Changes with age (from 0 to 37 D) in tibiae bone mineralization, chemical composition and structural organization in broiler chickens

Effects of the early incubation temperature on the muscle physiology, meat quality, bone strength and gait score in Ross broilers

1. Modern broiler chickens are among the most efficient livestock in terms of resource requirements and production time. To maintain and improve production efficiency and meat quality and account for welfare problems, early interventions, such as incubation temperature, require investigation2. In this study, Ross 308 broiler eggs were incubated at either 36.5°C or 38.5°C on embryonic days (ED) 4-7. The control group eggs were incubated at a constant temperature of 37.5°C. Musculus pectoralis and musculus gastrocnemius samples were taken for the investigation of muscle physiology, and the tibia was sampled for bone strength analysis from chickens aged 35 and 36 d. In addition, meat quality was analysed and gait scoring was performed.3. The performance of chickens in the 36.5°C group was inferior to those in the other groups up to d 10 post-hatch, but compensatory growth was seen by d 35 of age. Meat quality was unaffected, but significant differences between sexes were observed. Males had lighter meat colour than females. Muscle glycogen and intramuscular fat were unaffected by the incubation temperature, but the muscularis pectoralis and gastrocnemius intramuscular fat contents were greater in males than in females, accompanied by the increased expression of enzymes involved in lipolysis. In the 38.5°C group, males had less bone elasticity than females, and the inverse was observed in the other groups. Gait scores were affected by sex but not incubation temperature.4. The results of this study showed a stronger effect of sex than incubation temperature on broiler muscle physiology, bone strength, performance and meat quality.

Skeletal disorders in laying hens: a systematic review with a focus on non-cage housing systems and hemp-based dietary interventions for bone health

1. The poultry sector is possibly the fastest growing and most flexible of all livestock sectors. At present, the main changes to the table egg production system include the gradual abandonment and closure of all cage-housing systems for laying hens, driven by animal welfare concerns and stricter legislation in many countries. In the future, keeping hens in enriched cage systems may be restricted or phased out in response to evolving animal welfare guidelines and public demand. To meet the welfare and behavioural requirements of the hens, it is desirable to choose housing on litter or housing in aviaries as a substitute for housing in enriched cages.2. The objective of this systematic review was to examine non-cage housing systems and hemp-based dietary interventions in relation to skeletal health in laying hens. This review focussed on the risks associated with alternative housing systems, particularly the increased incidence of bone fractures and the potential of nutritional strategies to mitigate skeletal disorders, including osteoporosis.3. The proportion of hens housed in non-cage alternative housing systems is currently increasing sharply but carries certain risks. One of the most significant concerns is skeletal integrity, as hens in aviaries experience a higher rate of keel bone fractures due to collisions, falls and deviations thought to be related to internal pressure. Numerous studies have shown that the incidence of keel bone damage (i.e. fractures and deviations) was greater in aviaries compared to enriched cage systems.4. Optimal skeletal health can be supported through proper nutrition, which plays a crucial role in bone metabolism. Key nutritional elements, including calcium, vitamins D, E and K, polyunsaturated fatty acids and hemp-based products, have been shown to be beneficial in preventing skeletal disorders and associated fractures due to their specific roles in maintaining bone structure and strength.

Comparison of Hydroxychloride Versus Oxide and Sulfate Sources of Manganese, Zinc, and Copper in Rearing Diets on Pullet Growth, Tibia Traits, and Egg Production and Eggshell Quality in ISA Brown Hens up to 50 Weeks

(1) Background: this study compared hydroxychloride and traditional oxide/sulfate sources of zinc (Zn), manganese (Mn), and copper (Cu) in ISA Brown pullet diets, focusing on growth, tibia strength, egg production, and eggshell quality. (2) Methods: in total, 120 pullets were divided into two groups, each with six replicates of 10 birds, receiving diets with hydroxychloride or oxide/sulfate sources of Mn, Zn, and Cu (65, 50, and 5 mg/kg, respectively) during rearing. At 16 weeks, 18 pullets per group transitioned to individual cages and were fed a standard diet with Mn-oxide, Zn-oxide, and Cu-sulfate until 50 weeks. (3) Results: pullets fed hydroxychloride minerals exhibited a higher feed conversion ratio (p = 0.023) and a trend toward higher average daily feed intake (p = 0.059) compared to those on oxide/sulfate sources during the rearing phase. During the laying phase, while no significant differences were observed in egg production until 24 weeks, hens previously fed hydroxychloride minerals demonstrated increased average daily feed intake and egg weight from 25 to 50 weeks of age (p < 0.05). (4) Conclusions: rearing diets supplemented with hydroxychloride minerals influenced feed intake and efficiency, with carryover effects that enhanced laying-phase performance.

The effect of salidroside on the bone and cartilage properties in broilers

Leg disorders frequently occur in fast-growing broiler chickens, constituting severe health and welfare problems. Although salidroside (SAL) promotes osteogenesis and inhibits apoptosis of chondrocytes in rats, it remains to be determined whether SAL can effectively improve bone growth in broilers. The present study was designed to investigate the effects of dietary SAL supplementation on bone and cartilage characteristics in broiler chickens. Ninety-six Arbor Acres broiler chickens were randomly divided into 4 groups: control, low-dose SAL, medium-dose SAL, and high-dose SAL groups. The broiler chickens were raised until 42 d of age, with samples of bone and cartilage collected for biomechanical testing and bone metabolism index detection. The results showed that SAL significantly increased the vertical external diameter, cross-sectional moment of inertia, and cross-sectional area of the femur and tibia. Additionally, SAL enhanced bone mineral density and strength, as evidenced by significant increases in stiffness, Young's modulus, ultimate load, and fracture work of the femur and tibia. Furthermore, SAL influenced the relative content of phosphate, carbonate, and amide I in cortical bone. Moreover, SAL upregulated the expression of osteogenic genes (Collagen-1, RUNX2, BMP2, and ALP) in a dose-dependent manner and maintained the homeostasis of the extracellular matrix (ECM) of chondrocytes. These results indicated that SAL promoted leg health in broilers by improving bone and cartilage quality and enhancing chondrocyte activity.

