The most recent research cited by the NRC Nutrition Requirements of Poultry to establish choline recommendations was published in 1987, so choline guidelines for modern broilers are outdated and may be insufficient to optimize growth. The objective was to determine the effect of additional dietary choline chloride supplementation on growth performance and carcass characteristics of modern broilers reared for 66 days. As-hatched Ross 708 × Yield Plus broiler chicks (n = 2160; 30 birds per pen) were randomly allotted to one of six experimental corn and soybean meal-based diets formulated to contain an additional 0, 400, 800, 1200, 1600, or 2000 mg of choline chloride above the choline content of the basal diet ingredients. Diets were fed in four phases, and birds were processed at day 66 of age. Growth performance and breast myopathy incidence was not impacted by added choline. While there were differences in breast, wing, thigh, and drum yields, the effects of added choline were not linear. Supplemental choline chloride was not beneficial for growth performance but did impact the carcass characteristics of modern, large frame broilers reared for 66 days.

Research on the impact of supplementing additional dietary choline to modern, large-frame broiler chickens is limited, and current choline recommendations are outdated. The objective of this study was to determine the effect of additional dietary choline chloride supplementation on growth performance and carcass characteristics of modern broilers reared to 32 days of age. Corn and soybean meal-based diets were formulated to contain an additional 0, 400, 800, 1200, 1600, or 2000 mg of choline chloride per kg of feed above the choline present in the basal diet ingredients. As-hatched Ross 708 × Yield Plus broiler chicks (n = 2160; 30 birds per pen; 44 ± 0.2 g initial BW) were randomly allotted to the experimental diets, reared for 31 days, and processed at day 32. Growth performance, carcass yield, and breast myopathy incidence were not impacted by supplemental choline. However, abdominal fat pad weight tended to diminish with increasing dietary choline, and drumstick yield was reduced in birds fed over 800 mg per kg of feed. These results indicate feeding additional choline does not impact growth performance but may result in changes in carcass characteristics of modern, high-yielding broilers reared for 32 days.

Choline has been demonstrated to partially substitute methionine in broiler chicken diets due to their interconnected biosynthesis pathways. Yet, research on the impacts of dietary choline supplementation on modern strains of high-yielding broilers is limited. The objective was to evaluate the effect of increasing additions of choline chloride on the performance and carcass characteristics of broilers fed reduced methionine diets and reared under summer environmental conditions. Ross 708 x Yield Plus male broilers were reared for 41 days on used litter in floor pens (n = 2232; 31 birds per pen). Birds were fed one of six corn and soybean meal-based, reduced methionine diets containing 0, 400, 800, 1200, 1600, or 2000 mg of added choline chloride per kg of feed. Diets were provided in three phases. On day 43, 10 birds per pen were processed. Increasing dietary choline resulted in similar body weight gain, reduced feed intake, and improved feed efficiency. Choline chloride supplementation linearly increased both breast and carcass yields while concomitantly increasing the incidence and severity of wooden-breast-affected fillets. These results indicate that supplementing reduced-methionine broiler diets with choline chloride during high environmental temperatures may improve feed efficiency and increase carcass and breast yields but may also increase wooden breast.

The etiology of Wooden Breast (WB) is unknown; therefore, it is difficult to produce broiler flocks with similar proportions of WB-affected and unaffected birds. Because WB has been detected as early as 15 d posthatch, the objective of this randomized complete block experiment with a 2 × 2 factorial treatment arrangement was to determine whether combining the effects of light intensity (LI) and early nutrient reduction strategies could reliably produce WB-affected and normal broilers to further investigate the physiological mechanisms underlying WB. On day of hatch, male, Ross 708 × Yield Plus broilers (n = 384; 16 birds per pen; 3 replicate blocks) were randomly allotted to floor pens in the same facility and exposed to either 2 (LOWLI) or 30 (HIGHLI) lux of light from d 0 to 35. Birds were fed either a commercial starter diet (CON) or the CON diet with a 10% reduction in both ME and digestible lysine (dLys; RED) from d 0 to 14 and then a common grower diet from d 15 to 35. Broiler growth performance, breast yield, and incidence and severity of WB and White Striping (WS) were assessed. Data were analyzed as a 2-way ANOVA with SAS PROC GLIMMIX and means separated at P < 0.05 with PDIFF. No interaction among LI and diet was observed (P > 0.05). Broilers reared with HIGHLI were heavier on d 35 and consumed more feed in all phases compared with broilers reared under LOWLI (P ≤ 0.0096). Broilers reared under LOWLI gained less BW from d 15 to 35 and d 0 to 35 compared with broilers reared under HIGHLI (P = 0.0073). Broilers fed the RED starter diet consumed more feed and had higher FCR from d 0 to 14 compared with broilers fed the CON diet (P ≤ 0.0012). In conclusion, combining reductions in LI and starter diet ME and dLys did not produce the hypothesized reductions in breast yield and incidence and severity of WB or WS.

Low uniformity of broiler live body weight, carcass, and parts weights can reduce overall processing yields and profitability. The objective of this study was to evaluate the effects of thermal manipulation (TM) during late-stage incubation (LSI) and sex on the uniformity and coefficient of variation (CV) in high yielding broilers. Yield Plus ′ Ross 708 broiler breeder eggs (n = 2,160) were incubated at 37.5 °C from embryonic day (ED) 0 to 10. From ED 11 to 18, eggs were incubated at 1 of 3 air temperature set points: 37.5 °C (CTL), 36.4 °C (COLD), or 38.6 °C (HOT; n = 2 incubators per treatment). On ED 18, all eggs were transferred to baskets in hatchers set to 36.7 °C. Chicks were vent sexed, placed in floor pens blocked by incubation treatment and sex (n = 6 replicate pens of 30 birds per treatment), and fed a common diet. Broilers were individually weighed at d 9, 23, and 32, then, the 15 birds from each pen closest to the pen median BW were processed on d 33. The distance of each bird BW from the pen mean and median, TM treatment, sex, and whole flock BW over time, uniformity of BW (within 10% of the mean), and intra-pen CV were calculated. Data were analyzed as a 2-way ANOVA using the GLIMMIX procedure of SAS ver. 9.4 with TM treatment and broiler sex serving as the main effects. Means were separated at P ≤ 0.05 with the PDIFF option. On d 9, a TM by sex interaction was observed, and the BW of female CTL chicks was less variable from the pen mean compared with broilers hatched from COLD and females from HOT incubators (P ≤ 0.026). On d 9, sub-optimal incubation temperatures (HOT and COLD) during LSI resulted in higher individual female bird BW variation from the pen mean and median (P = 0.013). Incubating chicks in COLD incubators during LSI increased d-9 individual bird BW distance from the treatment, sex, and flock mean and median BW compared with CTL and HOT (P ≤ 0.037). In addition, BW uniformity within a pen was less in broilers hatched from COLD incubators than both CTL and HOT on d 9 (P = 0.033) and tended to be less on d 32 (P = 0.099). The inverse was observed for CV (P ≤ 0.040). Broilers hatched from COLD and HOT incubators had greater CV for carcass (P = 0.049) and wing (P = 0.028) as well as drumstick (P = 0.079) weights. These results indicate that sub-optimal LSI conditions can negatively influence uniformity of broiler live BW, carcass and parts weights and highlights the importance of achieving optimal incubation conditions.