Absorption and excretion of cholecalciferol and of 25-hydroxycholecalciferol and metabolites in birds

Automatic analysis of high, medium, and low activities of broilers with heat stress operations via image processing and machine learning

Heat stress is a major welfare problem in the poultry industry, altering broilers' activity levels. Advancements in image processing and machine learning provide opportunities to automatically quantify and analyze broiler activity. This study aimed to evaluate the effects of moderate heat exposure on broiler behavioral activity via image processing and machine learning. 132 Cobb 500 broilers were raised in 2 nutritional treatment groups, each with 3 replicates. The control groups were fed a basal diet, while the variation groups were fed a diet with 0.05 % 25-hydroxyvitamin D3. All birds were raised under standard environmental conditions for 27 days before exposure to cyclic heat of 29.56 ± 1.34 °C and humidity of 76.97 % ± 5.98 % from 8:00-18:00 and thermoneutral conditions of 26.67 ± 1.76 °C and 80.23 % ± 3.05 % from 18:00-8:00. Birds were continuously video recorded, and the bird activity index (BAI) was analyzed by subtracting consecutive frames and summing up pixel differences. The treatment effect was analyzed using two-way ANOVA with a P-value < 0.05. K-means clustering was used to determine BAI as high, medium, and low levels. The result showed a significantly higher (P < 0.01) activity index in the variation group in contrast to the control. Absolute values of high and medium BAI were significantly lower with cyclical heating operations than those without heating operations. The BAI was also higher at the onset and end of the heating operations and moderately correlated to flock age (|r| = 0.35-0.45). The high, medium, and low BAI performed differently with different nutritional treatments, temperature ranges, and relative humidity ranges. It is concluded that the BAI is a useful tool for predicting broiler heat stress, but the prediction effectiveness could be influenced by bird age, diets, temperature, humidity, and behavior metrics.

Effect of 25-hydroxycholecalciferol and high phytase doses on performance, vitamin D status, bone mineralization, and mechanistic target of rapamycin gene expression of broilers

The use of exogenous phytase and vitamin D3 metabolites such as 25-hydroxycholecalciferol (25-OH-D3) for poultry is well consolidated, but the potential for additive effects when supplementing both requires further investigation. This study investigated possible interactions between supplementation of 25-OH-D3 and high doses of phytase for broilers fed Ca- and P-deficient diets. A total of 1 200 one-d-old male broiler chicks were randomly allocated from one of four dietary treatments in a 2 × 2 factorial arrangement: 600 or 2 000 phytase units (FYT)/kg and with or without the inclusion of 25-OH-D3 at 69 µg/kg, with 12 replicates of 25 broilers each. Two feeding phases were stablished (1-to-21 and 22-to-42 d) and all diets contained commercial levels of vitamin D3 (100 µg/kg) with total Ca and available P respectively set to 0.6 and 0.3%. Supplementation with 25-OH-D3 increased body weight gain (BWG) and reduced feed conversion ratio (FCR) from 1 to 21 d (P < 0.05), as well as increased BWG from 1 to 42 d (P < 0.05). Serum 25-OH-D3 levels at 21 and 42 d were increased with 25-OH-D3 (P < 0.001). Phytase did not affect growth performance from 1 to 21 d, but a higher dose (2 000 FYT/kg) reduced feed intake and FCR from 22 to 42 d compared to 600 FYT/kg, also reducing FCR in the total period (P < 0.05). The mRNA expression of mechanistic target of rapamycin in breast muscle assessed at 42 d was enhanced with 2 000 FYT/kg (P < 0.001). Bone weight, bone contents of ash, Ca, and P, and bone breaking strength of tibia bone measured at 42 d were not affected by any dietary treatment. Although both additives are known to improve dietary Ca and P utilization, there were no detected additive or synergic effects. The results suggested that the inclusion of 25-OH-D3 and phytase combined with regular vitamin D3 levels can help minimize losses of performance and bone mineralization of broilers fed Ca- and P-deficient diets. Furthermore, vitamin D status is refined with dietary 25-OH-D3 and potential improvements on breast meat yield can be obtained with a high phytase dose of 2 000 FYT/kg.

Ross 708 broiler small intestine morphology and immunity improvements in response to in ovo Marek's Disease vaccine administration alone or in conjunction with in ovo and dietary supplemental calcifediol

Investigations were performed to determine the systemic immune and small intestine (SI) morphological responses of Ross 708 broilers to the Marek's Disease vaccine (MDV) administered alone or in conjunction with the in ovo and dietary administration of calcifediol (25OHD3). Live embryonated hatching eggs were assigned at random to 3 in ovo treatments at 18 d of incubation. Pre-specified in ovo treatments were: commercial MDV-alone-injected (50 µL) or commercial MDV containing 1.2 (MDV+25OHD3-1.2) or 2.4 (MDV+25OHD3-2.4) μg of 25OHD3. A noninjected control treatment was also included. For the growing phase, broilers received a commercial diet containing 250 IU of vitamin D3 /kg (control) or a commercial diet supplemented with 2,760 IU of 25OHD3 /kg (Hy-D diet). For determination of serum IgG, nitric oxide, and α-1-acid glycoprotein (AGP) at 14 and 40 d of age (doa), blood was collected from 1 bird per pen (48 total). In the duodenum, jejunum, and ileum of the same bird, villus length (VL), crypt depth (CD), VL to CD ratio (VCR), and villus surface area were also determined. There were no significant dietary x in ovo treatment interactions for any of the variables examined. However, birds fed Hy-D diets had lower serum AGP levels at 14 doa when compared to those fed un-supplemented commercial diets. Additionally, at 40 doa, birds in the MDV+25OHD3-1.2 and MDV+25OHD3-2.4 treatments experienced a decrease in serum AGP in comparison to those belonging to the noninjected and MDV-alone treatment groups. A higher jejunal VCR was observed at 14 and 40 doa in birds that belonged to the MDV+25OHD3-1.2 treatment when compared to those in the noninjected and MDV-alone treatment groups, and dietary Hy-D increased the VL of the duodenum and jejunum in birds at 14 and 40 doa when compared to those fed the commercial diet. In conclusion, both dietary or in ovo administration of 25OHD3 lowered inflammatory reactions and improved the SI morphology of broilers that were in ovo-injected with the MDV.

Effects of the Marek's Disease Vaccine on the Performance, Meat Yield, and Incidence of Woody Breast Myopathy in Ross 708 Broilers When Administered Alone or in Conjunction with In ovo and Dietary Supplemental 25-Hydroxycholecalciferol

The effects of the Marek's disease vaccine (MDV) on the live performance, breast meat yield, and incidence of woody breast myopathy (WBM) of Ross 708 broilers were investigated when administered alone or in conjunction with in ovo and dietary supplemental 25-hydroxycholecalciferol (25OHD3). At 18 d of incubation (doi), four in ovo injection treatments were randomly assigned to live embryonated Ross 708 broiler hatching eggs: (1) non-injected; (2) commercial MDV alone; or MDV containing either (3) 1.2 or (4) 2.4 μg of 25OHD3. An Inovoject multi-egg injector was used to inject a 50 μL solution volume into each egg. The birds were provided a commercial diet that contained 250 IU of cholecalciferol/kg of feed (control) or a commercial diet that was supplemented with an additional 2760 IU of 25OHD3/kg of feed (HyD-diet). In the growout period, 14 male broilers were placed in each of 48 floor pens resulting 6 replicated pens per in ovo x dietary treatment combination. Live performance variable were measured at each dietary phases from 0 to 14, 15 to 28, and 29 to 40 d of age (doa). At 14 and 40 doa, pectoralis major (P. major) and pectoralis minor (P. minor) muscles were determined for one bird within each of the six replicate pens. At 41 doa, WBM incidence was determined. No significant main or interaction effects occurred for WBM among the dietary or in ovo injection treatments. However, in response to in ovo 25OHD3 supplementation, BW and BWG in the 29 to 40 doa period and BWG and FCR in the 0 to 40 doa period improved. In addition, at 40 and 41 doa, breast meat yield increased in response to in ovo and dietary 25OHD3 supplementation. Future research is needed to determine the possible reasons that may have been involved in the aforementioned improvements.

