Analytical bone calcium and bone ash from mature laying hens correlates to bone mineral content calculated from quantitative computed tomography scans.

Laying hen skeletal health continues to be an industry priority. Bone ash and bone Ca quantification in laying hen long bones provides valuable information on skeletal health. Unfortunately, these measurements can only be accomplished by sacrificing hens, thus making longitudinal measurements on the same hen impossible. Quantitative computed tomography (QCT), used with a calcium hydroxyapatite phantom, has been used to determine bone density of wings and legs as well as live hens throughout the production cycle by scanning with a calcium hydroxyapatite phantom. QCT has also been used to scan live hens throughout the production cycle. The purpose of this study was to determine how QCT calculated bone mineral content (QCT BMC) corresponds to analytical bone Ca and bone ash. Wing and leg quarters from 72-wk-old W-36 hens were QCT scanned along with a QCT Phantom. After scanning, humeri, femurs, and tibias were cleaned, divided into epiphysis (E) and diaphysis (D), fat extracted, ashed, and digested under nitric acid, and Ca was determined by atomic absorption spectroscopy was used to determine E, D, and whole bone Ca. Four bones/type were used for E and D, while 6 bones/type were used for whole bone measurements. A second set of bones were prepared to determine correlation of BMC to bone ash. QCT scans were analyzed with Mimics software (Materialise NV, Leuven, Belgium) to calculate bone volume and density in Hounsfield units. Utilizing the QCT phantom and bone volume, BMC was calculated for E, D, and whole bone. Data were analyzed with regression analysis and Pearson correlation coefficients were determined. Analytical Ca was correlated to QCT BMC for E (R = 0.84, P < 0.01), D (R = 0.99, P < 0.01), and whole bone (R = 0.97, P < 0.01). Whole bone ash was highly correlated to QCT BMC for femur (N = 47, R = 0.97, P < 0.001), tibia (N = 50, R = 0.94, P < 0.001), and keel (N 50, R = 0.94, P < 0.001). Whole bone ash and QCT BMC values of femur and tibia were not different (P = 0.39 and 0.22 respectively). Based on this information, QCT could provide relative quantitative assessment of total bone mineral in live birds proving useful in long-term studies.

Laying hen production and welfare in enriched colony cages at different stocking densities.

Many laying hen companies in the United States are pledging to move away from intensive conventional cages to extensive housing systems. Enriched colony cages (ECC) are a practical alternative to conventional cage systems. Scientific research is limited on the effects of ECC on hen production and welfare. Therefore, the objective of this study was to evaluate the effects of stocking density on welfare and performance with the overall outcome to provide guidance on stocking density for ECC. At 16 wk, W-36 pullets were placed into 2 commercial ECC housing systems. Within each ECC enclosure, hens were allocated into 1 of 6 stocking densities: A) 465 to 484 cm2/bird, B) 581 to 606 cm2/bird, C) 652 to 677 cm2/bird, D) 754 to 780 cm2/bird, E) 799 to 832 cm2/bird, and F) 923 to 955 cm2/bird. Body weight, egg production, mortality, and Welfare Quality data were collected each 28 d period from 17 to 68 wk. The 6 ECC stocking densities had several transient effects on production measures within age periods with no difference in hen-day production (P > 0.05). Body weight was affected by stocking density (P < 0.05) where hens raised at stocking density A (465 to 484 cm2/bird) weighed at least 25 g less than hens from other stocking densities. Stocking density differences for Welfare Quality assessments were only apparent for feather coverage. Hens raised at stocking density A (465 to 484 cm2) consistently had the poorest (P < 0.05) crop, keel, belly, back, and rump feather coverage. The keel, neck, and back body regions had poorer feather coverage when hens were raised at stocking densities B (581 to 606 cm2) and C (652 to 677 cm2) compared to hens from lower stocking densities (P < 0.05). Therefore, the minimum area per hen housed in commercial ECC systems should be 754 cm2 per bird for greater feather coverage.

Effects of different litter substrates and induced molt on production performance and welfare quality parameters of white Leghorn hens housed in multi-tiered aviary system.

