A comparison between cholecalciferol and 25-OH-cholecalciferol on performance and eggshell quality of hens fed different levels of calcium and phosphorus

Comparative effects of zinc hydroxy chloride, zinc sulfate, and zinc-methionine on egg quality and quantity traits in laying hens

The aim of this experiment was to evaluate the effect of different levels of zinc supplements on egg quality and quantity traits as well as egg enrichment with zinc in laying hens from 40 to 50 weeks of age. A total of 240 Hy-line laying hens were distributed among eight treatments and five replications (six birds per replication). The control group received no zinc diet, while the other treatments were supplemented with varying levels of zinc sulfate (80, 120, and 160 mg/kg) or zinc hydroxy chloride (50, 75, and 100 mg/kg). An additional group of zinc-methionine supplement at 124 mg/kg was also included. Results showed that different levels of zinc supplementation caused a significant improvement in eggshell resistance, eggshell percentage, feed conversion ratio, and Haugh unit compared to the control group. Adding organic and hydroxy sources of zinc significantly increased zinc contents in egg yolk, tibia bone, and blood. In addition, the treatments containing zinc supplements caused an increase in the antibody level against the Newcastle disease compared to the control (P < 0.05). Different levels and sources of zinc had no significant effect on eggshell thickness, specific gravity, and egg mass. Results showed that adding zinc in hydroxy chloride form at 100 mg/kg could improve performance indices, safety, and egg enrichment with zinc.

Dietary 25-hydroxyvitamin D improves productive performance and intestinal health of laying hens under Escherichia coli lipopolysaccharide challenge

The effect of 25-hydroxyvitamin D (25OHD) on the immune response of laying hens is not well elucidated. This study investigated the effects of 25OHD on egg production, egg quality, immune response, and intestinal health of laying hens challenged with Escherichia coli lipopolysaccharide (LPS). One hundred and sixty laying hens at 45 wk of age were randomly divided into 4 dietary treatments with 10 replicates of 4 birds. Hens were fed the corn-soybean based diets contained either 0 or 80 µg/kg 25OHD for 8 wks. At wk of 53 wk, birds of each dietary treatment were injected into the abdomen with 1.5 mg/kg body weight of either LPS or saline a day at 24-h intervals for continuous 7 d. LPS injection significantly decreased (P_LPS < 0.05) egg laying rate, feed intake and feed efficiency; while the supplementation of 25OHD increased (P_Interaction < 0.05) egg laying rate, feed efficiency and decreased (P_Interaction < 0.05) the broken egg rate in layers under LPS injection. LPS challenge decreased (P_LPS < 0.05) eggshell strength, eggshell thickness, albumen height and Haugh unit, while dietary 25OHD supplementation increased eggshell strength and eggshell thickness (P_25OHD < 0.05). The serum proinflammatory factors [tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6)], endotoxin and diamine oxidase (DAO) levels were higher in layers under LPS challenge (P_LPS < 0.05); whereas the dietary addition of 25OHD were shown to decrease (P_25OHD < 0.05) serum IL-1β and IL-6 concentration irrespective of LPS challenge and led to a higher serum 25OHD level and a reduction in endotoxin concentration in layers under LPS challenge (P_Interaction < 0.05). The layers under LPS challenge had higher crypt depth and lower villus height/crypt depth (V/C) ratio in duodenum and jejunum (P_LPS < 0.05), while feeding 25OHD were shown to have decreasing effect on crypt depth and increasing effect V/C ratio in layers under LPS challenge (P_Interaction < 0.05). Layers under LPS challenge had lower mRNA expression of intestinal barrier associated proteins (claudin-1 and mucin-1) (P_LPS < 0.05), while the addition of 25OHD up-regulated claudin-1 and mucin-1 expression (P_interaction < 0.05). Lower antioxidant enzymes activities, including superoxide dismutase (SOD), catalase (CAT), total antioxidant capacity (T-AOC), glutathione peroxidase (GPx) and higher malondialdehyde (MDA) content in jejunum were found in layers challenged with LPS (P_25OHD < 0.05). The effect of 25OHD reversed the effect of LPS on SOD, T-AOC, and MDA content (P_Interaction< 0.05). These results suggest that supplementing 80 µg/kg 25OHD in diets may elevate laying performance and egg quality through the improvement of intestinal barrier function, antioxidant capacity, and decreased the proinflammatory cytokines levels in laying hens with Escherichia coli LPS challenge.

A Comparison between Vitamin D3 and 25-Hydroxyvitamin D3 on Laying Performance, Eggshell Quality and Ultrastructure, and Plasma Calcium Levels in Late Period Laying Hens

