Effect of dietary sulfur and selenium concentrations on selenium balance of lactating Holstein cows

The effects of dietary sulfate and selenium concentrations on selenium balance in dairy cows were investigated. Midlactation Holstein cows (n = 30) were fed diets containing either 0.1 or 0.3 mg of supplemental Se (from sodium selenate)/kg of dry matter and 0, 0.2, or 0.4% added S from a mix of calcium and magnesium sulfate in a factorial arrangement. The experiment lasted 112 d. Dry matter intake was linearly reduced with increasing S, but the effect was greater when 0.3 mg/kg of Se was fed (significant interaction). Treatment effects for yields of milk, milk fat, and milk protein were similar to those for dry matter intake. Increased dietary S linearly reduced plasma Se concentrations. Increasing dietary S linearly reduced apparent (42.7, 33.1, and 30.1%) and estimated true (50.5, 46.0, and 42.3%) Se digestibility. Excretion of Se via feces (1.6 vs. 2.8 mg/d) and urine (0.5 vs. 1.3 mg/d) was higher and output in milk (0.4 vs. 0.3 mg/d) was lower for cows fed 0.3 mg/kg of Se compared with 0.1 mg/kg, but no Se effect was found for estimated true Se digestibility. Dietary S from sulfate reduced Se balance especially when cows were fed diets with less than 0.3 mg of Se/kg of diet dry matter.     

Effects of feeding fish meal and n-3 fatty acids on milk yield and metabolic responses in early lactating dairy cows

The study was designed to test the effects of feeding fish meal (FM) and specific n-3 fatty acids on milk yield and composition, dry matter intake, plasma concentrations of metabolic hormones and metabolites, and liver triglyceride accumulation in early lactating cows. From 5 to 50 d in milk (DIM), cows were fed diets that were isonitrogenous, isoenergetic, and isolipidic containing none (control), 1.25, 2.5, or 5% menhaden FM or 2.3% Ca salts of fish oil fatty acids (CaFOFA). Milk yield (48.2, 49.8, 48.6, 53.5, and 52.2 ± 1.0 kg/d, respectively) and dry matter intake (22.7, 22.8, 23.0, 23.8, and 24.7 ± 0.5 kg/d, respectively) differed among diets. Average daily plasma glucose concentration (53.4, 55.3, 51.1, 57.6, and 57.3 ± 1.3 mg/dL, respectively) was also affected by diet, and plasma insulin concentration was increased by 5% FM and 2.3% Ca-FOFA. At 25 and 50 DIM, blood was collected before feeding and hourly for 11 h after feeding. Plasma glucose concentrations in cows during the day were similar among diets at 25 DIM, but differed at 50 DIM (54.6, 54.4, 52.4, 60.5, and 58.3 ± 1.4 mg/dL for 0, 1.25, 2.5, and 5% FM or 2.3% CaFOFA, respectively). Plasma insulin was increased in cows fed 5% FM and 2.3% CaFOFA at 25 DIM and was similar among diets at 50 DIM. Dietary treatments had no significant effect on milk composition, energy balance, or on daily plasma concentrations of nonesterified fatty acids, β-hydroxybutyrate, and urea. Plasma aspartate aminotransferase and hepatic triglyceride concentration in cows did not differ among diets at 21 DIM. Results from this experiment demonstrate that dietary supplementation with FM or n-3 polyunsaturated fatty acids in early lactating dairy cows significantly increased milk yield and DMI with no change in milk composition.     

Effect of duration of supplementation of selenium and vitamin E on periparturient dairy cows

