Sternal carina damage (keel bone damage, KBD) is an important welfare concern for laying hen producers and backyard flock owners. Quantitative radiographic measures of KBD severity are helpful for researchers who study causes for this problem and the effects of novel interventions. The objectives of the current retrospective secondary analysis study were to develop and test intraobserver repeatability for a standardized protocol to quantify three categories of radiographic KBD using open‐source image analysis software and discrete and continuous variables. The standardized protocol was developed and evaluated using triplicate measurements of 470 keel bone radiographs that had been previously acquired for a prospective study. Intraobserver repeatability was assessed using intra‐class correlation coefficient (ICC) and control chart methods. Based on control chart analyses, measures within the acceptable range of intra‐observer variation using the standardized protocol were the number of complete cranial fractures (97.02%), incomplete cranial fractures (96.38%), complete caudal fractures (95.32%), incomplete caudal fractures (98.09%), cranial calluses (99.79%), and caudal calluses (98.09%); proportion of deviation (POD) measurements (97.87%); and angle of displacement (AOD) measurements (93.60%). Findings can be used as background to support future research studies on KBD in laying hens.

Laying hens are increasingly being kept in backyard flocks and considered family pets; however, diagnostic imaging characteristics of bone for clinically normal backyard hens are currently limited. This prospective, descriptive study was to describe radiographic, computed tomographic, and histologic characteristics of bone for a group of clinically normal laying hens housed in conditions comparable to those of backyard flocks. Sixteen 60‐week‐old Lohmann Brown laying hens were included. Hens were housed in a free‐range unit with outdoor access at a university research and teaching farm. Hens were defined as clinically normal by the farm manager and a veterinary researcher in laying hen behavior and welfare. Findings from the horizontal beam, left lateral, sternal radiographs ( n = 16), postmortem, and whole‐body CT scans ( n = 4) were recorded by a veterinary radiologist and a research technician. Histologic findings for sternal, femoral, and tibiotarsal bone samples ( n = 5) were recorded by a veterinary pathologist. The most frequent radiographic findings for the sternal carina (keel bone) were smoothly marginated concave deviations of the ventral margin and caudal section fractures. Multiple punctate mineral opacities (PMOs) were present in radiographs and CT images for all hens and were involved in the sternal carina and multiple other bones in the axial and appendicular skeleton. No bone abnormalities were identified in any histologic sections where PMOs were radiographically detected. Authors propose that PMOs are normal radiographic and CT findings in the bones of mature, laying hens and may represent temporary calcium reservoirs formed during osteoclastic activities.

Laying hens can experience a progressive increase in bone fragility due to the ongoing mobilization of calcium from bones for eggshell formation. Over time, this escalates their susceptibility to bone fracture, which can reduce their mobility and cause pain. The provision of perches as an exercise opportunity could potentially enhance bone strength, but the timing of exposure to perches during the birds’ development may modulate its impact. The objective of this study was to investigate the enduring impacts of perch provision timing on the musculoskeletal health of laying hens. A total of 812 pullets were kept in different housing conditions (seven pens/treatment, 29 birds/pen) with either continuous access to multi-tier perches from 0 to 40 weeks of age (CP), no access to perches (NP), early access to perches during the rearing phase from 0 to 17 weeks of age (EP), or solely during the laying phase from 17 to 40 weeks of age (LP). At weeks 24, 36, and 40 of age (n = 84 birds/week), three birds per pen were monitored for individual activity level, and blood samples were collected from a separate set of three birds per pen to analyze serum levels of tartrate-resistant acid phosphatase 5b (TRACP-5b) and C-terminal telopeptide of type I collagen (CTX-I) as markers of bone demineralization. At 40 weeks of age, three birds per pen (n = 84) were euthanized for computed tomography scans to obtain tibial bone mineral density (BMD) and cross-sectional area (CSA) with further analysis including muscle deposition, tibial breaking strength, and tibial ash percent. During week 24, hens from CP, EP, and LP pens had the highest overall activity compared to hens from NP pens (p < 0.05) with no differences between treatments for overall activity level during weeks 36 or 40 (p > 0.05). During weeks 24, 36, and 40, hens from CP and LP pens showed greater vertical and less horizontal activity compared to hens from EP and NP pens (p < 0.05). TRACP-5b and CTX-I concentrations did not differ between treatments at week 24 of age (p > 0.05). Hens from CP pens had the lowest TRACP-5b and CTX-I concentrations at 36 weeks of age with EP and LP hens showing intermediate responses and NP hens having the highest concentration (p < 0.05). At 40 weeks of age, CP hens had the lowest TRACP-5b and CTX-I concentrations compared to NP hens (p < 0.05). Total bone CSA did not differ between treatments (p > 0.05), but CP had greater total BMD than NP (p < 0.05) with no differences between EP and LP treatments. CP and LP hens had larger biceps brachii, pectoralis major, and leg muscle groups as well as greater tibial breaking strengths than EP and NP treatments (p < 0.05). CP hens had higher tibial ash percentages compared to EP, LP, and NP (p < 0.05). Our results indicate that providing continuous perch access improves the musculoskeletal health and activity of laying hens at 40 weeks of age compared to no access and that late access to perches has a beneficial impact on activity, muscle deposition, and bone strength.