The objective of this study was to compare high supplementary doses (125 µg/kg) of vitamin D3 (VD3) or 25-hydroxyvitamin D3 (25-OHD3) with commercial supplementary doses (62.5 µg/kg) of VD3 on laying performance, eggshell quality and ultrastructure, and plasma calcium levels in late period laying hens. A total of 1512 Roman Gray (60-week-old) laying hens were allotted into three treatments with 12 replicates and 42 birds in each replicate. During the 12-week trial period, the layers were fed a basal diet supplemented with different doses of VD3 or 25-OHD3 (62.5 µg/kg VD3 in control group, CON; 125 µg/kg VD3 in high level VD3 group, VD3; 125 µg/kg 25-OHD3 in high level 25-OHD3 group, 25-OHD3). The results showed that high supplementary doses of VD3 or 25-OHD3 increased laying rate (p < 0.05). Moreover, the layers fed high doses of VD3 or 25-OHD3 diets had decreased unqualified egg rate and mortality (p < 0.05). High supplementary doses of VD3 or 25-OHD3 increased eggshell strength and eggshell thickness (p < 0.05). From observation in eggshell ultrastructure, high doses of VD3 or 25-OHD3 diets increased the palisade layer thickness and mammillary knob density (p < 0.05). Furthermore, high doses of VD3 or 25-OHD3 diets increased the calcium levels in plasma (p < 0.05). In summary, compared with 62.5 µg/kg doses of VD3, supplementary 125 µg/kg doses of VD3 or 25-OHD3 improved the laying performance, eggshell quality, and plasma calcium levels in late period laying hens. Additionally, there was an equal effect on laying performance and eggshell quality in the hens fed dietary 125 µg/kg doses of VD3 or 25-OHD3.

The importance of nutrition in alleviating high stocking density stress in poultry

In recent decades, the number of birds reared per unit area has dramatically spiked to increase profitability in egg and meat production. However, nowadays, the increase in sensitivity to animal welfare and consumer demands brings along with it a raised interest in stocking density. Stocking density is defined either as the number of animals or body weight per unit area or as the area per animal. High stocking density, which is a stress factor, can be defined as an increase in the number of animals per unit area or a decrease in the area per animal. Stress caused by high stocking density negatively affects the bird’s physiology and performance as well as the quality of the product obtained. The ideal stocking density should be 9 laying hens, 35 kilogrammes for broilers, and 45 quails per square metre. Otherwise, one will observe stress indicators in birds reared in more than the recommended stocking density per unit area and, consequently, a decrease in bird growth, egg production, feed efficiency, and egg or meat quality. Apart from increasing the concentrations of amino acids such as lysine, methionine, tryptophan and arginine, minerals such as selenium and chromium, and vitamins such as C and E in the diet, the addition of additives such as probiotics, humates, phytophenol compounds, and propolis is also effective in reducing or eliminating these negative effects caused by high stocking density. As a result, regulations in the nutrition of animals are effective in reducing/preventing such negative effects, thus improving animal welfare and ensuring the maintenance of optimum yield.

Effect of 25-hydroxyvitamin D and essential oil complex on productive performance, egg quality, and uterus antioxidant capacity of laying hens

This study was conducted to determine the effect of 25-hydroxyvitamin D (HDV) and essential oils (EO) on the uterus antioxidant capacity, egg quality, and eggshell ultrastructure in laying hens. A total of 400 48-wk-old Lohmann laying hens were randomly allocated into 2 groups and fed a basal diet (control) or a basal diet supplemented with a combination of 69 μg/kg HDV and EO (including 200 mg/kg thymol and 50 mg/kg carvacrol) for 12 wk. There are 10 replicates of 20 hens each. Compared with the control, dietary HDV+EO supplementation improved (P < 0.05) egg production rate, feed efficiency, eggshell thickness and strength, and decreased (P < 0.05) the translucent egg score. Ultrastructural changes indicated that dietary HDV+EO supplementation decreased (P < 0.05) mammillary knob width, mammillary thickness and the proportion of mammillary thickness, and increased (P < 0.05) the proportion of effective thickness and total thickness of the eggshells compared with the control. Supplementation with HDV+EO complex led to higher serum HDV concentration and increased antioxidant capacity in the uterus, indicated by higher (P < 0.05) antioxidant enzyme activities (catalase [CAT], total antioxidant capacity [T-AOC], and glutathione S-transferases [GST]) and lower malondialdehyde (MDA) content. Therefore, dietary HDV and EO complex (including thymol and carvacrol) supplementation can improve the productive performance and the eggshell quality in laying hens, and the improving effect on eggshell quality may through enhancing eggshell ultrastructure and antioxidant capacity of uterus.

Use of 25-hydroxyvitamin D3 in diets for sows: A review

Dietary supplementation with 25-hydroxyvitamin D₃ (25OHD₃), as an alternative source of vitamin D, is becoming increasingly popular due to its commercialization and more efficient absorbability. The addition of 25OHD₃ rather than its precursor vitamin D₃ can circumvent the 25-hydroxylation reaction in the liver, indicating that supplementation of 25OHD₃ can rapidly improve the circulating vitamin D status of animals. Emerging experiments have reported that maternal 25OHD₃ supplementation could increase sow performances and birth outcomes and promote circulating vitamin D status of sows and their offspring. Increased milk fat content was observed in many experiments; however, others demonstrated that adding 25OHD₃ to lactating sow diets increased the contents of milk protein and lactose. Although an inconsistency between the results of different experiments exists, these studies suggested that maternal 25OHD₃ supplementation could alter milk composition via its effects on the mammary gland. Previous studies have demonstrated that adding 25OHD₃ to sow diets could improve the mRNA expressions of insulin-induced gene 1 (INSIG1) and sterol regulatory element-binding protein 1 (SREBP1) in the mammary gland cells from milk and increase the mRNA expressions of acetyl-CoA carboxylase α (ACCα) and fatty acid synthase (FAS) in the mammary gland tissue. Maternal 25OHD₃ supplementation promotes skeletal muscle development of piglets before and after parturition, and improves bone properties including bone density and bone breaking force in lactating sows and their piglets. Interestingly, 25OHD₃ supplementation in sow diets could improve neonatal bone development via regulation of milk fatty acid composition related to bone metabolism and mineralization. In this review, we also discuss the effects of adding 25OHD₃ to sow diets on the gut bacterial metabolites of suckling piglets, and propose that butyrate production may be associated with bone health. Therefore, to better understand the nutritional functions of maternal 25OHD₃ supplementation, this paper reviews advances in the studies of 25OHD₃ for sow nutrition and provides references for practical application.