Cows were fed diets either supplemented with .2 ppm Se and 70 IU vitamin E/kg diet DM (21 cows) or unsupplemented (40 cows) during the dry period (approximately 60 d). From parturition to 21 d of lactation, cows were fed diets that were either supplemented with .3 ppm Se and 40 IU/kg vitamin E or unsupplemented. At d 21 following parturition, 18 cows fed the unsupplemented diet were switched to diets containing 0 or .3 ppm supplemental Se and 0 or 40 IU/kg supplemental vitamin E arranged factorially. These diets were fed for the next 32 d. The remaining cows continued their respective diets for 32 d. Plasma Se concentrations averaged .1 microgram/ml for supplemented cows but were .05 micrograms/ml for unsupplemented cows. Plasma Se concentration from cows fed supplemental Se from 21 to 53 d postpartum increased rapidly and were not different from long-term supplemented cows. Whole blood glutathione peroxidase activity was lower in unsupplemented than in supplemented cows. Short-term Se supplementation increased glutathione peroxidase activity above that for unsupplemented animals, but activity was still less than that in long-term supplemented animals. Plasma alpha-tocopherol concentrations at parturition and d 21 postpartum were lower in unsupplemented than in supplemented animals. On d 53 postpartum, no differences in plasma alpha-tocopherol concentrations were found between long-term supplemented and unsupplemented cows. Supplementing vitamin E during the dry period increased alpha-tocopherol content of colostrum.     

Milk conjugated linoleic acid response to fish oil supplementation of diets differing in fatty acid profiles

The objective of this experiment was to examine the effect of feeding fish oil (FO) along with fat sources that varied in their fatty acid compositions (high stearic, high oleic, high linoleic, or high linolenic acids) to determine which combination would lead to maximum conjugated linoleic acid (cis-9,trans-11 CLA) and transvaccenic acid (TVA) concentrations in milk fat. Twelve Holstein cows (eight multiparous and four primiparous cows) at 73 (+/- 32) DIM were used in a 4 x 4 Latin square with 4-wk periods. Treatment diets were 1) 1% FO plus 2% fat source high in stearic acid (HS), 2) 1% FO plus 2% fat from high oleic acid sunflower seeds (HO), 3) 1% FO plus 2% fat from high linoleic acid sunflower seeds (HLO), and 4) 1% FO plus 2% fat from flax seeds (high linolenic; HLN). Diets formulated to contain 18% crude protein were composed of 50% (dry basis) concentrate mix, 25% corn silage, 12.5% alfalfa haylage, and 12.5% alfalfa hay. Milk production (35.8, 36.3, 34.9, and 35.0 kg/d for diets 1 to 4) was similar for all diets. Milk fat percentages (3.14, 2.81, 2.66, and 3.08) and yields (1.13, 1.02, 0.93, and 1.08 kg/d) for diets 1 to 4 were lowest for HLO. Milk protein percentages (3.04, 3.03, 3.10, and 3.08) and dry matter intake (DMI) (25.8, 26.0, 26.2, and 26.2 kg/d) for diets 1 to 4 were similar for all diets. Milk cis-9,trans-11 CLA concentrations (0.70, 1.04, 1.70, and 1.06 g/100 g fatty acids) for diet 1 to 4 and yields (7.7, 10.7, 15.8, and 11.3 g/d) for diets 1 to 4 were greatest with HLO and were least with HS. Milk cis-9,trans-11 CLA concentrations and yields were similar for cows fed the HO and the HLN diets. Similar to milk cis-9,trans-11 CLA, milk TVA concentration (1.64, 2.49, 3.74, and 2.41 g/100 g fatty acids) for diets 1 to 4 was greatest with the HLO diet and least with the HS diet. Feeding a high linoleic acid fat source with fish oil most effectively increased concentrations and yields of milk cis-9,trans-11 CLA and TVA.     

Maternal diet during oogenesis is the major source of methylmercury in fish embryos

Development of the early life stages of fishes can be affected adversely by methylmercury (MeHg) transferred from the maternal parent to the developing egg. We examined maternal transfer of MeHg to eggs of fathead minnows Pimephales promelas and evaluated the role of maternal MeHg burden versus that in the maternal dietduring oogenesis on egg concentrations. Juvenile fish were fed one of four diets until sexual maturity (phase 1): A control diet (0.06 microg of Hg g(-1) dry weight) and three that were contaminated with MeHg at 0.88 (low), 4.11 (medium), and 8.46 microg of Hg g(-1) (high). At sexual maturity, female fish were paired with a male, again fed one of the four diets, and allowed to reproduce (phase 2). To assess the significance of female dietary exposure during oogenesis on MeHg in eggs, some fish were fed diets during phase 2 that differed from those during phase 1. Mean concentrations and burdens of MeHg in eggs from fish fed the same diet throughout the experiment varied with MeHg content of the maternal diet and were related positively to levels in the carcass of the maternal fish. However, MeHg in eggs was not proportional to that in carcasses among dietary treatments; MeHg in eggs from adults fed the control, low, medium, and high MeHg diets averaged 14%, 25%, 32%, and 35% of that in adults. For fish fed the control diet as juveniles and MeHg-contaminated diets after reaching sexual maturity, MeHg in eggs increased rapidly with duration of maternal dietary exposure prior to spawning. Moreover, concentrations of MeHg in eggs from fish fed the same contaminated diet as both juveniles and sexually mature adults were not related to the duration of adult exposure, and they were not appreciably greater than those from fish fed contaminated diets only just priorto spawning. These results indicate that the diet of the maternal adult during oogenesis, and not adult body burden, is the principal source of MeHg in fish eggs. Accordingly, the exposure of embryonic wild fishes to MeHg depends on levels of the contaminant in prey of the adult during oogenesis, which can vary intra- and interannually.     

