The effect of commercial selection on the growth, efficiency, and yield of broilers was studied using 2 University of Alberta Meat Control strains unselected since 1957 and 1978, and a commercial Ross 308 strain (2005). Mixed-sex chicks (n = 180 per strain) were placed into 4 replicate pens per strain, and grown on a current nutritional program to 56 d of age. Weekly front and side profile photographs of 8 birds per strain were collected. Growth rate, feed intake, and measures of feed efficiency including feed conversion ratio, residual feed intake, and residual maintenance energy requirements were characterized. A nonlinear mixed Gompertz growth model was used to predict BW and BW variation, useful for subsequent stochastic growth simulation. Dissections were conducted on 8 birds per strain semiweekly from 21 to 56 d of age to characterize allometric growth of pectoralis muscles, leg meat, abdominal fat pad, liver, gut, and heart. A novel nonlinear analysis of covariance was used to test the hypothesis that allometric growth patterns have changed as a result of commercial selection pressure. From 1957 to 2005, broiler growth increased by over 400%, with a concurrent 50% reduction in feed conversion ratio, corresponding to a compound annual rate of increase in 42 d live BW of 3.30%. Forty-two-day FCR decreased by 2.55% each year over the same 48-yr period. Pectoralis major growth potential increased, whereas abdominal fat decreased due to genetic selection pressure over the same time period. From 1957 to 2005, pectoralis minor yield at 42 d of age was 30% higher in males and 37% higher in females; pectoralis major yield increased by 79% in males and 85% in females. Over almost 50 yr of commercial quantitative genetic selection pressure, intended beneficial changes have been achieved. Unintended changes such as enhanced sexual dimorphism are likely inconsequential, though musculoskeletal, immune function, and parent stock management challenges may require additional attention in future selection programs.

The effects of four stocking and water nipple densities on broiler performance and carcass traits were measured in two trials. The stocking densities of 23.8, 17.9, 14.3, and 11.9 birds/m2 corresponded to 260, 195, 156, and 130 birds per pen, respectively. The water nipple densities were 5, 10, 15, and 20 birds per water nipple. Birds in Trial 1 were processed at Day 39 and those in Trial 2 were processed at Day 42. Water and feed were provided ad libitum and light was provided 23 h/ d. Water nipple density had no effect on broiler performance or carcass quality. Birds grown at 23.8 birds/m2 had lower BW (1,898 g) and carcass weights (1,334 g), whereas birds grown at 14.3 birds/m2 had the highest BW (1,985 g) and carcass weights (1,432 g). Although the treatment with 23.8 birds/m2 gave the lowest BW, the yield of broilers per unit of floor space was highest (46.0 kg/m2). The coefficient of variation for BW was higher in the treatment with 11.9 birds/m2 (15.3 %) than in the other treatments (13.0%). The birds in the treatment with 11.9 birds/m2 consumed the least feed (2,993 g/bird) and those in the 14.3 birds/m2 treatment consumed the most feed (3,183 g/bird). The amount of water consumed and the water to feed ratio was highest in the 23.8 birds/m2 treatment (5,546 mL/bird and 1.85 mL/g, respectively). Stocking density had no effect on mortality, breast yield, carcass grading, incidence of scratches, or carcass quality. It was concluded high yield per unit area with good carcass quality could be achieved when ventilation rate and air circulation were adequate.

Consumers are becoming more aware of the effect of the food they eat on their health. One of the ways they hope to reduce their risk of cardiovascular disease is by consuming more foods enriched with n-3 polyunsaturated fatty acids (PUFA). Due to the high content of alpha-linolenic acid (LNA), dietary flaxseed is a good source for increasing n-3 PUFA in poultry meat. A study was conducted with 2 primary objectives: to establish the distribution of n-3 PUFA between triacylglycerol (TAG) and phospholipid of broiler chicken breast and thigh meat and to determine the duration of dietary flaxseed supplementation required to ensure a level of n-3 PUFA of 300 mg per 100 g of meat necessary to label meat as a source of n-3 PUFA. This experiment was conducted as a 2 x 8 factorial, with 2 dietary levels of ground flaxseed (10 and 17%) and 8 durations of dietary flaxseed before processing [0 (control), 4, 8, 12, 16, 20, 24, and 35 d]. A total of 128 Ross x Ross 308 mixed-sex broilers were evaluated to 35 d of age. Breast and thigh meat fatty acid composition was analyzed on duplicate samples of ground meat pooled from 8 birds per treatment. Broken-stick analysis was used to estimate the duration required to achieve 300 mg of n-3 PUFA per 100 g of breast meat. Results clearly indicated that LNA was mainly deposited in the TAG fraction of both breast and thigh meat. Enriching the chicken breast meat with 300 mg of n-3 PUFA per 100 g of meat was achieved in 11.3 and 26.2 d with a 17 and 10% level of flaxseed in diet, respectively. Although a significant increase of n-3 long-chain PUFA (20:5n-3, 22:5n-3, and 22:6n-3) was found in the phospholipid and TAG fraction of both tissues, the concentration of these functional components was low. More than 95% of n-3 PUFA enrichment was due to LNA.

