High Levels Of Dietary Vitamin Research Articles

Evaluating the American Urologic Association (AUA) dietary recommendations for kidney stone management using the National Health And Nutritional Examination Survey (NHANES).

The objective of this study is to evaluate the conventional dietary recommendations for stone prevention among patients in the National Health and Nutritional Examination Survey (NHANES) and compare dietary components and special diets between stone formers and non-stone formers. We analyzed the NHANES 2011-2018 dietary and kidney condition questionnaires, among 16,939 respondents who were included in this analysis. Dietary variables were selected based on the American Urological Association (AUA) guideline for Medical Management of Kidney Stones and from other studies on kidney stone prevention. Weighted multivariate logistic regression models were used to assess the relationship of dietary food components (categorized into quartiles) and dietary recommendations with kidney stone formation (yes vs no), adjusted for total caloric intake, comorbidities, age, race/ethnicity, and sex. The prevalence of kidney stones was 9.9%. Our results showed association of kidney stones with lower levels of potassium (p for trend = 0.047), which was strongest for < 2000mg (OR = 1.35; 95% CI 1.01-1.79). Higher vitamin C intake was inversely associated with stone formation (p for trend = 0.012), particularly at daily intake levels between 60 and 110mg (OR = 0.76; 95% CI 0.60-0.95) and above 110mcg (OR = 0.80; 95% CI 0.66-0.97). There were no associations between other dietary components and kidney stone formation. Higher levels of dietary vitamin C and potassium intake may be indicated for stone prevention and warrants further investigation.

Appearance of systemic granulomatosis is modulated by the dietary supplementation of vitamin E and C in meagre (Argyrosomus regius) larvae fed inert microdiets

Systemic granulomatosis has already been reported in meagre larvae with an adequate feeding protocol and enrichment media preventing its appearance in the first weeks of life. Afterwards, the control of this disease could be prevented through nutritional components of the inert food, being the antioxidants the key to success. For this reason, in the present study, meagre larvae were reared from 30 days post hatching (dph) with five isonitrogenous and isolipidic experimental microdiets with different levels of vitamin E and C: C– (40 mg kg−1 E, 100 mg kg−1C), C+ (400 mg kg−1 E, 1000 mg kg−1C), Krill (400 mg kg−1 E, 1000 mg kg−1C and substitution of fish oil by krill oil), EC (200 mg kg−1 E, 500 mg kg−1C) and EECC (800 mg kg−1 E, 2000 mg kg−1C). Prior to this, larvae were co-fed with rotifers and Artemia following a protocol which prevented the appearance of granulomas, as previously demonstrated. The substitution of fish oil by krill oil significantly increased levels of eicosapentaenoic acid (EPA, 16.6%) and docosahexaenoic acid (DHA, 17.6%) in meagre, consequently increasing the peroxidation index, which in turn translated into a higher incidence of granulomas. Although even low levels of vitamin E and C (40 mg kg−1 E, 100 mg kg−1C; C-) allowed the adequate growth of larvae, these levels were not enough to prevent the appearance of granulomas, requiring superior levels of both antioxidant vitamins (800 mg kg−1 E and 2000 mg kg−1C) to mitigate systemic granulomatosis. This mitigation was simultaneous with the reduction of thiobarbituric acid reactive substances TBARs content in larvae, which were highly correlated with the appearance of granulomas (R2 = 0.892, y = 0.0446× + 0.0756). A strong negative correlation was observed between the dietary levels of vitamin E (y = −0.0098× + 11.174, R2 = 0.8766, p value = .019, r = −0.93) and vitamin C (y = −0.0022× + 6.4777, R2 = 0.9278, p value = .003, r = −0.96) and the percentage of larvae with granulomas. The results showed that the occurrence of systemic granulomatosis seems to be associated to the larvae peroxidation status, so that high dietary levels of vitamin E and C (800 and 2000 mg kg−1, respectively; Diet EECC), reduced lipid peroxidation and completely prevented the appearance of granulomas in meagre larvae at 44 dph.