Effects of spray-dried plasma on performance, carcass parameters, tibia quality and Newcastle disease vaccine efficacy in broiler chicken fed corn-soy diets with two varying levels of digestible amino acids and AMEn density

This study aimed to determine the effects of spray dried plasma (SDP) on growth performance, carcass traits, tibia quality, and hemagglutination inhibition titers in broilers fed two nutritional strategies with high or low nutrient density. In the study, 816 one-day-old Ross 308 male broiler chickens were divided into a 2 × 2 factorial arrangements consisting of four treatment groups with 12 replicates (17 birds/replicate) based on diets with high nutrient density (HND) or low nutrient density (LND) from d 0 to 42 and receiving either control or 1% SDP diets during d 0 to 10. The results showed that feed intake (FI) and body weight gain (BWG) were increased (P < 0.05) and feed conversion ratio (FCR) was significantly reduced (P = 0.003) for broilers fed HND diets from d 0 to 42. The inclusion of SDP increased the BWG (P < 0.001), FI (P < 0.001), and FCR (P < 0.05) during d 0 to 10 of broiler life but not effect of SDP was observed for the whole 0-42 d period. Carcass yield increased with HND (P < 0.001) and dietary SDP (P = 0.002). However, HND feeding significantly decreased liver (P < 0.001), bursa of Fabricius (P = 0.002), abdominal fat (P < 0.001), proventriculus (P < 0.001) and gizzard weight (P < 0.001), but increased heart weight (P = 0.013), although spleen weight remained unaffected (P > 0.05) on d 42. Tibial bone morphometric and mechanical properties improved (P < 0.05) with SDP supplementation, and bone ash, Ca, and P remained unaffected (P > 0.05) on d 14. With the exception at d 28 (P = 0.037), the antibody titer to ND virus was similar among all treatment groups (P > 0.05) at d 0, 14, and 42. In conclusion, HND diets improve performance of broilers during the whole period and SDP supplementation during starter phase improve performance at this period, but also increased carcass yield, and tibial quality. Therefore, inclusion of SDP in the starter diet could be a beneficial nutritional strategy to improve the health and production of broilers provided feeding strategies using various nutrient densities.

Tibial Damage Caused by T-2 Toxin in Goslings: Bone Dysplasia, Poor Bone Quality, Hindered Chondrocyte Differentiation, and Imbalanced Bone Metabolism

T-2 toxin, the most toxic type A trichothecene, is widely present in grain and animal feed, causing growth retardation and tissue damage in poultry. Geese are more sensitive to T-2 toxin than chickens and ducks. Although T-2 toxin has been reported to cause tibial growth plate (TGP) chondrodysplasia in chickens, tibial damage caused by T-2 toxin in geese has not been fully demonstrated. This study aims to investigate the adverse effects of T-2 toxin on tibial bone development, bone quality, chondrocyte differentiation, and bone metabolism. Here, forty-eight one-day-old male Yangzhou goslings were randomly divided into four groups and daily gavaged with T-2 toxin at concentrations of 0, 0.5, 1.0, and 2.0 mg/kg body weight for 21 days, respectively. The development of gosling body weight and size was determined by weighing and taking body measurements after exposure to different concentrations of T-2 toxin. Changes in tibial development and bone characteristics were determined by radiographic examination, phenotypic measurements, and bone quality and composition analyses. Chondrocyte differentiation in TGP and bone metabolism was characterized by cell morphology, tissue gene-specific expression, and serum marker levels. Results showed that T-2 toxin treatment resulted in a lower weight, volume, length, middle width, and middle circumference of the tibia in a dose-dependent manner (p < 0.05). Moreover, decreased bone-breaking strength, bone mineral density, and contents of ash, Ca, and P in the tibia were observed in T-2 toxin-challenged goslings (p < 0.05). In addition, T-2 toxin not only reduced TGP height (p < 0.05) but also induced TGP chondrocytes to be disorganized with reduced numbers and indistinct borders. As expected, the apoptosis-related genes (CASP9 and CASP3) were significantly up-regulated in chondrocytes challenged by T-2 toxin with a dose dependence, while cell differentiation and maturation-related genes (BMP6, BMP7, SOX9, and RUNX2) were down-regulated (p < 0.05). Considering bone metabolism, T-2 toxin dose-dependently and significantly induced a decreased number of osteoblasts and an increased number of osteoclasts in the tibia, with inhibited patterns of osteogenesis-related genes and enzymes and increased patterns of osteoclast-related genes and enzymes (p < 0.05). Similarly, the serum Ca and P concentrations and parathyroid hormone, calcitonin, and 1, 25-dihydroxycholecalciferol levels decreased under T-2 toxin exposure (p < 0.05). In summary, 2.0 mg/kg T-2 toxin significantly inhibited tibia weight, length, width, and circumference, as well as decreased bone-breaking strength, density, and composition (ash, calcium, and phosphorus) in 21-day-old goslings compared to the control and lower dose groups. Chondrocyte differentiation in TGP was delayed by 2.0 mg/kg T-2 toxin owing to cell apoptosis. In addition, 2.0 mg/kg T-2 toxin promoted bone resorption and inhibited osteogenesis in cellular morphology, gene expression, and hormonal modulation patterns. Thus, T-2 toxin significantly inhibited tibial growth and development with a dose dependence, accompanied by decreased bone geometry parameters and properties, hindered chondrocyte differentiation, and imbalanced bone metabolism.

Comparative Analysis of Morphometric, Densitometric, and Mechanical Properties of Skeletal Locomotor Elements in Three Duck Species (Anatidae: Anatinae)

Ducks (Anatinae) play a crucial role in wetland ecosystems, contributing to seed dispersal and nutrient cycling. This study investigates the skeletal adaptations of three duck species: the Mallard (Anas platyrhynchos), Tufted Duck (Aythya fuligula), and Green-Winged Teal (Anas crecca). The focus is on the tibiotarsus and humerus bones to understand how these adaptations support their different locomotion and habitat preferences. Bone samples n = 6 of deceased ducks (both male and female) from each species (for a total of 36 samples) were cleaned and measured for length, weight, and density. Dual-energy X-ray absorptiometry was used to determine bone mineral density (BMD) and bone mineral content (BMC), and mechanical properties like yield force and stiffness were tested using a 3-point bending test. The results show significant differences in body weight, bone weight, and bone length among the species, with Mallards being the largest and Teals the smallest. Male Teals displayed higher relative bone weight (RBW) in their tibia compared to male Mallards, and male Mallards had significantly lower RBW in the humerus compared to the other species. Female Teals had higher RBW than the other species. Teals also exhibited much lower BMD in the tibia, whereas female Mallards had lower BMD in the humerus. The Seedor index revealed that male Mallards had the highest values in the tibia, while female Teals had the lowest. Mechanical testing indicated that Teals had lower yield force and breaking force in the tibia, whereas Mallards showed the highest stiffness in both bones. Tufted Ducks had intermediate values, consistent with their diving behaviour. These findings suggest that the Mallard's robust bones support its adaptability to various environments and diverse locomotion and foraging strategies. The Teal's lighter and less dense bones facilitate rapid flight and agility in shallow wetlands. The Tufted Duck's intermediate bone characteristics reflect its specialization in diving, requiring a balance of strength and flexibility. Understanding these skeletal differences may provide valuable insights into the evolutionary biology and biomechanics of these species, aiding in their conservation and enhancing our knowledge of their roles in wetland ecosystems. By exploring the functional morphology of these ducks, this study aims to shed light on the biomechanical mechanisms that underpin their locomotion and foraging behaviours.

