Selenium supplementation influences growth performance, antioxidant status and immune response in lambs

To investigate and compare the effect of inorganic and organic Se supplementation, 18 male lambs (24.68 ± 2.89 kg mean body weight, about 8–9 months of age) were divided into three groups of six animals in each, following randomized block design. While animals in the control group (Gr I) were fed a standard TMR containing 195 g/kg crushed maize grain, 175.5 g/kg soybean meal, 260 g/kg wheat bran, 13 g/kg mineral mixture (without Se), 6.5 g/kg common salt and 350 g/kg wheat straw, animals in Gr II and Gr III were additionally supplemented with 0.15 mg Se/kg of diet through sodium selenite (inorganic Se) and Jevsel-101 (organic Se), respectively. Experimental feeding was done for a period of 90 days. To assess the humoral immune response, all the lambs were intramuscularly inoculated with a single dose (2 mL) of Haemorrhagic septicaemia oil adjuvant vaccine on day 0; and blood samples were collected on day 0, 30, 60 and 90. Supplementation of Se had no effect on serum total cholesterol, total protein, albumin, globulin, albumin:globulin ratio, T₃, T₄, T₄:T₃ ratio; serum Ca and P levels and SGOT and SGPT activity. However, there was a significant increase in the serum Se level, RBC GSH-Px activity and humoral immune response in both the Se supplemented groups as compared to control group. Average daily gain (g) was highest (110) in Gr III, followed by Gr II (98.2) and lowest in Gr I (89.1). Thus, supplementation of organic as well as inorganic Se was found to improve the growth rate, humoral immune response and antioxidant status of the lambs; and between two sources, organic Se was more effective than inorganic Se.     

Influence of Different Amounts and Sources of Selenium Supplementation on Performance, Some Blood Parameters, and Nutrient Digestibility in Lambs

Two trials were conducted in a 2?×?2?+?1 factorial arrangement based on a completely randomized design to evaluate the effects of different sources of selenium (Se) on performance, blood metabolites, and nutrient digestibility in male lambs on a barley-based diet. The first trial lasted for 70 days and consisted of 30 lambs (35.6?±?2.6 kg mean body weight, about 4–5 months of age) which were randomly allotted to five treatments including: (1) basal diet (containing 0.06 mg Se/kg DM; control) without supplementary Se, (2) basal diet?+?0.20 mg/kg Se as sodium selenite (SeS 0.20), (3) basal diet?+?0.40 mg/kg Se as sodium selenite (SeS 0.40), (4) basal diet?+?0.20 mg/kg Se as selenium yeast (SeY 0.20), and (5) basal diet?+?0.40 mg/kg Se as selenium yeast (SeY 0.40). For the second trial, four lambs from each group of experiment 1 were randomly allocated to individual metabolic cages for 14 days to measure the effects of dietary Se on nutrient digestibility. The results revealed that there were no significant differences for average daily gain, average daily feed intake, feed/gain ratio, hematological parameters (packed cell volume, red blood cell, white blood cell, and hemoglobin values), serum total protein, albumin, globulin, aspartate amino transferase, alkaline phosphatase, and creatine phosphokinase due to supplementation of different amounts and sources of Se in lambs. Dietary Se supplementation significantly improved (P?<?0.001) glutathione peroxidase activity in blood. Furthermore, at the end of the trial, serum tri-iodothyronine (T3) amount also increased (P?<?0.05), while serum thyroxine (T4) amount decreased (P?<?0.05). Digestibility of dry matter, organic matter, crude protein, neutral detergent fiber, and acid detergent fiber increased (P?<?0.05) by Se yeast supplementation. It may be concluded that supplementation of Se in lambs had no significant effect on performance and blood hematology, but increased blood glutathione peroxidase activity and serum T3 amount and decreased serum T4 amount as compared to non-supplemented control lambs. Furthermore, Se yeast improved nutrient digestibility in lambs.     