Association of rs2282679 A>C polymorphism in vitamin D binding protein gene with colorectal cancer risk and survival: effect modification by dietary vitamin D intake

BackgroundThe rs2282679 A>C polymorphism in the vitamin D binding protein gene is associated with lower circulating levels of vitamin D. We investigated associations of this SNP with colorectal cancer (CRC) risk and survival and whether the associations vary by dietary vitamin D intake and tumor molecular phenotype.MethodsA population-based case-control study identified 637 incident CRC cases (including 489 participants with follow-up data on mortality end-points) and 489 matched controls. Germline DNA samples were genotyped with the Illumina Omni-Quad 1 Million chip in cases and the Affymetrix Axiom® myDesign™ Array in controls. Logistic regression examined the association between the rs2282679 polymorphism and CRC risk with inclusion of potential confounders. Kaplan-Meier curves and multivariable Cox models assessed the polymorphism relative to overall survival (OS) and disease-free survival (DFS).ResultsThe rs2282679 polymorphism was not associated with overall CRC risk; there was evidence, however, of effect modification by total vitamin D intake (Pinteraction = 0.019). Survival analyses showed that the C allele was correlated with poor DFS (per-allele HR, 1.36; 95%CI, 1.05–1.77). The association of rs2282679 on DFS was limited to BRAF wild-type tumors (HR, 1.58; 95%CI, 1.12–2.23). For OS, the C allele was associated with higher all-cause mortality among patients with higher levels of dietary vitamin D (HR, 2.11; 95%CI, 1.29–3.74), calcium (HR, 1.93; 95%CI, 1.08–3.46), milk (HR, 2.36; 95%CI, 1.26–4.44), and total dairy product intakes (HR, 2.03; 95%CI, 1.11–3.72).ConclusionThe rs2282679 SNP was not associated with overall CRC risk, but may be associated with survival after cancer diagnosis. The association of this SNP on survival among CRC patients may differ according to dietary vitamin D and calcium intakes and according to tumor BRAF mutation status.

Vitamin D and pancreatic cancer: a pooled analysis from the Pancreatic Cancer Case–Control Consortium

The potential role of vitamin D in the aetiology of pancreatic cancer is unclear, with recent studies suggesting both positive and negative associations. We used data from nine case-control studies from the International Pancreatic Cancer Case-Control Consortium (PanC4) to examine associations between pancreatic cancer risk and dietary vitamin D intake. Study-specific odds ratios (ORs) were estimated using multivariable logistic regression, and ORs were then pooled using a random-effects model. From a subset of four studies, we also calculated pooled estimates of association for supplementary and total vitamin D intake. Risk of pancreatic cancer increased with dietary intake of vitamin D [per 100 international units (IU)/day: OR = 1.13, 95% confidence interval (CI) 1.07-1.19, P = 7.4 × 10(-6), P-heterogeneity = 0.52; ≥230 versus <110 IU/day: OR = 1.31, 95% CI 1.10-1.55, P = 2.4 × 10(-3), P-heterogeneity = 0.81], with the association possibly stronger in people with low retinol/vitamin A intake. Increased risk of pancreatic cancer was observed with higher levels of dietary vitamin D intake. Additional studies are required to determine whether or not our finding has a causal basis.

Dietary vitamin A regulates wingless-related MMTV integration site signaling to alter the hair cycle.

Alopecia areata (AA) is an autoimmune hair loss disease caused by a cell-mediated immune attack of the lower portion of the cycling hair follicle. Feeding mice 3-7 times the recommended level of dietary vitamin A accelerated the progression of AA in the graft-induced C3H/HeJ mouse model of AA. In this study, we also found that dietary vitamin A, in a dose dependent manner, activated the hair follicle stem cells (SCs) to induce the development and growth phase of the hair cycle (anagen), which may have made the hair follicle more susceptible to autoimmune attack. Our purpose here is to determine the mechanism by which dietary vitamin A regulates the hair cycle. We found that vitamin A in a dose-dependent manner increased nuclear localized beta-catenin (CTNNB1; a marker of canonical wingless-type Mouse Mammary Tumor Virus integration site family (WNT) signaling) and levels of WNT7A within the hair follicle bulge in these C3H/HeJ mice. These findings suggest that feeding mice high levels of dietary vitamin A increases WNT signaling to activate hair follicle SCs.