Effect of Dietary Mineral Content and Phytase Dose on Nutrient Utilization, Performance, Egg Traits and Bone Mineralization in Laying Hens from 22 to 31 Weeks of Age

Simple Summary

The aim of this work was to elucidate how the dietary inclusion of phytase, at a normal dose and overdosed, could affect the utilization of nutrients and performance in young laying hens. When a diet deficient in Ca and P was applied, the dietary inclusion of phytase at low doses (500 FTU/kg) led to an improvement in the digestive efficiency of P in the first weeks after introduction. However, when these deficient diets were maintained in the long term, laying hens improved their digestive utilization of both Ca and P, a higher dose of phytase (1000 FTU/kg) being required to achieve greater P availability. This overdosage also provided additional extraphosphoric advantages, slightly improving access to other nutrients and the feed conversion rate of the hens.

Abstract

A total of 192 laying hens were used to evaluate the effect of dietary mineral content and phytase dose on nutrient utilization, egg production and quality and bone mineralization of young laying hens. Four dietary treatments were studied: PC, positive control with no added phytase, 4.07% Ca and 0.61% P; NC, negative control with no added phytase, 2.97% Ca and 0.37% P; and P500 and P1000, where NC diet was supplemented with phytase at 500 and 1000 FTU/kg, respectively. Hens’ performance and egg traits were controlled from 22 to 31 weeks of age. Coefficients of total tract apparent digestibility (CTTAD) of nutrients were determined at 25 and 31 weeks of age. Apparent ileal digestibility (AID) and blood content of Ca and P, as well as bone traits, were determined at 31 weeks of age. Ca and P retention was higher in birds on PC diet at 25 weeks, but not at 31 weeks of age compared to those on NC diet (p < 0.05). P1000 birds had the highest CTTAD values for dry and organic matter at both ages (p < 0.001). CTTAD of Ca was significantly higher in P1000 diet than in NC diet at 31 weeks of age (p < 0.001). Birds fed with P500 diet at 25 weeks of age and P1000 at 31 weeks of age showed higher CTTAD and retention of P, but lower excretion of P than those fed NC diet (p < 0.05). Phytase inclusion linearly increased AID of dry matter and P (p < 0.001). P500 hens fed had the greatest body weight at the end of the trial (p < 0.05) and P1000 birds had the best feed conversion ratio (p < 0.05). Fowl fed a PC diet produced eggs with higher shell thickness and yolk color than those fed on NC diet (p < 0.05). Phytase inclusion linearly increased the yolk color (p < 0.05). Tibia of laying hens fed with PC had significantly higher ash content than those on NC diet (p < 0.05), and birds fed with P1000 presented intermediate values. It can be concluded that it would be advisable to increase the dose of phytase in the feed of laying hens to obtain long-term benefits.

Effects of Replacing Inorganic with Organic Iron on Performance, Egg Quality, Serum and Egg Yolk Lipids, Antioxidant Status, and Iron Accumulation in Eggs of Laying Hens

This study compared the effects dietary organic (ferrous glycine [FG]) versus inorganic (ferrous sulfate [FS]) iron in laying hens on performance, egg quality, serum and egg yolk lipids, antioxidant status, and iron enrichment of eggs. A total of 378 Shaver White layers were allotted to 7 treatments with 6 replicates (9 birds each) from 30 to 42 weeks of age. A basal diet (19 mg iron/kg) served as control, while the other six diets were supplemented with either FS or FG to provide 30, 60, and 120 mg/kg of added iron. Dietary FG and FS treatments improved (P < 0.05) laying rate, egg weight, and egg quality of layers, relative to the control, albeit eggshell strength and eggshell calcium also deteriorated with the highest level of FS (P < 0.05). The iron treatment groups exhibited a lower serum and egg yolk levels of triglycerides, total cholesterol, and low-density lipoprotein cholesterol that accompanied by higher levels of high-density lipoprotein cholesterol and greater activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) as compared with the control (P < 0.05). The contents of malondialdehyde and protein carbonyl were conversely related to the activities SOD and GPx (P < 0.05). The serum and egg fractions (yolk, albumen, and shell) displayed gradually increases in iron contents as the level of iron increased in the diet (P < 0.05), while FG was superior to FS at all tested levels (P < 0.05). To summary, FS can be replaced by FG, with more favorable impacts on egg quality and iron enrichment.