Effect of 25-hydroxycholecalciferol supplementation with different dietary available phosphorus levels for broilers

1. Based on the hypothesis that 25-hydroxycholecalciferol (25-OH-D3) inclusion would optimise dietary mineral digestibility and ameliorate growth performance and bone mineralisation in available phosphorus (AvP) deficient-fed broilers, a trial was conducted to evaluate its effect on diets with different levels of AvP.2. Broilers aged 1-21 d were randomly assigned one of the eight treatments, consisting of four dietary levels of AvP (0.45%, 0.42%, 0.39%, and 0.36%) and with or without supplementation with 25-OH-D3 at 69 μg/kg of feed. All diets contained 100 µg/kg of vitamin D3 (cholecalciferol).3. The addition of 25-OH-D3 resulted in higher feed intake and body weight gain, and lower FCR (P < 0.05) compared to non-supplemented diets, whereas AvP levels had a quadratic effect only on feed intake. There were no interactions between treatment factors.4. Increasing AvP levels linearly reduced the ileal digestibility of Ca and P (P < 0.01) and supplementing 25-OH-D3 increased both Ca and P ileal digestibility (P < 0.05), without any interactions observed for ileal digestibility.5. There was an interaction, whereby 25-OH-D3 inclusion increased serum metabolites in broilers fed 0.36% to 0.42% AvP compared to the non-supplemented diets (P < 0.001), whereas, at 0.45% AvP, diets with or without 25-OH-D3 had similar results.6. The P content in bone linearly increased in line with AvP levels (P < 0.05) and supplementation of 25-OH-D3 increased ash bone content (P < 0.001).7. Broilers can benefit from 25-OH-D3 supplementation combined with cholecalciferol with regard to Ca and P utilisation and vitamin D status, allowing for a reduction of dietary AvP levels down to 0.36% without impairing growth performance or bone status.

In ovo administration of the Marek's disease vaccine in conjunction with 25-hydroxyvitamin D3 and its subsequent effects on the performance and immunity-related characteristics of Ross 708 broiler hatchlings1,2,3

The combined effects of the in ovo injection of commercial Marek's disease vaccine (MDV) and various levels of 25-hydroxyvitamin D3 (25OHD3) on the hatch variables, immunological measurements, and gene expression of Ross 708 hatchling broilers were investigated. A total of 5 in ovo injection treatments that were applied at 18 d of incubation (doi) included: 1) noninjected (control); or a 50 μL solution volume of 2) MDV alone; or MDV combined with 3) 0.6 μg of 25OHD3; 4) 1.2 μg of 25OHD3; or 5) 2.4 μg of 25OHD3. At hatch, hatchability of set and live embryonated eggs, hatchling body weight, hatch residue analysis, serum IgY and alpha-1 acid glycoprotein (AGP) concentrations, and the expression of genes related to immunity (INFα, INFβ, INFγ, TLR-3, and TLR-21) and vitamin D3 activity (1 α-hydroxylase, 24 hydroxylase, and vitamin D receptor) were determined. No significant treatment differences were observed for hatchability of set and live embryonated eggs, or for serum IgY and AGP concentrations. However, hatchling body weight was higher when MDV was combined with either 1.2 or 2.4 μg of 25OHD3 than when MDV was provided alone or in combination with 0.6 μg of 25OHD3. Also, in comparison to the noninjected treatment group, the expression of the genes for 1 α-hydroxylase and 24 hydroxylase was improved when MDV was combined with either 1.2 or 2.4 μg of 25OHD3. Lastly, expression of the genes linked to viral detection (TLR-3) and antibody production (INF-β) was increased in those treatments that contained any level of 25OHD3. These results indicate that in comparison to controls, the effects of MDV were observed to be greater on hatchling BW and splenic gene expression when it was administered in combination with the 1.2 or 2.4 μg doses of 25OHD3. Further research is needed to determine the posthatch effects of the administration of various levels of 25OHD3 in combination with MDV.

Safety and efficacy of a feed additive consisting of 25-hydroxycholecalciferol (produced by Pseudonocardia autotrophicaDSM 32858) for all pigs, all poultry for fattening and ornamental birds and other poultry species (Huvepharma NV)

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of a feed additive consisting of 25-hydroxycholecalciferol (produced by Pseudonocardia autotrophica DSM 32858) for all pigs, all poultry for fattening and ornamental birds and other poultry species. The production strain P. autotrophica DSM 32858 is not genetically modified however, uncertainties remain on the possible presence of its viable cells in the final product. Due to the lack of adequate safety data and uncertainty on the presence of nano particles, the FEEDAP Panel cannot conclude on the safety of the additive for the target species and the consumer. The additive was shown not to be irritant to skin or eyes and it is not a skin sensitiser. Considering the low dusting potential of the additive, the FEEDAP Panel concluded that the exposure through inhalation is unlikely. However, the FEEDAP Panel considered that uncertainties remain on genotoxicity and on the possible presence of viable cells of P. autotrophica DSM 32858 in the final product which might have an impact on the safety for the users. The use of the feed additive is considered safe for the environment. The Panel concluded that the additive has a potential to be efficacious under the proposed conditions of use.

Phytase dose-dependent response of kidney inositol phosphate levels in poultry

Phytases, enzymes that degrade phytate present in feedstuffs, are widely added to the diets of monogastric animals. Many studies have correlated phytase addition with improved animal productivity and a subset of these have sought to correlate animal performance with phytase-mediated generation of inositol phosphates in different parts of the gastro-intestinal tract or with release of inositol or of phosphate, the absorbable products of phytate degradation. Remarkably, the effect of dietary phytase on tissue inositol phosphates has not been studied. The objective of this study was to determine effect of phytase supplementation on liver and kidney myo-inositol and myo-inositol phosphates in broiler chickens. For this, methods were developed to measure inositol phosphates in chicken tissues. The study comprised wheat/soy-based diets containing one of three levels of phytase (0, 500 and 6,000 FTU/kg of modified E. coli 6-phytase). Diets were provided to broilers for 21 D and on day 21 digesta were collected from the gizzard and ileum. Liver and kidney tissue were harvested. Myo-inositol and inositol phosphates were measured in diet, digesta, liver and kidney. Gizzard and ileal content inositol was increased progressively, and total inositol phosphates reduced progressively, by phytase supplementation. The predominant higher inositol phosphates detected in tissues, D-and/or L-Ins(3,4,5,6)P4 and Ins(1,3,4,5,6)P5, differed from those (D-and/or L-Ins(1,2,3,4)P4, D-and/or L-Ins(1,2,5,6)P4, Ins(1,2,3,4,6)P5, D-and/or L-Ins(1,2,3,4,5)P5 and D-and/or L-Ins(1,2,4,5,6)P5) generated from phytate (InsP6) degradation by E. coli 6-phytase or endogenous feed phytase, suggesting tissue inositol phosphates are not the result of direct absorption. Kidney inositol phosphates were reduced progressively by phytase supplementation. These data suggest that tissue inositol phosphate concentrations can be influenced by dietary phytase inclusion rate and that such effects are tissue specific, though the consequences for physiology of such changes have yet to be elucidated.

Dietary supplementation of 25-hydroxycholecalciferol as an alternative to cholecalciferol in swine diets: A review

25-hydroxycholecalciferol (25-OHD₃ ) formed via hepatic hydroxylation from vitamin D, cholecalciferol, represents the precursor of the biologically active vitamin D hormone, 1,25-dihydroxyvitamin D. Due to a higher absorption rate and the omission of one hydroxylation, dietary supplementation of 25-OHD₃ instead of vitamin D₃ is considered to be more efficient as plasma concentrations of 25-OHD₃ are increased more pronounced. The present review summarises studies investigating potential beneficial effects on mineral homeostasis, bone metabolism, health status and performance in sows, piglets and fattening pigs. Results are inconsistent. While most studies could not demonstrate any or only a slight impact of partial or total replacement of vitamin D₃ by 25-OHD₃ , some experiments indicated that 25-OHD₃ might alter physiological processes when animals are challenged, for example, by a restricted mineral supply.