Effect of vitamin A depletion on fat deposition in finishing pigs, intramuscular fat content and gene expression in the longissimus muscle

Nutritional strategies like reduction of dietary vitamin A have been proposed with the aim of increasing intramuscular fat (IMF) and improving the meat quality. The purpose of the study was to evaluate if reduction of dietary vitamin A would increase IMF, without affecting backfat deposition and pig performance parameters. Forty eight barrows were fed diets with different vitamin A levels: without supplemental vitamin A (0 IU vitamin A /kg; n=16), a level close to the requirement of NRC (1998) (1250 IU vitamin A/kg; n=16) or a level typically used in commercial formulation (5000IU vitamin A/kg; n=16). The treatment without supplemental vitamin A did not affect growth performance parameters, only a trend to increase final body weight was observed when compared with animals fed with vitamin A in the diet. However, reduced perirenal fat and a trend to increase muscle depth between the 3th and 4th ribs was observed in the animals fed the diet with no supplemental vitamin A. These results suggested a reduction of fatness when vitamin A was omitted in the diet, contrary to the initial hypothesis. Intramuscular fat content was not affected by the reduction of the dietary vitamin A levels below the requirements; in fact the trend was opposite to the original hypothesis. The content of retinol in the liver was increased when the animals were fed higher levels of dietary vitamin A but animals fed without vitamin A diet also produced retinol, although in a reduced amount, which could explain the lack of effects of vitamin A reduction on performance. When comparing 5000IU/kg with 0IU/kg diets, only a trend in reduced expression of PPARα without impaired modification on fat content was observed in longissimus muscle. From this study, it can be concluded that omitting supplemented vitamin A does not affect performance, decreases perirenal fat and possibly overall fat deposition, without a significant reduction on IMF, contrary to the original hypothesis.

Plasma Vitamin C, but Not Vitamin E, Is Associated With Reduced Risk of Heart Failure in Older Men

Oxidative stress has been implicated in the pathogenesis of heart failure (HF). However, data on the association between antioxidant intakes and circulating levels and risk of incident HF in the older general population are limited. We have examined prospectively the associations between plasma vitamin C and E, dietary intakes of vitamin C and E, and incident HF. Prospective study of 3919 men aged 60 to 79 years with no prevalent HF followed up for a mean period of 11 years, in whom there were 263 cases with incident HF. Higher plasma vitamin C level was associated with significantly lower risk of incident HF in both men with and without previous myocardial infarction after adjustment for lifestyle characteristics, diabetes mellitus, blood lipids, blood pressure, and heart rate (hazards ratio [95% confidence interval], 0.81 [0.70, 0.93] and 0.75 [0.59, 0.97] for 1 SD increase in log vitamin C, respectively). Plasma vitamin E and dietary vitamin C intake showed no association with HF. High levels of dietary vitamin E intake (which correlated weakly with plasma vitamin E) were associated with increased risk of HF in men with no previous myocardial infarction even after adjustment (adjusted hazards ratio [95% confidence interval], 1.23 [1.06, 1.42] for 1 SD increase). Higher plasma vitamin C is associated with a reduced risk of HF in older men with and without myocardial infarction. High intake of dietary vitamin E may be associated with increased HF risk. Primary intervention trials assessing the effect of vitamin C supplements on HF risk in the elderly are needed.

Beef quality attributes as affected by increasing the intramuscular levels of vitamin E and omega-3 fatty acids

In order to investigate the effects of increasing beef n-3 fatty acid content and the protective effects of vitamin E antioxidant activity on meat quality characteristics, 80 feedlot steers were fed 4 different diets (control, high vitamin E, 10% ground flaxseed or high vitamin E–10% ground flaxseed). While dietary treatments had no effect (P>0.05) on meat composition or tenderness values, the increase in oxidation products was lower (P=0.046) in meat from vitamin E supplemented steers and higher (P=0.006) in meat from flaxseed fed animals. The increase in α-tocopherol tissue levels (P<0.001) in meat from animals fed flaxseed and increased dietary vitamin E resulted in the lowest drip loss values (P=0.013). As expected, display time had a large effect on retail traits in both steaks and patties (P<0.001). While retail traits of steaks were not affected by the dietary treatments (P>0.05), feeding flaxseed decreased (P<0.05) ground beef retail scores, which were not corrected by higher levels of dietary vitamin E. Finally, although no effect (P>0.05) was observed among treatments for sensory attributes in steaks, the correlations of a combined n-3:α-tocopherol ratio against retail and sensory attributes (P<0.05) suggest that increased n-3 fatty acids levels require increased dietary antioxidants, such as vitamin E to avoid negative effects on meat quality from a loss in oxidative stability.

