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 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.

Sodium and anion transport across the avian uterine (shell gland) epithelium

The uterine (shell gland) epithelium from the domestic chicken was mounted in Ussing chambers, bathed in symmetric avian saline solution on both apical and basolateral aspects and voltage clamped at 0 mV. The epithelium exhibited a basal short circuit current (I(sc)) that was partially inhibited by the epithelial Na(+) channel (ENaC) blockers, amiloride and benzamil (IC(50) values of 0.8 and 0.12 micromol l(-1), respectively). Inhibition of basal Na(+) absorption by 10 micromol l(-1) amiloride was confirmed by measurements of transepithelial Na(+) and Cl(-) fluxes, where inhibition of the apical-to-basolateral and net Na(+) flux occurred, but no significant effects on Cl(-) fluxes were detected. The amiloride-insensitive portion of the basal I(sc) was both Cl(-) and HCO(3)(-) dependent and was inhibited by the Cl(-) channel blocker, diphenyl-2-carboxylate (DPC; 100 micromol l(-1)). Stimulation with 8-(4-chlorophenylthio)-cyclic 3'-5', adenosine monophosphate (8-cpt cAMP) produced a sustained increase in I(sc) that was dependent on both Cl(-) and HCO(3)(-). The magnitude of the amiloride-sensitive I(sc) was approximately twofold greater in birds where shell formation was complete, but oviposition had not yet occurred. In addition, the amiloride-sensitive I(sc) was greater in hens over the age of 55 weeks and in molting birds. The anion-dependent component of the basal I(sc) was reduced in older birds, and electrogenic HCO(3)(-) transport was nearly absent in molting birds. These results demonstrated that electrogenic Na(+) transport in avian shell gland was similar to the mammalian uterine epithelium and increased with age and during molting. Electrogenic Cl(-) and HCO(3)(-) transport were coupled under basal and cAMP stimulated conditions and basal anion transport decreased with age and during molting.

Role of estrogen in avian osteoporosis

One of the difficulties associated with commercial layer production is the development of osteoporosis in hens late in the production cycle. In light of this fact and because of hens' unique requirements for Ca, many studies have focused on the regulation of Ca and the role of estrogen in this process. The time course of estrogen synthesis over the productive life of hens has been well documented; increased circulating estrogen accompanies the onset of sexual maturity while decreases signal a decline in egg production prior to a molt. Numbers of estrogen receptors decrease with age in numerous tissues. The parallel changes in calcium-regulating proteins, primarily Calbindin D28K, and in the ability of duodenal cells to transport Ca, are thought to occur as a result of the changes in estrogen, and are also reversible by the molt process. In addition to the traditional model of estrogen action, evidence now exists for a possible nongenomic action of estrogen via membrane-bound receptors, demonstrated by extremely rapid surges of ionized Ca in chicken granulosa cells in response to 17beta-estradiol. Estrogen receptors have also been discovered in duodenal tissue, and tamoxifen, which binds to the estrogen receptor, has been shown to cause a rapid increase in Ca transport in the duodenum. In addition, recent evidence also suggests that mineralization of bone per se may not explain entirely the etiology of osteoporosis in the hen but that changes in the collagen matrix may contribute through decreases in bone elasticity. Taken together, these studies suggest that changes in estrogen synthesis and estrogen receptor populations may underlie the age-related changes in avian bone. As with postmenopausal women, dietary Ca and vitamin D are of limited benefit as remedies for osteoporosis in the hen.

1alpha-hydroxycholecalciferol has little effect on phytate phosphorus utilization in laying hen diets

