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A study was conducted to evaluate the effect of dietary 25-hydroxyvitamin D3 (25OHD) on pullet and egg-laying hen growth performance, egg production, and egg quality. Three hundred and ninety 1-day-old Hy-Line W36 pullets were randomly allocated to 3 treatments with 10 replicated cages and 13 birds per cage. Dietary treatments were vitamin D3 at 2,760 IU/kg (D); vitamin D3 at 5,520 IU/kg (DD), and vitamin D3 at 2,760 IU/kg plus 25OHD at 2,760 IU (69 μg)/kg (25D). Body weight and feed intake were recorded at the end of each stage: starter 1 (0–3 wk), starter 2 (4–6 wk), grower (7–12 wk), developer (13–15 wk), prelay (15–17 wk), peaking (18–38 wk), layer 2 (39–48 wk), layer 3 (49–60 wk), layer 4 (61–75 wk), and layer 5 (76–95 wk). Egg production was recorded daily. Egg quality was evaluated every 8 wk starting from 25 wk. There was no difference in growth performance during the rearing period (0–17 wk). In the laying period (18–95 wk), DD showed lower feed intake at layer 2, but higher intake at layer 3 along with lower hen day production (HDP) from 22 to 48 wk compared to the other treatments. During the same period, the DD group laid smaller eggs with higher specific gravity and shell thickness compared with the other treatments or D alone at 40 wk, which may be partly due to the lower body weight. In contrast, 25D had better feed conversion ratio (feed intake per dozen of eggs) at layer 2, and higher overall (22–60 wk) HDP compared with DD. For the egg quality analysis, at 25 and 33 wk, both DD and 25D had higher Haugh unit compared with D. However, 25OHD has no effects on eggshell quality during the entire production period and no beneficial effects on egg production during the later laying period (after 60 wk). In summary, long-term and early supplementation of 25OHD has positive effects on egg production and egg quality, and the beneficial effects were mainly observed during the early laying stage.

The application of micro-CT in small animal research, especially on bone health, has risen exponentially in recent years. However, its application in egg-laying hen bone analysis was still limited. This review introduces the technical aspects of micro-CT in egg-laying hen bone analysis, especially with the medullary bones presented in the cavity. In order to acquate application of micro-CT for laying hen bone research, image acquisition, reconstruction, and analysis settings need to be adjusted properly. The key difference regarding the application of micro-CT in laying hen bone compared to other small animals such as mice and rats was the larger bone size and more complex structures of medullary and trabecular bones. In order to analyze the details of laying hen bone structures, the volume of interest for laying hen should be selected at a region where all 3 bones are present (critical, trabecular, and medullary bone). Owing to the complexity of bone structures, the conventional techniques are not useful to distinguish the trabecular bone and medullary bone in laying hens accurately. In the current review, an automated segmentation algorithm is described to allow researchers to segment bone compartments without human bias. The algorithm is designed according to the morphology difference of medullary bones compared to trabecular and cortical bones. In this procedure, the loosely woven bones were separated by applying dual thresholds. The medullary calcium chunks were separated by opening or closing procedures, where we defined the diameter of medullary chunks being higher than the trabecular bone thickness as a separation trait. The application of micro-CT in laying hen bone health assessment will significantly expand our understanding of chicken bone physiology and osteoporosis, contributing to improve welfare in laying hens.

Egg-laying hens have a unique bone development pattern due to the medullary bone formation and high bone turnover rate. The role of long-term supplementation of an intermediate form of vitamin D3, 25-hydroxyvitamin D3 (25OHD), on skeletal development of pullets and laying hens is not well established. Exploring its effects on layer bone development will help develop a strategy for preventing laying hen osteoporosis. The purpose of this study was to investigate the role of long-term supplementation of 25OHD in layer diets on bone 3-dimensional structural development. A total of 390 1-day-old Hy-Line W36 pullets were randomly allocated to 3 treatments with 10 replicate cages and 13 birds/cage. Dietary treatments were 1) vitamin D3 at 2,760 IU/kg, 2) vitamin D3 at 5,520 IU/kg, and 3) vitamin D3 at 2,760 IU/kg plus 25OHD at 2,760 IU (69 μg)/kg. The level of 25OHD in the serum was tested throughout the whole experimental period (0–95 wk). Bone growth rate (BGR) was measured at 10 wk using a calcein injection technique. Femurs were scanned using Micro-CT for 3D structural analysis, and the whole-body composition analysis was performed using a dual-energy x-ray absorptiometry method at 17, 60, and 95 wk. Dietary supplementation of 25OHD significantly increased 25OHD level in the serum from 0 to 95 wk. During the rearing period (0–17 wk), 25OHD increased BGR, cortical tissue volume, and bone marrow area at 17 wk, simultaneously. 25OHD created more pores in cortical bone, which resulted in a lower cortical bone mineral density (BMD) but without alerting bone mineral content (BMC). This effect allowed more space for mineral deposition in bones during the later egg-laying period. At 60 wk, the 25OHD group had significantly greater BMD, which led to the highest total BMC, cortical volume, and trabecular bone connectivity. At 95 wk, the birds fed 25OHD had significantly higher cortical bone volume and lower porosity. The 25OHD group also had higher total BMD and medullary bone volume but a lower BMC and volume of trabecular bone than vitamin D3 or double dosage vitamin D3 treatment. This indicated that the bone resorption rate was lower in cortical bone than that in trabecular bone in the late laying period. In conclusion, supplementation with dietary 25OHD could stimulate bone growth and increase bone volume in pullets to provide more space for mineral deposition during the laying period with positive effects on laying hen bone quality.

