shape profiles were also evaluated. No difference in tenderness was observed during the first 2 mo compared to the control (0 mo), but significantly decreased between 2 and 4 mo. The 8-mo-old fillets were the least tender, with a 31.5% increase in shear energy between 4 and 8 mo. Moisture content of cooked meat gradually decreased, showing a significant drop between 2 and 6 mo of storage, while thaw and cooking loss consistently increased over the entire storage period. The color of the frozen fillets tended to be darker, redder, and less yellow than the control, with increased storage duration. The results suggest that for optimal tenderness, frozen broiler breast fillets are best consumed within 2 mo of freezing.

Five experiments (EXP) were conducted to assess the efficacy of an Escherichia coli phytase compared with 2 commercially available fungal phytases. In EXP 1 and 2, male broiler chicks were fed experimental diets that included a P-deficient control (0.13% available P; 0.88% Ca) alone or with graded levels of KH(2)PO(4) (0, 0.05, 0.10, or 0.15%) or phytase at levels of 250, 500, 1,000, 2,000, or 4,000 phytase units/kg of E. coli phytase (EXP 1 and 2), fungal phytase 1 (EXP 2), or fungal phytase 2 (EXP 2). In EXP 1 and 2, weight gain and tibia ash (mg/chick and %) responded linearly (P0.05) to inorganic P addition. In EXP 2, each level of E. coli phytase released more P than either fungal phytases 1 or 2, whether based on tibia ash weight (mg/chick) or percentage. In EXP 3, 4, and 5, dietary treatments containing adequate or deficient levels of P were fed with or without supplemental E. coli phytase. In EXP 3, weight gain and tibia ash were reduced (P0.05) by P deficiency, but gain and tibia ash of chicks fed E. coli phytase (250, 500, or 1,000 phytase units/kg) did not differ (P0.05) from that of chicks fed the P-adequate diet. In addition, carcass yield of broilers fed E. coli phytase was not reduced (P0.05). In EXP 4, E. coli phytase effectively supported weight gain, tibia ash, breast yield, and leg yield compared with birds fed the P-adequate diet, but clavicle breakage during processing was increased in birds fed E. coli phytase. In EXP 5, E. coli phytase again effectively supported weight gain, and no differences (P0.05; compared with the P-adequate diet) were noted for clavicle ash, diameter, or breaking strength. No differences (P0.05) in bone breakage during processing were noted among treatments. These results indicate that the addition of E. coli phytase to P-deficient broiler diets improves growth, bone, and carcass performance and is more effective at releasing phytate-bound P than the other phytase products that were tested.

A total of 1,040 birds from 5 common commercial genetic broiler strains were raised and processed to analyze the effect of strain and deboning time on meat quality. The birds were processed at either 6 or 7 wk of age in 4 replications each. Carcasses were deboned at either 2 or 4 h postmortem (PM; n = 52 birds per treatment). Carcass and breast weights were measured on each bird to calculate breast yield. Muscle pH was measured at time of deboning. Fillets deboned at 4 h PM were measured for length, width, and height to evaluate footprint analysis. At 24 h PM, fillets were weighed to calculate drip loss, and color (L*) was also measured. The fillets were then cooked to 76 degrees C, and cook loss was calculated. Fillets were then subjected to shear analysis using the Meullenet-Owens razor shear method where shear energy (N x mm) was calculated to evaluate tenderness. The strains in this study were chosen for differences in yield; therefore, as expected, breast yield was significantly different among strains. Variation in meat quality attributes existed among strains deboned at 2 h PM, but there was no consistent relationship between meat quality and breast yield. However, at 4 h PM, fewer differences among strains existed in meat quality characteristics (tenderness, water holding capacity, and pH). As expected, deboning at 2 h PM resulted in higher shear energy, higher muscle pH, and lower L* value compared with deboning at 4 h PM in all but one strain. However, water-holding capacity was not affected by deboning time at either age interval. Footprint analysis showed that most differences among strains were in heights measured at the fillet midpoint and caudal end. These results suggest that early deboning may affect meat quality of broiler strains differently, resulting in greater variation within the industry.

Consumer interest in organic and natural poultry products raised with outdoor access is growing. An experiment was conducted to assess the effects of outdoor access and genotype on meat quality. One slow-growing genotype (S), 2 medium-growing genotypes (M1 and M2), and a commercial fast-growing genotype (F) were raised (straight-run) for 81, 67, or 53 d, respectively. The placement date was staggered in order to achieve a similar final body weight. Each genotype was assigned to 3 pens of 24 birds each and raised in indoor floor pens in a naturally ventilated facility; the S and F genotypes were also assigned to 2 floor pens with outdoor access containing 36 birds each. All birds were provided with the same starter, grower, and finisher feeds, and birds were commercially processed. Pectoralis samples were collected at 6 h postmortem for proximate analysis and evaluation of meat quality. The principal effect of outdoor access was to make the meat more yellow in the case of the S genotype (P0.05) although not the F genotype (P0.05). Drip loss and cook loss (%) were affected (P0.05) by genotype, with the highest losses occurring with the S genotype and the lowest losses occurring with the F and M genotypes. Tenderness was affected (P0.05) by gender as well as production system but only in the F birds. Pectoralis dry matter (%), fat (%), and ash (%) were largely unaffected (P0.05) by genotype or outdoor access. These data indicate that meat quality differences exist among genotypes with very different growth rates and reared with or without outdoor access.