Comparative Study of the Effects of Two Dietary Sources of Vitamin D on the Bone Metabolism, Welfare and Birth Progress of Sows Fed Protein- and Phosphorus-Reduced Diets

To investigate the influence of two dietary sources of vitamin D on the vitamin D status, bone metabolism, welfare and birth progress of gestating and lactating sows, forty-nine multiparous sows were randomly assigned to one of two diets: “CON” (n = 25; 50 μg vitamin D3/kg feed) and “HYD” (n = 24; 50 μg 25-hydroxycholecalciferol/kg feed). The basal diets were protein- and phosphorus-reduced. The trial started on day 3 ante insemination of the sows and ended with weaning of the piglets on day 28 postpartum. Dietary supplementation of 25-hydroxycholecalciferol resulted in improved maternal vitamin D status (p < 0.001), fewer gait changes (p < 0.01) and longer standing time after feeding (day 5 ante partum; p < 0.05) compared to vitamin D3. However, the bone markers CrossLaps and osteocalcin were not affected. Overall, the present results suggest that sows fed 25-hydroxycholecalciferol instead of vitamin D3 showed improved locomotion and stance strength. However, this outcome is probably not related to altered bone metabolism. The underlying mechanisms must be investigated in further studies.

Effects of the In Ovo Injection of Vitamin D3 and 25-Hydroxyvitamin D3 in Ross 708 Broilers Subsequently Challenged with Coccidiosis: II Immunological and Inflammatory Responses and Small Intestine Histomorphology

In broilers challenged with coccidiosis, effects of in ovo vitamin D3 (D3) and 25-hydroxyvitamin D3 (25OHD3) administration on their inflammatory response and small intestine morphology were evaluated. At 18 d of incubation (doi), a 50 μL volume of the following 5 in ovo injection treatments was administrated: non-injected (1) and diluent injected (2) controls, or diluent injection containing 2.4 μg D3 (3) or 2.4 μg 25OHD3 (4), or their combination (5). Four male broilers were randomly allocated to each of eight isolated replicate wire-floored battery cages at hatch, and birds were challenged at 14 d of age (doa) with a 20x live coccidial vaccine dosage. One bird from each treatment-replicate (40 birds in each of 8 replicates per treatment) was bled at 14 and 28 doa in order to collect blood for the determination of plasma IL-1β and nitric oxide (NO) concentrations. The duodenum, jejunum, and ilium from those same birds were excised for measurement of villus length, crypt depth, villus length to crypt depth ratio (VCR), and villus surface area. In ovo injection of 2.4 μg of 25OHD3 resulted in a reduction in plasma NO levels as compared to all other treatments at 28 doa. Additionally, duodenal VCR increased in response to the in ovo injection of 25OHD3 when compared to the diluent, D3 alone, and the D3 + 25OHD3 combination treatments at two weeks post-challenge (28 doa). Therefore, it can be concluded that 2.4 μg of 25OHD3, when administrated in ovo at 18 doi, may be used to decrease the inflammatory reaction as well as to enhance the small intestine morphology of broilers during a coccidiosis challenge.

Combined Maternal and Post-Hatch Dietary Supplementation of 25-Hydroxycholecalciferol Alters Early Post-Hatch Broiler Chicken Duodenal Macrophage and Crypt Cell Populations and Their Mitotic Activity

The previous work has demonstrated that maternal supplementation of the circulating metabolite of vitamin D3 (D3), 25-hydroxycholecalciferol (25OHD3), enhances the immunocompetence of broiler chick offspring. In post-hatch broiler diets, 25OHD3 has been shown to affect intestinal morphology and improve the immune status of broilers. An experiment with a 2 × 2 factorial treatment arrangement was conducted to assess the effects of combining maternal (MDIET) and post-hatch (PDIET) dietary 25OHD3 inclusion on duodenal crypt and macrophage cell populations and mitotic activity in young broiler chickens. All diets were formulated to provide 5,000 IU of vitamin D. Broiler breeder hens were offered 1 of 2 MDIET: 5,000 IU D3 per kg of feed (MCTL) or 2,240 IU of D3 + 2,760 IU of 25OHD3 per kg of feed (M25OHD3) from week 25 to 41. Male broiler offspring (n = 480) hatched from eggs collected during week 41 of breeding age were allotted in raised floor pens (4 birds per pen from day 0 to 7 and individually allotted from day 8 to 21). Chicks were fed 1 of 2 PDIET (starter day 0 to 21): 5,000 IU D3 per kg of feed (PCTL) or 2,240 IU D3 + 2,760 IU 25OHD3 (P25OHD3). DUO samples (n = 12 birds per treatment per day) were collected on days 3, 6, 9, 12, 15, 18, and 21 for cryohistological and immunofluorescence analysis to facilitate the enumeration of the total macrophages, CD80+ macrophages (pro-inflammatory macrophages), and mitotically active cells (BrdU+) to calculate the proportion of proliferating cells (PPC) per duodenal crypt. Bird age impacted crypt PPC with the greatest PPC per duodenal crypt observed on days 3 and 9, and the lowest PPC per crypt was observed on day 21 (P < 0.0001). Broilers from the M25OHD3:PCTL treatment had a greater PPC (P =.002) than birds from the MCTL:PCTL treatment at day 3. An interaction among MDIET and PDIET was observed for proliferating macrophages at day 21 (P = 0.029) where M25OHD3:P25OHD3 birds had more proliferating macrophages than M25OHD3:PCTL-fed birds. These results indicate that combined MDIET and PDIET 25OHD3 supplementation may alter early post-hatch duodenal development and innate immunity.

Dietary supplementation with canthaxanthin and 25-hydroxycholecalciferol on the incubation performance and fertility of European quail breeders

This study assessed the effects of combined supplementation with canthaxanthin (Cx) and 25-hydroxycholecalciferol (25-OH-D₃) on incubation performance, fertility, and chick quality in European quail breeders. A total of 240 birds were distributed in a completely randomized design with 5 diets and 8 replicates. The animals were fed a basal diet containing 50 µg of vitamin D₃ or the basal diet supplemented with 3 ppm Cx and 34.5 µg 25-OH-D₃, 6 ppm Cx, and 69 µg 25-OH-D₃, 9 ppm Cx and 103.5 µg 25-OH-D₃, or 12 ppm Cx and 138 µg 25-OH-D₃. Incubation performance was analyzed in 2 periods (32 and 38 wk). Breeders aged 32 wk produced eggs with higher hatchability (P = 0.024), hatchability of fertile eggs (P = 0.026) and lower initial plus mid embryonic mortality (P = 0.021), whereas 38-week-old breeders generated chicks with a higher length at hatching (P < 0.001) and lower final plus pipped embryonic mortality (P = 0.021). In both age groups, Cx + 25-OH-D₃ levels had a quadratic effect on egg fertility (P < 0.001), hatchability of total (P < 0.001), and fertile eggs (P < 0.001). The fertility and the number of sperm cells in the perivitelline membrane was analyzed in two periods (26 and 40 wk). A quadratic effect of diet and days after mating on both parameters (P < 0.05) was observed. Eggs from supplementing breeders showed a high fertility (P < 0.001) and sperm cell counts (P < 0.001) for up to 7 and 3 d after mating, respectively, then the control group. Moreover, the supplementation of quail breeder diets with 6 ppm Cx + 69 µg 25-OH-D₃ enhances sperm cell longevity in sperm storage tubules, hatchability of total and fertile eggs, fertility, and chick quality, especially in older quail's breeders and reduces embryonic mortality.

Classic and Non-Classic Effects of the Duration of Supplementation of 25-Hydroxicholecalciferol in Broiler Chicken Diets

Simple Summary

Genetic programs of modern commercial-type broiler chickens are based on growth performance parameters associated with muscular growth, feed efficiency, and meat and breast yield. Therefore, highly bioavailable vitamin D₃ to sustain optimal muscle and bone development is necessary. In the present study the effect of different durations of supplementing of 25-hydroxycholecalciferol (25(OH)D₃) in broiler chickens was evaluated. Growth performance response, carcass and cuts yield, bone resistance, plasma concentration of 25(OH)D₃, and expression of the mTOR gene were evaluated. The use of 25(OH)D₃ in the diets for broilers during different feeding periods did not influence growth performance but increased the plasma concentration of 25(OH)D₃, and increased breast yield as the duration of the supplementation was extended. The supplementation of 25(OH)D₃ increased breast yield and protein deposition in the breast muscle which may have been a result of the epigenetic changes caused by this vitamin D (Vit D) metabolite.