More than 90% of the commercial egg production in the United States is pledged to be in cage-free systems by 2025. Management practices like induced molting and litter area management have come under scrutiny because of the housing system change. The aim of this study was to determine the welfare and production implications of different litter substrates and also evaluate induced molting of hens in a cage-free system. Bovan White hens were housed in a multi-tier aviary system with daily access to open litter area of either Astroturf (AT), wood shavings (SH), or straw (ST) and bare concrete floor (CO) serving as control. At 68 wk of age, molt was induced in half of the hens whereas the other half continued without molting to 116 wk. Production and welfare parameters were measured periodically throughout first and second cycles. Litter substrate did not influence hen-day production and case-weight measurements. However, CO had the lowest total number of eggs produced during the first cycle (P < 0.05). Hen-day percentage was approximately 14% greater in molted hens during the second cycle with egg case weight being heavier in non-molt hens toward the end of second cycle (P < 0.05). The only welfare parameter influenced by litter substrate during the first cycle was a greater crop feather loss in AT than ST at mid-lay (P < 0.05). Keel deformations increased with age irrespective of the litter substrate with 91.5% of palpated hens having keel deformations at the end of first cycle (P < 0.05). Molting did not influence the keel palpation and footpad scores whereas frequency of moderate comb wound was greater in molt hens during molt (P < 0.05). Severe feather loss was seen in non-molt hens during the second cycle (P < 0.05). Litter substrate does not affect production and physical parameters of welfare of hens in a multi-tier aviary system. Additionally, induced molting can be successfully carried out in the multi-tier cage-free system.

Calcium and phosphorus loss from laying hen bones autoclaved for tissue removal.

Standard procedure for most conventional bone assays rely on bones being free of attached muscle or integumentary tissue. Use of an autoclave for bone cleaning is advantageous, as parts may be cleaned afterward by peeling the muscle away as opposed to tediously scrapping muscle tissue from the bone by hand. However, autoclave use for tissue removal has not been validated and published studies typically do not specify the cleaning method. One concern is that autoclave usage could cause mineral leaching out of the bone. The objective was to determine any change in bone mineral content as a result of autoclaving bone samples to remove muscle tissue. Ten pairs of frozen chicken legs were randomly selected and thawed from 72-wk-old W36 hens. Right legs were autoclaved at 121°C for 25 min in individual trays. Left legs were thawed and cleaned by hand. The tibia, meat, and exudate were collected from each leg. Cleaned bones were placed in a soxhlet to extract the fat for 30 h and ashed at 600°C for 8 h. Bone and muscle samples underwent microwave digestion in 10 mL of 70% nitric acid. Digested samples were analyzed for calcium using a flame atomic absorption spectrophotometer. Phosphorus was determined by a colorimetric assay measuring phosphate ion complexes. Statistical analysis was completed by paired t-tests. We found no significant calcium (P = 0.6319) or phosphorus (P = 0.1698) loss from bones autoclaved as compared with bones that were hand cleaned. This study provides evidence that affirms that the use of the autoclave on bones is a suitable method for tissue removal from the leg bones of adult laying hens.

Correlation analysis of cortical geometry of tibia and humerus of white leghorns using clinical quantitative computed tomography and microcomputed tomography scans.

Peripheral quantitative computed tomography (QCT) has been used in poultry bone research in recent years to analyze cortical and cross-sectional geometry. For QCT to be used as a standard research tool for analysis of bones of laying hens (cortical thickness <2 mm), the accuracy of the scans must be assessed. The primary difference between the QCT and micro-computed tomography (micro-CT) is image resolution. Image resolution is inversely related to the pixel size. The aim of the current study was to correlate the cortical parameters measured using clinical CT scans with the measurements from micro-CT, the current gold standard. A total of 15 tibiae and 14 humeri of Lohmann White hens was scanned using clinical CT and micro-CT. Reconstruction of the scans generated images with final voxel resolution of 195 µm for clinical CT scans and 46 µm for micro-CT scans. Cortical and total area were measured using MIMICS® software at proximal, middle, and distal locations of 20 mm sections of humerus diaphysis and 30 mm sections of tibia diaphysis. The total area for proximal and middle locations as well as proximal cortical area measurements for humeri produced strong correlation coefficients (R ≥ 0.70). Moderate strength correlation coefficients (R = 0.40 to 0.60) in humeri were seen in middle and distal cortical areas. Distal total area in humeri displayed a weak correlation coefficient (R ≤ 0.3; P = 0.25). Overall, tibiae demonstrated a weaker correlation. Proximal and middle cortical areas indicated moderate correlation coefficients (R = 0.40 to 0.60), while proximal and middle total areas accompanied by distal cortical and total area displayed weak correlation coefficients (R ≤ 0.3). Only the middle cortical area measurement for tibiae was significant (P = 0.03). These results indicate stronger correlation for humeri measurements among the scans than tibia. Overall, cross-sectional area measurements were only low to moderately correlated between clinical and micro-CT scans.