Molecular distribution and localization of extracellular calcium-sensing receptor (CaSR) and vitamin D receptor (VDR) at three different laying stages in laying hens (Gallus gallus domesticus)

The extracellular calcium-sensing receptor (CaSR) and vitamin D receptor (VDR) play important roles in regulating calcium mobilization, calcium absorption, and calcium homeostasis, and they could be potential therapeutic targets to osteoporosis in laying hens. The present study investigated the molecular distribution of CaSR and VDR and the localization of CaSR in the kidney, proventriculus (true stomach), duodenum, jejunum, ileum, colon, cecum, shell gland, and tibia of laying hens at 3 different laying stages (19, 40, and 55 wk). The results showed that the relative mRNA abundance of CaSR in the kidney, ileum, proventriculus, duodenum, and colon was higher (P < 0.05) than the other tissues at 40 and 55 wk. The relative mRNA abundance of CaSR in the tibia was higher (P < 0.05) at 55 wk than at 40 wk. However, there were no significant differences in the relative protein abundance of CaSR among all tested tissues at peak production or in each tissue at the 3 different laying stages (P > 0.05). The relative mRNA abundance of VDR was higher (P < 0.05) in the small intestine (duodenum, jejunum, and ileum) when compared with other tissues at the 3 different laying stages. The relative protein abundance of VDR in the duodenum was higher (P < 0.05) than that in the proventriculus, colon, and cecum. There were no significant differences in the VDR expression among the tested tissues at the 3 different laying stages (P > 0.05). The immunohistochemical results showed that the positive staining was found widely in each tissue. Moreover, different laying stages did not affect the localization of CaSR except for the tibia tissue. In conclusion, similar to VDR, CaSR was widely expressed not only in the gut but also in the tibia and shell gland in laying hens. The expression level of CaSR and VDR in all tested tissues was unchanged at the different laying stages.

Role of long-term supplementation of 25-hydroxyvitamin D3 on egg production and egg quality of laying hen

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.

Effects of normal and low calcium and phosphorus levels and 25-hydroxycholecalciferol supplementation on performance, serum antioxidant status, meat quality, and bone properties of broilers

To determine the effects of normal and low dietary calcium (Ca) and phosphorus (P) levels and 25-hydroxycholecalciferol (25-OH-D₃) supplementation on performance, serum antioxidant status, meat quality, and bone properties of broilers, 224 1-day-old Arbor Acre male broilers were used in this study. Broilers were allotted randomly to 1 of 4 treatments in a 2 × 2 factorial arrangement that included normal or low Ca and P diet with or without 69 μg/kg 25-OH-D₃. The trial consists of a starter phase from day 1 to 21 and a grower phase from day 22 to 42. Dietary 25-OH-D₃ supplementation increased (P < 0.05) average daily weight gain from day 22 to 42 and decreased feed conversation ratio from day 22 to 42 and day 0 to 42. On day 21, 25-OH-D₃ increased serum concentrations of total antioxidant capacity (T-AOC), catalase (CAT), and glutathione peroxidase in broilers fed low Ca and P diet (Interaction, P < 0.05). 25-hydroxycholecalciferol significantly decreased serum malondialdehyde concentration. Dietary Ca and P deficiencies significantly decreased serum Ca and P concentrations and increased serum parathyroid hormone (PTH) concentration, and serum Ca and 25-OH-D₃ concentrations were significantly increased by 25-OH-D₃ supplementation. On day 42, serum T-AOC and CAT concentrations were decreased by dietary Ca and P deficiencies without 25-OH-D₃ (Interaction, P < 0.05) and unaffected by dietary Ca and P deficiencies with 25-OH-D₃. Dietary Ca and P deficiencies significantly decreased Ca, P, and alkaline phosphatase concentrations and increased PTH concentration in serum. Dietary 25-OH-D₃ increased (P < 0.05) serum Ca and 25-OH-D₃ concentrations and decreased (P < 0.05) serum tartrate-resistant acid phosphatase concentration. The interaction between CaP level and 25-OH-D₃ was observed (P < 0.05) for tibial Ca content and femoral bone density. 25-hydroxycholecalciferol significantly increased tibial breaking strength. These data indicated that 25-OH-D₃ supplementation at 69 μg/kg increased growth performance in some periods, enhanced serum antioxidant capacity, and improved bone mineralization and breaking strength of broilers.

Calcium and Cholecalciferol Levels in Late-Phase Laying Hens: Effects on Productive Traits, Egg Quality, Blood Biochemistry, and Immune Responses