Previous research in our laboratory demonstrated marked increases in phytate P utilization when P-deficient corn-soybean meal diets were supplemented with 1a-hydroxycholecalciferol [1alpha-(OH) D3] and fed to chicks. Our objective was to determine if 1alpha-(OH) D3 would improve phytate P utilization when supplemented to vitamin D-adequate laying hen diets. The five experimental treatments were 1) P-deficient corn-soybean basal diet [17% CP, 3.8% Ca, and 0.10% nonphytate NPP)], 2) basal with 2.5 microg/kg 1alpha-(OH) D3, 3) basal with 5 microg/kg 1alpha-(OH) D3, 4) basal with 10 microg/kg 1alpha-(OH) D3, and 5) basal with 0.35% supplemental inorganic P (0.45% NPP, positive control). Diets were fed to six replicate groups of 12 HyLine W-98 White Leghorn laying hens from 44 to 52 wk of age. Hen-day egg production was significantly depressed by 47 wk of age for the basal diet treatment and by 47, 49, and 48 wk of age, respectively, for the 2.5, 5, and 10 microg/kg of 1alpha-(OH) D3 treatments compared to the positive control diet. Supplementation with 5 or 10 microg/kg 1alpha-(OH) D3 did improve (P < 0.05) egg production, but egg production for those treatments was much lower than that for the 0.45% NPP treatment. Our results indicate that 1alpha-(OH) D3 did not substantially improve P utilization in laying hens fed corn-soybean meal diets.

The effects of 1,25-dihydroxycholecalciferol and phytase on the natural phytate phosphorus utilization by laying hens

Two experiments were conducted to investigate the effects of supplementing a corn-soybean layer diet with either phytase, 1,25-dihydroxycholecalciferol [1,25-(OH)2D3], or their combination. The basal diet was formulated to contain 3.00% Ca and 0.33% total P. In Experiment 1, 160, 56-wk-old laying hens were randomly assigned to treatment groups fed either the basal diet alone or diets supplemented with either 600 phytase units (FTU) per kilogram feed, 5 microg 1,25-(OH)2D3/kg feed, or their combination for an experimental period of 9 wk. Experiment 2 had the same design and treatment groups except that laying hens 24 wk of age were used for 8 wk. In both experiments, phytase had a positive effect on BW and increased plasma dialyzable P, tibia bone ash, and phytate P retention. In the first experiment, the addition of phytase, 1,25-(OH)2D3, or their combination prevented a rapid decrease in egg production due to a Mycoplasma gallisepticum infection observed in hens fed the basal diet. However, no benefit in egg production was obtained in the second experiment. No effects on egg weight and egg specific gravity were observed in both experiments. These results clearly indicate that phytase, and to a lesser extent 1,25-(OH)2D3, can be used to increase the utilization of phytate P by laying hens.

Studies on effects of nutritional factors on bone structure and osteoporosis in laying hens

1. A modern hybrid strain of laying hen (Hisex) was fed from point of lay to 68 weeks on a control diet and diets containing oystershell, fluoride, 1,25-dihydroxycholecalciferol, ascorbic acid, a lower concentration of phosphorus and a combination of a lower concentration of crude protein and higher concentration of vitamin K. Hens from a much older strain (Brown Leghorn J-line) were fed on the control diet. 2. Plasma variables were measured during lay. End-of-lay trabecular and medullary bone volumes in the proximal tarsometatarsus and free thoracic vertebra were measured by histomorphometry. 3. The majority of Hisex hens were considered to be osteoporotic by the end of lay. In contrast, none of the J-line were osteoporotic. 4. None of the nutritional treatments affected trabecular bone volumes. Medullary bone volumes were increased significantly by feeding oystershell or fluoride. 5. There was no phenotypic correlation between egg production and trabecular bone volume in the Hisex hens. 6. The experiment provided evidence that osteoporosis in laying hens, as assessed by trabecular bone volumes, is not caused by calcium deficiency and could not be prevented by any of the nutritional treatments studied.