Effects of selenium source and level of supplementation on the performance and meat quality of lambs

Objective of this study was to evaluate the performance, the quality and oxidative stability of meat, the total Se and specific selenoamino-acids content of muscle of lambs that were fed diets supplemented from different Se sources and at different levels. Forty-eight Apennine lambs 30 day old (12.78 ± 0.94 kg) received, during a 63 day period, a total mixed ration (TMR) which was either Se unsupplemented (Control group - background only- 0.13 mg/kg Se) or supplemented with Na selenite (0.30 mg/kg Se as sodium selenite) or selenium enriched yeast (0.30 mg/kg and 0.45 mg/kg Se as Se-yeast).Growth performance, feed to gain ratio, carcass and meat quality (pH, drip and cooking losses, colour, GSH-Px activity and chemical analysis) did not show any difference between the treatments. Meat colour and oxidative stability during 9 days of refrigerated storage were unaffected by dietary supplementation, suggesting that, at the levels of Se used in this experiment, dietary Se, even from an organic source, had limited potential for reducing lipid oxidation. Selenium supplementation raised the Se content in muscle (P < 0.001) with the greatest increase when Se-yeast was fed. Although selenite increased total Se, it did not influence total or specific selenoamino-acids in this tissue. On the contrary, Se-yeast supplementation led to an increase in muscle Se-methionine content. We conclude that Se supplementation can increase significantly muscle Se levels and produce, particularly when Se-yeast is fed, a source of Se enriched meat as Se-methionine.     

Effects of dietary methylmercury on reproductive endocrinology of fathead minnows

Recent laboratory studies have demonstrated that environmentally realistic concentrations of dietary methylmercury can impair reproduction of fish. To evaluate relations between reproductive success and biomarkers of methylmercury exposure, we fed juvenile fathead minnows (Pimephales promelas) one of three diets contaminated with methylmercury: 0.06 (control), 0.87 (low), and 3.93 (medium) microg of Hg g(-1) dry weight. At sexual maturity, fish were paired, allowed to reproduce, and then analyzed for total mercury, plasma testosterone (T), and 17beta-estradiol (E2). Diets did not affect survival or growth of fathead minnows. Methylmercury suppressed levels of T in males and E2 in females. Male fathead minnows fed the control diet had mean T concentrations 20% and 106% greater than those fed the low and medium diets; control females had mean E2 concentrations 149% and 402% greater than those fed the low and medium diets. Methylmercury also inhibited gonadal development of females; the gonadosomatic index (GSI) of females fed the medium diet was 40% less than that of females fed control or low diets. Plasma levels of T in males and E2 in females were positively related to GSI. Methylmercury reduced the reproductive success of fathead minnows. Spawning success was 32% for pairs fed the control diet, 12% for pairs fed the low diet, and 0% for pairs fed the medium diet. Pairs fed the low diet required, on average, 5 d longer to spawn a clutch of eggs than the controls. Concentrations of methylmercury fed to fathead minnows in this study are also encountered by invertivorous and piscivorous fish in some methylmercury-contaminated aquatic ecosystems. This suggests that reproduction of wild fishes may be adversely affected by methylmercury and that suppressed hormone levels may be used to indicate diminished reproduction of fish.     