Abstract

The present study aimed to determine the effect of different times of supplementation of 25-hydroxycholecalciferol (25(OH)D₃) in broiler chickens on the performance, carcass and cuts yield, bone resistance, plasma concentration of 25(OH)D₃, and expression of the mTOR gene. The treatments were a control diet (CD) supplemented with 3000 IU vitamin D₃/kg of feed from 1 to 46 d, or the CD + 2760 IU (69 mcg) of 25(OH)D₃/kg of feed from 1 to 21 d, from 1 to 35 d, or from 1 to 46 d. The period of supplementation of 25(OH)D₃ did not affect the growth performance of broilers, but the breast meat yield was linearly increased in response to increasing days of supplementation (p < 0.05). Birds supplemented with 25(OH)D₃ at the time of the analysis showed an increase (p < 0.05) in the plasma concentration of 25(OH)D₃ when compared to non-supplemented birds. The mTOR gene expression (p < 0.05), and breast protein deposition (p < 0.05) presented a quadratic response related to the supplementation period of 25(OH)D₃. The fat content of the breast linearly decreased (p < 0.05) as the period of supplementation was extended. The results also showed a positive linear correlation between mTOR expression and 25(OH)D₃ plasma levels (r = 0.593; p < 0.05).

Effects of the in ovo injection of vitamin D3 and 25-hydroxyvitamin D3 in Ross 708 broilers subsequently challenged with coccidiosis. I. performance, meat yield and intestinal lesion incidence1,2,3

Effects of the in ovo administration of vitamin D₃ (D₃) and 25-hydroxyvitamin D₃ (25OHD₃) on broiler intestinal lesion incidence, performance and breast meat yield after a coccidiosis challenge were investigated. On each of 10 incubator tray levels, 10 Ross 708 broiler hatching eggs were randomly assigned to each of the following 5 in ovo injection treatments administrated at 18 d of incubation (doi): 1) noninjected; 2) diluent; diluent containing either 3) 2.4 μg D₃ (D₃), 4) 2.4 μg 25OHD₃ (25OHD₃), or 5) 2.4 μg D₃ + 2.4 μg 25OHD₃ (D₃+25OHD₃). A 50 μL solution volume was injected into each egg using an Inovoject multi-egg injector. Four male chicks were randomly assigned to each of 80 battery cages in each of 2 rooms. Half of the treatment-replicate cages (8) in each room were challenged with a 20× live coccidial vaccine at 14 d of age (doa). One randomly selected bird from each of 4 treatment-replicate cages was scored for coccidiosis lesions before and 2 wk after challenge. Mean BW, BW gain (BWG), feed intake, and feed conversion ratio were determined for all birds from 0 to 14, 15 to 28, and 29 to 41 doa. Carcass weight, and the absolute and relative (% of carcass weight) weights of carcass parts were determined in 3 birds per treatment-replicate cage at 42 doa. Hatchability of live embryonated injected eggs and hatch residue were not affected by treatment. Across challenge treatment, birds in the 25OHD₃ treatment group experienced an increase in BWG between 29 and 41 doa when compared to the D₃ or diluent-injected birds. Furthermore, pectoralis major muscle percentage tended (P = 0.059) to increase in birds belonging to the 25OHD₃ treatment in comparison to birds in the D₃ or diluent-injected treatments. These results indicate that regardless of challenge treatment, 2.4 μg of 25OHD₃ may increase the BWG and breast meat yield of birds relative to those that only received an injection of commercial diluent.

Effects of the in ovo injection of vitamin D3 and 25-hydroxyvitamin D3 in Ross 708 broilers subsequently fed commercial or calcium and phosphorus-restricted diets. II. Immunity and small intestine morphology1,2,3

Effects of the in ovo injection of vitamin D₃ (D₃) and 25-hydroxyvitamin D₃ (25OHD₃) on the immunity and small intestine morphology of broilers fed calcium and phosphorus-restricted diets were investigated. At 18 d of incubation (doi), live embryonated Ross 708 broiler hatching eggs were in ovo-injected with a 50 μL solution of one of the following treatments using an Inovoject multiegg injector: 1) diluent (control); diluent containing either 2) 2.4 μg D₃; 3) 2.4 μg 25OHD₃; or 4) 2.4 μg D₃ + 2.4 μg 25OHD₃. At hatch, 18 randomly selected male broilers belonging to one of the 4 in ovo injection treatments were placed in each of 12 floor pens and were fed either a commercial diet or a diet restricted by 20% in calcium and available phosphorus (ReCaP) content for the starter, grower and finisher dietary phases. Concentrations of plasma IgG and IgM at 14 d of age (doa) and α-1-acid glycoprotein at 40 doa were determined. Bursa, liver, spleen, duodenum, jejunum, and ileum weights were recorded at 7, 14, and 40 doa and small intestine histology was evaluated at 14 and 40 doa. Blood and organ samples were randomly collected from 1 bird in each of the 6 replicate pens within each of the 8 (4 in ovo x 2 dietary) treatment groups. Plasma IgG levels were higher in 25OHD₃ than in diluent or D₃ in ovo-injected birds. At 14 doa, a higher jejunal villus length (VL) to crypt depth (CD) ratio (RVC) was observed in birds that were in ovo-injected with 25OHD₃ alone as compared to all other in ovo injection treatments. At 40 doa, ileal VL increased and jejunal CD decreased in commercial diet-fed birds compared to ReCaP diet-fed birds. In conclusion, the in ovo injection of 25OHD₃ alone increased the immune response and improved the small intestine morphology and subsequent nutrient uptake of Ross 708 broilers. However, a ReCaP diet was observed to be detrimental to their small intestine morphology.

Implications of Vitamin D Research in Chickens can Advance Human Nutrition and Perspectives for the Future

The risk of vitamin D insufficiency in humans is a global problem that requires improving ways to increase vitamin D intake. Supplements are a primary means for increasing vitamin D intake, but without a clear consensus on what constitutes vitamin D sufficiency, there is toxicity risk with taking supplements. Chickens have been used in many vitamin-D-related research studies, especially studies involving vitamin D supplementation. Our state-of-the-art review evaluates vitamin D metabolism and how the different hydroxylated forms are synthesized. We provide an overview of how vitamin D is absorbed, transported, excreted, and what tissues in the body store vitamin D metabolites. We also discuss a number of studies involving vitamin D supplementation with broilers and laying hens. Vitamin D deficiency and toxicity are also described and how they can be caused. The vitamin D receptor (VDR) is important for vitamin D metabolism; however, there is much more to understand about VDR in chickens. Potential research aims involving vitamin D and chickens should explore VDR mechanisms that could lead to newer insights into VDR. Utilizing chickens in future research to help elucidate vitamin D mechanisms has great potential to advance human nutrition. Finding ways to increase vitamin D intake will be necessary because the coronavirus disease 2019 (COVID-19) pandemic is leading to increased risk of vitamin D deficiency in many populations. Chickens can provide a dual purpose with addressing pandemic-caused vitamin D deficiency: 1) vitamin D supplementation gives chickens added-value with the possibility of leading to vitamin-D-enriched meat and egg products; and 2) using chickens in research provides data for translational research. We believe expanding vitamin-D-related research in chickens to include more nutritional aims in vitamin D status has great implications for developing better strategies to improve human health.

Effects of the in ovo injection of vitamin D3 and 25-hydroxyvitamin D3 in Ross 708 broilers subsequently fed commercial or calcium and phosphorus-restricted diets. I. Performance, carcass characteristics, and incidence of woody breast myopathy1,2,3

Effects of the in ovo-injection of vitamin D₃ (D₃) and 25-hydroxyvitamin D₃ (25OHD₃) on broiler performance, carcass characteristics, and woody breast myopathy (WBM) incidence were investigated. Live embryonated Ross 708 broiler hatching eggs (2,880) were randomly assigned to one of the following in ovo injection treatments: (1) diluent (50 μL); diluent (50 μL) containing either (2) 2.4 μg D₃; (3) 2.4 μg 25OHD₃; or (4) 2.4 μg D₃ + 2.4 μg 25OHD₃. Eggs were injected at 18 d of incubation (doi) using an Inovoject multiegg injector. At hatch, 18 male chicks were randomly placed in each of 6 replicate pens belonging to each in ovo injection and, dietary treatment combination. Birds were fed either a commercial diet or a diet restricted in calcium and phosphorous (ReCaP) content by 20% for the starter, grower and finisher dietary phases. Broiler performance was determined in each dietary phase and breast muscle yield was also determined at 14 and 40 d of age (doa). At 41 and 46 doa, birds were processed for determination of WBM, carcass weight, and the absolute and relative (% of carcass weight) weights of various carcass parts. Compared to birds fed the commercial diet, birds fed ReCaP diets experienced a reduction in performance from 14 to 40 doa, in breast meat yield at 41 and 46 doa, and in WBM at 41 and 46 doa. At 14 and 40 doa, breast meat yield in birds that received an in ovo injection of 25OHD₃ alone was higher compared to birds that received diluent alone or a combination of D₃ and 25OHD₃. Lower WBM incidence in ReCaP-fed birds was associated with a lower breast weight. An increase in breast meat yield in response to 25OHD₃ alone may be due to improved immunity and small intestine morphology. However, further study is needed to determine the aforementioned effects.