Postbiotic derived from Bacillus subtilis ACCC 11025 improves growth performance, mortality rate, immunity, and tibia health in broiler chicks

Introduction

The objective of this study was to evaluate the effects of dietary supplementation of postbiotics on growth performance, mortality rate, immunity, small intestinal health, tibia characteristics, and hematological parameters of broiler chicks. he postbiotics were derived from Bacillus subtilis ACCC 11025.

Methods

A total of 480 day-old Arbor acre broiler chicks (52.83 ± 1.38 g) were used in a 42-day study and were randomly allocated into four groups. Each group comprised 6 replicate cages, each containing 20 birds. Dietary treatments were based on a basal diet, supplemented with postbiotics at concentrations of 0.000%, 0.015%, 0.030%, or 0.045%.

Results and discussion

The results demonstrated an improvement in growth performance, antibody titers against avian influenza virus and Newcastle disease virus, serum albumin levels, and serum total protein levels, as well as a reduction in mortality rate among broiler chicks with increasing levels of postbiotic supplementation. The most significant effect were observed in the group receiving 0.015% postbiotics. Furthermore, a dose-dependent enhancement in tibia weight and tibia weight to length ratio, coupled with a reduction in the robusticity index, was noted. The most favorable outcomes for tibia health were observed in the group receiving 0.030% postbiotics. This improvement in tibia health corresponded to a linear increase in serum calcium and inorganic phosphorus contents. In summary, supplementing broiler chicks with 0.015% postbiotics effectively enhances immunity, leading to improved growth performance and reduced mortality rates. Additionally, a postbiotic dose of 0.030% is suitable for optimizing tibia health.

Comparative Impact of Hydroxychloride and Organic Sources of Manganese, Zinc, and Copper in Rearing Diets on Pullet Growth, Tibia Traits, Egg Production, and Eggshell Quality in Lohmann Brown Birds up to 50 Weeks of Age

(1) Background: This study assessed the efficacy of hydroxychloride sources of zinc (Zn), manganese (Mn), and copper (Cu) compared with organic sources in the rearing diets of Lohmann brown pullets, focusing on pullet performance, tibia quality, egg production, and eggshell quality. (2) Methods: A total of 120 birds (six replications and 10 birds each) received diets with Mn, Zn, and Cu from organic or hydroxychloride sources during the rearing phase. After the onset of lay, birds were fed diets containing oxide/sulfate sources up to 50 weeks of age. (3) Results: no significant differences were observed in growth performance and tibia quality during the rearing phase (p > 0.05). From 18 to 24 weeks of age, no carryover effect on egg production performance was observed. However, from 25-50 weeks, pullets fed hydroxychloride sources showed lower feed intake and egg mass compared to the organic group (p < 0.05), whereas egg production and eggshell quality remained similar between groups (p > 0.05). (4) Conclusions: These findings suggest the potential of hydroxychloride sources in rearing diets without compromising overall growth in the pullet phase and feed efficiency in the laying cycle.

Tibia properties in broilers raised on their own commercial diets with different growth rates and sex during a 10-week rearing period

BACKGROUND

Genetic selection applied to broilers results in fast growth and an increase in meat yield. However, this situation causes welfare problems in broilers.

OBJECTIVES

The aim of this study is to determine the weekly changes in the tibia characteristics in broilers raised on their own commercial diets.

METHODS

In the study, 168 (84 female and 84 male) slow-growing (Hubbard-Isa Red JA) and 168 (84 female and 84 male) fast-growing (Ross-308) day-old broiler chicks were used. Six broilers from each genotype and sex group were weighed weekly and slaughtered to determine the tibia properties during the 10-week fattening period.

RESULTS

Fast-growing broilers had higher tibia weight and longer length, diaphysis diameter and medullary canal diameter than those of slow-growing broilers at the same age. In fast-growing genotypes, the cortical index was low only in the 2nd week, and Robusticity and Seedor indices were observed to be better throughout the whole fattening. The ash content of the total tibia in the fast-growing broilers was higher in all of the examined weeks except the 4th week and the 9th week of fattening than that in the slow-growing broilers. Although the amount of ash per unit body weight in the 1st week of fattening was higher in fast-growing broilers, this situation reversed after the 4th week. The level of all minerals examined in total tibia weight is high in fast-growing broilers, and they differed according to the fattening period.

CONCLUSIONS

When comparing tibia characteristics of two different genotypes fed their own commercial diets, the tibia structure was found to be stronger in fast-growing broilers compared to other genotypes at the same age, but slow-growing broilers were more prominent in terms of body weight. It was observed that the mineral density was higher in male broilers, except in the 1st week.

Immature porcine cortical bone mechanical properties and composition change with maturation and displacement rate

Computational models of mature bone have been used to predict fracture; however, analogous study of immature diaphyseal fracture has not been conducted due to sparse experimental mechanical data. A model of immature bone fracture may be used to aid in the differentiation of accidental and non-accidental trauma fractures in young, newly ambulatory children (0-3 years). The objective of this study was to characterize the evolution of tissue-level mechanical behavior, composition, and microstructure of maturing cortical porcine bone with uniaxial tension, Raman spectroscopy, and light microscopy as a function of maturation. We asked: 1) How do the monotonic uniaxial tensile properties change with maturation and displacement rate; 2) How does the composition and microstructure change with maturation; and 3) Is there a correlation between composition and tensile properties with maturation? Elastic modulus (p < 0.001), fracture stress (p < 0.001), and energy absorption (p < 0.014) increased as a function of maturation at the quasistatic rate by 110%, 86%, and 96%, respectively. Fracture stress also increased by 90% with maturation at the faster rate (p = 0.001). Fracture stress increased as a function of increasing displacement rate by 28% (newborn p = 0.048; 1-month p = 0.004; 3-month p= < 0.001), and fracture strain decreased by 68% with increasing displacement rate (newborn p = 0.002; 1-month p = 0.036; 3-month p < 0.001). Carbonate-to-phosphate ratio was positively linearly related to elastic modulus, and fracture stress was positively related to carbonate-to-phosphate ratio and matrix maturation ratio. The results of this study support that immature bone is strain-rate dependent and becomes more brittle at faster rates, contributing to the foundation upon which a computational model can be built to evaluate immature bone fracture.