Residues of deoxynivalenol (DON) in pig tissue after feeding mash or pellet diets containing low concentrations

Residues of deoxynivalenol (DON) and its metabolite de-epoxy-DON (DOM) were analyzed in specimens of pigs fed diets containing 0, 25, and 50% contaminated wheat (2.5 mg DON/kg) fed as mash or pellets over the final growing period of 11 wk. Median DON concentrations decreased from bile > kidney > serum > liver = muscle, while DOM was only detected in bile and kidney. Maximum carry over rates were 0.0319 for kidney, 0.0064 for liver, and 0.0043 for muscle, demonstrating that the contribution of animal derived food to the consumers' exposure is very low. The high interindividual variation of DON concentrations in all analyzed specimen of pigs fed diets containing similar concentrations of DON does not allow a diagnostic differentiation of animals fed diets containing DON concentrations of approximately 61% of the guidance level of 0.9 mg DON/kg, and those fed diets containing 137% of this concentration. The different feed forms did not affect residue concentrations in any of the investigated specimens.     

Effect of selenium source on selenium status, neutrophil function, and response to intramammary endotoxin challenge of dairy cows

The effects of feeding dry and early lactation dairy cows diets with selenate or selenized yeast (Se-yeast) on concentrations of Se in serum, milk, and newborn calves, neutrophil function, and inflammatory response were determined. At 60 d before anticipated calving until approximately 30 d in milk (DIM), cows were fed diets that contained 0.3 mg of supplemental Se/kg of DM from sodium selenate or Se-yeast. Diets also contained 0.2% supplemental S (as sulfate) because it has been shown to reduce absorption of Se by dairy cows. The concentration of Se in serum at calving and 28 DIM was about 1.4 times greater for cows fed Se-yeast than for those fed selenate. Serum concentrations decreased 45 and 23% from dry-off to calving for cows fed selenate or Se-yeast, respectively. Selenium concentrations in serum from newborn calves were also about 1.4 times greater when the dams were fed Se-yeast. Concentrations of Se in colostrum and milk were about 1.8 times greater when cows were fed Se-yeast. Blood neutrophils were isolated from cows at 28 DIM and were used in an in vitro kill assay. Selenium treatment did not affect bacterial kill or the percentage of neutrophils that phagocytized bacteria. At approximately 28 DIM, one quarter from each cow was infused with a solution containing endotoxin. Peak body temperature (40.7°C) occurred 6 h postinfusion, and peak somatic cell count (6.5 log₁₀/mL) occurred at 12 h postinfusion. Neither measure was influenced by Se treatment.     

Selenium in Finnish foods after beginning the use of selenate-supplemented fertilisers

In Finland all agricultural multinutrient fertilisers have been supplemented with sodium selenate since 1984 in order to increase the selenium (Se) content of domestic foods and to raise the population's low Se intake. In the present study the Se contents of 125 food items, most of them produced locally but some imported, have been analysed using electrothermal atomic absorption spectrophotometry. The quality of Se analyses was verified by accuracy and precision measures of certified references and non-certified controls. In all cases the Se-supplemented fertilisation increased the Se levels of domestic agricultural products. The mean Se values (mg kg^?1 dry weight) in different food groups varied as follows: cereals 0.05–0.35; vegetables and fruit < 0.01,–1.20; meat and meat products 0.16–4.90; fish 0.54–3.80; dairy products and eggs 0.05–1.30; and ready to eat foods 0.04–0.78. The highest Se contents were in kidney, liver and roe whereas the lowest concentrations were found in some fruits and berries. Generally, foods of high protein content, such as meat, fish and high protein dairy products, were abundant sources of Se. The present Se intake, calculated according to Finnish national food statistics and the present results, is about 0.11 mg day^?1 at an energy level of 10 MJ (2400 keal). Cereals, meat, dairy products, eggs and fish, respectively, contributed 26%, 29%, 20%, 10% and 9% of the total intake. The Se intake now very probably meets the recommendations. Only diets with a very exceptional composition provide less than 0.05 mg or more than 0.2 mg per 10 MJ.     