Improvement in the performance and inflammatory reaction of Ross 708 broilers in response to the in ovo injection of 25-hydroxyvitamin D3

The effects of the in ovo administration of vitamin D₃ (D₃) and its metabolite, 25-hydroxyvitamin D₃ (25OHD₃)_, on the performance, breast meat yield, and inflammatory responses of broilers fed commercial diets were investigated. Live embryonated Ross 708 broiler hatching eggs were randomly assigned to one of the following 5 in ovo injection treatments at 18 d of incubation: 1) noninjected; 2) diluent; diluent containing 3) 2.4-μg D₃, 4) 2.4-μg 25OHD₃, or 5) 2.4-μg D₃ + 2.4-μg 25OHD₃. A 50-μL solution volume of each prespecified treatment was injected into each egg using an Inovoject multiegg injector. At hatch, 18 male chicks were randomly assigned to each of 30 floor pens. The BW, BW gain, feed intake, and feed conversion ratio of the birds were determined in each dietary phase. At 14, 28, and 39 d of posthatch age (doa), plasma α-1-acid glycoprotein (AGP) levels in 1 bird in each of 6 replicate pens per treatment were determined at 14 and 39 doa. The pectoralis major and minor weights of those same birds were also determined. The remaining birds were processed at 43 doa, and the weights of their processing parts were determined. At 39 doa, the in ovo injection of 25OHD₃ alone decreased plasma AGP concentrations in comparison with the noninjected, diluent, and D₃-alone treatment groups. In addition, birds that received 25OHD₃ alone had a greater BW at 42 doa than birds in the noninjected, diluent, and D₃-alone treatment groups. At 39 and 43 doa, breast meat yield was increased in response to the in ovo injection of 25OHD₃ alone in comparison to all other treatments. These results indicate that the in ovo injection of 2.4 μg of 25OHD₃ resulted in an improvement in the performance and inflammatory responses of broilers. A reduction in the inflammatory response subsequent to the in ovo injection of 2.4 μg of 25OHD₃ may have led to an increase in broiler performance.

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.

Effects of source and level of in ovo-injected vitamin D3 on the hatchability and serum 25-hydroxycholecalciferol concentrations of Ross 708 broilers

Effects of the in ovo injection of vitamin D3 (D3) and 25-hydroxycholecalciferol (25OHD3) on broiler embryo serum 25OHD3 concentrations, hatchability, and hatchling somatic characteristics were determined. Eggs from a 35-wk-old commercial Ross 708 broiler breeder flock were set in a single-stage incubator with 11 treatments represented on each of 8 incubator tray levels (blocks). Each treatment group within a flat on each tray level contained 30 eggs. Control treatments were noninjected and diluent injected. Vitamin treatments were commercial diluent containing 0.6 μg D3, 0.6 μg 25OHD3, 0.6 μg D3 + 0.6 μg 25OHD3, 1.2 μg D3, 1.2 μg 25OHD3, 1.2 μg D3 + 1.2 μg 25OHD3, 2.4 μg D3, 2.4 μg 25OHD3, or 2.4 μg D3 + 2.4 μg 25OHD3. At 432 h of incubation (hoi), 50-μL solution volumes were injected. Blood samples were collected at 462 hoi for serum 25OHD3 analysis, and hatchability of injected live embryonated eggs (HI) was determined at 492 and 516 hoi. At 516 hoi, hatchling yolk-free BW and weights of the liver and yolk sac were determined. Percentage of yolk moisture and dry mater was calculated. At 492 and 516 hoi, HI did not differ between treatments. Embryos that received 1.2 μg or more of either vitamin D3 source alone or in combination had higher serum 25OHD3 concentrations than those that were injected with diluent alone or diluent containing 0.6 μg of D3. Hatchlings that received 1.2 or 2.4 μg of 25OHD3 had higher percentage of yolk dry matter or lower percentage of yolk moisture levels than noninjected controls and those that received D3 alone at any level. These results indicate that the in ovo injection of either vitamin D3 source at levels equal to or higher than 1.2 μg resulted in serum 25OHD3 concentrations that were higher than that of noninjected controls. In addition, the in ovo injection of 1.2 μg or higher of either vitamin D3 source did not negatively affect broiler HI or chick quality.

Dietary supplementation with canthaxanthin and 25-hydroxycholecalciferol has beneficial effects on bone and oxidative metabolism in European quail breeders

This study aimed to investigate the effect of supplementation with canthaxanthin (Cx) and 25-hydroxycholecalciferol (25-OH-D₃) on the production performance, egg quality, bone mineral content, blood biochemical parameters, and antioxidant status of European quail breeders. Two hundred and forty quail breeders were distributed in a completely randomized design with 5 diets and 8 replicates of 4 females and 2 males were used. All quail breeders received one of 5 diets: basal diet (containing 2,000 IU vitamin D₃) or the same diet supplemented with 3 ppm Cx and 34.5 μg 25-OH-D₃, 6 ppm Cx and 69 μg 25-OH-D₃, 9 ppm Cx and 103.5 μg 25-OH-D₃, or 12 ppm Cx and 138 μg 25-OH-D₃. Production performance and internal and external egg quality parameters were not influenced by diet. Eggshell dry weight decreased linearly with increasing supplementation levels, and eggshell ash and calcium content increased quadratically. Plasma phosphorus, calcium, and ionic calcium levels in females and plasma ionic calcium levels in males showed a positive quadratic response to dietary supplementation. Femoral and tibiotarsal dry weight and calcium content were influenced by diet. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity in the liver of males and females and in the serum of females showed a positive quadratic relationship with Cx and 25-OH-D₃ levels, whereas the malonaldehyde concentration showed a negative quadratic relationship. DPPH scavenging activity in the serum of male quail increased linearly with supplementation. There was a positive quadratic effect on superoxide dismutase gene expression and a positive linear effect on glutathione peroxidase 7 gene expression, suggesting that dietary enrichment with Cx and 25-OH-D₃ might help protect spermatozoa against oxidative damage. The dietary supplement was pro-oxidative at high concentrations (above 9 ppm Cx). The results indicate that diets with adequate levels of Cx and 25-OH-D₃ have a beneficial effect on calcium and phosphorus metabolism as well as on the antioxidant defense system. We recommend supplementing European quail breeders in the laying period with 6 ppm Cx and 69 μg 25-OH-D₃.

Interactions between dietary calcium and phosphorus level, and vitamin D source on bone mineralization, performance, and intestinal morphology of coccidia-infected broilers1

Coccidiosis penalizes calcium (Ca), phosphorus (P), and fat-soluble vitamin status, as well as bone mineralization in broiler chickens. We hypothesized that dietary vitamin D (VitD) supplementation in the form of 25-hydroxycholecalciferol (OHD), compared to cholecalciferol (D3), would improve bone mineralization in broilers receiving marginally deficient Ca/P diets, with more pronounced effects during malabsorptive coccidiosis. In a 2 VitD source × 2 Ca/P levels × 2 levels of infection factorial experiment (n = 6 pens per treatment, 6 birds/pen), Ross 308 broilers were assigned to an Aviagen-specified diet supplemented with 4,000 IU/kg of either OHD or D3 between days 11 and 24 of age. The diet contained adequate (A; 8.7:4.4 g/kg) or marginally deficient (M; 6.1:3.1 g/kg) total Ca and available (av)P levels. At day 12 of age, birds were inoculated with water (C) or 7,000 Eimeria maxima oocysts (I). Pen performance was measured over 12 days post-infection (pi). One bird per pen was assessed for parameters of bone mineralization and intestinal histomorphometric features (day 6 and 12 pi), as well as E. maxima replication and gross lesions of the small intestine (day 6 pi). There was no interaction between infection status and Ca/avP level on bone mineralization. Bone breaking strength (BS), ash weight (AW), and ash percentage (AP) were highest in broilers fed the OHD-supplemented A diets irrespective of infection status. Eimeria maxima infection impaired (P < 0.05) ADG and FCR pi; Ca and P status at day 6 pi; OHD status, BS, AW, and AP at day 12 pi; and intestinal morphology at day 6 and 12 pi. A- compared to M-fed broilers had higher BS, AW, and AP at day 6 pi, and AW at day 12 pi. VitD source affected only OHD status, being higher (P < 0.001) for OHD- than D3-fed broilers at day 6 and 12 pi. In conclusion, offering OHD and adequate levels of Ca and P improved bone mineralization, with no effect on performance. Dietary D3 and OHD supplemented at 4,000 IU/kg had similar effects on coccidiosis-infected and uninfected broilers, which led to the rejection of our hypothesis.