Different methionine to cysteine supplementation ratios altered bone quality of broilers with or without Eimeria challenge assessed by dual energy X-ray absorptiometry and microtomography

Despite the acknowledged significance of nutrition in bone development, effects of methionine (Met) and cysteine (Cys) on bone quality remain under-researched, particularly during Eimeria challenge. We investigated the effects of different supplemental Met to Cys ratios (MCR) on bone quality of broilers under Eimeria challenge. A total of 720 fourteen-day old Cobb500 broilers were allocated into a 5 × 2 factorial arrangement. Five diets with Met and Cys supplemented at MCR of 100:0, 75:25, 50:50, 25:75, and 0:100 were fed to the birds with or without Eimeria challenge. Body composition was measured by dual energy x-ray absorptiometry, and the femur bone characteristics were assessed by microtomography. Data were analyzed by two-way ANOVA and orthogonal polynomial contrast. The results reaffirmed the detrimental effects of Eimeria challenge on bone quality. On 9 d post inoculation (DPI), significant interaction effects were found for whole body bone mineral content (BMC), lean tissue weight, and body weight (P < 0.05); in the nonchallenged group (NCG), these parameters linearly decreased as MCR decreased (P < 0.05). In the challenged group (CG), body weight and lean tissue weight were unaffected by MCR, and BMC linearly increased as MCR decreased (P < 0.05). For the cortical bone of femoral metaphysis on 6 DPI, bone mineral density (BMD) linearly increased as MCR decreased (P < 0.05). Bone volume to tissue volume ratio (BV/TV) in the CG linearly increased as MCR decreased (P < 0.05). On 9 DPI, BMC and TV linearly increased as MCR decreased (P < 0.05) in the NCG. BMD and BV/TV changed quadratically as MCR decreased (P < 0.05). For the trabecular bone of femoral metaphysis on 9 DPI, BV/TV, and trabecular number linearly increased as MCR decreased (P < 0.05) in the NCG. For the femoral diaphysis, BV, TV, BMC on 6 DPI, and BMD on 9 DPI linearly increased as MCR decreased (P < 0.05). In conclusion, this study showed that both Eimeria challenge and varying supplemental MCR could influence bone quality of broilers.

Effects of monensin sodium and live attenuated oocyst vaccine as coccidiosis management programs on productive performance, bone quality and mineral utilisation in broiler chickens

1. The following study was conducted to evaluate the influence of coccidiosis vaccine-induced metabolic stress on the utilisation of minerals in broilers. The starter, grower and finisher phase diets, including macro- and micro minerals at the recommended levels for the breed standards, were fed to chickens between 1 and 39 d of age.2. A total of 486, one-d-old male broilers were randomly distributed into three coccidiosis management programs (CMP) with six replications each. The CMP comprised: monensin sodium (MON), coccidiosis vaccine (VAC), not treated with MON or VAC (CNT).3. No significant differences between CMP were observed for body weight and weight gain among treatments. When compared to the CNT, the VAC program increased feed intake (P < 0.05) between d 1 to 13 and 14 to 26, while FCR worsened in the latter (P < 0.05) and the former (P = 0.05) periods.4. For birds in the MON and VAC programs, tibia bone length at d 13 and bone diameter at d 39 were both enhanced (P < 0.05). Meat yield characteristics were comparable among the CMP.5. Faeces of VAC birds had a lower (P < 0.05) dry matter and ash content than those in CNT program. CMP had no effect on serum or bone mineral concentrations at any point in time. For minerals, Mg, Na, and K faecal excretion was reduced (P < 0.01) as a result of the VAC program at d 13 with a trend at d 26.6. Compared to the CNT, the VAC program decreased the percentage ratio of drip loss (P = 0.08), water holding capacity (P < 0.01) and cooking loss (P < 0.01) in breast meat.7. Overall, the results showed that current broiler industry practices are capable of meeting the mineral needs of broilers vaccinated against coccidiosis.

Influence of two levels of phytic acid and particle size of oyster shell on the performance, calcium digestibility, gastrointestinal pH, and bone traits in broilers

1. Phytic acid (PA) is an antinutritional factor in poultry diets. The effect of high dietary PA in chicken diets might be exacerbated when the particle size of oyster shell (OS) is too fine. Thus, this study investigated the hypothesis that high PA with fine OS particle size would impair growth in broilers.2. Two hundred and eighty Cobb 500 broilers were assigned to four diets in a 2 × 2 factorial arrangement in a CRD. The factors were PA (low or high) and OS particle size (fine or coarse) in starter, grower and finisher diets. Data collected were performance, Ca digestibility, gastrointestinal pH and bone traits.3. On d 21, high PA increased intake (P < 0.05), gain (P = 0.099) and body weight (BW; P = 0.093) compared to low PA. On d 42, high PA increased BW (P = 0.086) and gain (P = 0.089) compared to low PA. High PA increased intake (P = 0.063), BW (P = 0.054) and gain (P = 0.056) compared to low PA on d 56. High PA improved liveability on d 56 (P < 0.05) compared to low PA. In birds fed coarse OS, crop and ileal pH were reduced (P < 0.05) by high PA on d 28. The OS × PA interaction was observed for ileal pH (P < 0.05) on d 56, where in birds fed coarse OS, low PA increased ileal pH. Fine OS increased crop (P = 0.056) and proventriculus pH (P < 0.05) on d 56. There were no treatment effects on calcium digestibility. In birds fed fine OS, high PA decreased the BS (P < 0.05).4. Overall, the study showed that a combination of high PA and coarse OS particle size improves the production performance of broilers, while low PA and coarse OS improve their bone health.

Developmental changes in tibia and humerus of goose: morphometric, densitometric, and mechanical analysis

The skeletal system of young animals undergoes a series of intensive and rapid changes. In this study, we aimed to verify the hypothesis that geese exhibit a distinct pattern of bone growth compared to gallinaceous species. Specifically, we hypothesised that geese would experience an accelerated growth rate in the humerus bone, which can be attributed to the increased wing mobility facilitated by their rearing in free-range systems. This need for access to both ground and water environments contributes to the unique demands placed on their skeletal development. We focused on evaluating the mechanical properties and geometry of the humerus as the forelimb bone, and the tibia as the hindlimb bone. The 320 geese used in this study were divided into 12 groups according to sex (females and males) and age (0-,1-,3-,6-,8-,12-,14-week-old). To assess bone mechanical properties, a three-point bending test was performed, along with densitometry and morphological measurements. The tibiae of the geese showed the most intensive growth until 6 weeks of age and then stabilised. The wing bones (humerus) showed only slight changes in the first weeks after hatching, and then a rapid growth between the third and sixth week, both in terms of mechanical and morphological properties. This is most likely due to a change in the geese's living environment during this period, i.e., allowing them to leave their enclosures and enter open space, which gives them the opportunity to use their wings, resulting in the rapid growth of the wing bones to support increasing muscle mass in this area. This study increases our understanding of bone growth and development in domesticated birds, specifically waterfowl species, and highlights the importance of rearing methods on the proper bone development and functionality of the entire skeletal system, and thus, on their welfare.