Nutritional status affects the absorption and whole-body and organ retention of cadmium in rats fed rice-based diets

Staple grains such as rice, wheat and maize consumed by different societal groups differ greatly in their concentrations and bioavailability of the cadmium (Cd) antagonists, zinc (Zn), iron (Fe), and calcium (Ca). We hypothesized thatthe low nutritional status of rice consumers, which results from an inadequate supply of these minerals from rice, could contribute significantly to a higher apparent susceptibility to soil Cd contamination from rice than the higher nutritional status of those who consume other grains with higher mineral content. To test this hypothesis, a 2 x 2 x 2 factorial study was conducted. Rats were fed diets with adequate or marginal amounts of dietary Zn, Fe, or Ca. The basal diets contained 40% unenriched, milled rice fortified with 0.62 mg of Cd/kg as CdCl2 (0.25 mg of Cd/kg diet). Rat consumed the diets for 5 weeks and then were fed 1 g of a similar diet containing 10(9)Cd-labeled rice. After 2 weeks, whole-body (WB) retention of 109Cd was determine. Rats then were killed, and the organs were removed for total Cd determinations. Rats fed marginal concentrations of dietary Zn had slightly but significantly more WB retention of 109Cd than controls; however, rats fed marginal Fe or Ca had as much as 3-fold higher retention of the label. Rats fed marginal amounts of Zn, Fe, and Ca combined retained as much as 8 times more 109Cd than rats fed adequate minerals. The effects on Cd concentrations in liver and kidney were similar to the effects on 109Cd retention. These results support the hypothesis that populations exposed to dietary sources of Cd and subsisting on marginal mineral intakes could be at greater risk than well-nourished populations exposed to similar amounts of dietary Cd. Thus, different food crops can cause unequal Cd risk at equal Cd concentration if diets containing the food are not balanced to provide adequate interacting mineral concentrations.     

Influence of dietary vitamin C and selenium,alone and in combination,on the composition and oxidative stability of meat of broilers

Information on the combined effect of dietary vitamin C and Se on the composition and oxidative stability of meat of broilers is not available in the literature. In the present experiment, male broiler chickens were fed a maize–wheat–soya diet supplemented with vitamin C at 280 and 560 mg/kg of diet, and Se (sodium selenite or selenised yeast; Se) at 0.3 mg/kg for 5 weeks. After slaughter, samples of thigh meat were analysed. The supplementation of diets with vitamin C or Se increased the protein concentration of the meat at the expense of fat. Vitamin C supplementation increased the vitamin C content of the meat in a dose-dependent manner and decreased the vitamin A concentration in the meat of broilers fed diets with sodium selenite or without a Se supplement. In the meat of the broilers that were fed these diets, the vitamin C decreased the lipid oxidation in meat that was stored for 5 days. No sparing effect of vitamin C was apparent on the amount of vitamin E in the meat. Selenised yeast was more effective in the enrichment of meat with Se than was selenite. Both Se sources increased the activity of glutathione peroxidase and the oxidative stability of the meat.     

Glucoraphanin does not reduce plasma homocysteine in rats with sufficient Se supply via the induction of liver ARE-regulated glutathione biosynthesis enzymes

Data from human and animal trials have revealed contradictory results regarding the influence of selenium (Se) status on homocysteine (HCys) metabolism. It was hypothesised that sufficient Se reduces the flux of HCys through the transsulphuration pathway by decreasing the expression of glutathione (GSH) synthesising enzymes. Glucoraphanin (GRA) is a potent inducer of genes regulated via an antioxidant response element (ARE), including those of GSH biosynthesis. We tested the hypothesis that GRA supplementation to rat diets lowers plasma HCys levels by increasing GSH synthesis. Therefore 96 weaned albino rats were assigned to 8 groups of 12 and fed diets containing four different Se levels (15, 50, 150 and 450 μg kg(diet)(-1)), either without GRA (groups: C15, C50, C150 and C450) or in combination with 700 μmol GRA kg(diet)(-1) (groups G15, G50, G150 and G450). Rats fed the low Se diets C15 and G15 showed an impressive decrease of plasma HCys. Se supplementation increased plasma HCys and lowered GSH significantly by reducing the expression of GSH biosynthesis enzymes. As new molecular targets explaining these results, we found a significant down-regulation of the hepatic GSH exporter MRP4 and an up-regulation of the HCys exporter Slco1a4. In contrast to our hypothesis, GRA feeding did not reduce plasma HCys levels in Se supplemented rats (G50, G150 and 450) through inducing GSH biosynthesis enzymes and MRP4, but reduced their mRNA in some cases to a higher extent than Se alone. We conclude: 1. That the long-term supplementation of moderate GRA doses reduces ARE-driven gene expression in the liver by increasing the intestinal barrier against oxidative stress. 2. That the up-regulation of ARE-regulated genes in the liver largely depends on GRA cleavage to free sulforaphane and glucose by plant-derived myrosinase or bacterial β-glucosidases. As a consequence, higher dietary GRA concentrations should be used in future experiments to test if GRA or sulforaphane can be established as HCys lowering compounds.     

