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A study was conducted to investigate the impact of phytase source, citric acid, and wheat middlings (WM) on growth performance, bone strength, carcass yield, and P release in broilers fed marginally-deficient P diets from d 21 to 55. The experiment consisted of 13 dietary treatments, which were replicated five times, where each replicate consisted of 20 birds and utilized the standard-curve methodology using monobasic potassium phosphate (KH2PO4) as the standard. Treatments were as follows: diets 1 to 4) corn -soybean meal (C-SBM) basal (0.13% iP) supplemented with graded levels (0, 0.04, 0.08, 0.12%) of KH2PO4; diets 5 to 8) as in diet 1 with 500 FTU/kg of phytase (E. coli (EP) or fungal (FP)) and two levels of citric acid (0 or 3 %); diet 9) as in diet 1 with 10% corn replaced by WM; and diets 10 to 13) as in diet 9 supplemented with 500 FTU/kg of phytase (EP or FP) and two levels of citric acid (0 or 3 %). Reducing dietary IP had no impact on growth performance. Phytase had the main effect of increasing weight gain in the grower and withdrawal phases (P < 0.05); weight gain was greater in broilers fed the EP diets compared to those fed the FP diets during the grower phase (P < 0.05). When all the periods were combined only broilers fed the EP diets had weight gains and feed efficiencies that were greater than broilers fed no supplemental phytase (P < 0.05). The inclusion of phytase had the main effect of increasing adjusted bone breaking strength (ABBS) and tibia ash (P < 0.05) and released at least 0.083% P. Broilers fed the FP diets had lower carcass yield, whereas broilers fed the EP diets had lower wing yield (P < 0.05). Citric acid had the main effect of increasing feed efficiency, ABBS, and tibia ash (P <0.05) when all the periods were combined. Phytase and citric acid released at least 0.100% P, whereas the inclusion of WM alone released 0.051% P using ABBS data. The combination of phytase and WM increased P release by 67% (P <0.05), whereas phytase, citric acid, and WM released at least 0.148% P. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Phase feeding (PF) has been effective at 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. Three strains of commercial broilers were fed a diet containing average industry nutrient levels from 0 to 18 d. From 18 to 32 d, birds were fed either diets with average industry nutrient levels or diets with phased levels of amino acids. For PF, diets were prepared that contained Lys, sulfur amino acids, and Thr levels matching the predicted requirements for birds at the beginning (high nutrient deiisity) and end (low nutrient density) of PF. Pelleted high and low nutrient-density diets were blended to produce rations containing amino acid levels that matched the predicted PF requirements over 2-d intervals, and diets were switched every other day during PF. Treatments were replicated in 6 pens; each pen contained 15 males and 15 females. Weight gain, feed intake, and feed efficiency were calculated. All birds were commercially processed; yield and fillet dimensions were calculated. Differences among strain BW were noted on d 0, 18, 32, and at processing. Males weighed more than females on d 18 (excluding strain C), 32, and the day of processing. Weight gain was affected by strain (P < 0.05) but not by feeding regimen in the overall growth period (18-39 d). Feed efficiency was improved by PF in strains B and C during the overall growth period. Fillet yield was improved with PF for strain B, and there were no significant differences between PF and industry fillet yields for the other 2 strains. Phase feeding had no effect on fillet dimensions, and there was little effect of strain. These results suggest that different strains may vary in their response to PF, although performance was similar or better in PF birds compared with birds fed the industry diet, regardless of strain. [ABSTRACT FROM AUTHOR]

Phase feeding (PF) has been effective at maintaining broiler growth while reducing production cost, but the effect on different broiler strains and sex has not been assessed. An experiment was conducted using 4 commercial broiler strains grown up to 63 d of age (n 1,440), comparing a PF approach to an industry-type diet. At d 17, birds began either the industry or PF regimen. The industry regimen consisted of average industry nutrient levels with periods from 17 to 32 d, 32 to 40 d, 40 to 49 d, and 49 d to the end of trial. For PF, diets were prepared that contained Lys, sulfur amino acids, and Thr levels matching the predicted requirements for birds at the beginning (high nutrient density) and end (low nutrient density) of PF. Pelleted high and low nutrient density diets were blended to produce rations containing amino acid levels that matched the predicted PF requirements over 2-d intervals. Weight gain, feed intake, and feed efficiency were calculated through d 58. Birds were commercially processed at 59, 61, or 63 d; yield and fillet dimensions were measured. Phase feeding did not effect weight gain or feed intake of broilers during the overall growth period (17-58 d). For most strains, PF did not effect final BW, yield, or fillet dimensions. However, strain and sex had greater effects on growth performance, yields, and fillet dimensions. Strains B and D had greater breast yield than strains A and C. Reduced feed costs ($0.01 to $0.04 per kilogram of gain, depending on strain) were observed for all strains with PF for the overall growth period (17-58 d). Therefore, potential savings on feed costs are possible for all strains used in this study with the incorporation of the PF regimen. [ABSTRACT FROM AUTHOR]