Productive traits and immunity in laying hens decrease sharply during the late phase of laying due to aging, which negatively affects the metabolism and hormonal status of the animals. The influence of Ca levels (3.5, 4.0, and 4.5%) and/or cholecalciferol [Vitamin D₃ (VD₃)] supplementation (800-, 1,000-, and 1,200-IU/kg diet or as total of 3,800, 4,000, and 4,200 IC VD₃) on performance, egg quality, blood biochemistry, and immunity of brown egg layers was investigated. Three hundred and sixty H&N Brown egg layers (60 weeks old) were allocated at random into nine nutritional treatments of five replications (cages) of eight hens each. The control diet in this experiment contained a 3.5% Ca level with 800 IU VD₃. The addition of VD₃ at 1,000 and 1,200 IU to 3.5 and 4% Ca diets significantly (P ≤ 0.05) increased the rate of laying, egg mass, and feed conversion ratio (FCR) compared to the control diet on 3.5% and 800 U of VD₃. Besides this, the addition of VD₃ at 800 and 1,200 IU to 3.5% Ca level diets enhanced the Haugh unit score. Similar results were observed in eggshell quality measurements and tibia ash. Increasing the Ca concentration from 3.5 to 4 and 4.5% and increasing VD₃ levels from 800 to 1,000 or 1,200 IU significantly and similarly increased serum total protein and globulin. In addition, VD₃ at 1,000 IU increased serum albumin, compared to 800 IU. Increasing Ca level increased IgA, and 4 and 4.5% Ca levels similarly increased IgG and α-2 globulin compared to the 3.5% Ca diet. VD₃ addition at 1,200 IU to the 4% Ca diet significantly increased γ-globulin compared to 1,000 IU, but decreased β-globulin. Increasing the Ca level to 4% significantly reduced serum triglycerides, and the very low-density lipoprotein and the triglyceride/high-density lipoprotein ratio were both decreased with 4 and 4.5% Ca level diets. Increasing the Ca level caused a stepwise increase in catalase, which was markedly increased with VD₃ supplementation at 1,200 IU. Plasma estrogen was increased considerably with VD₃ supplementation at 3.5% Ca, but parathyroid hormone levels were not affected. In conclusion, increasing Ca levels in the diet of laying hens to 4% during the late production phase could be a useful tool to improve laying performance, eggshell quality, Haugh unit score, and physiological and immunological status. Besides, VD₃ at a 1,000 IU/kg diet to 3.5% Ca improved performance of hens fed 3.5% Ca, showing that the potential impact of VD₃ depends on Ca concentrations.

Effect of dietary 25-hydroxycholecalciferol supplementation and high stocking density on performance, egg quality, and tibia quality in laying hens

This study was conducted to determine the effects of 25-hydroxycholecalciferol (25-OH-D₃) on performance, egg quality, tibia quality, and serum hormones concentration in laying hens reared under high stocking density. A total of 800 45-week-old Lohmann laying hens were randomly allotted into a 2 × 2 factorial design with 2 levels of dietary 25-OH-D₃ levels (0 and 69 μg/kg) and 2 rates of stocking densities [506 (low density) and 338 (high density) cm²/hen]. Laying hens were monitored for 16 wk. High stocking density decreased laying rate, egg weight, and feed intake compared with low stocking density (P < 0.01) during 1 to 8 wk and 1 to 16 wk. Overall, high stocking density increased eggshell lightness value and decreased shell redness and yellowness value, strength, thickness, and relative weight compared with low stocking density (P < 0.05). Dietary supplementation with 25-OH-D₃ reduced the value of the eggshell lightness and increased its yellowness and eggshells weight (P ≤ 0.05). The increase in eggshell thickness was more pronounced when 25-OH-D₃ was supplemented to layers under high stocking density (interaction, P < 0.05). Layers under high stocking density had lower ash content and calcium content in the tibia than layers under low stocking density (P = 0.04); dietary 25-OH-D₃ increased tibia strength compared with no addition (P = 0.05). Layers under high stocking density had higher serum concentrations of 25-OH-D₃, corticosterone (CORT), lipopolysaccharide (LPS), and osteocalcin (OC; P < 0.05), lower content of parathyroid hormone (PTH) compared with layers under low stocking density (P < 0.01). Dietary 25-OH-D₃ increased serum concentration of 25-OH-D₃, carbonic anhydrase (CA), and calcitonin (CT) (P < 0.01) and reduced corticosterone, lipopolysaccharide and osteocalcin concentration (P ≤ 0.05). The increase effect in PTH was more pronounced when 25-OH-D₃ was supplemented to layers under high stocking density (interaction, P = 0.05). Overall, the results gathered in this study indicate that high stocking density result in reducing production performance, shell color and quality, and tibia health, whereas dietary 25-OH-D₃ was able to maintain tibia health and to mitigate the negative impact of high stocking density on productive performance.

Dietary supplementation with protected calcium effects production and egg quality of Hy-line brown laying hens

Context Currently, the commonly used dietary calcium sources are not sufficiently bioavailable to be used for eggshell formation or bone health in laying hens. Protected calcium, a blend of calcium and medium-chain fatty acids with matrix coating, may exert an effective absorption and metabolism ability for calcium consumption in the laying hen. Aims The present study was conducted to evaluate the effects of protected-calcium supplementation on egg production, egg quality, and serum calcium and phosphorus concentrations in laying hens. Methods In total, 144 Hy-line brown laying hens (25 weeks old) were randomly allotted to three treatments (8 replicates with 6 hens, 1 hen per cage) in a 10-week trial. Treatments consisted of corn–wheat–soybean meal-based basal diet with limestone (coarse limestone:fine limestone = 50:50) as a calcium source (CON) or basal diet supplemented with 0.5% (P1) or 1% (P2) protected calcium in substitution for an equal quantity of coarse limestone. Data were statistically analysed using linear and quadratic contrast with the GLM procedure of SAS. Probability values of &lt;0.05 indicate significance. Key results At Weeks 31–33 and 35, the cracked-egg rates were lower in the P1 and P2 groups than in the CON group (P &lt; 0.05; linear, P &lt; 0.05) and, at Weeks 29 and 34, the cracked-egg rates in the P2 group were also significantly (P &lt; 0.05) decreased. At Weeks 26, 30 and 32, the Haugh units in the P2 group were significantly (P &lt; 0.05) higher than those in the CON group. In addition, eggshell strength was increased significantly (P &lt; 0.05) in the P2 group at Weeks 26, 27 and 31–35. The serum calcium concentration of the P2 group was significantly (P &lt; 0.05) greater than that of the CON group in the morning. Conclusions In conclusion, a replacement of limestone with 1% protected calcium can increase eggshell quality. Implications Protected-calcium supplementation can be used in practice for decreasing the breakage of eggs.