Uterine,ovarian, and production responses of lactating dairy cows to increasing dietary concentrations of menhaden fish meal

The primary objective was to determine whether the dietary polyunsaturated fatty acids, eicosapentaenoic (EPA, C20:5, n-3) and docosahexaenoic (DHA, C22:6, n-3), present in fish meal (FM) can attenuate uterine secretion of PGF2alpha in response to a challenge with estradiol and oxytocin in lactating dairy cows. Cycling multiparous cows (n = 32) were fed diets containing 0 (OFM), 2.6 (2.6FM), 5.2 (5.2FM), or 7.8% menhaden FM (7.8FM). The diet consisting of 7.8FM also contained fish oil (0.28% of dietary dry matter) to increase intake of EPA and DHA. Average dry matter intake was 24.9 kg/d and unaffected by diet. Combined intakes of EPA and DHA averaged 0, 12.8, 24.1, and 54.0 g/d from the OFM, 2.6FM, 5.2FM, and 7.8FM diets, respectively. At 30 to 34 d after initiation of dietary treatments, cows received an i.m. injection of 100 microg of GnRH followed by i.m. administration of 25 and 15 mg of PGF2alpha after 7 and 8 d, respectively. Synchronous ovulation was induced by an injection of 3000 IU of human chorionic gonadotropin (hCG) given 24 h later on d 9. Subsequent luteal phase increases in plasma progesterone concentrations did not differ (0.88 ng/ml per day). At 15 d after hCG injection, cows were injected with estradiol-17beta (3 mg, i.v.) at 0900 h and oxytocin (100 IU, i.v.) at 1300 h. Plasma PGF2alpha metabolite concentrations after oxytocin injection were reduced in cows fed diets containing FM compared with those fed OFM. Milk production (39.1 kg/d) and concentrations of fat, protein, or urea nitrogen in milk were not affected by diet. Feeding fish meal and fish oil containing eicosapentaenoic acid and docosahexaenoic acid reduced the proportion of n-6 fatty acids and increased that of n-3 fatty acids in milk in a dose-responsive manner.     

Milk production and composition from cows fed small amounts of fish oil with extruded soybeans

Eight Holstein (189 ± 57 DIM) and 4 Brown Swiss (126 ± 49 DIM) multiparous cows were used in a replicated 4 × 4 Latin square with 28-d periods to determine the minimal dietary concentration of fish oil necessary to maximize milk conjugated linoleic acid (CLA) and vaccenic acid (VA). Treatments consisted of a control diet with a 50:50 ratio of forage to concentrate (dry matter basis), and 3 diets with 2% added fat consisting of 0.33% fish oil, 0.67% fish oil, and 1% fish oil with extruded soybeans providing the balance of added fat. Dry matter intake (23.1, 22.6, 22.8, and 22.9 kg/d, for control, low, medium, and high fish oil diets, respectively) was similar for all diets. Milk production (21.5, 23.7, 22.7, and 24.2 kg/d) was higher for cows fed the fat-supplemented diets vs. the control. Milk fat (4.42, 3.81, 3.80, and 4.03%) and true protein (3.71, 3.58, 3.54, and 3.55%) concentrations decreased when cows were fed diets containing supplemental fat. Concentration of milk cis-9,trans-11 CLA (0.55, 1.17, 1.03, and 1.19 g/100 g of fatty acids) was increased similarly by all diets containing supplemental fat. Milk VA (1.12, 2.47, 2.13, and 2.63 g/100 g of fatty acids) was increased most in milk from cows fed the low and high fish oil diets. Milk total n-3 fatty acids were increased (0.82, 0.96, 0.92, and 1.01 g/100 g of fatty acids) by all fat-supplemented diets. The low fish oil diet was as effective at increasing VA and CLA in milk as the high fish oil diet, showing that only low concentrations of dietary fish oil are necessary for increasing concentrations of VA and CLA in milk.     