25-hydroxycholecalciferol in poultry nutrition

Vitamin D is a complex of secosteroids that must undergo metabolic alterations to reach optimal biological activity. The parent compounds 1) ergocalciferol (D2) and 2) cholecalciferol (D3) can be synthesized in the leaves of many plants or in the skin of most animals, respectively. Transport of vitamin D steroids after absorption is associated with vitamin D binding proteins (DBP). In general, the relative binding affinities of the vitamin D steroids are: 25-hydroxy vitamin D3 [25-(OH)D3] = 24,25-dihydroxy vitamin D3 [24,25-(OH)2D3] = 25,26-dihydroxy vitamin D3 [25,26-(OH)2D3] > 25-hydroxy vitamin D2 (25-(OH)D2) > 1,25-dihydroxy vitamin D3 [1,25-(OH)2D3] > vitamin D3. The DBP in poultry does not bind D2 forms effectively, and therefore poultry can not use this form of vitamin D adequately. The concentration of 25-(OH)D3 in blood seems to be well correlated with dietary vitamin D intake or exposure to ultraviolet light. The 1 alpha hydroxylase enzyme in the kidney is subject to negative feedback regulation and is critical for formation of the active metabolite 1,25-(OH)2D3. The intracellular vitamin D receptor (VDR) specifically binds 1,25-(OH)2D3 and is necessary for cellular action. Increased levels of two to three orders of magnitude are required for 25-(OH)D3 to compete with 1,25-(OH)2D3 for binding on VDR. Feeding studies with 25-(OH)D3 suggest it has nearly twice the activity of vitamin D3. Hatchability studies have shown that 25-(OH)D3 supports good fertility and hatchability, whereas hens fed only 1,25-(OH)2D3 did not have normal hatchability. Likewise, 1,25-(OH)2D3 seems to reach toxic levels at dietary concentrations only two to three times optimal dietary levels whereas feeding 25-(OH)D3 for extended periods at levels 8 to 10 times requirement seems to have no adverse effects. It seems that 25-(OH)D3 is the most active metabolite of vitamin D3, ultimately capable of supporting both cellular functions and embryonic development in chickens and turkeys when fed as the sole source of vitamin D3.

Effect of dietary contents of cholecalciferol, 1 alpha,25-dihydroxycholecalciferol and 24,25-dihydroxycholecalciferol on blood concentrations of 25-hydroxycholecalciferol, 1 alpha,25-dihydroxycholecalciferol, total calcium and eggshell quality

1. Withdrawal of cholecalciferol (D3) supplement from a layers diet drastically reduced blood 25-hydroxycholecalciferol (25-OH-D3), 1 alpha,25-dihydroxycholecalciferol (calcitriol) and egg specific gravity (SG) within two weeks, followed by a decrease in blood total calcium (Ca). 2. Doubling the D3 supplement in the control diet (27.5 micrograms or 1100 IU/kg) almost linearly increased the circulating concentration of 25-OH-D3 without raising the concentration of calcitriol, Ca, or egg SG. 3. Replacing D3 by the optimal concentration of calcitriol (5 micrograms/kg diet) improved egg SG after 21 weeks of treatment without increasing blood calcitriol or total Ca. 4. By itself, 24,25-dihydroxycholecalciferol [24,25-(OH)2D3] was unable to maintain normal blood levels of calcitriol, Ca or egg SG and, when added together with calcitriol in the diet, tended to elevate blood Ca but suppress the beneficial effect of calcitriol on shell quality, with little or no effect on blood calcitriol.

Effect of cimetidine on eggshell quality and plasma 25-hydroxycholecalciferol in laying hens

Experiments were conducted to investigate the effect of feeding cimetidine (CIMET), ranging from 0 to 750 mg/kg, on vitamin D3 metabolism and eggshell calcification in laying hens fed two levels of vitamin D3 (500 and 2,000 ICU/kg). Final BW and feed intake were not significantly affected by either CIMET or vitamin D3 level. Feeding 500 and 750 mg of CIMET significantly decreased total egg production in hens fed either level of vitamin D3, but no differences were observed at lower CIMET levels. Tibia ash decreased significantly in hens fed 150 to 750 mg of CIMET, regardless of the vitamin D3 level. Plasma Ca and inorganic P concentrations were decreased in hens fed high CIMET levels (500 and 750 mg/kg) at Week 2, but no differences were observed at Week 4. Feeding CIMET (500 and 750 mg/kg) significantly decreased plasma 25-hydroxycholecalciferol (25-OHD3) levels at Week 2 in hens fed both vitamin D3 diets but not at Week 4. Eggshell breaking force, shell thickness, and percentage shell weight were decreased significantly by CIMET in all experiments; however, in one experiment, shell quality recovered by Week 8. These results suggest that the CIMET-induced reduction in bone mineralization, eggshell quality, and plasma 25-OHD3 levels could be due to interference of CIMET with vitamin D3 metabolism in vitamin D3-replete laying hens. Shell quality decreased in CIMET-treated hens fed the higher vitamin D diet even though 250-HD3 plasma levels were three times higher than in hens fed the lower vitamin D diet, suggesting that CIMET affected shell quality through some mechanism other than inhibition of 250-HD3 synthesis.