Effects of additional dosage of vitamin D3, vitamin D2, and 25-hydroxyvitamin D3 on calcium and phosphorus utilization, egg quality and bone mineralization in laying hens

Vitamin D is essential for the metabolism of calcium (Ca) and phosphorus (P) in birds. The objective of the study was to evaluate the effect of different isoforms of dietary vitamin D on Ca and P utilization, egg quality, and bone mineralization of laying hens. A total of 42 Lohmann white laying hens at 57 wk of age were randomly assigned to 7 dietary treatments for 6 wk. Dietary treatments were: 3,000 IU/kg Vit D₃ as control, and control with additional 3,000 IU/kg 25-hydroxyvitamin D₃ (T1), 9,000 IU/kg 25-hydroxyvitamin D₃ (T2), 3,000 IU/kg vitamin D3 (T3), 9,000 IU/kg vitamin D₃ (T4), 3,000 IU/kg of vitamin D₂ (T5), or 9,000 IU/kg of vitamin D₂ (T6). Egg production and egg quality were measured weekly. Fecal samples were collected at weeks 2 and 6 to measure Ca and P utilization. After 6 wk, the left tibia and femurs were collected to measure bone mineral density (BMD) and bone mineral content (BMC). A 1-way ANOVA with Tukey HSD means separation test was used for statistical analysis. There were no significant differences in egg production, egg quality, BMD, or BMC of tibia and femurs among the treatments (P > 0.05). T6 significantly reduced feed intake (P < 0.05). The apparent total tract digestibility (ATTD) of Ca was higher (P < 0.012) in treatments supplemented with additional vitamin D, irrespective of forms. The ATTD of P was higher (P < 0.0001) in T5 compared to the other treatments at both time points. The utilization of Ca and P by laying hens can be improved through the addition of different isoforms of vitamin D in diets. However, additional vitamin D supplementation to laying hens, regardless of forms, had no effect on either bone mineralization or measures of egg quality.

The effects of coarse and wet feeding on performance parameters, gastrointestinal tract and tibia traits, and digesta phytase activity in egg-type pullets, either fed a low or moderate phosphorus diet

In a 2 × 2 × 2 factorial design, the effects of dietary non-phytate phosphorus (NPP) levels, 0.17% (low) and 0.33% (moderate), diet moisture (dry and wet), and diet particle size (coarse and fine), were studied on egg production, characteristics of gastrointestinal tract (GIT) and tibia, digesta pH, and phytase activity in layer pullets (16 to 28 wk of age). The low NPP diet increased average daily water intake (ADWI) to ADFI ratio (4.2%) from 16 to 17 wk, but decreased this ratio (2.8%) from 23 to 27 wk. It decreased ADFI (1.5%) and egg mass production (3.8%) from 19 to 22 wk. It decreased egg weight (0.29 g) and ADWI (2.1%) from 23 to 27 wk. At 22 wk, the GIT relative empty organ weights were (g/kg BW) higher for proventriculus + gizzard (0.96), duodeneum (0.94), and jejunum + ileum (1.95) with the low vs. moderate NPP diet. The low NPP diet decreased digesta phytase activity in crop and proventriculus+gizzard at 28 wk. The wet diet increased ADFI, ADWI, and ADWI/ADFI ratio from 16 to 27 wk, egg mass production (3.0%) from 19 to 22 wk, and egg weight (0.45 g) from 23 to 27 wk. The wet diet also increased digesta phytase activity in proventriculus+gizzard. The coarse diet decreased ADFI from 19 to 22 wk (1.7%) and 23 to 27 wk (1.2%). The coarse diet caused reduced egg mass production (2.6%) from 23 to 27 wk. Egg shell breaking strength was increased on the coarse diet (0.9 Newton). The coarse diet increased ADWI/ADFI ratio from 16 to 27 wk, and increased relative gizzard weight by 1.95 and 0.81 g/kg BW at 22 and 28 wk, respectively. The coarse diet increased jejunal/ileal pH with 0.16 units at 28 wk. None of the tested parameters affected tibia characteristics. It was concluded that a low NPP diet did not clearly affect the studied parameters. The wet diet increased ADFI, ADWI, and egg production. The coarse diet increased ADWI, egg shell breaking strength, relative gizzard weight, and reduced ADFI and egg production.