Influence of commercial laying hen housing systems on the incidence and identification of Salmonella and Campylobacter.

The housing of laying hens is important for social, industrial, and regulatory aspects. Many studies have compared hen housing systems on the research farm, but few have fully examined commercial housing systems and management strategies. The current study compared hens housed in commercial cage-free aviary, conventional cage, and enriched colony cage systems. Environmental and eggshell pool samples were collected from selected cages/segments of the housing systems throughout the production cycle and monitored for Salmonella and Campylobacter prevalence. At 77 wk of age, 120 hens per housing system were examined for Salmonella and Campylobacter colonization in the: adrenal glands, spleen, ceca, follicles, and upper reproductive tract. All isolates detected from environmental swabs, eggshell pools, and tissues were identified for serotype. Two predominant Salmonella were detected in all samples:S.Braenderup andS.Kentucky.Campylobacter coli and C. jejuni were the only Campylobacter detected in the flocks. Across all housing systems, approximately 7% of hens were colonized with Salmonella, whereas >90% were colonized with Campylobacter Salmonella Braenderup was the isolate most frequently detected in environmental swabs (P<0.0001) and housing system impacted Salmonella spp. shedding (P<0.0001).Campylobacter jejuni was the isolate most frequently found in environmental swabs (P<0.01), while housing system impacted the prevalence of C. coli and jejuniin ceca (P<0.0001). The results of this study provide a greater understanding of the impact of hen housing systems on hen health and product safety. Additionally, producers and academia can utilize the findings to make informed decisions on hen housing and management strategies to enhance hen health and food safety.

Effect of rearing environment on bone growth of pullets.

Alternative housing systems for laying hens provide mechanical loading and help reduce bone loss. Moreover, achieving greater peak bone mass during pullet phase can be crucial to prevent fractures in the production period. The aim of this study was to determine the housing system effects on bone quality of pullets. Tibiae and humeri of White Leghorn pullets reared in conventional cages (CCs) and a cage-free aviary (AV) system were studied. At 16 wk, 120 birds at random from each housing system were euthanized. Right and left tibiae and humeri were collected and further analyzed. Cortical bone density and thickness were measured using computed tomography. Periosteal and endosteal dimensions were measured at the fracture site during mechanical testing. At 4, 8, 12, and 16 wk, serum concentrations of osteocalcin and hydroxylysyl pyridinoline were analyzed as markers of bone formation and resorption. Cortical bone density was higher (P<0.05) in humeri of AV pullets, and tibiae were denser (P<0.05) for AV pullets in the distal section of the bone compared to CC pullets. Ash content was higher (P<0.05) in AV humeri with no difference in tibiae ash content. Tibiae and humeri of AV pullets had a thicker cortex than the CC pullets (P<0.05). Additionally, the tibiae and humeri of AV pullets had greater (P<0.05) second moment of areas than the CC pullets. While some bone material properties between groups were different (P<0.05), the differences were so small (<7%) that they likely have no clinical significance. Serum osteocalcin concentrations were not different between the treatments, but hydroxylsyl pyridinoline concentrations were higher in CC pullets at 12 wk compared to the AV pullets and the effect reversed at 16 wk (P<0.05). These findings indicate that tibiae and humeri respond differently to load bearing activities during growth. The improved load bearing capability and stiffness in bones of AV pullets were related to increased cross-sectional geometry.

Microbiological impact of three commercial laying hen housing systems.