Influence of vitamin D3, 1 alpha-hydroxyvitamin D3, and 1,25-dihydroxyvitamin D3 on eggshell quality, tibia strength, and various production parameters in commercial laying hens

Four hundred 53-wk-old Hyline W36 laying hens were randomly allocated to 10 treatments. The effects of feeding two vitamin D3 metabolites, 1 alpha-hydroxyvitamin D3 [1 alpha-(OH) D3] and 1,25-dihydroxyvitamin D3 [1,25-(OH)2 D3], each at five dietary levels (0, .75, 1.50, 3.00, and 4.50 micrograms/kg of feed) were determined on eggshell quality and tibia strength in commercial laying hens (Experiment 1). In Experiment 2, 1,440 Hyline W36 65-wk-old laying hens were used to determine the effects of four levels of vitamin D3 (0, 500, 1,000, and 1,500 ICU vitamin D3/kg) and three levels of dietary 1,25-(OH)2 D3 (0, .5, and 1.0 microgram/kg of feed) on eggshell quality, tibia strength, and egg production. In Experiment 1, neither 1,25-(OH)2 D3 nor 1 alpha-(OH) D3 affected eggshell quality or production criteria. Tibia weight was increased by adding either 1,25-(OH)2 D3 or 1 alpha-(OH) D3. In Experiment 2, 1,25-(OH)2 D3 increased percentage of shell, shell weight, and egg breaking strength when 0 ICU D3/kg was fed but had no effect at higher levels of vitamin D3. Egg production, feed consumption, and egg weight were also increased with supplemental 1,25-(OH)2 D3 when 0 ICU D3/kg was fed. Tibia weight and tibia breaking strength were also increased by adding 1,25-(OH)2 D3 to the diet. The commercial laying hen metabolizes sufficient 1,25-(OH)2 D3 from dietary vitamin D3 to maintain shell quality but not enough to maintain tibia strength.

Optimal dietary level of 1 alpha,25-dihydroxycholecalciferol for eggshell quality in laying hens

The optimal dietary level of 1 alpha,25-dihydroxycholecalciferol [1,25-(OH)2D3] for eggshell quality was established. White Leghorn hens, 59 wk of age, were fed one of eight diets that contained the same basal ingredients, including 3.1% calcium, but different levels (microgram/kg) or forms of calciferol supplements: no calciferol supplement of any form (56 hens); 27.5 (control) or 55.0 micrograms of cholecalciferol (56 hens each); 3, 5, or 7 micrograms of 1,25-(OH)2D3 (28 hens each); 5 micrograms of 24,25-dihydroxycholecalciferol [24,25-(OH)2D3] with 28 hens; 5 micrograms each of 1,25-(OH)2D3 and 24,25-(OH)2D3 (28 hens). All groups were fed the control diet prior to the 21-wk treatment. The group fed 5 micrograms 1,25-(OH)2D3/kg diet ranked first in specific gravity (SG), e.g., 1.081 versus 1.077 for the control group at Week 21 (P less than .05). The group fed 7 micrograms 1,25-(OH)2D3/kg consumed 30% less feed and laid 20% fewer eggs than the control, but shell quality was not affected. The groups receiving no calciferol supplement or receiving only 24,25-(OH)2D3 laid eggs with significantly lower SG than the control after 2 wk of treatment (1.072 or less versus 1.082 at Week 2). The rest of the treatment groups mentioned were comparable to the control in eggshell quality and egg production. Groups fed the combination of 1,25-(OH)2D3 and 24,25-(OH)2D3 per kilogram of feed, or 1,25-(OH)2D3 alone at 5 micrograms/kg, had significantly higher tibial weights relative to the control group. All groups receiving the diets without cholecalciferol supplementation had markedly reduced hatchability. It was concluded that the optimal dietary level of 1,25-(OH)2D3 for improving eggshell quality without affecting egg production was approximately 5 micrograms/kg and the toxic level was 7 micrograms/kg.