The Functional Roles of Methionine and Arginine in Intestinal and Bone Health of Poultry: Review

This review explores the roles of methionine and arginine in promoting the well-being of poultry, with a specific focus on their impacts on intestinal and bone health. The metabolic pathways of methionine and arginine are elucidated, highlighting their distinct routes within the avian system. Beyond their fundamental importance in protein synthesis, methionine and arginine also exert their functional roles through their antioxidant capacities, immunomodulating effects, and involvement in the synthesis of metabolically important molecules such as S-adenosylmethionine, nitric oxide, and polyamines. These multifaceted actions enable methionine and arginine to influence various aspects of intestinal health such as maintaining the integrity of the intestinal barrier, regulating immune responses, and even influencing the composition of the gut microbiota. Additionally, they could play a pivotal role in promoting bone development and regulating bone remodeling, ultimately fostering optimal bone health. In conclusion, this review provides a comprehensive understanding of the potential roles of methionine and arginine in intestinal and bone health in poultry, thereby contributing to advancing the nutrition, overall health, and productivity of poultry in a sustainable manner.

Reduced bone formation and increased bone resorption drive bone loss in Eimeria infected broilers

Coccidiosis is an economically significant disease in the global poultry industry, but little is known about the mechanisms of bone defects caused by coccidiosis; thus, the study focused on effects of coccidiosis on the bone homeostasis of young broiler chickens. A total of 480 male Cobb500 broilers were randomly allocated into four treatment groups, including an uninfected control consuming diet ad libitum, two infected groups were orally gavaged with two different concentrations of sporulated Eimeria oocysts, and an uninfected pair-fed group fed the same amount of feed as the high Eimeria-infected group consumed. Growth performance and feed intake were recorded, and samples were collected on 6 days post infection. Results indicated that coccidiosis increased systemic oxidative status and elevated immune response in bone marrow, suppressing bone growth rate (P < 0.05) and increasing bone resorption (P < 0.05) which led to lower bone mineral density (P < 0.05) and mineral content (P < 0.05) under Eimeria infection. With the same amount of feed intake, the uninfected pair-fed group showed a distinguished bone formation rate and bone resorption level compared with the Eimeria infected groups. In conclusion, inflammatory immune response and oxidative stress in broilers after Eimeria infection were closely associated with altered bone homeostasis, highlighting the role of inflammation and oxidative stress in broiler bone homeostasis during coccidiosis.

Untargeted metabolomics reveals the effect of rearing systems on bone quality parameters in chickens

The objective of this study was to investigate the effects of rearing systems on the bone quality parameters in chickens using a metabolomics strategy. A total of 419 male one-day-old chicks were randomly allocated to two groups, a floor rearing group (FRG, n = 173) and a cage rearing group (CRG, n = 246). At 6, 8, 10, and 12 weeks of age, all chickens were radiographed by a digital X-ray machine, and body weight was recorded. At 12 weeks of age, 12 birds were selected from each group to obtain tibia and femur, and bone quality parameters of bone mineral density (BMD), mineral content (BMC), breaking strength (BBS), stiffness, Young's modulus (YM), ash content, calcium content, and phosphorus content were determined. An untargeted metabolomics assay was performed to identify changes in the serum metabolic profile (n = 8 birds/group). The results showed that cage-reared chickens had wider tibiae and greater body weight compared with floor-reared chickens. There were no significant differences in BMC or BBS between the two groups (p > 0.05), but BMD, ash content, calcium content, and phosphorus content of the tibia and femur of FRG were significantly higher than those of CRG (p < 0.05). Greater stiffness and YM of the femur were also observed in birds raised in the FRG compared with those raised in the CRG (p < 0.05). Taken together, the results suggest that rearing systems affected bone quality parameters. Furthermore, 148 and 149 differential metabolites were identified in positive and negative ion modes by LC-MS/MS analysis, among which 257 metabolites were significantly correlated with 16 bone quality parameters, including leucine, myristoleic acid, glycocholic acid, and N-phenylacetamide. KEGG analysis indicated that 15 metabolic pathways, including six pathways of amino acid metabolism, two pathways of lipid metabolism, and two pathways of carbohydrate metabolism, were responsible for bone quality. Overall, the present study demonstrated the effect of rearing systems on bone quality parameters, and identified several metabolites and metabolic pathways associated with bone quality parameters.

Effect of the combination of 25-hydroxyvitamin D3 and higher level of calcium and phosphorus in the diets on bone 3D structural development in pullets

Bone issues such as osteoporosis are major concerns for the laying hen industry. A study was conducted to improve bone-health in pullets. A total of 448 one-day-old Hyline W36 pullets were randomly assigned to four treatments (8 rep; 14 birds/rep) until 17 weeks (wks). Dietary treatments were: 1) vitamin D₃ at (2,760 IU/kg) (D), 2) vitamin D₃ (2,760 IU/kg)+62.5 mg 25-(OH)D₃/ton (H25D), 3) vitamin D₃ (2,760 IU/kg) + 62.5 mg 25-(OH)D₃/ton + high Ca&P (H25D + Ca/P), and 4) vitamin D₃ (2,760 IU/kg) + high Ca&P (D + Ca/P). The high calcium (Ca) and phosphorus (P) diet was modified by increasing both high calcium and phosphorus by 30% (2:1) for the first 12 wks and then only increasing P for 12-17 wks to reduce the Ca to P ratio. At 17 wk, growth performance was measured, whole body composition was measured by dual energy x-ray absorptiometry (DEXA), and femur bones were scanned using Micro-computed tomography (Micro-CT) for bone 3D structure analyses. The data were subjected to a one-way ANOVA using the GLM procedure, with means deemed significant at p < 0.05. There was no significant outcome for growth performance or dual energy x-ray absorptiometry parameters. Micro-computed tomography results indicated that the H25D + Ca/P treatment had lower open pore volume space, open porosity, total volume of pore space, and total porosity in the cortical bone compared to the D + Ca/P. It also showed that a higher cortical bone volume/tissue volume (BV/TV) in the H25D + Ca/P than in the D + Ca/P. Furthermore, the H25D + Ca/P treatment had the lowest trabecular pattern factor and structure model index compared to the other treatments, which indicates its beneficial effects on trabecular structural development. Moreover, the H25D + Ca/P had a higher trabecular percentage compared to the D and 25D, which suggests the additional high calcium and phosphorus supplementation on top of 25D increased trabecular content in the cavity. In conclusion, the combination of 25D with higher levels of high calcium and phosphorus could improve cortical bone quality in pullets and showed a beneficial effect on trabecular bone 3D structural development. Thus, combination of a higher bio-active form of vitamin D₃ and higher levels of high calcium and phosphorus could become a potential feeding strategy to improve bone structural integrity and health in pullets.