Hen housing for commercial egg production continues to be a societal and regulatory concern. Controlled studies have examined various aspects of egg safety, but a comprehensive assessment of commercial hen housing systems in the US has not been conducted. The current study is part of a holistic, multidisciplinary comparison of the diverse aspects of commercial conventional cage, enriched colony cage, and cage-free aviary housing systems and focuses on environmental and egg microbiology. Environmental swabs and eggshell pools were collected from all housing systems during 4 production periods. Total aerobes and coliforms were enumerated, and the prevalence of Salmonella and Campylobacter spp. was determined. Environmental aerobic and coliform counts were highest for aviary drag swabs (7.5 and 4.0 log cfu/mL, respectively) and enriched colony cage scratch pad swabs (6.8 and 3.8 log cfu/mL, respectively). Aviary floor and system wire shell pools had the greatest levels of aerobic contamination for all eggshell pools (4.9 and 4.1 log cfu/mL, respectively). Hens from all housing systems were shedding Salmonella spp. (89-100% of manure belt scraper blade swabs). The dry belt litter removal processes for all housing systems appear to affect Campylobacter spp. detection (0-41% of manure belt scraper blade swabs) considering detection of Campylobacter spp. was much higher for other environmental samples. Aviary forage area drag swabs were 100% contaminated with Campylobacter spp., whereas enriched colony cage scratch pads had a 93% positive rate. There were no differences in pathogen detection in the shell pools from the 3 housing systems. Results indicate egg safety is enhanced when hens in alternative housing systems use nest boxes. Additionally, current outcomes indicate the use of scratch pads in hen housing systems needs to be more thoroughly investigated for effects on hen health and egg safety.

The impact of dietary long-chain polyunsaturated fatty acids on bone and cartilage in gilts and sows.

Dietary long-chain PFO including arachidonic acid (ARA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) are precursors for several inflammatory mediators. The objective of this study was to characterize the effects of dietary PFO supplementation on bone, cartilage, and synovial fluid in 2 ages of pigs. Sows and gilts were fed either control corn/soybean meal based diets or the control diet supplemented with PFO from Gromega (PFO; JBS United, Sheridan, IN). Sows were fed their diets for 24.5 mo and slaughtered at 43 mo while gilts were fed their diets from weaning until slaughter at 111 kg. Cartilage was harvested from both humeroulnar joints of 14 sows (7/treatment) and 16 gilts (8/treatment) within 30 h of slaughter for fatty acid analysis and explant cultures. Synovial fluid was collected from the carpal joints of each pig postmortem. The right fused radius/ulna was collected for computed tomography (CT) analysis. Cortical width and density were determined and trabecular density was measured at the distal radius. Cartilage explants were allocated to 24-well culture plates with 2 discs per well and cultured over 72 h at 37°C in serum-free Dulbecco's modified Eagle's medium: nutrient mixture F-12 (Ham) medium. Six wells/pig were treated with 10 ng/mL of recombinant porcine interleukin-1 (rpIL-1). At 24, 48, and 72 h of culture, media were removed and reserved for analysis of proteoglycans, nitric oxide (NO), and PGE2 concentrations. The CT scans of the radius/ulna from gilts revealed no differences for cortical width and bone density. Sows fed PFO had greater cortical width of the proximal ulna (P < 0.05) and decreased cortical width of the distal radius (P < 0.05). Sows fed PFO had increased DHA (P < 0.01) and a decrease in the omega-6 to omega-3 ratio (P < 0.05) in cartilage. Gilts fed PFO had increased DHA (P < 0.01), C22:1 (P < 0.01), and docosapentaenoic acid (P < 0.01) and a tendency for increased EPA (P = 0.093) concentrations in cartilage. Changes in dietary fatty acids in the gilts and sows had no effect on the variables tested in vitro. Although the PFO diet increased omega-3 incorporation into chondrocytes, the biological significance is unclear since concentrations of ARA were at least 9-fold higher than EPA or DHA. Therefore, if omega-3 fatty acids can mitigate inflammation in joints, the benefit would likely either be the result of systemic changes in inflammatory mediators or higher concentrations in the diet.

Effects of phytase supplementation in mature horses fed alfalfa hay and pelleted concentrate diets.