Laying hens usually have 16 h of light and 8 h of darkness during egg laying, with eggshell formation primarily occurring during darkness when dietary calcium is lacking, leading to bone calcium resorption and osteoporosis. This study examined how interrupting the dark phase affects bone health in 396 Hy-line W36 hens assigned to control (C) or treatment groups (W1 and W2). All hens received 16 h of light and 8 h of darkness daily in different variations of scotophase interruption. Blood samples were taken at weeks 20, 30, 50, and 70, serum calcium was measured during darkness at two timepoints (SRT and END), and bone demineralization markers were examined using enzyme concentrations (TRACP-5b and CTX-I). Across weeks, tibias were CT-scanned for density (mg/cm³) and area (mm²), then used for breakage strength analysis (N) and ash%. No SRT Ca level differences emerged, but C hens had lower END Ca levels compared to W1 and W2 hens across all weeks, while W1 and W2 hens showed no significant differences. C hens displayed higher TRACP-5b and CTX-I concentrations across all weeks compared to W1 and W2 (all p ≤ 0.05). At week 70, C hens had the lowest cortical bone cross-sectional area and mineral density compared to W1 and W2 (all p ≤ 0.05). Tibiotarsi bone breakage strength was lower in C hens compared to W1 and W2. C hens had significantly lower ash% than treatment birds. Interrupting the scotophase period improved overall bone health in Hy-line W36 laying hens.

Longissimus muscles (LM) in sheep are important for animal scientists who study meat quality and translational researchers who study thoracolumbar spinal disease. Computed tomography (CT) is an established technique for characterizing paraspinal muscles in sheep; however, studies reporting reproducibility of CT measures using open‐source software are lacking. The objectives of this prospective pilot study were to develop a standardized protocol for measuring LM area and density in sheep using CT and to determine the reproducibility for measurements. Thoracolumbar CT images were acquired for four sheep at five time points each as part of another study. Six observers applied a standardized CT image analysis protocol to record triplicate transverse area (cm ² ) and water phantom‐corrected mean density (Hounsfield units, HU) values for the left and right LM. Average coefficients of variation (CVs) for 4 of 6 observers were good to excellent ( .05).

Bone fractures and keel bone damage as a result of osteoporotic implications on skeletal health due to high rates of egg production are of significant concern in the egg industry. This study was conducted to evaluate the effects of two aviary housing configurations and associated exercise opportunities on musculoskeletal health in laying hens. Two commercial aviary designs were compared: Big Dutchman NATURA STEP (STEP) and Big Dutchman NATURA 60 (N60). Musculoskeletal assessments were performed at 60 weeks of age (n = 180), where measurements included CT imaging and radiography, muscle dissections, tibial and humeral biomechanical properties, and bone ash percentage. Results indicated that hens in the STEP aviary exhibited higher tibial breaking strength, humeral stiffness, and heavier muscle groups compared to the N60 system. However, rates of new and old fractures, as well as rates of deviation, were more prevalent in STEP hens compared to N60 hens. These results indicate that housing system design influences musculoskeletal health in laying hens.