Antioxidative effect of dietary tea catechins on lipid oxidation of long-term frozen stored chicken meat

The antioxidative effect of dietary tea catechins (TC) supplementation at levels of 50, 100, 200 and 300 mg kg(-1) feed on susceptibility of chicken breast and thigh meat to lipid oxidation during frozen (-20°C) storage for 9 months was investigated. Day-old chickens (Cobb 500, n=200) were randomly divided into six groups. Chickens were fed a basal diet containing 20 mg α-tocopheryl acetate kg(-1) feed as control, or a vitamin E supplemented diet (basal diet plus 200 mg α-tocopheryl acetate kg(-1) feed), or TC supplemented diets (basal diet plus 50, 100, 200 or 300 mg TC kg(-1) feed) for 6 weeks prior to slaughter. Lipid oxidation (TBARS) was assessed after 0 and 10 days of refrigerated display (4°C) following 1, 3, 6, and 9 months of frozen (-20°C) storage. TC supplementation at all concentrations showed antioxidative effects for both breast and thigh chicken meat during the 9 months of frozen storage compared to the control sample. TC supplementation at levels of 200 and 300 mg kg(-1) feed were more effective (P<0.05) in delaying lipid oxidation in all meat samples compared to the control. TC supplementation at a level of 200 mg kg(-1) feed showed antioxidant activity equivalent to α-tocopheryl acetate fed at the same level up to 3 months of frozen storage. For long-term frozen storage up to 9 months, however, TC supplementation at 300 mg kg(-1) feed was required as a replacement for α-tocopheryl acetate at a level of 200 mg kg(-1) feed. The results obtained showed a long-term antioxidative effect exhibited by dietary tea catechins on chicken meat during frozen storage and demonstrated that tea catechins are effective alternatives to vitamin E as natural dietary antioxidants.     

Effects of Selenium and Methionine Supplementation of Breeder Hen Diets on Selenium Concentration and Oxidative Stability of Lipids in the Thigh Muscles of Progeny

ABSTRACT:  The effects of dietary supplementation to female chickens with selenium (Se) and methionine (Met) on the next generation were studied. Lang-shan breeding hens (450) were obtained at 52 wk of age and randomly allotted to 9 treatments; 5 replicates of each treatment were carried out. The breeders were fed a basal corn–soybean meal diet (0.13 mg Se/kg) supplemented with 0, 0.30, or 0.60 mg/kg Se from Sel-Plex and 0.32%, 0.40%, or 0.54% Met for the 30-d adapting period and 70-d experiment period. Se and glutathione (GSH) concentrations, glutathione peroxidase (GSH-Px) activity, and the oxidative stability of muscular lipids of 90-d progeny were determined by testing the TBARS values. When breeders received the highest levels of Met or Se, GSH-Px activity was decreased, the Se concentration and the oxidative stability of muscular lipids were increased with the supplementation of Se or Met. When breeder hens were given a Met-deficient diet, supplementing with Se decreased the Se deposition in progeny thigh. With regard to lipid oxidation, 0.3 mg/kg maternal dietary Se supplementation decreased the oxidative stability of muscle lipid and 0.6 mg/kg Se supplementation showed no difference from the control. When breeders were fed a Se-deficient diet, the GSH-Px activity was increased significantly and the oxidative stability of progeny muscles was decreased with the supplementation of Met. It was concluded that supplementation of the maternal diet with higher Se and Met can increase Se deposition in progeny muscle and lead to more effective protection against lipid oxidation in progeny thighs.     