A reassessment of the vitamin D requirements of modern broiler genotypes

We hypothesized that performance and bone mineralization of 2 broiler lines will benefit from increasing vitamin D (vitD) supplementation above current commercial levels and by partial substitution of D3 by 25-OH-D3. Male Ross 308 and 708 chicks (n = 576), were offered diets with low (LD; 1,000), medium (MD; 4,000) or high levels of D3 (HD; 7,000 IU/kg), and medium levels of vitD where the majority of D3 was substituted by 25-OH-D3 (25MD; 1,000 D3+3,000 25-OH-D3 IU/kg). Performance was measured at the end of starter (day 10), grower (day 24), and finisher periods (day 38). Three birds per pen were dissected at the end of each period to assess tibia and femur ash percentage (%), ash weight, bone breaking strength (BBS), and serum levels of 25-OH-D3. Remaining birds were gait scored (GS) at day 37 of age. Genotype and diet did not interact for any trait, whilst performance was not affected by diet. Ross 708 had lower body weight (P < 0.005), higher feed conversion ratio over the grower period (P < 0.05), similar levels of 25-OH-D3, but higher GS (P < 0.05) than Ross 308. Serum 25-OH-D3 levels were affected by diet at the end of the starter and grower periods (P < 0.05), being lowest for LD and highest for 25MD. Diet affected GS (P < 0.01), being higher in LD than 25MD. Femur ash % was higher at the end of the starter and grower periods for 25MD than LD and for both HD and 25MD than LD (P < 0.05). Femur and tibia ash weight were higher for 25MD in comparison to LD birds (P < 0.05) at the end of the grower period. Femur and tibia BBS were higher (P < 0.05) for 25MD in comparison to LD at the end of the grower and finisher periods, respectively. Overall, effects of vitD supply were more pronounced for femur than for tibia mineralization. Results do not suggest supplementation of vitD above current maximum levels and support partial substitution by 25-OH-D3.

Effect of production system, supermarket and purchase date on the vitamin D content of eggs at retail

The vitamin D content of eggs from three retail outlets was measured over five months to examine the effects of production system (organic vs. free range vs. indoor), supermarket and purchase date on the concentration of vitamin D₃ and 25-hydroxyvitamin D₃. Results demonstrated a higher vitamin D₃ concentration in free range (57.2±3.1μg/kg) and organic (57.2±3.2μg/kg) compared with indoor (40.2±3.1μg/kg) (P<0.001), which was perhaps related to increased vitamin D synthesis by birds having more access to sunlight, while 25-hydroxyvitamin D₃ concentration was higher (P<0.05) only in organic eggs. The interaction (P<0.05) between system and supermarket for both forms of vitamin D may relate to some incorrect labelling. Concentration of 25-hydroxyvitamin D₃ was higher (P<0.05) in July and September than in August_. The results indicate variations in vitamin D concentrations in eggs from different sources, thus highlighting the importance of accurate labelling.

Effect of dietary canthaxanthin and 25-hydroxycholecalciferol supplementation on the performance of duck breeders under two different vitamin regimens

BACKGROUND

Dietary canthaxanthin (CX), 25-hydroxycholecalciferol (25-OH-D 3 ) and vitamins have been widely reported to be involved in productive and reproductive performance of broiler breeders. However, limited information is available for duck breeders. In this study, a total of 1,560 Cherry Valley SM3 duck breeder females and 312 males were used to assess if the addition of CX and 25-OH-D3 could increase the performance of duck breeders under two different dietary vitamin regimens. Four diets were used under a 2 × 2 factorial arrangement with 2 kinds of vitamin premixes (REGULAR and HIGH; HIGH premix had higher levels of all vitamins except K3 than REGULAR premix), and with or without the supplementation of the mixture of CX (6 mg/kg) and 25-OH-D3 (0.069 mg/kg). The ducks were fed ad libitum with pelleted diets based on corn-soybean meal from 38 to 77 wk of age.

RESULTS

HIGH vitamin premix decreased malondialdehyde (MDA) level (P < 0.001) of egg yolk, increased hatchability of fertile eggs (P = 0.029), increased hatchability of total eggs (P = 0.029), and decreased serum protein carbonyl level (P = 0.037) of breeder males. The mixture of CX and 25-OH-D3 increased serum calcium of breeder females (P = 0.010), decreased the cracked egg rate (P = 0.001), increased the pigmentation of egg yolk (P < 0.001) and male bill (P < 0.001), and decreased MDA level of egg yolk (P < 0.001) and male serum (P = 0.034). Interactive effects were observed in cracked egg rate (P = 0.038), shell thickness (P = 0.011) and serum phosphorus (P = 0.026) of breeder females. HIGH vitamin premix together with the mixture of CX and 25-OH-D3 decreased cracked egg rate and increased shell thickness of duck breeders. Serum phosphorus was decreased in duck breeder females fed REGULAR vitamin premix without the addition of the CX and 25-OH-D3 mixture.

CONCLUSIONS

Dietary HIGH vitamin premix increased antioxidant status of eggs and breeder males, and increased hatchability. The mixture of CX and 25-OH-D3 enhanced egg shell quality, and promoted pigmentation and antioxidant status of eggs and breeder males.

The effects of maternal dietary vitamin premixes, canthaxanthin, and 25-hydroxycholecalciferol on the performance of progeny ducklings

This trial studied the effects of maternal dietary vitamin premixes, and the mixture of canthaxanthin (CX) and 25-hydroxycholecalciferol (25-OH-D3) on the performance of progeny ducklings. Four maternal diets were used under a 2 × 2 factorial arrangement with 2 kinds of vitamin premixes (Regular and High; High premix had higher levels of all vitamins except K3 than the Regular premix), and with or without the addition of the mixture of CX (6 mg/kg) and 25-OH-D3 (0.069 mg/kg). Cherry Valley duck breeders (38-wk-old) were fed with corn-wheat flour-soybean meal-based diets for 8 wk, and then eggs were collected and hatched. Healthy ducklings (equal number of female and male) from each maternal group were randomly selected and received the same commercial starter (1 to 14 d) and grower (15 to 35 d) pellet diet for 35 d. Maternal High vitamin premix increased shank pigmentation (1 d, P = 0.001), BW (1 d, P < 0.001 and 14 d, P = 0.006), BW gain (1 to 14 d, P = 0.008), G:F ratio (1 to 14 d, P = 0.007), superoxide dismutase (SOD; 1 d liver, P = 0.027 and 14 d serum, P = 0.031), and total antioxidant capacity (1 d liver, P < 0.001); and decreased protein carbonyl (14 d serum, P = 0.011) of ducklings. The mixture of CX and 25-OH-D3 increased yolk pigmentation (P < 0.001); increased shank pigmentation (1 d, P < 0.001 and 14 d, P < 0.001), BW (1 d, P < 0.001), feed intake (15-35 d, P = 0.014), SOD (1 d liver, P = 0.032), and tibia ash (14 d, P = 0.010) of ducklings; and decreased malondialdehyde (P < 0.001) and protein carbonyl (P = 0.044) of yolks, and malondialdehyde (14 d serum, P < 0.001) of ducklings. In conclusion, either maternal High vitamin premix or maternal supplementation of the CX and 25-OH-D3 mixture improves growth performance and antioxidant status of ducklings.