Effect of Boron as an Antidote on Dry Matter Intake,Nutrient Utilization and Fluorine Balance in Buffalo (<Emphasis Type="Italic">Bubalus bubalis</Emphasis>) Exposed to High Fluoride Ration

Twenty male buffalo calves (8–9 months, 112.1 ± 7.69 kg) were divided into four groups of five animals in each and fed diets without (T1) or supplemented with 0.3 ppm selenium (Se) (T2), 0.3 ppm Se + 10 ppm copper (Cu) (T3), and 10 ppm Cu (T4) for 120 days during which blood samples were collected on day 0, 40, 80, and 120. Concentrations of glucose, total protein, urea, uric acid, and creatinine were similar in all the four groups, but the level of globulin was significantly (P < 0.01) increased in groups T2 and T3, leading to reduced levels of albumin and A:G ratio (P < 0.01) in these groups. The level of different serum enzymes viz. lactate dehydrogenase (LDH), alkaline phosphatase (ALP), glutamate pyruvate transaminase (SGPT), and glutamate oxaloacetate transaminase (SGOT) and hormones viz. T₃, T₄, testosterone and insulin and T₄:T₃ ratio were similar (P > 0.05) among the four groups. It was deduced that supplementation of 0.3 ppm Se and/or 10.0 ppm of Cu had no effect on blood metabolic profile in buffalo calves, except for an increased globulin level, indicating improved immunity status of these animals.     

Effect of Selenium,Zinc, and Copper Supplementation on Blood Metabolic Profile in Male Buffalo (<Emphasis Type="Italic">Bubalus bubalis</Emphasis>) Calves

Twenty male buffalo calves (15 months, 200.2 ± 9.75) were divided into four groups of five animals in each and fed diets without (T1) or supplemented with 0.3 ppm selenium (Se) + 40 ppm zinc (Zn) (T2), 0.3 ppm Se + 40 ppm Zn + 10 ppm copper (Cu) (T3), and 40 ppm Zn + 10 ppm Cu (T4) for 120 days, during which blood samples were collected on days 0, 40, 80, and 120. Concentrations of glucose, total protein, albumin, globulin, urea, uric acid, and creatinine were similar in all the four groups. The level of different serum enzymes viz. lactate dehydrogenase, alkaline phosphatase, glutamate pyruvate transaminase, and glutamate oxaloacetate transaminase, and hormones viz. T₃, T₄, testosterone and insulin were similar (P > 0.05) among the four groups but the ratio of T₄/T₃ was reduced (P < 0.05) in the groups (T2 and T3) where selenium was supplemented at 120th day of supplementation. It was deduced that supplementation of 0.3 ppm Se and/or 10.0 ppm of Cu with 40 ppm Zn had no effect on blood metabolic profile in buffalo calves, except the ratio of T₄ and T₃ hormone which indicates that selenium plays an important role in converting T₄ hormone to T₃ which is more active form of thyroid hormone.     

Effect of organic zinc supplementation on growth, nutrient utilization and mineral profile in lambs

To study the efficacy of organic zinc (Zn) supplementation on growth, nutrient utilization and mineral profile as compared to inorganic source [zinc sulphate (ZnSO₄)], 18 Muzaffarnagari male lambs of 11.30 ± 0.45 kg mean body weight (4–5 months of age) were divided into three groups of six animals in each in a randomized block design. Lambs in the control group were fed a standard total mixed ration (TMR) consisted of 60 kg/100 kg of concentrate mixture (CM) and 40 kg/100 kg of wheat straw. CM was consisted of 300 g/kg crushed maize grain, 270 g/kg soybean meal, 400 g/kg wheat bran, 20 g/kg mineral mixture (without Zn) and 10 g/kg common salt. Animals in the experimental groups were additionally supplemented with 20 mg Zn/kg of diet either through inorganic (ZnSO₄) or organic [Zn-methionine AA complex (Zn-meth)] sources. Experimental feeding was done for a period of 150 days including a 6 days metabolism trial. The intake of dry matter (DM), organic matter (OM), crude protein (CP), digestible CP and total digestible nutrients and digestibility of DM, OM, CP, ether extract, neutral detergent fibre and hemicellulose were comparable (P>0.05) among the three groups. However, digestibility of cellulose and acid detergent fibre was significantly (P<0.05) higher in Zn-meth group as compared to control group. Though the balance of calcium was adversely affected (P<0.01) in both the Zn supplemented groups, but it was significantly higher in Zn-meth group compared to ZnSO₄ group. While apparent absorption and retention of nitrogen, phosphorus, copper, iron and manganese were similar (P>0.05) among different groups, retention of Zn (P<0.05) as well as its concentration in the serum (P<0.01) were highest in Zn-meth group, followed by ZnSO₄ group and lowest in the control group, suggesting higher bioavailability of Zn from Zn-meth as compared to ZnSO₄. Average daily gain of the lambs and feed conversion efficiency were also significantly (P<0.05) higher in Zn-meth group as compared to control and ZnSO₄ groups, suggesting a positive role of organic zinc supplementation on the performance of lambs.     