Ascites syndrome in poultry: a review

Excessive specialisation and production requirements place high demands on the metabolism of the broiler chicken. A number of metabolic problems, such as ascites, arise in chickens due to intensive selection to manifest their genetic potential for rapid growth. Ascites syndrome (Pulmonary Hypertension Syndrome) is one of the major causes of mortality and morbidity in modern broiler production today. Genetics, the environment, and management all seem to interact to produce a cascade of events that culminate in ascites syndrome. It is generally accepted that the high metabolic rate of current broiler lines causes an increased demand for oxygen, especially in cold environments or when birds are fed high nutrient density diets. In such situations, the relatively underdeveloped cardio-respiratory system of modern broilers fails to fulfil the required oxygen demand, which leads to hypoxemia, resulting in the development of pulmonary hypertension and subsequently ascites. Many nutritional, medicinal and management strategies have been proposed to alleviate the ascites. Higher levels of dietary vitamin C and E along with selenium might be beneficial, as they decrease the free radicals that are generated in birds with ascites. As the high metabolic rate (fast growth) is a major factor contributing to the susceptibility of broilers to ascites, appropriate selection strategies or feed restriction or light restriction in order to slow down the growth rate seem practically viable methods, since final body weight is not compromised. Optimisation of the house temperature and ventilation in cold weather seem helpful practices to decrease the incidence of ascites.

Calcium, Vitamin D, VDR Genotypes, and Epigenetic and Genetic Changes in Rectal Tumors

Calcium, vitamin D, exposure to sunshine, and vitamin D receptor (VDR) genotypes have been associated rectal cancer. We used data from 750 rectal tumors and 1,205 population-based controls examine associations with TP53, KRAS2, and CpG Island methylator phenotype (CIMP) markers. Rectal tumors were associated with high levels of calcium overall and with TP53 tumor mutations specifically (OR = 0.6, 95% CI = 0.42–0.84). High levels of sunshine exposure had a borderline protective effect for TP53 tumor mutations (OR = 0.78, 95% CI = 0.59–1.03). A mutation at codon 248 was significantly associated with dietary calcium intake (OR = 0.26, 95% CI = 0.09–0.77); having the Ff/ff genotypes of the FOK1 VDR polymorphism significantly increased the odds of a mutation at codon 245 (OR = 4.74, 95% CI = 1.05–21.39); high levels of dietary vitamin D (OR = 3.42, 95% CI = 1.15–10.17) and the Ff/ff genotypes of FOK1 (OR = 3.34, 95% CI = 1.11–10.02) and the GA/AA genotypes of the CDX2 VDR polymorphism (OR = 2.85, 95% CI = 1.23–6.58) increased the odds of a TP53 mutation at codon 273. These data support an association between calcium and rectal tumors overall as well as specifically with TP53 mutations. However, given the number of comparisons, findings need to be confirmed in other studies.

Calcium, Dairy Foods, Vitamin D, and Colorectal Cancer Risk: The Fukuoka Colorectal Cancer Study

Epidemiologic evidence supporting a protective role of calcium and vitamin D in colorectal carcinogenesis has been accumulating in Western populations, but it is limited in Asian populations, whose intake of calcium is relatively low. We investigated the association of intakes of these nutrients with colorectal cancer risk in Japanese. Study subjects were participants of a large-scale case-control study in Fukuoka, Japan. Diet was assessed through interview regarding 148 dietary items by showing typical foods or dishes on the display of a personal computer. In a multivariate analysis adjusting for potential confounding variables, calcium intake was significantly, inversely associated with colorectal cancer risk (P for trend=0.01); the odds ratio for the highest versus lowest quintile of calcium intake was 0.64 (95% confidence interval, 0.45-0.93). Higher levels of dietary vitamin D were significantly associated with decreased risk of colorectal cancer among those who had fewer chances of sunlight exposure at work or in leisure (P for trend=0.02). A decreased risk of colorectal cancer associated with high calcium intake was observed among those who had higher levels of vitamin D intake or among those who had a greater chance of daily sunlight exposure, but not among those with medium or lower intake of vitamin D or among those with potentially decreased sunlight exposure. These results add to support for a joint action of calcium and vitamin D in the prevention of colorectal carcinogenesis.

