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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of Poultry to establish choline recommendations was published in 1987, so choline guidelines for modern broilers are outdated and may be insufficient to optimize growth.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.

As antibiotic-free (ABF) broiler production continues to increase, understanding the development and local immune response in the intestines of ABF broilers is essential. Mitotically active cells, the majority of which will become enterocytes, help maintain the intestinal epithelial barrier. Macrophages prevent pathogen invasion by their phagocytic activity, functioning as immune response amplifying cells to aid in the recruitment of additional immune cells, and stimulating cytokine production in other adjacent cells. The objective of this experiment was to evaluate commonly used practical production practices on intestinal cell mitotic activity and local intestinal immunological responses. A randomized complete block design experiment with a 3 × 2 factorial treatment structure was conducted. The 3 dietary protein sources were: soybean meal (SBM), a mix of 50% poultry by-product meal and 50% feather meal (PFM), and porcine meat and bone meal (MBM) and broilers were reared on either new litter (NL) or used litter (UL). On d 3, 8, 11, 15, and 21, 6 birds per treatment from 6 blocks (total n = 36 per d) were randomly selected for sampling. Broilers were injected intraperitoneally with 5'-bromo-2'-deoxyuridine (BrdU) 1 h prior to sampling to label mitotically active cells. Samples were analyzed using cryohistology and immunofluorescence to determine the density of mitotically active cells and macrophages. Mitotically active cell and macrophage densities changed in both the duodenum and ileum over time. Neither dietary protein source nor litter condition affected mitotically active cell or macrophage densities in the duodenum on d 11 and 21 or in the ileum on d 3, 8, 11, and 15. However, on d 3 and 15 in the duodenum ( P ≤ 0.0126) and d 21 in the ileum ( P ≤ 0.0009), broilers reared on UL had greater mitotically active cell densities than those reared on NL. On d 8 in the duodenum, broilers fed MBM had increased macrophage density compared with those fed PFM and SBM ( P ≤ 0.0401). These results indicate dietary protein source and litter condition may impact the physiology of the broiler small intestine, though additional work with this model is necessary to understand the underlying mechanisms., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Keel, Calderon, Tejeda, Starkey and Starkey.)

The aim of this study was to evaluate the effect fiber type, particle size, and inclusion level on the performance parameters, intestinal development and gene expression in broiler chickens. A total of 648 one-day old Cobb male broilers were randomly assigned to a control diet and 8 other dietary treatments divided in 2 fiber types (cellulose vs. soyhulls), 2 particle sizes (100 and 600 µm), and 2 inclusion levels (4 and 8% crude fiber). Birds were reared to 21 days of age in battery cages (n = 6 replicates). Growth performance parameters and intestinal viscosity were measured on da 7, 14, and 21. On d 14 and 21, digestive organ weights were recorded for analyses of organ growth. On d 21, intestinal samples were taken for analyses of histology, and jejunal mucosas were collected for analyses of nutrient transporters. Data were analyzed as a 2 × 2 × 2 factorial design using JMP 2021. Treatments were compared against the control group using one-way analysis of variance, whereas the main effect interactions were evaluated as a factorial excluding the control group to be able to assess the effect of the independent variables without the variability introduced by the control group. The groups fed 8% crude fiber from cellulose (8% CL) had the lowest weight gain regardless of the particle size (P < 0.01). The control group had the highest feed intake among the treatments (P < 0.01). The groups fed 8% crude fiber from soyhulls (8% SH) with a coarse particle size had the heaviest relative gizzard weight among the treatments (P = 0.045). The groups fed 8% SH had the heaviest small intestine weights regardless of the particle size (P = 0.009). No differences were observed in the relative weights of the ceca. The highest viscosity was observed in the group fed 8% SH with a fine particle size (P < 0.001). The group fed 4% SH with a coarse particle size had the longest duodenal villus (P < 0.001). The shortest jejunal villus height was observed in the group fed 8% CL with a fine particle size (P < 0.001). Ileal villus was highest in the groups fed high CL levels regardless of the particle size (P < 0.001). The highest digestibility of dry matter was observed in the group 4% SH with fine particle (P = 0.017). The group 4% CL with fine particle had the highest digestibility of crude protein (P = 0.033). The highest expression of peptide transporter 1 was observed in the group fed 8% CL with a coarse particle size (P = 0.008). In conclusion, fiber type, particle size, and inclusion levels are important factors in the regulation of intestinal morphology, viscosity, nutrient transporters, and growth performance., Competing Interests: DISCLOSURES There is no conflict of interest., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Large variations in hatching egg incubation temperatures have been previously shown to negatively impact posthatch growth in broiler chickens. The objective was to determine whether small incubation temperature variations owing to incubator tray location (LOC) could alter posthatch female and male broiler growth performance and carcass characteristics. Broiler hatching eggs were obtained from a 40-week-old commercial broiler breeder flock and incubated in trays placed in the bottom (BOT), middle (MID), and top (TOP) thirds of the racks (n = 4 racks per incubator tray LOC) in a single-stage incubator in a commercial hatchery. Chicks hatched from the 3 LOC (n = 720 per LOC) were vent sexed, vaccinated, and separate-sex reared with 12 birds per pen in a floor-pen facility and fed a common corn and soybean meal-based diet for 41 d. At day 41, all birds (n = 720) were processed to determine carcass and carcass part yields and incidence and severity of the meat quality defects wooden breast (WB) and white striping (WS). No LOC × Sex interactions were observed (P > 0.05). Growth performance and incidence and severity of WB and WS were similar among LOC (P > 0.05). However, broilers from BOT trays had heavier tender and breast weights than broilers from warmer MID trays (P < 0.05). Broilers from the BOT trays had higher breast meat yield as a proportion of carcass weight (25.00%) than warmer MID (24.54%) broilers (P < 0.05). However, broilers from warmer MID trays had greater carcass yield than those from cooler TOP trays (P < 0.05). As expected, male broilers had heavier carcass, breast, tender, wings, drumsticks and thighs weights and were more severely affected by WB than females (P < 0.05). Overall, these data indicate that the inherent differences in environmental factors among incubation LOC can impact broiler carcass and breast meat yields., (Copyright © 2020. Published by Elsevier Inc.)