Comparative study on the responses of broiler chicken to hot and humid environment supplemented with different dietary levels and sources of selenium

Present study was carried out with the objective of investigating the role of green synthesized nano Se (GNS) in growth performance, digestibility of minerals, immunity, stress alleviation, antioxidant status, and body Se content of broiler chicken raised under hot and humid environment with respect to market nano Se (MNS) and inorganic Se. The experimental design was 3 × 3 factorial, in which three levels (0.15, 0.20, and 0.25 ppm) and three sources (inorganic, green nano, and market nano) of Se resulted in nine treatments viz. IS-0.15, GNS-0.15, MNS-0.15, IZ-0.20, GNS-0.20, MNS-0.20, IS-0.25, GNS-0.25, and MNS-0.25 (IS: inorganic Se, GNS: green nano Se, MNS: market nano Se). A total of 432 broiler chicken were divided among nine treatments with six replicates of birds per treatment (8 birds/replicate). Results of present study revealed significantly better growth performance of birds supplemented with 0.25 ppm nano Se. The supplementation of 0.25 ppm nano Se improved the immune response and lymphoid organ development of birds. Significantly higher Se and nitrogen digestibility coefficients, serum antioxidant activity and decline of Heterophil: Lymphocyte ratio and expression of HSP70 gene were observed in birds supplemented with 0.25 ppm Se and nano source of Se compared to inorganic Se. Significantly higher Se concentration in liver and breast muscle and higher serum Se concentration were observed in birds fed 0.25 ppm nano Se. The liver Se concentration was much higher than that of breast muscle. However, the nano Se synthesized by green method in this study did not differ significantly from the chemically synthesized nano Se. It was concluded that 0.25 ppm Se and nano form of Se are superior to lower levels and inorganic form of Se, respectively, in improving the immunity, growth, antioxidant status, and in stress alleviation of broiler chicken. However, GNS is equally efficient as chemically synthesized MNS.     

Effects of selenium supplementation on virus-induced inflammatory heart disease

The effects of 10 wk of selenium (Se) supplementation (5 ppm) in drinking water on immune responses and resistance to a myocarditic Coxsackie virus B3 (CB3) infection were studied in female Balb/c mice. Se supplementation reduced CB3-induced mortality: at day 14 postinoculation, survival was 58% in the Se-treated group as compared to 25% in the untreated group. Whole-blood glutathione peroxidase (GSH-Px) activity was elevated by 68% (p < 0.001) and Se content in the liver by 24% (p < 0.001). Red (RBC) and white blood cell (WBC) counts, as well as the number of cells in the spleen and thymus, were unaffected. The cellular counts of T-lymphocytes (CD4⁺, CD8⁺) and natural killer (NK⁺) cells in the blood were not affected. However, the CD4⁺/CD8⁺ ratio (5.2) tended to increase after Se supplementation (5.9). The spleen lymphoproliferative response to T and B-cell mitogens were increased by 9 and 43%, respectively (ns), in the Se-supplemented group. The total NK cell activity in blood and spleen showed minor increases, but when the activity in the blood was expressed per cell, the increase amounted to 35% (ns) with Se supplementation. The inflammatory and necrotic lesions in the ventricular myocardium at 7 and 14 d postinoculation were not significantly reduced by Se treatment, probably owing to the increased survival with Se even of mice with the most pronounced heart damage; comparable untreated mice were estimated to have died at day 14. Results indicate that modest doses of Se can improve immune function, which may increase the general resistance to this viral infection.     

Modulation of hypercholesterolemia-induced alterations in apolipoprotein B and HMG-CoA reductase expression by selenium supplementation

Various studies demonstrated a significant association between the trace element selenium (Se), hypercholesterolemia and the risk of cardiovascular disorders. Present study was aimed to reveal the role of Se supplementation in modulation of hypercholesterolemia-induced changes in apolipoprotein B (apoB) and 3-hydroxy 3-methylglutaryl co-enzyme A (HMG-CoA) reductase expression during experimental hypercholesterolemia in Sprague-Dawley male rats. Animals were fed 0.2 and 1 ppm Se-supplemented control diet as well as 2% cholesterol-supplemented diet for 3 months. Apolipoprotein B levels were measured by ELISA and Western blot. HMG-CoA reductase mRNA expression was studied by RT-PCR. ApoB levels increased significantly on 2% cholesterol-supplemented diet feeding. On 1 ppm Se supplementation apoB levels decreased significantly. HMG-CoA reductase mRNA expression decreased significantly on cholesterol-supplemented diet feeding and on 1 ppm Se supplementation the mRNA expression further decreased. So the present results demonstrate that 1 ppm Se supplementation is responsible for down regulation of apoB and HMG-CoA reductase expression during hypercholesterolemia. These findings highlight the therapeutic potential of selenium supplementation in lipid metabolism.     