Research Note: Comparison of two methods to measure broiler tibia morphology

The skeletal integrity of chickens is an important area of research and detailed measures are needed to better understand the influence of experimental manipulation on bone health. The objective of this experiment was to compare 2 methods to measure the superficial tibiotarsus (tibia) morphology of broiler chickens collected in the wet laboratory (WL) or from digital images (DIG). The length, width at 90%, 75%, 50%, 25%, and 10% of the length, proximal and distal head width, medial, lateral, and distal intercondylar groove depth (ID), and proximal head angle were measured on the right and left tibias collected from broilers in 2 experiments (E1, E2). In both experiments, tibias had a greater width at 90% of the length when measured with the WL method compared with the DIG method (P ≤ 0.04), while tibias measured with the DIG method had a greater length, distal ID, and widths at 10%, 25%, 50%, and 75%, of the length compared with the WL method (P < 0.0001). In E1, tibias measured with the DIG method had a greater medial, lateral, and distal ID compared with the WL method (P ≤ 0.04). In E2, compared with the DIG method, tibias measured with the WL method had a greater distal head width and lateral ID, yet a shallower distal ID (P ≤ 0.03). The use of the DIG method provided more precise measures but, due to the limitations of measures from digital images and the opportunity for more accurate measures to be collected with the WL method, the WL method is recommended to measure the superficial morphology of broiler chickens because it was more accessible and practical.

Dentin Matrix Protein 1 Silencing Inhibits Phosphorus Utilization in Primary Cultured Tibial Osteoblasts of Broiler Chicks

Three experiments were carried out in the present study to investigate whether dentin matrix protein 1 (DMP1) was involved in regulating phosphorus (P) metabolic utilization in primary cultured tibial osteoblasts of broiler chicks. Experiment 1 was conducted to select the optimal osteogenic inductive culture medium and the optimal induction time in primary cultured tibial osteoblasts of broiler chicks. In experiment 2, the siRNAs against DMP1 were designed, synthesized and transfected into primary cultured tibial osteoblasts of broiler chicks, and then the inhibitory efficiencies of siRNAs against DMP1 were determined, and the most efficacious siRNA was selected to be used for the DMP1 silencing. In experiment 3, with or without siRNA against DMP1, primary cultured tibial osteoblasts of broiler chicks were treated with the medium supplemented with 0.0, 1.0 or 2.0 mmol/L of P as NaH₂PO₄ for 12 days. The P metabolic utilization-related parameters were measured. The results showed that the osteogenic induced medium 2 and 12 days of the optimal induction time were selected; Among the designed siRNAs, the si340 was the most effective (P < 0.05) in inhibiting the DMP1 expression; DMP1 silencing decreased (P < 0.05) the expressions of DMP1 mRNA and protein, P retention rate, mineralization formation, alkaline phosphatase activity and bone gla-protein content in tibial osteoblasts at all of added P levels. It is concluded that DMP1 silencing inhibited P utilization, and thus DMP1 was involved in regulating P metabolic utilization in primary cultured tibial osteoblasts of broiler chicks, which provides a novel insight into the regulation of the P utilization in the bone of broilers, and will contribute to develop feasible strategies to improve the bone P utilization efficiency of broilers so as to decrease its excretion.

Effects of pen enrichment on leg health of fast and slower-growing broiler chickens

Pen enrichment for broiler chickens is one of the potential strategies to stimulate locomotion and consequently contribute to better leg health and welfare. This study was designed to evaluate effects of using a plethora of pen enrichments (barrier perches, angular ramps, horizontal platforms, large distance between feed and water and providing live Black Soldier fly larvae in a dustbathing area) on tibia characteristics, locomotion, leg health and home pen behaviour of fast and slower-growing broiler chickens. The experiment was set up as a 2 x 2 factorial arrangement with a total of 840 male broiler chickens in a complete randomized design (7 pens per treatment and 30 chickens per pen) with the following treatments: 1) pen enrichment (enriched pen or non-enriched pen); 2) broiler strain (fast-growing Ross 308 or slower-growing Hubbard JA 757). Home pen behaviour and use of enrichment were observed. At approximately 1400 and 2200 g body weight, two chickens per pen were randomly selected and slaughtered, to investigate tibia morphological, biophysical and mechanical characteristics and leg health. Pen enrichment positively affected tibia biophysical characteristics, e.g., osseous volume (Δ = 1.8 cm3, P = 0.003), total volume (Δ = 1.4 cm3, P = 0.03) and volume fraction (Δ = 0.02%, P = 0.002), in both fast and slower-growing chickens, suggesting that pen enrichment particularly affects ossification and mineralization mechanisms. Accordingly, locomotion and active behaviours were positively influenced by pen enrichment. However, pen enrichment resulted in lower body weight gain in both strains, which might be due to higher activity or lower feed intake as a result of difficulties of crossing the barrier perches. Regarding the strain, slower-growing chickens showed consistently more advanced tibia characteristics and more active behaviour than fast-growing chickens. It can be concluded that pen enrichment may lead to more activity and better bone development in both fast and slower-growing chickens.