The industry trend toward early deboning of chickens has led to the need to explore the effect on meat quality, including the effects of strain and sex. An experiment was conducted using broilers of 4 different high-yielding commercial strains chosen because of their common use in big-bird production. Of each strain, 360 birds were commercially processed at 59, 61, and 63 d of age in 2 replicates per day. Breast fillets were harvested at 2, 4, and 6 h postmortem (PM). Muscle pH and instrumental color (L*, a*, and b*) were measured at the time of deboning and at 24 h PM. Fillets were cooked to 76°C and cook loss was calculated, followed by Meullenet-Owens razor shear (MORS) analysis. Muscle pH significantly decreased over time as aging before deboning increased. Furthermore, L* values significantly increased as aging time increased, with the fillets deboned at 6 h PM having the highest L* value, followed by 4 h, and then 2 h PM. After 24 h, the fillets deboned at 6 h still had the highest L* compared with those deboned at 2 or 4 h PM. Fillets from strain B had the highest L* values. Fillets deboned at 2 h PM had significantly higher cook losses and MORS energy (indicating tougher fillets) than fillets deboned at 4 or 6 h PM, but there was no difference in cook loss due to strain at any deboning time. Fillets deboned at 4 h PM also had higher MORS energy than fillets deboned at 6 h PM, and differences in MORS energy among the strains were observed at 4 h PM. There was no difference in instrumental color values or cook loss due to sex. However, fillets of males had significantly greater MORS energy (tougher fillets) when deboned at 2, 4, and 6 h PM than those of females. Results of this study suggest that deboning time, sex, and strain can affect meat quality in big-bird market programs. [ABSTRACT FROM AUTHOR]

Broiler breast fillets are sometimes characterized grossly by white parallel striations in the direction of the muscle fibers, and the condition is referred to as white striping. Depending on the severity of white striping, fillets can be classified as normal (NORM), moderate (MOD), or severe (SEV). The present study was intended to determine the factors associated with the occurrence of white striping in broiler breast fillets. Broiler birds (59 to 63 d) of 4 different commercial high-yielding strains (both males and females) fed with industrial type or phase-feeding regimens, were processed and ready-to-cook carcass weight was recorded. The carcasses were deboned at either 4 or 6 h postmortem. Fillets were scored for the degree of white striping at 24 h postmortem, and dimensions of fillets (length, width, cranial thickness, and caudal thickness), pH, color (L*, a* and b* values), cook loss, and Meullenet- Owens razor shear energy (MORSE) values were determined. About 55.8% of the birds used in the study showed some degree of white striping with MOD and SEV categories as 47.5 and 8.3%, respectively. Higher degrees of white striping were significantly (P<0.05) related to higher cranial fillet thickness and ready-tocook weights. The occurrence of SEV degrees of white striping was accompanied with increased b* values or yellowness of the meat. The growth differences in strains could influence the incidence of this condition, but feeding regimens and chill hour during processing did not. In addition, the degree of white striping did not show any significant (P>0.05) relationship between various meat quality parameters such as pH, L*, a*, cook loss, and MORSE. In conclusion, the results of this study suggest that there is a greater chance of higher degrees of white striping associated with heavier birds, but the condition is not related to any major changes in cooked meat quality. [ABSTRACT FROM AUTHOR]

The article presents an abstract of the research paper "Case report: Necropsy findings during a phytase research trial in broilers," by T.O. Conner-Dennie and colleagues.