An experiment was conducted to study P digestibility in mature horses because of the growing environmental concerns regarding P runoff and previous equine research focused mostly on young and growing animals or used ponies as a model. Phytase supplementation of swine and poultry diets can result in greater phytate-P digestibility, leading to a decreased need for inorganic P supplementation and a decrease in P excreted to the environment; this, however, has not been demonstrated in the horse. Six mature Arabian geldings were fed 6 diets consisting of pelleted concentrate and alfalfa hay. The concentrates consisted mainly of soybean hulls, ground corn, wheat midds, broken rice, and beet pulp, and phytase was added to the concentrates accordingly before pelleting. There were 3 diet types: control (concentrate and hay), high P (greater P concentrate and hay), and forage only, and each diet type included 1 phytase-supplemented diet and 1 non-phytase-supplemented diet, resulting in 6 total diets. Phytase supplementation for the forage only diet was accomplished by feeding a nominal amount of concentrate formulated solely as a vehicle for the phytase. Horses had unrestricted access to water throughout the experiment. Using a Latin square design, all horses received all diets over a period of 12 wk. In each week, the new diet was fed for 11 d of diet acclimation, which was followed by a 3-d total collection of feces and urine for each horse. There was no effect (P < 0.05) of phytase supplementation on P output in the urine or feces, resulting in no differences in P apparent digestibility. Analysis of the feed and feces for phytate revealed a 93% average disappearance rate of phytate, indicating that horses are highly capable of degrading phytate and that phytase supplementation was not beneficial. Thus, the results indicate that mature horses are able to maintain a near 0 P balance, with adequate P provided in the diet even as phytate, and increased P intakes above requirement may result in increased potentially detrimental outputs to the environment.

Sodium zeolite a supplementation and its impact on the skeleton of dairy calves.

Twenty calves were placed on study at 3 days of age and were placed according to birth order into one of two groups: SS, which received 0.05% BW sodium zeolite A (SZA) added to their milk replacer, and CO, which received only milk replacer. Blood samples were taken on days 0, 30, and 60 for osteocalcin (OC) and deoxypyridinoline (DPD) analysis. On day 60, the calves were euthanized, and synovial fluid, articular cartilage, and both fused metacarpals were collected for bone quality analyses such as architecture and mechanical properties, mineral composition, and glycosaminoglycan concentration. There were no differences in OC concentrations because of treatment (p = 0.12), and CO calves had lower DPD concentrations than SS calves (p = 0.01), but the OC-to-DPD ratio was not different between treatments (p = 0.98). No differences in bone architecture or mechanical properties were detected. SZA supplementation increased cortical bone (p = 0.0002) and articular cartilage (p = 0.05) aluminum content. Glycosaminoglycan concentrations were not different in synovial fluid or cartilage. Supplementation of SZA appeared to alter the rate of bone turnover without altering bone strength. Aluminum concentrations in the bone and cartilage increased, which may be a concern, although the long-term consequences of such remain to be determined.

Tissue response to a supplement high in aluminum and silicon.

The objective was to determine the effects of sodium zeolite A (SZA) on mineral metabolism and tissue mineral composition in calves. Twenty calves were placed on study at 3 days of age and were placed into one of two groups: SS, which received 0.05% BW SZA added to their milk replacer, and CO, which received only milk replacer. Blood samples were taken on days 0, 30, and 60 for mineral analysis. Urine and feces were collected on day 30 for mineral metabolism, and on day 60, the calves were euthanized, and samples were taken from numerous organs for mineral analyses. Aluminum retention was increased in the SS calves (p = 0.001). Silicon concentrations were increased in the aorta, spleen, lung, muscle, and kidney of the SS calves, and aluminum was increased in all SS tissues (p < 0.05). Calcium concentrations were increased in aorta, liver, muscle, and tendon; phosphorus concentrations were increased in aorta, but decreased in plasma; magnesium concentrations were increased in aorta, heart, kidney, liver, and pancreas, but decreased in plasma; and iron concentrations were decreased in kidney and liver (p < 0.05). The accumulation of tissue aluminum and therefore potential adverse consequences may preclude any benefits of using SZA as a dietary supplement.