LIPID PEROXIDATION IN SARCOPLASMIC RETICULUM AND MUSCLE OF TILAPIA IS INHIBITED BY DIETARY VITAMIN E SUPPLEMENTATION

Lipid peroxidation was analyzed in muscle and sarcoplasmic reticulum (SR) of hybrid tilapia fed diets containing 0, 100, 200, and 300 IU vitamin E/kg for 8 months. Iron-catalyzed NADH-dependent lipid peroxidation in SR of tilapia fed diet containing no supplemented vitamin E was significantly greater than that of fish fed other diets (P < 0.05). No difference was observed in SR lipid peroxidation between fish fed 200 and 300 IU vitamin E/kg. Thiobarbituric acid reactive substances (TBARS) produced in muscle stored at either 4C or -40C for 7 days and 8 weeks, respectively, increased when storage time increased. When muscle TBARS were plotted against storage time, the lag phases were longer for fish fed high vitamin E (≥ 200 IU/kg) diets than those from fish fed low vitamin E diets.     

Feeding fish meal and extruded soybeans enhances the conjugated linoleic acid (CLA) content of milk

Twelve multiparous Holstein cows averaging 65 (33 to 122) DIM were used in a 4 x 4 Latin square for 4-wk periods to determine whether feeding fish oil as fish meal would stimulate increased amounts of milk conjugated linoleic acid (cis-9, trans-11 C18:2; CLA) and transvaccenic acid (trans-11 C18:1; TVA) when the cows were fed extruded soybeans to supply additional linoleic acid. Treatment diets were 1) control; 2) 0.5% fish oil from fish meal; 3) 2.5% soybean oil from extruded soybeans; and 4) 0.5% fish oil from fish meal and 2% soybean oil from extruded soybeans. Diets were formulated to contain 18% crude protein and were composed (dry basis) of 50% concentrate mix, 25% corn silage, and 25% alfalfa hay. Intake of DM was not affected by diet. Milk production was increased by diets 2, 3, and 4 compared with diet 1 (control). Milk fat and milk protein percentages decreased with diets 3 and 4. Milk fat yield was not affected by treatments, but yield of milk protein was increased with supplemental fish meal and extruded soybeans or their blend. When diets 2, 3, or 4 were fed, concentrations of cis-9, trans-11 CLA in milk fat increased by 0.4-, 1.4-, and 3.2-fold, and TVA concentrations in milk fat increased by 0.4-, 1.8-, and 3.5-fold compared with the control milk fat. Increases in TVA and cis-9, trans-11 CLA were 91 to 109% greater when a blend of fish meal and extruded soybeans was fed than the additive effect of fish meal and extruded soybeans. This suggested that fish oil increased the production of CLA and TVA from other dietary sources of linoleic acid such as extruded soybeans.     

Short communication: Effects of supplementing diets of Holsteins with copper,zinc, and manganese on blood neutrophil function

The effects of supplementing diets with sulfate or glycinate Cu, Zn, and Mn on blood neutrophil function were examined in 27 late-lactation Holstein cows having a mean (± standard deviation) days in milk at time of neutrophil assays of 216 ± 31 d. Cows were assigned to 9 blocks of 3 and were grouped by parity, milk production, and days in milk. Cows within each block were randomly assigned to 1 of 3 treatments: (1) control diet devoid of supplemental Cu, Zn, and Mn; (2) diet supplemented with Cu, Zn, and Mn via sulfates; and (3) diet supplemented with Cu, Zn, and Mn via glycinate form. All cows were initially fed a control total mixed ration with basal mineral concentrations of 8 mg/kg of Cu, 35 mg/kg of Zn, and 35 mg/kg of Mn for 30 d. During the treatment period, cows fed diets with mineral supplementation via sulfates or glycinate forms had target total dry matter dietary concentrations of 18 mg/kg of Cu, 60 mg/kg of Zn, and 60 mg/kg of Mn for 30 d. Control cows were fed the control diet devoid of supplemental minerals for an additional 30 d. In vitro neutrophil functions were measured after 30 d on experimental or control diets. Percentage of neutrophils phagocytizing, intracellular kill, and phagocytic index did not differ among treatments. Serum concentrations of Cu, Zn, and Mn were also not affected by dietary treatment after 30 d. Results from this study demonstrated that dietary Cu, Zn, and Mn supplemented either as sulfates or glycinate form for 30 d had no effect on either in vitro blood neutrophil function or serum concentrations of Cu, Zn, and Mn in late-lactation Holstein cows.