Consumers are becoming more aware of the impact on their health of the food they eat. One of the ways they hope to reduce their risk of cardiovascular disease is by consuming more foods enriched with polyunsaturated fatty acids (PUFA), particularly n-3 fatty acids. Flaxseed is a good source for increasing the n-3 PUFA in poultry meat because of the high content of alpha-linolenic acid. A study was conducted to identify an optimal process to enrich of broiler diets with n-3 PUFA by using 2 levels of flaxseed fed for various times before processing. The acceptability of broiler meat functional properties was tested to ensure that further processing efficiencies would not be compromised by the enrichment strategy. This experiment was conducted as a 2 x 8 factorial, with 2 dietary levels of ground flaxseed (10 and 17%) fed for 8 lengths of time before processing [0 (control), 4, 8, 12, 16, 20, 24, and 35 d]. Of 650 Ross x Ross 308 mixed-sex broilers reared in this study, 128 were used to evaluate breast and thigh meat functional properties, oxidative stability, and sensory analysis. No statistical interactions were found between treatments for chicken breast meat quality traits. The duration of feeding flaxseed strongly affected meat quality parameters. In particular, feeding flaxseed for 16 d resulted in a final pH of 5.65, compared with 5.93 in the control. The lower ultimate pH found in animals fed flaxseed affected meat cooking loss, drip loss, and shear value (P < 0.0001). Shear value significantly increased after 16 d of feeding flaxseed (P < 0.0001). Susceptibility to oxidation increased in both breast and thigh broiler meat with the duration of feeding flaxseed. Enriching the diet for less than 16 d did not result in perceivable sensory defects. Duration of flaxseed feeding significantly affected the color characteristics, functional properties, and oxidative stability of broiler meat.

Background:Chicken meat has the highest per capita consumption among all meat types in North America. The practice of feeding 3-nitro-4-hydroxyphenylarsonic acid (Roxarsone, Rox) to chickens lasted for more than 60 years. However, the fate of Rox and arsenic metabolites remaining in chicken are poorly understood.Objectives:We aimed to determine the elimination of Rox and metabolites from chickens and quantify the remaining arsenic species in chicken meat, providing necessary information for meaningful exposure assessment.Methods:We have conducted a 35-day feeding experiment involving 1,600 chickens, of which half were control and the other half were fed a Rox-supplemented diet for the first 28 days and then a Rox-free diet for the final 7 days. We quantified the concentrations of individual arsenic species in the breast meat of 229 chickens.Results:Rox, arsenobetaine, arsenite, monomethylarsonic acid, dimethylarsinic acid, and a new arsenic metabolite, were detected in breast meat from chickens fed Rox. The concentrations of arsenic species, except arsenobetaine, were significantly higher in the Rox-fed than in the control chickens. The half-lives of elimination of these arsenic species were 0.4–1 day. Seven days after termination of Rox feeding, the concentrations of arsenite (3.1 μg/kg), Rox (0.4 μg/kg), and a new arsenic metabolite (0.8 μg/kg) were significantly higher in the Rox-fed chickens than in the control.Conclusion:Feeding of Rox to chickens increased the concentrations of five arsenic species in breast meat. Although most arsenic species were excreted rapidly when the feeding of Rox stopped, arsenic species remaining in the Rox-fed chickens were higher than the background levels.Citation:Liu Q, Peng H, Lu X, Zuidhof MJ, Li XF, Le XC. 2016. Arsenic species in chicken breast: temporal variations of metabolites, elimination kinetics, and residual concentrations. Environ Health Perspect 124:1174–1181; http://dx.doi.org/10.1289/ehp.1510530