Consumer interest in organic and free-range poultry production is growing. An experiment was conducted to assess the impact of genotype and outdoor access on growth rate and carcass yield. One slow-growing genotype (S), 2 medium-growing genotypes (M1 and M2), and a commercial fast-growing genotype (F) were raised (straight-run) for 81, 67, and 53 d, respectively. The placement date was staggered in order to achieve a similar final body weight and each genotype was processed on the same day. Each genotype was assigned to 3 pens of 24 birds each and raised in indoor floor pens in a curtain-sided house with ventilation fans; the S and F genotypes were also assigned to 2 floor pens with outdoor access (during daylight hours) containing 36 birds each. All birds were provided with the same starter, grower, and finisher feeds, and birds were commercially processed. Weight gain was similar (P > 0.05) among genotypes, but males gained more weight (P < 0.05) than females. The S and F genotypes had the highest and lowest (P < 0.05) feed intakes and, consequently, the lowest and highest (P < 0.05) feed efficiencies, respectively. The F genotype had the greatest (P < 0.05) breast yield (%) and the lowest (P < 0.05) wing yield (%). The S genotype exhibited the lowest (P < 0.05) breast yield (%) and the greatest leg quarter yield (%). Birds given outdoor access had greater (P < 0.05) bone strength in the tibia, and the F genotype had highest (P < 0.05) bone strength. These data indicate that substantial growth performance and yield differences exist among genotypes in alternative poultry systems.

In each of 2 trials, 75 female and 75 male broilers of different sizes (large and small) were obtained from a commercial grower and were commercially processed. Breast fillets were deboned at 0.25, 1.5, 3, 6, and 24 h postmortem (total n = 15 per treatment per time point). Muscle pH and L* value were determined for each deboning time. Breast fillets were subjected to texture analysis using Allo-Kramer (10-blade), needle puncture (2 mm diameter), or razor blade shear (8.9 mm wide) methods. Allo-Kramer tests were performed on a strip (40 x 20 x 7 mm); needle puncture and razor blade shear were performed on intact muscles. Body size and sex had no effect on rigor development or color as indicated by no significant difference in breast muscle pH, R-value, or L* value. Allo-Kramer and razor blade tests exhibited significant shear value differences among samples deboned early (1.5 h) and late (6 h) PM. Allo-Kramer shear and razor blade tests performed similarly for differentiating breast meat of different toughness though Allo-Kramer shear force and razor blade energy were only moderately correlated (r = 0.72). Although both instrumental tests were performed in the same approximate area on each breast, it is possible that variation within the breast would have caused this marginal correlation. Although further studies would be necessary to compare the performance of both tests for assessing poultry meat toughness, the proposed razor blade test has the advantage of requiring no sample preparation (i.e., cutting a strip of constant dimensions) other than cooking.

When broilers are exposed to high ambient temperatures, their cardiac output can increase by 20 to 50%. Previously, we developed an intravenous micro-particle injection technique to select broilers having a cardiopulmonary capacity capable of accommodating increases in cardiac output associated with fast growth and cool temperatures. In the present study, male broilers were injected at 18 to 20 d of age with cellulose micro-particles sufficient to trigger >50% mortality by 35 d of age. The survivors of micro-particle injections (cellulose survivors) and saline-injected flock mates (control group) were exposed to a moderate cyclic heat challenge (peak temperature of 35 to 37 degrees C) beginning on d 36 and continuing through d 57. We tested the hypothesis that if the cellulose survivors represent the population cohort having the most robust cardiopulmonary capacity, then during a subsequent heat challenge these survivorspotentially may perform better than their unselected flock mates. Based on data combined from two independent experiments, the cellulose survivors exhibited improved livability and body weight gain when compared with their unselected flock mates during the cyclic heat challenge. Meat quality characteristics did not differ between the groups. In a third experiment, cellulose survivors and saline-injected male broilers were reared at thermoneutral temperatures or were exposed to a cyclic heat challenge beginning on d 36. Arterial blood samples were collected from unanesthetized birds at 47 to 49 d of age and were analyzed for pH, partial pressure of CO2, bicarbonate, partial pressure of O2, and saturation of hemoglobin with O2. The blood gas values for the cellulose survivors and saline-injected broilers did not differ within a temperature regimen, regardless of whether the broilers were chronically acclimated to heat or were exposed to an acute heat challenge at the end of the experiment. The cellulose survivors did not differ in susceptibility to panting-induced respiratory alkalosis or hypoxemia when compared with their saline-injected flock mates. Overall, these observations indicate that selection for a robust cardiopulmonary capacity can confer advantages in growth and livability without affecting meat quality when broilers are exposed to a moderate heat challenge.

This experiment was conducted to evaluate the effects of electrical stimulation (ES) on breast fillets harvested at 1 h post-mortem and individually quick frozen (IQF) or aged on ice (ICE). Twelve birds were electrically stimulated (450 V, 750 mA, 2 s on/1 s off for 15 s) at the neck in a saline bath. Twenty-four unstimulated birds were used as controls. Breast fillets were harvested at 1 h post-mortem from ES and control carcasses or at 4 h post-mortem from control carcasses and were either IQF or ICE until 24 h post-mortem. Fillets were then analyzed for shear value, pH, R value, and color. Electrical stimulation significantly reduced shear values compared to the 1 h controls for both IQF and ICE treatments. The ICE fillets deboned at 1 h from ES-treated carcasses had shear values similar to those of ICE fillets deboned from the 4 h controls. Electrical stimulation increased the percentage of shear values at or below 8 kg/g for the fillets from ES-treated carcasses compared to the 1 h controls. Electrical stimulation accelerated the normal post-mortem decline in pH and increase in R value. There was no significant difference in L* or a* values between the fillets held for 1 or 24 h. The results suggest that by electrically stimulating carcasses at the neck using a saline bath, the aging period could be eliminated by removing fillets immediately after chilling at 1 h, decreasing the costs associated with aging whole carcasses or front halves.