Medullary bone attributes in aged Lohmann LSL-lite layers fed different levels of calcium and top-dressed 25-hydroxy vitamin D3

Structural bone depletion over the course of lay cycle predisposes hens to skeletal problems. We investigated the effects of dietary calcium (Ca) and top-dressed 25-hydroxy vitamin D3 (25OHD3) on attributes [relative weight, ash content (AC), and ash concentration (ACN)] in whole ulna, femur, tibia, and subparts of femur and tibia (epiphysis, medullary, and cortical) in 74-wk-old Lohmann LSL-lite layers. Four levels of Ca (3.0%, 3.5%, 4.0%, and 4.5%) and three levels of 25OHD3 (0, 69, and 138 μg kg−1) were tested. All diets had basal level of 3300 IU of vitamin D3 kg−1. Eighty-four, 74-wk-old hens were placed in individual cages, and 13 spare hens were sacrificed for baseline samples. Diets (n = 7) were fed to 81 wks of age, and hens were sacrificed for bone samples. There were no (P > 0.05) diet effects on whole bone attributes. Interaction (P < 0.05) between Ca and 25OHD3 on femur subparts was such that 25OHD3 linearly increased medullary ACN and concomitantly decreased cortical ACN at all Ca levels. In tibia, 25OHD3 (P < 0.05) increased AC and ACN in medullary and reduced these parameters in cortical. The results suggested that subparts and not whole medullary bone attributes are more amenable to dietary interventions in aged hens.

Vaccine to fibroblast growth factor 23 peptides increases eggshell strength

Strategies that would increase eggshell quality could be of considerable value to egg producers. This research demonstrated the effective use of fibroblast growth factor 23 (FGF-23) peptide vaccines to increase eggshell quality of Single Comb White Leghorn laying hens (from 69 to 72 wk of age). Hens, fed a standard diet (containing 900 IU/kg vitamin D3), were intramuscularly injected (and boosted) with either a control vaccine (n = 14 hens) or one of 2 FGF-23 peptide vaccines (peptides NP1, GMNPPPYS; and NP7, YTSTERNSFH; n = 15 hens for each peptide). During peak antibody titer, eggs were collected for shell and internal quality analysis, hens were artificially inseminated, and the hatchability of fertilized eggs was determined. Laying hens vaccinated with either FGF-23 peptide NP1 or NP7 had increased (P < 0.05) plasma phosphate level (mmol/L; NP1 = 1.74, NP7 = 1.76, control = 1.47), egg specific gravity (NP1 = 1.083, NP7 = 1.083, control = 1.079), and eggshell strength (g of force; NP1 = 4002, NP7 = 4157, control = 3102) when compared to control vaccinated hens. FGF-23 peptide NP1 vaccinated hens also had increased eggshell thickness (mm, P < 0.001), shell weight (g, P = 0.032), and shell index (% of whole egg, P = 0.023) when compared to control vaccinated hens. FGF-23 peptide NP7 vaccinated hens tended to have decreased eggshell weight (P = 0.064) when compared to control vaccinated hens. Hatchability of fertilized eggs was not affected in incubations 1 and 3, but tended to be decreased (P = 0.097) by FGF-23 peptide NP1 vaccination in incubation 2. In conclusion, vaccines to FGF-23 peptides increased eggshell quality of laying hens with minimal adverse effects on egg internal quality. The effect of FGF-23 peptide vaccination on hatchability remains to be clarified.

Effect of selected feed additives on egg performance and eggshell quality in laying hens fed a diet with standard or decreased calcium content

The aim of the experiment with 240 ISA Brown hens fed the diets with standard or decreased Ca level was to evaluate the effect of selected feed additives on laying performance and eggshell quality. The hens were allocated to 10 treatments, each containing 12 cages (replicates) of 2 birds. A 2 × 5 experimental arrangement was used. From 26 to 70 wks of age, experimental diets containing 3.20 or 3.70% Ca were used. The diets were either not supplemented, or supplemented with sodium butyrate, probiotic bacteria, herb extracts blend or chitosan. The decreased dietary Ca reduced eggshell quality indices in older hens (43-69 wks) (P<0.05) without effect on performance indices. The addition of the probiotic, herb extracts, or chitosan increased the laying rate (P<0.05). In older hens, i.e. at 69 wk, chitosan increased eggshell thickness and breaking strength, while herb extracts increased eggshell thickness (P<0.05). There was no interaction between the experimental factors in performance and eggshell quality. The used feed additives had no influence on fatty acid profile of egg lipids, however diet supplementation with chitosan decreased cholesterol concentration in egg yolk lipids (P<0.05). It can be concluded that such feed additives as probiotic, herb extracts, or chitosan may positively affect performance and eggshell quality, irrespective of Ca dietary level.

Effects on performance and eggshell quality of particle size of calcium sources in laying hens' diets with different Ca concentrations

Abstract. The objective of this study was to evaluate the effect of particle size of a dietary Ca source on egg production and eggshell quality when added to hens' diets that have different levels of calcium. The experiment was carried out on 216 ISA Brown hens (25 to 70 weeks of age), allocated to 9 groups of 12 replicates (cages), with two birds in each cage. A 3 × 3 factorial arrangement was used, with three dietary levels of calcium (3.20, 3.70 and 4.20 %) and three levels of dietary substitutions (0, 25 and 50 %) of fine particles of limestone (FPL, diameter 0.2–0.6 mm) with large particles of limestone (LPL, diameter 1.0–1.4 mm) as a Ca source. The level of Ca in the diet had no effect on egg production, mean egg weight, feed intake, feed conversion ratio or eggshell quality parameters (P > 0.05). Substitution of FPL with LPL did not affect laying performance indices or eggshell quality at 30, 43 and 53 weeks of age (P > 0.05); however, it increased (P < 0.05) eggshell percentage, thickness, density and breaking strength in older hens (69 weeks of age). In conclusion, the results of this study demonstrated that a level of 3.20 % Ca in a layer's diet is sufficient through the entire laying cycle to maintain good egg production and eggshell quality and that partial (25 or 50 %) substitution of fine- with large-particle limestone can, irrespective of the level of Ca in the diet, improve eggshell quality in aged laying hens.