Effect of Higher Levels of Dietary Vitamin E on Performance and Immune Response in Growing Japanese Quail

Biswas, A., Mohan, J., Sastry, K.V.H. and Tyagi, J.S. 2008. Effect of higher levels of dietary vitamin E on performance and immune responses in growing Japanese quail. J. Appl. Anim. Res., 33: 61–64. To study the effect of increasing dietary vitamin E (VE) on performance and immune response, 240 day old chicks were randomly selected and divided into 12 groups with 20 chicks in each group (3 dietary treatments × 4 replicates). The basal diet contained 15 IU VE/kg and the two experimental diets were supplemented with 150 IU and 300 IU VE/kg. Body weight gain, feed intake, feed conversion ratio and mortality were not affected by VE supplementation. Antibody titres, response to intradermally injected phytohaemagglutinin (PHA) and the relative weights of the bursa of Fabricius and thymus were significantly (P<0.05) higher after feeding the two VE-supplemented diets. It is concluded that VE supplementation improved immune response but not performance in growing Japanese quail.

Use of vitamin C as an immunostimulant. Effect on growth, nutritional quality, and immune response of Labeo rohita (Ham.)

Teleost fish lack the enzyme for endogenous synthesis of ascorbic acid (AA), an essential micronutrient for fish. The aim of this study was to examine the effect of higher levels of dietary vitamin C on growth, nutritional quality, and immunomodulation in the Indian major carp, rohu (Labeo rohita). Four groups of L. rohita were fed experimental diets containing either no vitamin C (control) or supplemented with vitamin C at 500 mg kg(-1) (Exp-1), 1000 mg kg(-1) (Exp-2), or 1500 mg kg(-1) (Exp-3) for 60 days. Growth parameters (NWG, ADG, and SGR), serological parameters (TSP, TSA, TSG, and A:G), haematological parameters (TLC, TEC, Hct, MCV, and MCH), and different non-specific immunological parameters (PR, PI, respiratory burst activity, and bactericidal activity) were evaluated during the experimental trial. Fish fed a vitamin C-supplemented diet showed higher specific growth rate (SGR) up to 1000 mg kg(-1) compared with control fish. Different haematological and serological parameters along with non-specific immune parameters were influenced by vitamin C supplementation. Among the non-specific immune parameters phagocytic activity (PR and PI) and respiratory burst activity (NBT cells) were significantly (P < or = 0.05) enhanced by increasing doses of vitamin C supplementation. Higher levels of dietary vitamin C significantly (P < or = 0.05) enhanced protection against Aeromonas hydrophila (AH1) infection compared with controls. Results from this study help to establish the beneficial effect of vitamin C on growth and immunmodulation in rohu (L. rohita).

Effects of dietary fish oil and vitamin E supplementation on canine lymphocyte proliferation evaluated using a flow cytometric technique

Lymphocyte proliferation and peripheral blood mononuclear cell (PBMC) production of PGE 2 were assayed in 15 healthy dogs fed a basal diet supplemented with either sunflower oil (Group Sunflower oil), sunflower oil and menhaden fish oil (Group Fish oil), or sunflower oil and menhaden fish oil plus α-tocopherol acetate for 12 weeks (Group Fish oil + E). Lymphocyte proliferation was determined by a flow cytometric technique utilizing the fluorochrome carboxyfluorescein diacetate succinimidyl ester (CFSE). The PBMC supernatant PGE 2 concentration was assayed using a competitive enzyme-linked immunoassay. Group Fish oil had a significant decrease in lymphocyte proliferation at week 12. PBMC production of PGE 2 was decreased in all three groups but only significantly reduced in groups receiving fish oil supplementation. Based on these results, this level of fish oil supplementation appears to suppress the lymphoproliferative response in healthy, young dogs but this response can be attenuated by high levels of dietary vitamin E supplementation. Furthermore, fish oil-induced reduction in lymphocyte proliferation appears to manifest through a PGE 2-independent mechanism and is not associated with increased lipid peroxidation.

Generation of superoxide and singlet oxygen from α-tocopherolquinone and analogues

Three potential routes to generation of reactive oxygen species (ROS) from α-tocopherolquinone (α-TQ) have been identified. The quinone of the water-soluble vitamin E analogue Trolox C (Trol-Q) is reduced by hydrated electron and isopropanol α-hydroxyalkyl radical, and the resulting semiquinone reacts with molecular oxygen to form superoxide with a second order rate constant of 1.3 × 108 dm3/mol/s, illustrating the potential for redox cycling. Illumination (UV-A, 355 nm) of the quinone of 2,2,5,7,8-pentamethyl-6-hydroxychromanol (PMHC-Q) leads to a reactive short-lived (ca. 10− 6 s) triplet state, able to oxidise tryptophan with a second order rate constant greater than 109 dm3/mol/s. The triplet states of these quinones sensitize singlet oxygen formation with quantum yields of about 0.8. Such potentially damaging reactions of α-TQ may in part account for the recent findings that high levels of dietary vitamin E supplementation lack any beneficial effect and may lead to slightly enhanced levels of overall mortality.