Efficacy of 25-OH Vitamin D3 prophylactic administration for reducing lameness in broilers grown on wire flooring

Bacterial chondronecrosis with osteomyelitis (BCO) is the most common cause of lameness in commercial broilers. Growing broilers on wire flooring provides an excellent experimental model for reproducibly triggering significant levels of lameness attributable to BCO. In the present study we evaluated the efficacy of adding HyD (25-OH vitamin D3) to the drinking water as a preventative/prophylactic treatment for lameness. Broiler chicks were reared on 5 x 10 ft flat wire floor panels within 6 environmental chambers. Three chambers were supplied with tap water (Control group) and the remaining chambers were supplied with HyD (HyD group: 0.06 mL HyD solution/L water; dosing based on the HyD Solution label to provide 33.9 μg 25-OHD3/L) from d 1 through 56. Feed was provided ad libitum and was formulated to meet or exceed minimum standards for all ingredients, including 5,500 IU vitamin D3/kg. Lameness initially was detected on d 28, and the cumulative incidence of lameness on d 56 was higher in the Control group than in the HyD group (34.7 vs. 22.7%, respectively; P = 0.03; Z-test of proportions; chambers pooled). The most prevalent diagnoses for lame birds were osteochondrosis and osteomyelitis (BCO) of the proximal femora (52%) and tibiae (79%), accompanied by minor incidences of tibial dyschondroplasia (0.33%), spondylolisthesis, or kinky back (0.67%), and twisted legs (1%). Broilers that survived to d 56 without developing lameness did not differ in BW when compared by group within a gender. The wire flooring model imposes a rigorous, sustained challenge that undoubtedly is much more severe than typically would be experienced by broilers under normal commercial conditions. Therefore the encouraging response to HyD supplementation in the present study supports the potential for 25-OH vitamin D3 to attenuate outbreaks of lameness caused by BCO in commercial broiler flocks.

25-Hydroxycholecalciferol Enhances Male Broiler Breast Meat Yield through the mTOR Pathway

BACKGROUND

In recent years, there has been a growing body of evidence indicating that replacing cholecalciferol (vitamin D₃) with 25-hydroxycholecalciferol [25(OH)D₃] through dietary supplementation enhances breast meat yield in broiler chickens. However, the underlying molecular mechanisms are still unknown.

OBJECTIVE

We investigated the effect of 25(OH)D₃ on male broiler growth performance (body weight, feed intake, feed conversion ratio, and breast meat yield), muscle protein synthesis, and the potential underlying molecular mechanisms.

METHODS

Male Cobb 500 broiler chickens were divided into 4 body weight-matched groups and received a control diet with normal cholecalciferol (2760 IU/kg feed) for 42 d, a diet with high concentrations of cholecalciferol (5520 IU/kg feed) for 42 d, or a diet with 25(OH)D₃ (5520 IU/kg feed) for 42 d (HyD-42). A fourth group consumed the HyD-42 for 21 d and then control feed for 21 d (HyD-21) (n = 360 birds, 12 replicates/treatment). Food and clean water were available for ad libitum consumption. At the end of the 42-d experiment, protein turnover was measured by phenylalanine flooding dose. Breast muscle tissues were collected and protein synthesis-related gene and protein expression were measured by real time polymerase chain reaction and Western blot, respectively. Functional studies were performed in vitro with the use of a quail myoblast (QM7) cell line. QM7 cells were treated with 2 doses (1 nM and 10 nM) of cholecalciferol or 25(OH)D₃ alone or in combination with 100 nM rapamycin, and cell proliferation was determined by cell proliferation assay. Protein synthesis-related gene and protein expression were also determined.

RESULTS

The HyD-42 increased 25(OH)D₃ circulating concentrations by 126% (P < 0.05), enhanced breast meat yield (P < 0.05), and increased the fractional rate of protein synthesis by 3-fold (P < 0.05) compared with the control diet. Molecular analyses revealed that breast muscle from chickens consuming the HyD-42 expressed significantly higher concentrations of vitamin D receptor (VDR), phospho mechanistic target of rapamycin(Ser2481), phospho ribosomal P70 S6 kinase (RPS6K)(Thr421/Ser424), and antigen Ki-67 (Ki67) compared with the other groups. In line with the in vivo data, in vitro functional studies showed that cells treated with 25(OH)D₃ for 24 h had increased VDR expression, and activated the mechanistic target of rapamycin (mTOR)/S6 kinase (S6K) pathway, enhanced Ki67 protein concentrations, and induced QM7 cell proliferation compared with untreated or cholecalciferol-treated cells. Blocking the mTOR pathway with rapamycin reversed these effects.

CONCLUSION

Taken together, our findings provide evidence that the effects of 25(OH)D₃ on male broiler breast muscle are likely mediated through the mTOR-S6K pathway.

Effect of vitamin D status improvement with 25-hydroxycholecalciferol on skeletal muscle growth characteristics and satellite cell activity in broiler chickens

Skeletal muscle satellite cells (SC) play a critical role in the hypertrophic growth of postnatal muscle. Increases in breast meat yield have been consistently observed in broiler chickens fed 25-hydroxycholecalciferol (25OHD3), but it is unclear whether this effect is mediated by SC. Thus, our objective was to determine the effect of vitamin D status improvement by replacing the majority of dietary vitamin D3 (D3) with 25OHD3 on SC activity and muscle growth characteristics in the pectoralis major (PM) and the biceps femoris (BF) muscles. Day-old, male Ross 708 broiler chickens (n = 150) were fed 1 of 2 corn and soybean meal-based diets for 49 d. The control diet (CTL) contained 5,000 IU D3 per kg of diet and the experimental diet (25OHD3) contained 2,240 IU D3 per kg of diet + 2,760 IU 25OHD3 per kg of diet. Ten birds per treatment were harvested every 7 d. Two hours before harvest, birds were injected intraperitoneally with 5'-bromo-2'deoxyuridine (BrdU) to label mitotically active cells. Blood was collected from each bird at harvest to measure circulating concentrations of 25OHD3, a marker of vitamin D status. The PM and BF muscles were weighed and processed for cryohistological determination of skeletal muscle fiber cross-sectional area, enumeration of Myf-5+ and Pax7+ SC, and mitotically active (BrdU+) SC using immunofluorescence microscopy. Circulating 25OHD3 concentrations were greater in 25OHD3-fed birds on d 7, 14, 21, 28, 35, 42, and 49 when compared with CTL (P < 0.001). Growth performance and feed efficiency did not differ among dietary treatments (P > 0.10). Improved vitamin D status as a result of feeding 25OHD3 increased the number of mitotically active (Pax7+;BrdU+) SC (P = 0.01) and tended to increase the density of Pax7+ SC (P = 0.07) in the PM muscles of broilers on d 21 and 35, respectively. Broiler chickens fed 25OHD3 also tended to have greater Myf-5+ SC density (P = 0.09) on d 14, greater total nuclear density (P = 0.05) on d 28, and a greater muscle fiber cross-sectional area (P = 0.09) on d 49 in their PM muscles compared with CTL birds. Collectively, these results suggest that improvement of vitamin D status by replacing the majority of D3 in the diet with 25OHD3 can stimulate SC activity in the predominantly fast-twitch PM muscle and provide evidence toward understanding the mechanism behind previously observed increases in breast meat yield in 25OHD3-fed commercial broiler chickens.

An evaluation of the effects of added vitamin D3 in maternal diets on sow and pig performance

A total of 84 sows (PIC 1050) and their litters were used to determine the effects of supplementing maternal diet with vitamin D3 on sow and pig performance, serum 25-hydroxyvitamin D3 (25(OH)D3), milk vitamin D3, neonatal bone mineralization, and neonatal tissue vitamin D3. After breeding, sows were randomly assigned to 1 of 3 dietary vitamin D3 treatments (1,500, 3,000, or 6,000 IU/kg of complete diets). Sows were bled on d 0 and 100 of gestation and at farrowing and weaning (d 21). Pig BW was recorded at birth and weaning, and serum was collected from 2 pigs/litter at birth, on d 10 and at weaning. A total of 54 pigs (18/treatment) were euthanized at birth and necropsied to sample bones and tissues. Sow and suckling pig performance and neonatal bone ash and bone density did not differ among maternal vitamin D3 treatments; however, sow 25(OH)D3 and milk vitamin D3 increased (linear, P < 0.01) with increasing maternal vitamin D3 supplementation. Piglet serum 25(OH)D3 increased (quadratic, P < 0.03) with increased maternal vitamin D3. Neonatal kidney vitamin D3 tended (quadratic, P = 0.08) to decrease with increasing maternal vitamin D3, but liver vitamin D3 tended (linear, P = 0.09) to increase with increasing maternal vitamin D3. At weaning, a subsample of 180 pigs (PIC 327 × 1050) were used in a 3 × 2 split plot design for 35 d to determine the effects of maternal vitamin D3 and 2 levels of dietary vitamin D3 (1,800 or 18,000 IU/kg) from d 0 to 10 postweaning on nursery growth and serum 25(OH)D3. Overall (d 0 to 35), nursery ADG and G:F were not affected by either concentration of vitamin D3, but ADFI tended (quadratic, P < 0.06) to decrease with increasing maternal vitamin D3 as pigs from sows fed 3,000 IU had lower ADFI compared with pigs from sows fed 1,500 or 6,000 IU/kg. Nursery pig serum 25(OH)D3 increased with increasing maternal vitamin D3 (weaning) on d 0 (linear, P < 0.01), and maternal × diet interactions (P < 0.01) were observed on d 10 and 21 because pigs from sows fed 1,500 IU had greater increases in serum 25(OH)D3 when fed 18,000 IU compared with pigs from sows fed 3,000 IU. In conclusion, sow and pig serum 25(OH)D3, milk vitamin D3, and neonatal tissue vitamin D3 can be increased by increasing maternal vitamin D3, and nursery pig 25(OH)D3 can be increased by increasing dietary vitamin D3; however, sow and pig performance and neonatal bone mineralization was not influenced by increasing vitamin D3 dietary levels.