The effect of 1 alpha,25-dihydroxyvitamin D3 added to a layer diet containing adequate amounts of vitamin D3 on the performance of layers

The effect of adding 1 alpha,25-dihydroxyvitamin D3 (calcitriol) to a well-balanced, commercial layer diet containing 1,900 IU vitamin D3/kg on eggshell quality and laying performance of 56-wk-old White Leghorn hens was investigated. After 8 wk of treatment, calcitriol at 1.5 micrograms/kg diet had no discernible effect on egg weight, egg deformation, percentage shell, shell thickness, feed consumption, and egg production. At 3.0 and 4.5 micrograms/kg, feed consumption, feed production, and egg weight were significantly reduced, whereas egg deformation, percentage shell, and shell thickness were not affected. The results show that calcitriol added to a diet already adequately supplemented with vitamin D3 does not improve eggshell quality and may impair laying performance.

Effect of 1 alpha,25-dihydroxycholecalciferol on egg shell quality and egg production

1. The effect of replacing dietary cholecalciferol (D3) by 1 alpha,25-dihydroxycholecalciferol (1,25-(OH)2D3) on egg shell quality and egg production was tested on 32-week-old White Leghorn laying hens over 9 weeks. 2. Hens fed on a diet supplemented with 5 micrograms 1,25-(OH)2D3/kg diet, tended to lay more eggs, and the eggs had significantly higher specific gravity and percentage shell than eggs from control hens fed on a diet supplemented with 27.5 micrograms D3/kg diet. 3. The effect became apparent after about 4 weeks of treatment and persisted until the end of the test. 4. Hens fed on a diet without D3 supplement started to lay very thin or soft shelled eggs within 4 weeks, suggesting that the birds' reserves of D3 or its metabolites were depleted within this period. 5. The results suggest that 1,25-(OH)2D3 can be substituted for D3 in layer diets to improve egg shell quality.

Some observations on the influence of vitamin D metabolites when added to the diet of commercial laying hens

Three experiments were conducted to study the influence of two vitamin D3 metabolites on the performance of commercial laying hens. In Experiment 1, adding of .75, 1.50, 3.00, and 4.50 micrograms of 1 alpha-hydroxycholecalciferol (1 alpha-OHD3) or of 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] per kg to the diet containing 2,200 ICU of vitamin D3 from 55 micrograms of cholecalciferol per kg of diet resulted in increased plasma calcium (Ca) and phosphorus (P). The response was greater from the 1,25-(OH)2D3 metabolite than from the 1 alpha-OHD3 metabolite. Neither metabolite affected tibia breaking strength (TBS), egg production (EP), egg weight (EW), feed consumption (FC), feed conversion, eggshell quality (ESQ), fertility, or the hatchability of eggs or the tibia ash (TA) of the day-old chick. In Experiment 2, the EP, EW, FC, ESQ and TA of the hens were not affected when 1.5 micrograms of 1,25-(OH)2D3 were added to each kilogram of a corn-soybean meal diet containing either .38 or .43% P with adequate vitamin D3. Adding the 1,25(OH)2D3 metabolite to the low-P diet reduced plasma Ca and increased TBS. However, adding 1,25-(OH)2D3 to the high-P diet increased plasma Ca and P. In Experiment 3, the EP, ESQ, FC, and TA of the hens were significantly lower when the diet contained 2.04% Ca rather than 3.04% Ca. Plasma Ca and P, EW, or TBS were not affected by the dietary Ca. Neither the plasma Ca and P, EP, EW, ESQ nor the TBS and TA were influenced by adding the 1,25-(OH)2D3 metabolite to either diet.