Strategies to alleviate the incidence of ascites in broilers: a review

Ascites is a complex problem caused by many interacting factors such as genetics, environment and management. Many nutritional, medicinal and management strategies have been proposed to alleviate the problem. Higher levels of dietary vitamin C and E along with selenium yeast might be beneficial, presumably because of their role in improving cellular integrity. Oils rich in n-3 fatty acids have been shown to reduce pulmonary hypertension and, consequently, ascites incidence. The potential use of flax oil has already been demonstrated, whereas the effects of other oils rich in n-3 fatty acids (fish, linseed and canola oils) remain to be investigated. The assessment of the effects of dietary electrolyte balance on ascites incidence seems to be a promising field of research in broiler nutrition. In general, reducing the dietary level of salt (NaCl) and adding bicarbonates to the diet and drinking water have been proposed as potential "cost-effective" methods to reduce ascites incidence. The use of nutrients/drug agents that increase the vascular capacity of the lungs or decrease the pulmonary vascular resistance may help to alleviate the problem, but economic and local feed regulations might restrict such use. Diuretics have also shown positive effects, presumably because there is a reduction of sodium and fluid retention in the body; litter humidity however must be closely monitored if diuretics are continuously administered. As the high metabolic rate (fast growth) is a major factor contributing to the susceptibility of broilers to ascites, early-age feed or nutrient restriction (qualitative or quantitative) or light restriction in order to slow down the growth rate seem practically viable methods, since final body weight is not compromised. Optimization of the house temperature and ventilation in cold weather seem helpful practices to decrease ascites incidence. Under practical conditions, it might be interesting to test the additive effects of different approaches when used in combination.

Supplementation of Vitamin C to Weaner Diets Increases IgM Concentration and Improves the Biological Activity of Vitamin E in Alveolar Macrophages

Vitamins E and C have been found to increase the cellular and humeral immunity of pigs. Vitamin E deficiency has also been found to predispose pigs to different diseases, E. coli infection is one among them. After weaning, the vitamin E status of pigs often decreases to a critical low level. In this experiment, we studied whether vitamin C supplementation would be a possible feeding strategy to optimize the immune status of weaners. The interaction between vitamin E and C is interesting due to the reported sparing action on vitamin E or synergism between these to vitamins. Piglets were weaned at day 28 of age from sows fed increasing dietary vitamin E during lactation, and piglets were during the following 3 weeks fed either a control diet or this diet supplemented with 500 mg STAY‐C per kg. Blood sampling was obtained weekly from day 28 and until day 49 of age. On the same days, one piglet per dietary treatment was killed and alveolar macrophages (AM) were harvested. Vitamin C supplementation increased the concentration of IgM in serum of piglets throughout the weaning period. Although the vitamin E concentration in AM decreased with increasing age of the piglets, the concentration was numerically higher in piglets of sows fed the high dietary level of vitamin E. However, vitamin C supplementation tended to increase the total AM concentration of vitamin E after weaning and increased the proportion of the biologically most active isomer of vitamin E [RRR‐(α‐tocopherol)] in the AM. The eicosanoid synthesis by AM was not influenced by the vitamin C supplementation, but the synthesis of leukotriene B4 was decreased 2 weeks after weaning compared to other days of AM harvesting. In conclusion, dietary vitamin C supplementation improved the immune responses of piglets after weaning.

Exogenous Estrogen Boosts Circulating Estradiol Concentrations and Calcium Uptake by Duodenal Tissue in Heat-Stressed Hens

