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Precision-fed rooster trials were conducted to evaluate standardized AA digestibility and TME

Four experiments were conducted to determine ME and amino acid (AA) digestibility of spray-dried animal plasma (SDAP) and soybean meal (SBM). The 48-h precision-fed adult rooster assay was used in 2 experiments; TME

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 (P0.05) related to higher cranial fillet thickness and ready-to-cook 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 (P0.05) 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.

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 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, 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 (P0.05) 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.

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.

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.

Consumer interest in free-range and organic poultry is growing. Two concurrent experiments were conducted to assess 1) the impact of alternative genotype and production system and 2) the impact of genotype and diet on meat quality of chickens for specialty markets. Specifically, a slow-growing genotype (slow) and a fast-growing genotype (fast) were raised for 91 and 63 d (females), respectively, or 84 and 56 d in the case of the second trial (males). In each trial, the slow birds were placed before the fast birds to achieve a similar final BW at processing. Each genotype was assigned to 4 pens of 20 birds each and raised in indoor floor pens in a conventional poultry research facility; each genotype was also assigned to 4 floor pens in a small facility with outdoor access. A low-nutrient diet was used, formulated for a slower rate of production. Birds were commercially processed and deboned at 4 h postmortem. In the second trial, the diets compared were a conventional diet that met NRC requirements or the low-nutrient diet, and all birds were raised indoors. There was an interaction between genotype and production system for the color (b*; P < 0.05). The meat and skin of the slow birds became more yellow when the birds had outdoor access; however, this did not occur when the fast birds had outdoor access. The breast meat of the slow birds had more protein and alpha-tocopherol (P < 0.05) than the fast birds and half the amount of fat (P < 0.05). In addition, the meat of the outdoor birds had more protein than the indoor birds (P < 0.05). The slow birds had poorer water-holding capacity but were more tender than the fast birds (P < 0.05). The type of diet had little impact on meat quality. These data indicate that meat quality differences exist between genotypes with different growth rates and raised in alternative production systems.

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.

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 CHO 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 (P0.05) with addition of 0.11% supplemental Met, whereas feed intake was maximized (P0.05) with addition of 0.07% supplemental Met. Overall, growth parameters were not affected (P0.05) 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 (P0.05) affect HCY remethylation, but remethylation through the Met synthase pathway was increased (P0.05) 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 methyltransferase 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.

Two experiments were conducted to assess effects of phase-feeding (PF) on broilers from 21 to 63 d. Experiment 1 evaluated the impact of PF on growth performance, whereas experiment 2 assessed the effects of PF on CP intake and nitrogen excretion. Diets were formulated using recommendations from NRC or linear regression equations. Two PF treatments were prepared: standard (PF) and low (PF10), in which predicted Lys, sulfur amino acid, and Thr recommendations were reduced by 10%. For PF and PF10, 2 diets (high-nutrient and low-nutrient density) were blended in variable quantities to produce rations matching predicted requirements. An NRC grower and finisher diet or a series of PF and PF10 diets that were switched every other day were fed. In experiment 1, weight gain and feed efficiency were improved (P0.05) by PF10 relative to broilers fed the NRC-based diet. Crude protein intake was reduced (P0.05) by PF10 relative to broilers fed NRC and PF diets. No differences (P0.05) in percentage carcass composition were observed when broilers were fed PF or PF10 diets. Significant reductions (P0.05) in dollars per kilogram of weight gain were noted with PF regimens. In experiment 2, PF and PF10 diets reduced (P0.05) CP intake and nitrogen excretion from 43 to 63 d. Results indicate that PF regimens may substantially reduce dietary costs and may have environmental benefits.

Over the last several decades, many poultry science programs have merged with other departments, but the poultry industry has undergone tremendous expansion worldwide, leading to a growing instructional void with regard to poultry production information. The objective of this project was to address the demand for information by developing two Web-based poultry production courses that cover management of broilers, turkeys, breeders, and layers. The Internet was chosen as the platform because it is asynchronous and may be accessed from any connected site around the world. To be effective, web-based courseware must be theoretically grounded and interactive, but university-level web-based distance education courses often fail to meet these standards. During courseware development, the impact of instructional techniques and technologies on interactivity and learning outcomes was explored. A content expert, an instructional designer, and a graphic artist carefully reviewed a variety of instructional techniques to increase interactivity. Concept mapping was chosen because it has been shown to be a superior learning tool for enhancing the exchange of ideas and knowledge between instructors, students, and content. A unique instructional interface was established that includes threaded e-mail discussion, thought questions, animation, hypertext, rollover interactions, video clips, and concept mapping exercises. Results indicate that the integration of concept mapping into web-based learning environments successfully increased interactivity and learning outcomes.

Phase-feeding (PF) was tested to evaluate its efficacy compared with NRC recommendations for broilers. Two modified PF regimens were also tested that involved lowering amino acid requirements predicted by PF linear regression equations by 10% (PF10) and increasing the slope of the linear regression equations by 15% (PF15). Experimental diets were fed from 43 to 71 d. Broilers fed the NRC regimen were given a single diet throughout the experiment, whereas PF, PF10, and PF15 were tested with a series of four diets (43 to 50 d, 50 to 57 d, 57 to 64 d, and 64 to 71 d). At 71 d, no differences (P0.05) in weight gain, feed intake, or feed efficiency were observed among treatments. Intake of crude protein, digestible lysine, sulfur amino acids (SAA), and threonine were decreased (P0.05) by PF, PF10, and PF15 relative to that of broilers fed the NRC diet. Gain per unit digestible lysine and threonine intake were increased (P0.05) by PF, PF10, and PF15, and gain per unit digestible SAA intake was increased (P0.05) by PF10 and PF15 relative to broilers fed the NRC diet. No differences (P0.05) were observed in carcass, breast, wing, or leg yield, but abdominal fat was increased (P0.05) by the PF10 regimen relative to that of broilers fed the NRC diet. Economic analysis indicated that PF and PF10 may lower the cost of feed consumed and the cost per unit weight gain or breast yield relative to broilers fed the NRC diet.