A meta-analysis of responses to dietary nonphytate phosphorus and phytase in laying hens

Reducing the level of nonphytate P (NPP) in diets for laying hens without negatively affecting their productivity and heath is crucial for sustainable egg production. A meta-analytical approach using a full quadratic model was applied to quantify relationships between dietary NPP and phytase levels and performance of laying hens. Egg production (EP, %), egg mass (EM, g/hen/day), and feed conversion ratio (FCR) were considered as model outputs. A data set containing 168 P or P plus phytase treatments was extracted from 12 published papers. The data were assembled from 14 trials with a total of 8,752 hens in the range of 36 to 76 wk of age. The EP, EM, and FCR were analyzed using a linear mixed model that included the linear and quadratic effects of dietary NPP and phytase levels and their interactions. Except for the quadratic effect of dietary phytase on FCR, all other model components (that is, intercept, linear, quadratic, and interactions) were significant (P<0.05). There was a relatively strong relationship between observed and predicted EP (R2=0.78, RMSE=3.73), EM (R2=0.84, RMSE=2.09), and FCR (R2=0.78, RMSE=0.11), demonstrating that observations within study are practically predictable. Analyses of the model revealed that corn-soybean meal-based diets containing 0.22% of NPP without supplemental phytase resulted in high EP, EM, and feed efficiency in layers. In the presence of 150, 300, and 400 phytase units (FTU)/kg of feed, the dietary NPP level may be decreased and optimal levels were calculated as 0.18, 0.15, and 0.14%, respectively.

Effect of different vitamin D supplementations in poultry feed on vitamin D content of eggs and chicken meat

According to a new European Union regulation, vitamin D(3) can be partially or totally substituted with 25-hydroxyvitamin D(3) (25-OH-D(3)) in hens' feed. The purpose of this study was to clarify how this regulation has affected the vitamin D content of commercial eggs and chicken meat. Another aim was to investigate how effectively 25-OH-D(3) is transferred from the hens' diet to egg yolk by analyzing eggs from farms using known commercial feeds and by conducting an animal study. Vitamin D determinations were made by HPLC methods. The vitamin D(3) contents of two commercial egg yolk pools were 4.9 ± 0.14 and 4.0 ± 0.10 μg/100 g, and the 25-OH-D(3) contents were 1.3 ± 0.19 and 1.0 ± 0.07 μg/100 g. The chicken meat pools contained 0.2-0.3 μg of vitamin D(3)/100 g, whereas the content of 25-OH-D(3) was ≤0.2 μg/100 g. These results are comparable to earlier data. The animal and farm studies showed that 25-OH-D(3) was effectively transferred from the hens' diet to yolk. However, because the relative activity between 25-OH-D(3) and vitamin D(3) is unknown, it remains questionable whether the use of 25-OH-D(3) in hens' feed is beneficial to human vitamin D intake from eggs.

Twenty-five hydroxycholecalciferol as a cholecalciferol substitute in broiler breeder hen diets and its effect on the performance and general health of the progeny

An experiment was conducted with broiler breeder hens to determine the relative biological value of 25-hydroxycholecalciferol (25-OHD3) compared with cholecalciferol (vitamin D3) for hen-day egg production, hatchability, embryo mortality (early, 1 to 10 d of incubation, late, 11 to 21 d), and body ash of the progeny. The study was conducted with 73-to-90-wk-old molted Ross broiler breeder hens in an environment excluding ultraviolet light. A basal vitamin D3 deficient diet supplemented with 4 levels of vitamin D3 (0, 3,125, 12,500, and 50,000 ng/kg of diet) and 2 levels of 25-OHD3 (3,125 and 12,500 ng/kg of diet) was fed. The relative biological values of 25-OHD3 in comparison to vitamin D3, using slope ratio techniques, were 138, 133, 128, and 111% for hen-day egg production, hatchability, late embryo mortality, and body ash of the progeny,, respectively (average = 128%). When comparing 25-OHD3 against D3 at the 3,125 ng/kg level, the relative biological values were 209, 167, 400, and 108% for the same criteria, respectively (average = 221%). However, at the 12,500 ng/kg level no statistical differences between 25-OHD3 and D3 were observed (average = 108%). Four trials were conducted to determine the effect of the maternal diet on the performance and leg abnormalities of the hens' progeny. In experiment 1, no vitamin D was added to the corn-soybean meal basal diet fed to the chicks, and in experiments 2, 3, and 4 the basal diet was supplemented with 27.5 microg of D3/kg of diet. In the progeny study, the average relative biological value of 25-OHD3 at the 3,125 and 12,500 ng/kg levels were 115 and 101%, respectively. The potency of 25-OHD3 in relation to vitamin D3 depended on the level tested. When comparing vitamin D sources, 25-OHD3 had greater potency than D3 only at very low levels of supplementation.