This study evaluated the effects of dietary fiber provided as purified cellulose (Solka-Floc, SF) or soybean hulls (SH) on the growth performance, organ growth, intestinal histomorphology, and nutrient digestibility. A total of 420 one-day-old Cobb male broilers were randomly assigned to 7 dietary treatments and reared to 20 d of age in battery cages (n = 6 replicates per treatment). The control group consisted of a simple corn and soybean-meal-based diet. The 6 fiber treatments had increasing amounts of SF or SH to achieve 4, 6, and 8% crude fiber (CF). Chromium oxide was added as an indigestible marker at 0.3% in all treatment diets from 14 to 20 d for nutrient digestibility analyses. Weights for digestive organs were taken on day 20. Growth performance was measured weekly. Birds fed 4% SH diet had a higher day 20 body weight gain than those fed 8% CF regardless of fiber sources (P = 0.0118). Control and 4% SH groups had the best feed conversion ratio among the treatments at 7, 14, and 20 d (P < 0.05). SH-containing diets had heavier relative gizzard and intestine weights (P < 0.001). Birds fed 8% SH diets had the highest duodenal villi height among the treatments (P < 0.001). Birds fed control and 4% SH had the highest jejunal villi height among the treatments (P < 0.001). Birds fed 4% SF and 4% SH had the highest ileal villi height among the treatments (P < 0.001). Dry matter digestibility was higher in 6% SF than in 8% SH (P = 0.0105). In general, birds fed high-SH diets had higher amino acid digestibility (P < 0.001). In conclusion, the study suggests that fiber type and inclusion level are crucial factors regulating intestinal development, nutrient digestion, and growth performance., (Copyright © 2020. Published by Elsevier Inc.)

Myogenic stem cells (MSC), also known as satellite cells, play a key role in mediating post-hatch skeletal muscle growth in broiler chickens. Information regarding the heterogeneity of MSC populations and myofiber size distributions in different muscles of modern broiler strains of both sexes is scarce. Thus, myofiber cross-sectional area (CSA) and myogenic regulatory factor expression by MSC populations in 2 functionally different muscles (Biceps femoris, BF and Pectoralis major, PM) from both sexes of broilers from 2 strains, Ross 708 x Ross 708 (ROSS; Aviagen Group, Huntsville, AL) and Red Ranger (RR; S&G Poultry, Clanton, AL) was evaluated. Female and male broilers from both strains (n = 80 birds per strain) were reared for 43 d on a common corn and soybean meal-based diet. At 43 d of age, 8 birds per sex per strain (n = 32 total) were euthanized and PM and BF muscle samples from each bird were analyzed using cryohistology, immunofluorescence (IF) staining, and fluorescence microscopy. Cryosections from each muscle from each bird were IF stained to detect Myf-5, MyoD, and Pax7-expressing MSC. The CSA of every fiber in each digital image was measured and MSC populations (Myf-5+, MyoD+, Pax7+, Myf-5+: MyoD+, Myf-5+: Pax7+, MyoD+: Pax7+, and Myf-5+: MyoD+: Pax7+) were enumerated. Myofiber CSA was similar among the 2 strains and 2 sexes (P > 0.05). As expected, mean myofiber CSA was greater in the predominantly fast-twitch PM than the predominantly slow-twitch BF muscle (P = 0.006). At 43 d of age, ROSS broilers had a 32% larger population of Myf-5+: MyoD+: Pax7+ MSC compared with RR (P = 0.04). The heterogeneity of MSC was similar among the sexes. While the total MSC population was larger in the BF muscle compared with the PM (P < 0.05), the Myf-5+ and Pax7+ MSC densities were similar among muscles (P > 0.05). The major differences in myofiber morphometrics and MSC heterogeneity were not among the different broiler strains or sexes but were instead, between the 2 functionally different muscles., (© 2019 Poultry Science Association Inc.)