Effects of organic macro and trace minerals in fast and slower growing broiler breeders' diet on offspring growth performance and tibia characteristics

This study was designed to evaluate effects of source of macro and trace minerals (inorganic vs. organic) in fast and slower growing broiler breeders' diets on egg and hatchling mineral content and on offspring tibia morphological, biophysical, and mechanical characteristics. After 10 wk feeding the breeders (at 30 wk of age), eggs were collected and incubated. Eggs and hatchlings were analysed on mineral content. Male chickens were assigned to 32 pens with 12 chickens per pen. At approximately 1,700 and 2,600 gram BW, three chickens per pen were slaughtered. Tibia characteristics were determined. Organic minerals in the broiler breeder diet resulted in higher Fe and Se concentration in the egg and in higher Se concentration in the hatchling. Despite effects of mineral source on mineral concentration in the eggs and hatchlings were limited, organic minerals in the slower-growing broiler breeder diet resulted in higher offspring BW (d 42, Δ = 115 g; P = 0.03) and advanced tibia development (higher thickness (∆ = 0.38 cm; P < 0.001), osseous volume (∆ = 5.1 cm³; P = 0.01), and mineral density (Δ = 0.13 g/cm³; P = 0.03) at 2,600 g BW), but this was not observed in fast-growing chickens. This suggests that 1) the difference in feed intake of the breeders between strains might affect offspring performance, which might indicate that current slower-growing breeder diets might be suboptimal in minerals or that transgenerational mineral availability in slower growing chickens appears to be more effective on bone development, which might be related to time available for bone development. 2) transgenerational mineral availability in offspring appears to play a role via other mechanisms than via absolute mineral concentrations.

Regulation of bone phosphorus retention and bone development possibly by related hormones and local bone-derived regulators in broiler chicks

BACKGROUND

Phosphorus is essential for bone mineralization in broilers, however, the underlying mechanisms remain unclear. We aimed to investigate whether bone phosphorus retention and bone development might be regulated by related hormones and local bone-derived regulators in broilers.

METHODS

Broilers were fed diets containing different levels of non-phytate phosphorus (NPP) 0.15%, 0.25%, 0.35%, 0.45% and 0.55% or 0.15%, 0.22%, 0.29%, 0.36% and 0.43% from 1 to 21 or 22 to 42 days of age. Serum and tibia samples were collected for determinations of bone phosphorus retention and bone development parameters, related hormones and local bone-derived regulators of broiler chickens on d 14, 28 and 42, respectively.

RESULTS

Tibia ash phosphorus, total phosphorus accumulation in tibia ash (TP_TA), bone mineral concentration (BMC), bone mineral density (BMD), bone breaking strength (BBS), and ash on d 14, 28 or 42, serum 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) on d 28 and 42, mRNA expressions of tibia fibroblast growth factor 23 (FGF23) and dentin matrix protein 1 (DMP1) on d 14 and 28 increased linearly or quadratically (P < 0.05), while serum parathyroid hormone (PTH) on d 28, tibia alkaline phosphatase (ALP) on d 14, 28 and 42, bone gal protein (BGP) on d 14, and mRNA expression of tibia phosphate-regulating gene with homologies to endopeptidases on the X chromosome (PHEX) on d 14 and 28 decreased linearly or quadratically (P < 0.04) as dietary NPP level increased. TP_TA, BMC, BMD, and ash on d 28 and 42, BBS on d 28, and ash phosphorus on d 42 were positively correlated (r = 0.389 to 0.486, P < 0.03) with serum 1,25(OH)₂D₃. All of the above parameters were positively correlated (r = 0.380 to 0.689, P < 0.05) with tibia DMP1 mRNA expression on d 14, 28 and 42, but negatively correlated (r = - 0.609 to - 0.538, P < 0.02) with serum PTH on d 28, tibia ALP on d 14, 28 and 42, and BGP on d 14. TP_TA, BMC and ash on d 14 and BMD on d 28 were negatively correlated (r = - 0.397 to - 0.362, P < 0.03) with tibia PHEX mRNA expression, and BMD on d 28 was positively correlated (r = 0.384, P = 0.04) with tibia FGF23 mRNA expression.

CONCLUSIONS

These results suggested that bone phosphorus retention and bone development parameters had moderate to strong correlations with serum PTH and 1,25(OH)₂D₃ and tibia DMP1, PHEX, FGF23, ALP and BGP in broilers during the whole growth period, and thus they might be partly regulated by these related hormones and local bone-derived regulators.

Endoplasmic reticulum stress, chondrocyte apoptosis and oxidative stress in cartilage of broilers affected by spontaneous femoral head necrosis

With the promotion of the intensive breeding model, the incidence of leg diseases has risen in fast-growing commercial broilers with higher body weight, seriously affecting their feed efficiency and causing animal welfare problems. Femoral head necrosis (FHN) is the most common leg disease in broilers. Previous studies reported that hormone-induced FHN is related to endoplasmic reticulum (ER) stress, apoptosis, and oxidative stress, but no detailed study has been conducted in broilers with spontaneous FHN. In the study, the articular cartilage of 5-wk-old Ross 308 broilers with spontaneous FHN was used to investigate the pathogenesis of the disease. According to the degree of femoral head injury, the birds participating in the experiment were divided into 3 groups, namely a control group, femoral head separation group and femoral head separation with growth plate lacerations group. The morphological changes in articular cartilage were observed by hematoxylin and eosin, toluidine blue, alcian blue and safranine O-solid green staining, and the expressions of genes related to cartilage homeostasis, ER stress, autophagy, apoptosis and oxidative stress was detected using Real-Time Quantitative PCR. In the results, the expression of aggrecan and collagen-2 mRNA levels decreased in the articular cartilage of spontaneous FHN broilers, and the same changes were observed in the tissue staining results, indicating the disordered nature of articular cartilage homeostasis. At the same time, FHN in broilers causes ER stress in articular chondrocytes and regulates oxidative stress by activating the nuclear factor erythroid 2-related factor 2/antioxidant response element pathway through protein kinase RNA-like ER kinase. Autophagy can be activated through the protein kinase RNA-like ER kinase-activating transcription factor-4 pathway, and apoptosis can even be activated through CCAAT-enhancer-binding protein homologous protein. Therefore, the secretory activity of articular chondrocytes in spontaneous FHN broilers is negatively affected, which leads to the disorder of cartilage homeostasis and results in FHN due to ER-stress-mediated chondrocyte apoptosis and oxidative stress.