Triennial Growth Symposium--A role for vitamin D in skeletal muscle development and growth

Although well known for its role in bone development and mineral homeostasis, there is emerging evidence that vitamin D is capable of functioning as a regulator of skeletal muscle development and hypertrophic growth. This review will focus on the relatively limited body of evidence regarding the impact of vitamin D on prenatal development and postnatal growth of skeletal muscle in meat animal species. Recent evidence indicating that improvement of maternal vitamin D status through dietary 25-hydroxycholecalciferol supplementation can positively affect fetal skeletal muscle fiber number and myoblast activity in swine as well as work demonstrating that posthatch vitamin D status enhancement stimulates a satellite cell-mediated skeletal muscle hypertrophy response in broiler chickens is discussed. The relative lack of information regarding how and when to best supply dietary vitamin D to promote optimal prenatal development and postnatal growth of skeletal muscle provides an exciting field of research. Expansion of knowledge in this area will ultimately improve our ability to efficiently and effectively produce the livestock required to meet the increasing worldwide demand for meat products.

Improvement of maternal vitamin D status with 25-hydroxycholecalciferol positively impacts porcine fetal skeletal muscle development and myoblast activity

There is little information available regarding the influence of maternal vitamin D status on fetal skeletal muscle development. Therefore, we investigated the effect of improved vitamin D status resulting from 25-hydroxycholecalciferol (25OHD3) supplementation of dams on fetal skeletal muscle developmental characteristics and myoblast activity using Camborough 22 gilts (n = 40) randomly assigned to 1 of 2 corn-soybean meal-based diets. The control diet (CTL) contained 2,500 IU cholecalciferol (D3)/kg diet, whereas the experimental diet contained 500 IU D3/kg diet plus 50 µg 25OHD3/kg diet. Gilts were fed 2.7 kg of their assigned diet once daily beginning 43 d before breeding through d 90 of gestation. On gestational d 90 (± 1), fetal LM and semitendinosus muscle samples were collected for analysis of developmental characteristics and myoblast activity, respectively. No treatment difference was observed in fetal LM cross-sectional area (P = 0.25). Fetuses from 25OHD3-supplemented gilts had more LM fibers (P = 0.04) that tended to be smaller in cross-sectional area compared with CTL fetuses (P = 0.11). A numerical increase in the total number of Pax7+ myoblasts was also observed in fetuses from 25OHD3-supplemented gilts (P = 0.12). Myoblasts derived from the muscles of fetuses from 25OHD3-fed dams displayed an extended proliferative phase in culture compared with those from fetuses of dams fed only D3 (P < 0.0001). The combination of additional muscle fibers and Pax7+ myoblasts with prolonged proliferative capacity could enhance the postnatal skeletal muscle growth potential of fetuses from 25OHD3-supplemented gilts. These data highlight the importance of maternal vitamin D status on the development of fetal skeletal muscle.

Effects of supplemental 25-hydroxycholecalciferol on growth performance, small intestinal morphology, and immune response of broiler chickens

Three experiments were conducted to evaluate the effects of 25-hydroxycholecalciferol (25-OH-D(3)) on the growth performance, small intestinal morphology, and immune response of broiler chickens. In experiment 1, 25-OH-D(3) neither increased nor decreased weight gain and feed efficiency compared with the controls during the 39-d feeding period. Birds fed 25-OH-D(3) exhibited numerically higher phagocytosis (45%) than the controls (35%). In experiment 2, chicks were fed diets similar to those used in experiment 1 and were killed at 7, 14, 21, 28, and 35 d of age to determine the relative weight and histology of the small intestine. The relative weight of the small intestine from birds fed 25-OH-D(3) was numerically lower (P < 0.1) at 7 d of age. It was found that 25-OH-D(3) consistently resulted in longer (P < 0.05) villus length of the duodenum in 21- and 28-d-old birds and of the jejunum in 14- and 28-d-old birds. Shorter (P < 0.05) crypt depth was observed in the duodenum at 14 d of age and in the jejunum at 21 and 28 d of age. A higher (P < 0.05) ratio of villus length to crypt depth was also observed in the duodenum and jejunum at 14, 21, and 28 d of age of birds fed 25-OH-D(3). The thickness of muscle layer increased in the duodenum at 14, 28, and 35 d of age in birds fed 25-OH-D(3). In experiment 3, birds were orally challenged with either Luria-Bertani broth or Salmonella Typhimurium E29 at 7 and 14 d of age. Uninfected birds fed 25-OH-D(3) had lower total serum IgA at 14 d of age and lower total serum IgG at 21 d of age. However, infected birds fed 25-OH-D(3) produced higher (P < 0.1) total serum IgG at 21 d of age. The results of this study suggest that supplemental 25-OH-D(3) improves small intestinal morphology and protective humoral immunity to infection.

Reproductive performance and bone status markers of gilts and lactating sows supplemented with two different forms of vitamin D

In swine nutrition, little is known about the vitamin D requirements for reproductive processes and bone health. Consequently, the vitamin D recommendation for sows during gestation and lactation is not based on scientific reports. The current study was undertaken to obtain information on the dose-response pattern of 2 vitamin D sources, the commonly used cholecalciferol, called vitamin D(3), and a newly developed Hy.D product (25-hydroxycholecalciferol). In Exp. 1, a total of 160 gilts were randomly assigned from the first estrus until d 28 of gestation to dietary treatments containing 4 concentrations of 1 of the 2 different vitamin D sources [200, 800, 1,400, and 2,000 IU/kg of vitamin D from cholecalciferol or corresponding doses of 5, 20, 35, and 50 microg/kg of feed from 25(OH)D(3) (Hy.D)]. In a concurrent experiment, the same 8 dietary treatments were provided to 160 multiparous sows from the first day of mating until weaning. Plasma concentrations of 25(OH)D(3) were influenced by a dose x form interaction (P < 0.001); furthermore, plasma 25(OH)D(3) concentrations were influenced by the lactation state of the sows. Irrespective of the dietary dose and form of vitamin D provided to the sows, very little vitamin D was transferred to the progeny. Reproductive performance was not influenced by dietary vitamin D treatments, except for a decreased number of stillborn piglets (P = 0.03, SE = 0.40) with the larger doses of vitamin D (1,400 and 2,000 IU of vitamin D, resulting in 1.17 and 1.13 stillborn piglets per litter, respectively) compared with the smaller doses of vitamin D (200 and 800 IU of vitamin D, resulting in 1.98 and 1.99 stillborn piglets per litter, respectively). In the gilt trial, the ultimate strength of the bones (P = 0.01) and their content of ash (P = 0.02) were greater when vitamin D(3) was supplemented in doses larger than 800 IU, compared with the same amount of Hy.D supplementation. In the sow experiment, lactation day (P < 0.001), rather than dietary vitamin D, influenced the concentrations of osteocalcin and Ca as well as the activities of total alkaline phosphatase and bone alkaline phosphatase in plasma. Age of the suckling piglets affected their plasma bone health markers. In conclusion, at doses greater than 200 IU, Hy.D was more bioavailable than vitamin D(3) and, as such, could be considered an equivalent or even more advantageous source of vitamin D. In addition, a dietary dose of approximately 1,400 IU of vitamin D is recommended for reproducing swine. Irrespective of the dietary dose and form of vitamin D provided to the sows, very little vitamin D was transferred to the progeny.

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.