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 KH2PO4 (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 (P < 0.05) 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 F. coli phytase. In EXP 3, weight gain and tibia ash were reduced (P < 0.05) 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 (P> 0.05) from that of chicks fed the P-adequate diet. in addition, carcass yield of broilers fed E. coli phytase was not reduced (P > 0.05). 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 (P> 0.05; compared with the P-adequate diet) were noted for clavicle ash, diameter, or breaking strength. No differences (P > 0.05) 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. [ABSTRACT FROM AUTHOR]

Experiments were conducted to assess the effect of surfeit choline (CHOL) or betaine (BET) on growth performance and homocysteine (HCY) remethylation of young broilers fed graded levels of DL-Met (DLM) or 2-hydroxy-4-(methylthio) butanoic acid (HMB). In Experiment 1, a corn-peanut meal diet deficient in Met (0.25% digestible) and Cys (0.28% digestible) was fed; treatments were formulated to contain graded levels (0, 0.04, or 0.08%) of Met from DLM or 0.04% HMB (adjusted for 88% purity) that were fed in the presence or absence of surfeit isomethyl CHOL (0.25%) or BET (0.28%). In Experiment 2, identical treatments were used, but an additional level of HMB (0.08%) was fed, and the basal diet was adequate in Cys (0.43% digestible). There was no overall effect of CHOL or BET on growth performance in Experiments 1 and 2 (P > 0.05); a significant improvement (P < 0.05) in weight gain and feed efficiency did occur with CHOL and BET addition to the basal diet in Experiment 2. In both experiments, weight gain increased linearly (P < 0.05) with the addition of DLM or HMB. Slope ratio methodology was used to assess HMB efficacy in Experiment 2. In the presence of adequate Cys, HMB efficacy was 81.3%; addition of surfeit BET or CHOL had minimal effect on efficacy. The stable isotope study revealed that CHOL and BET addition to diets deficient in Met and Cys or Met alone increased HCY remethylation. It also showed that CHOL and BET have greater influence on folate-dependent remethylation of HCY (via Met synthase) than on BET-dependent remethylation (via BET-HCY methyltransferase) and that levels of CHOL and BET and type of S amino acid deficiency effect remethylation and HMB efficacy. [ABSTRACT FROM AUTHOR]

Consumer interest in organic and natural poultry production is growing. An experiment was conducted to assess the impact of genotype and outdoor access on sensory attributes of broiler meat. 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 dates were staggered to achieve a similar final BW, and each genotype was processed on the same day. Each genotype was assigned to 3 pens of 24 birds each, and all birds were 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 (during daylight hours) containing 36 birds each. All birds were provided with the same starter, grower, and finisher feeds, and birds were commercially processed. Breast and thigh meat were evaluated for sensory attributes and acceptability by a consumer panel. The M1 and M2 breasts were more tender than other indoor genotypes (P < 0.05); however, all treatments scored ‘slightly to moderately tender.’ The thigh meat of the M2 birds was more flavorful than that of S birds (P < 0.05), and the flavor of the S thigh meat was less liked than other indoor genotypes (P < 0.05). Outdoor access did not impact flavor. These data indicate that differences in sensory attributes may exist among genotypes with different growth rates and reared with or without outdoor access. [ABSTRACT FROM AUTHOR]

Methionine is critical in amino acid nutrition for chickens, yet details of the flux of Met metabolites in the avian system are lacking. This study explored the interactions among dietary choline (CHO), betaine (BET), and sulfur amino acid levels on growth and hepatic homocysteine (HCY) remethylation. Graded levels (0, 0.07, 0.11, and 0.24%) of DL-Met were added to diets adequate in CR0 and deficient in sulfur amino acids (0.26% digestible Met, 0.26% digestible Cys). Each Met level was tested alone or with the addition of CHO (0.25%) or BET (0.28%). Broilers were reared from 8 to 22 d in raised wire floor battery cages, and the 12 dietary treatments were fed to 3 replicate pens containing 5 birds per pen. Weight gain and feed efficiency were maximized (P < 0.05) with addition of 0.11% supplemental Met, whereas feed intake was maximized (P < 0.05) with addition of 0.07% supplemental Met. Overall, growth parameters were not affected (P > 0.05) by CHO or BET addition. Hepatic tissue primed by the different dietary treatments was subjected to a newly developed stable isotope methodology and HPLC-mass spectrometry to quantify the impact of diet on HCY remethylation. Dietary Met level did not (P> 0.05) affect HCY remethylation, but remethylation through the Met synthase pathway was increased (P < 0.05) by addition of CHO or BET to diets containing deficient or excess levels of Met. Minimal changes in hepatic HCY remethylation through the betaine-homocysteine methyl transferase pathway occurred in response to dietary changes; therefore, data failed to support previous suggestions that BHMT might have a regulatory role when diets containing deficient or excess Met levels are fed. In contrast to previous suppositions based on enzyme activity, under most dietary conditions, the quantity of HCY remethylated by Met synthase appeared to exceed that remethylated by the alternate betaine-homocysteine methyltransferase pathway. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]