The objective of present study was to investigate the effects of alpha-lipoic acid (ALA) dietary supplementation on the behavior, physiological and oxidant stress indicators, and bone quality in broilers under high stocking density (HSD) stress. A total of one thousand eight hundred 22-day-old Arbor Acres male broiler chicks were randomly allocated to 18 pens (2.97 × 2.03 m) in 3 groups: 14 birds/m2 (NSD, normal stocking density) or 18 birds/m2 (HSD) or 18 birds/m2 plus 300 mg/kg ALA dietary supplement (HSD + ALA, high stocking density + alpha-lipoic acid). Each treatment had 6 replicates, and the experiment lasted 3 wk. The HSD group was significantly lower than the NSD group (P 0.05) in the standing and preening behavior, alkaline phosphatase activity, PTH concentration, H/L ratio, CAT, T-AOC, MDA, SOD, and GSH-Px. These results indicate that the increase of stocking density lowered the bone quality, increased the physiological and oxidative stress indicators, and modified the behavior of broilers, whereas ALA dietary supplementation could counteract the reduction in the performance and physiological responses of broilers under high-density environmental stress.

Broiler breeders are commonly feed restricted using some variation of skip-a-day feeding to prevent excessive body weight (BW) gain and poor flock uniformity that results in lower production levels. However, the level of feed restriction has increased leading to negative effects on broiler breeder welfare. Research needs to be conducted to evaluate alternative feeding programs to diminish the negative impact of restricted feeding on bird welfare. This research examined pullets that were fed soybean hulls (alternate day feeding, ATD) on the off day of a traditional skip-a-day feeding program in comparison to the standard skip-a-day program (SAD). The 2 dietary feeding treatments each had 3 replicate pens of 210 pullets each and were fed from wk 5 to 21 of age. Nitrogen-corrected true metabolizable energy and digestible amino acid coefficients of soybean hulls were determined. Body weight in the ATD feed program was significantly higher (P < 0.001) than the birds on the SAD feed program until 16 wk of age. Feed allocations for the SAD feeding program was increased at 11 wk of age to achieve similar BW prior to photo stimulation. The ATD feed program significantly improved BW uniformity of the birds for weeks 8, 12, 16, and 20. Hens fed on the SAD feed program had a lower mean egg production than the hens fed on the ATD program. There were significant differences on plasma corticosterone concentrations between the feeding days (24 or 48 h after feeding) in both feed programs. There was a shift in the behavior of the birds with significant differences in the feeding, foraging, and comfort behaviors between the feeding programs on the same feed day. Overall, feeding the ATD females soybean hulls on the off feed day improved the BW uniformity and egg production, but further research will be needed to determine potential differences in nutrient utilization or behavior of the pullets that positively impacted this flock performance.

A study was conducted to evaluate the effects of supplementing different levels of lysophospholipid (LPL) to normal or reduced energy diets on growth performance, carcass yield, intestinal morphology, and skeletal development in broilers. A total of 960 one-day-old Cobb 500 male birds were allocated using a 2 × 4 factorial arrangement with 2 energy levels (NE: normal and RE: 100 kcal/kg metabolizable energy reduction) and 4 LPL supplement levels (0, 0.025, 0.050, and 0.075%). Three diet phases were fed throughout the trial: starter (days 0 to 7), grower (days 8 to 21), and finisher (days 22 to 42) phases. Body weight (BW), feed intake (FI), and feed conversion ratio were calculated at the end of each phase. At day 7 and 21, duodenum and jejunum samples were collected for intestinal morphology and claudin-3 expression analyses, and tibia were sampled for bone quality analyses. At day 42, 4 birds per replicate were selected to measure carcass yield. The results showed low metabolizable energy diets impaired bird's growth performance, intestine development, and bone quality. The 0.075% LPL supplement in NE improved BW, BW gain, and FI in the finisher and overall period compared with no LPL supplement in NE (P < 0.05). In RE, the 0.025% LPL supplement significantly improved growth performance compared to the other treatments in RE (P < 0.05). The interactions on processing parameters were detected with LPL supplement in NE diets; 0.025, 0.05, and 0.075% LPL supplements significantly increased pectoral major percentages compared to the one without LPL supplement in NE (P < 0.05). The 0.075% LPL supplement increased dressing percentage (cold carcass weight/live BW) compared with the others (P < 0.05). The intestine morphology results showed LPL had positive effects on intestine development mainly during the early age (day 7) and claudin-3 expression at both day 7 and 21. Furthermore, LPL supplement significantly increased the total Ca and P deposition and positively affected the bone structure development. In summary, dietary LPL supplementation promoted growth performance, carcass yield, intestinal development, intestinal health, and bone quality.