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.

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.

Current commercial broiler products are derived from the crosses of various strains at the primary breeder level. This study investigated chick development, yolk utilization, and early growth rate of males from 8 broiler breeder strains. These strains were a combination of both specialized and commercial-line products. At hatch, 110 male chicks per strain were weighed and wing-banded, and chick quality was assessed. Traits included navel condition, hock color, chick length, shank length, and abdomen score by abdominal palpation (to evaluate residual yolk content on live chicks). At hatch, 50 chicks per strain were dissected to assess breast muscling and residual yolk weight. At 2 wk of age, 50 chicks per strain were dissected to characterize changes in weight, conformation, fleshing, and residual yolk content. Chick weight at hatch varied from 40.8 g in a heavily growth-selected line to a low of 36.9 g in a commercial strain. The mass of residual yolk at hatch ranged from 0.8 to 10.6 g across all chicks dissected at hatch. A heavily breast-selected pure-line strain had 5.8 g of residual yolk in contrast to the commercial strain that had only 3.0 g. Although there were no significant strain differences in abdomen score, this score correlated with dissected residual yolk weight (r = 0.50). Shank length and chick body length at hatch correlated more strongly with BW on d 14 than did hatch weight. This information stresses the importance of evaluating several characteristics at hatch to better quantify early chick quality.

Consumer awareness of the health benefits of n-3 fatty acids is growing and is driving consumer demand for enriched food products. Enrichment of meat with n-3 fatty acids is an opportunity for the broiler production sector to add value to their product, but enrichment can increase the cost of production. A study was conducted to determine an optimal production strategy for n-3 enrichment of broiler meat using ground full-fat flaxseed. Low and high levels of dietary flaxseed (10 and 17%, respectively) were fed to broilers for 8 lengths of time (0, 4, 8, 12, 16, 20, 24, or 35 d) before processing at 35 d. Increasing the level or duration decreased feed intake, BW, and the percentage yield of carcass and breast. Flaxseed level and duration of feeding increased feed conversion ratios and the cost of production. Feeding flaxseed at 10 and 17% increased breast n-3 fatty acid levels by 7.65 and 13.70 mg/100 g of meat per day, respectively. In breast meat, the threshold level of 300 mg/g, required in Canada for labeling foods as a source of n-3 fatty acids, was reached at 12.1 and 24.1 d in the high and low flaxseed treatments, respectively. This was due primarily to a tripling of alpha-linolenic acid (18:3n-3) levels in the breast meat. Levels of the long-chain n-3 fatty acid eicosapentaenoic acid increased significantly in the breast meat with increased level and duration of flax feeding, indicating that birds were able to desaturate and elongate alpha-linolenic acid to eicosapentaenoic acid. To minimize cost, while achieving adequate breast meat n-3 enrichment, carcass weight, and meat yield, feeding 10% flaxseed for 24.1 d before processing is recommended as an optimal breast meat n-3 enrichment strategy. The optimal thigh meat n-3 enrichment strategy was to feed 10% flaxseed for 4.54 d before processing.

Antemortem holding temperature and flapping can affect broiler pectoralis major (referred to as p. major) meat quality. The influence of environmental temperature 12 to 14 h before processing and antemortem handling on p. major functional properties and color was tested at multiple processing ages in a 3 × 2 × 5 factorial design study. At 28, 35, 42, 49, and 56 d of age, mixed-sex broilers were crated and held in one of 3 target temperature treatments: heat (30°C), thermoneutral (21°C), or cool (7°C). Following feed withdrawal, birds were transported to a processing facility where either a long (120 s) or short (<10 s) shackling treatment was imposed. Sex was determined at processing. Lightness, redness, and yellowness values were measured at deboning [4.50 to 8.25 h postmortem (PM)] and at 24 h PM. Ultimate pH was measured at 24 h PM. Drip loss, cook loss, and Allo-Kramer shear force were determined at 72 h PM. Ultimate pH was highest in the cool treatment, with no difference between heat and thermoneutral treatments (5.97 vs. 5.87 and 5.90, respectively; P = 0.0004). Ultimate pH correlated negatively with drip loss (r = -0.47; P < 0.0001). Drip loss was lowest in the cool treatment, with no difference between the heat and thermoneutral treatments (2.06 vs. 2.24 and 2.19%, respectively; P = 0.007). The p. major from broilers in the heat treatment had higher Allo-Kramer shear force values than those in both the thermoneutral and cool treatments (4.64 kg/g vs. 4.21 and 4.21 kg/g, respectively; P = 0.023). With the exception of 49 d, broilers subjected to the long shackling treatment had higher redness values at deboning than broilers subjected to the short shackling treatment; by 24 h PM only the 28-d broilers subjected to the long shackling treatment had higher redness values. Higher hue angles at deboning and 24 h PM were observed in the short treatment compared with the long treatment (65.58 vs. 57.46 and 68.48 vs. 63.31, respectively; P < 0.0001), indicating that p. major from long-shackled broilers were redder in appearance. Ultimate pH was lower in female broilers than in male broilers (5.87 vs. 5.96, respectively; P < 0.0001) and subsequent drip loss was higher in females compared with males (2.34 vs. 1.99%, respectively; P < 0.0001). Although temperature and handling before slaughter affected p. major color and texture traits, the differences may not be large enough to have commercial significance. Differences in p. major quality attributable to sex of the bird may have greater commercial significance than previously reported.