In the hen, heat stress (HS) disrupts shell calcification and reproductive processes, including hormone synthesis and egg production. Two studies were conducted to investigate palliative effects of exogenous estrogen or dietary vitamin D3 on Ca homeostasis and reproductive physiology during HS. Study 1: Hy-Line W36 hens were randomly assigned to thermoneutral (TN) or HS treatments and to 1 of 7 estrogen treatments: zero (control) or one Compudose 200 implant given 1, 2, 3, 8, 9, or 10 d before onset of HS. With no implant, HS reduced plasma estradiol (E2) and total Ca absorbed (CaT) by duodenal cells (P < 0.05). In TN hens with implants, plasma E2 tripled within 24 h (P < 0.05) and remained elevated (P < 0.05) through d 9. In HS hens with implants, plasma E2 rose 6-fold (P < 0.05) to equal TN+E2 concentrations and remained elevated through d 10. In TN and HS hens with implants, the rate of Ca absorption (CaTR) and CaT increased dramatically; the responses were quadratic and essentially identical. Study 2: Hy-Line W36 hens were provided diets formulated either according to NRC requirements (NRC, 1994), or with the addition of 22,000 IU/kg vitamin D3 (+VD hens). A 24-h HS episode was imposed 2 wk after initiation of the dietary regimen. Duodenal samples were collected for Ca absorption assays after the 24-h HS episode. Both CaTR and CaT in +VD hens were approximately 3-fold higher than in hens in the NVD group (P = 0.102). The results lead to the conclusion that exogenous estrogen, high levels of dietary vitamin D, or both, before a HS episode, are efficacious in alleviating at least some of the effects of HS and should be further investigated.

Effects of dietary n-3 polyunsaturated fatty acids, breed and dietary vitamin E on the fatty acids of lamb muscle, liver and adipose tissue.

The effect of feeding n-3 PUFA on the fatty acid composition of muscle, adipose tissue and liver of lambs was investigated. Groups of eight ram lambs per breed, SuffolkxLleyn (24 kg live weight) and Scottish Blackface (18 kg live weight), were each fed one of six diets containing one of three fat sources (50 g fatty acids/kg DM; Megalac((R)) (calcium soap of palm fatty acid distillate; Volac Ltd, Royston, Herts., UK) and formaldehyde-treated whole linseed (Trouw Nutrition UK, Northwich, Ches., UK) either alone or with fish oil (1:1, w/w) and either 100 or 500 mg alpha-tocopheryl acetate/kg DM. Feed was offered ad libitum until slaughter at approximately half breed mature live weight. The type of dietary fat had no effect on intake, growth rate or feed conversion ratio. The 3.0-fold higher concentration of 18 : 3n-3 in the linseed compared with the Megalac((R)) diet approximately doubled (P<0.001) the concentration in the neutral and polar lipid fractions of musculus semimembranosus and liver, and in adipose tissue it increased 2.5-fold. Feeding protected linseed also increased (P<0.001) concentrations of 20 : 5n-3 and 22 : 5n-3 in muscle polar lipids and both lipid fractions of liver. The linseed-fish oil raised the 20 : 5n-3 concentrations above those for the linseed diet and also increased 22 : 6n-3. Scottish Blackface lambs had lower concentrations of 18 : 3n-3 in all lipids compared with Suffolk x Lleyn lambs, but more 20 : 5n-3 in the polar lipids of muscle and liver. High levels of dietary vitamin E were associated with small decreases in the concentration of monounsaturated fatty acids and increases in PUFA. Linseed raised the PUFA : saturated fatty acid ratios in liver and adipose tissue but not in muscle, and improved the n-6 : n-3 fatty acid ratio, as did the linseed-fish oil. Different combinations of dietary fatty acids and better protection against rumen biohydrogenation are required to improve muscle PUFA : saturated fatty acids ratios.

Cataract formation in Atlantic salmon, Salmo salar L., smolt relative to dietary pro- and antioxidants and lipid level.

The development of cataracts in Atlantic salmon, Salmo salar L., was studied in 16 groups of smolts fed diets differing in prooxidant (iron, copper, manganese) and antioxidant (vitamin E, vitamin C, astaxanthin) composition and lipid level for 23 weeks in sea water, using a 2(7-3) reduced factorial design. The seven dietary variables were systematically varied at low (requirement level and 150 g lipid kg(-1)) and high levels (below known toxic levels and 320 g lipid kg(-1)). A mean endpoint cataract incidence of approximately 36% was observed. High dietary levels of vitamin C and astaxanthin reduced cataract frequency, whereas high dietary lipid level, iron and manganese were associated with increased cataract frequencies. Considering the nutritional status of selected organs of the fish, only the status of ascorbic acid correlated negatively to cataract development (P < 0.05). The lens glutathione (GSH) status was not correlated to cataract frequency, nor statistically explained by the dietary variables. However, the study shows that balancing the diet with respect to pro- and antioxidant nutrients may significantly protect Atlantic salmon against development of cataracts. An incidence of reversible osmotic cataract observed at week 14 was positively correlated to plasma glucose concentration.