A novel consensus bacterial 6-phytase variant totally replaced supplemental inorganic phosphate from one day of age in both male and female broilers

1. This study tested the capacity of a novel consensus bacterial 6-phytase variant (PhyG) to totally replace dietary supplemental inorganic phosphate (Pi) in broilers from one day of age, using a phased dosing strategy for the phytase and a phased reduction in phytate content of the diet. A 2x2 factorial arrangement including two treatments and two genders was used.2. A total of 1,248, one-day-old Ross 308 broilers were assigned to 24 floor pens (52 birds/pen). Two treatments included: 1) a positive control diet (PC) based on mixed grains and oilseed meals, containing inorganic phosphorus (Pi) from monocalcium phosphate (MCP) and 2,000 XU/kg xylanase, and; 2) an inorganic P free (IPF) diet reformulated without Pi, reduced in Ca (-2.0 g/kg) vs. PC and supplemented with PhyG at 3,000 FTU/kg in starter (d 0 to 11, 3.4 g/kg phytate-P (PP)), 2,000 FTU/kg in grower (d 11 to 22, 3.3 g/kg PP), and 1,000 FTU/kg in finisher 1 (d 22 to d 35, 2.9 g/kg PP) and finisher 2 (d 35 to d 42, 2.8 g/kg PP) phase. Each treatment was assigned to 12 pens, with six pens containing males and six containing females. Tibia samples were collected on d 11, 22 and 42 from two birds per pen.3. The IPF treatment maintained or improved ADG, ADFI and FCR compared to PC in all feed phases. IPF increased BW at 42 days of age by 3.97% (P<0.01) and ADG from d 0 to 42 by 4.10% (P<0.01), and reduced corresponding FCR by 1.5 points (P<0.05), respectively, vs. PC. Males exhibited higher BW, ADG and ADFI than females from 11 d of age onwards (P<0.05). An interaction (P<0.05) between treatment and gender was observed for FCR (d 0 to 22, d 0 to 42) and FCRc (body weight corrected FCR, d 0 to 42), whereby IPF treatment reduced (P<0.05) FCR vs. PC in males but not in females. Tibia ash from birds fed IPF was equivalent to PC at 11, 22 and 42 d of age and did not differ between males and females.4.The data demonstrated that the phytase, when applied in a phased dosing-regimen to broiler diets with a graded reduction in phytate-P content, was effective in totally replacing Pi during all growth phases, as determined by performance and tibia ash from both males and females.

Changes of lipid and bone metabolism in broilers with spontaneous femoral head necrosis

Blood biochemistry and bone metabolism were evaluated to investigate the etiology and mechanism of spontaneous femoral head necrosis (FHN) in broilers. According to the femoral head score of the fourth, fifth, and sixth week old FHN-affected broilers, they were divided into 3 groups, namely Normal group, femoral head separation group, and femoral head separation with growth plate lacerations group, and then carried out a comparative study. The results showed that the liver function (alanine aminotransferase and aspartate aminotransferase) and lipid metabolism (high-density lipoprotein and triglyceride) levels of broilers with spontaneous FHN were significant changed compared with the normal group. At the same time, accumulation of lipid droplets appeared in the liver, which illustrated that the occurrence of FHN may be related to lipid metabolism disorders. Tibia and femur parameters showed significant changes in bone mineral density and bone strength. The distribution of chondrocytes in the articular cartilage of broilers with FHN was irregular and vacuoles appeared, which indicated that cartilage homeostasis was destroyed. TUNEL staining showed that the apoptosis rate of articular chondrocytes in broilers with FHN in 6-week-old was significantly higher than that of normal broilers. Meanwhile, the bone markers (bone glaprotein and bone-specific alkaline phosphatase) changed significantly, indicating that the articular chondrocyte apoptosis and bone metabolism disorder may occur in FHN-affected birds. Therefore, FHN in broilers may be caused by dyslipidemia and abnormal bone metabolism.

Anatomical Variation of Human Bone Bioapatite Crystallography

This systematic investigation of bioapatite, the mineral component of human bone, aims to characterize its crystallographic state, including lattice parameters and average crystallite size, and correlate these values with respect to anatomical position (bone function), physicality, and bone chemical composition. In sample sets of buried bone from three different human adult skeletons, anatomical variation of crystallographic parameters and correlation to chemical composition were indeed observed. In general, the observed bioapatite a unit-cell edge-length among all analyzed human bones in this study was larger by 0.1–0.2% compared to that of stoichiometric hydroxylapatite (HAp), and substantially larger than that of fluorapatite (FAp). Across all analyzed samples, the a (=b) lattice parameter (unit cell edge-length) varies more than does the c lattice parameter. Average crystallite size (average coherent diffracting domain size) in the c-direction was equal to approximately 25 nm, ranging among the analyzed 18 bone samples from about 20–32 nm, and varying more than crystallite size in the a,b-direction (~8–10 nm). Neither lattice parameters nor average bioapatite crystallite sizes appeared to be correlated with bone mechanical function. The relative chemical composition of the bone material, however, was shown to correlate with the a (=b) lattice parameter. To our knowledge, this research provides, for the first time, the systematic study of the crystallographic parameters of human bone bioapatite in the context of anatomical position, physical constitution, and bone chemical composition using X-ray powder diffraction (XRPD) and Fourier transform infrared spectroscopy (FTIR).

RNA-seq reveals downregulated osteochondral genes potentially related to tibia bacterial chondronecrosis with osteomyelitis in broilers

Background

Bacterial chondronecrosis with osteomyelitis (BCO) develops in the growth plate (GP) of the proximal femur and tibia and is initiated by damage to the less mineralized chondrocytes followed by colonization of opportunistic bacteria. This condition affects approximately 1% of all birds housed, being considered one of the major causes of lameness in fast growing broilers. Although several studies have been previously performed aiming to understand its pathogenesis, the molecular mechanisms involved with BCO remains to be elucidated. Therefore, this study aimed to generate a profile of global differential gene expression involved with BCO in the tibia of commercial broilers, through RNA sequencing analysis to identity genes and molecular pathways involved with BCO in chickens.

Results

Our data showed 192 differentially expressed (DE) genes: 63 upregulated and 129 downregulated in the GP of the tibia proximal epiphysis of BCO-affected broilers. Using all DE genes, six Biological Processes (BP) were associated with bone development (connective tissue development, cartilage development, skeletal system development, organ morphogenesis, system development and skeletal system morphogenesis). The analyses of the upregulated genes did not indicate any significant BP (FDR < 0.05). However, with the downregulated genes, the same BP were identified when using all DE genes in the analysis, with a total of 26 coding genes explaining BCO in the tibia: ACAN, ALDH1A2, CDH7, CHAD, CHADL, COL11A1, COMP, CSGALNACT1, CYR61, FRZB, GAL3ST1, HAPLN1, IHH, KIF26B, LECT1, LPPR1, PDE6B, RBP4A, SERINC5, SFRP1, SOX8, SOX9, TENM2, THBS1, UCHL1 and WFIKKN2. In addition, seven transcription factors were also associated to BCO: NFATC2, MAFB, HIF1A-ARNT, EWSR1-FLI1, NFIC, TCF3 and NF-KAPPAB.

Conclusions

Our data show that osteochondral downregulated genes are potential molecular causes of BCO in broilers, and the bacterial process seems to be, in fact, a secondary condition. Sixteen genes responsible for bone and cartilage formation were downregulated in BCO-affected broilers being strong candidate genes to trigger this disorder.