Protective role of selenium status on T3/T4 kinetics in rats under hyperlipidemia

The effect of high fat diet (HFD) on thyroid hormones (T3/T4) and protective role of selenium (Se) were studied in rats. Se levels in serum and liver decreased significantly, whereas glutathione peroxidase (GSH-Px) in liver and lipid levels (cholesterol and triglycerides) in serum increased after 1, 2 and 3 months of HFD feeding in comparison to controls in all the three Se status i.e. deficient (0.02 ppm), adequate (0.2 ppm) and excess (1 ppm) groups. Levels of T3/T4 decreased significantly on HFD feeding, as compared to respective controls in all the groups. Within the deficient group, as Se deficiency progressed, T3/T4 levels decreased after 2 and 3 months in comparison to 1 month. A significant increase was observed in T3/T4 concentration on feeding 1 ppm (excess) Se supplemented diet, in comparison to adequate group. Also, in 1 ppm Se supplemented group as the Se deposition increased i.e. after 2 and 3 months, levels of T3/T4 increased significantly. So, the present study indicates that Se supplementation up to 1 ppm normalizes the T3 and T4 concentrations or regulates the hypothyroidism induced by hyperlipidemia.     

Effect of simulated American,Bulgarian, and Japanese human diets and of selenium supplementation on the incidence of virally induced mammary tumors in female mice

In attempts to simulate the effects of diet on human breast cancer development groups of female C3H mice infected with mammary tumor virus (MMTV-) were maintained on diets formulated to resemble the typical American, Bulgarian, and Japanese human diets. The incidence of mammary tumors was the highest (84%) in group of mice receiving the simulated meat- and fat-rich American diet, which was also low in selenium (Se content: 0.15 ppm). The appearance of mammary tumors was delayed in the mice maintained on the simulated Bulgarian diet, and the final tumor incidence (27%) paralleled the correspondingly lower Bulgarian breast cancer incidence. The simulated Bulgarian diet contained more Se (0.25 ppm), and was lower in fat, meat, and sugar and higher in complex carbohydrates (cereals) than the simulated American diet. In the mice fed the simulated Japanese diet, the appearance of mammary tumors was also delayed, and the tumor incidence was diminished to 47%. In this diet, fish meal was a major source of Se, which is known to have low bioavailability. Additional supplementation of the Japanese-type diet with bioavailable Se (1 ppm) lowered the tumor incidence to 10%. Based on these studies, recommendations are made for breast cancer risk reduction by dietary means.     

Effects of supplementation with fish oil and barium selenate on performance, carcass characteristics and muscle fatty acid composition of late season lamb finished on grass-based or concentrate-based diets

The objectives of this study were to investigate the effects of fish oil supplementation on performance and muscle fatty acid composition of hill lambs finished on grass-based or concentrate-based diets, and to examine the interaction with selenium (Se) status. In September 2006, 180 entire male lambs of mixed breeds were sourced from six hill farms after weaning and finished on five dietary treatments: grazed grass (GG), grass +0.4 kg/day cereal-based concentrate (GC), grass +0.4 kg/day cereal-based concentrate enriched with fish oil (GF), ad libitum cereal-based concentrate (HC) and ad libitum fish oil-enriched concentrate (HF). Within each treatment, half of the lambs were also supplemented with barium selenate by subcutaneous injection. At the start of the trial, the proportion of lambs with a marginal (<0.76 μmol/l) or deficient (<0.38 μmol/l) plasma Se status was 0.84 and 0.39, respectively. Compared with control lambs, GG lambs treated with Se had higher (P < 0.01) plasma Se levels, whereas erythrocyte glutathione peroxidase activity was higher (P < 0.01) for Se-supplemented lambs fed diets GG and GF. However, Se supplementation had no effects on any aspect of animal performance. Fish oil increased (P < 0.05) levels of 22:5n-3 and 22:6n-3 in the Longissimus dorsi of HF lambs but otherwise had no effect on the health attributes of lamb meat. There were no significant effects of fish oil on dry matter intake, animal performance or lamb carcass characteristics. Daily carcass weight gain (CWG; P < 0.001), carcass weight (P < 0.01) and conformation score (P < 0.01) increased with increasing concentrate inputs. Lambs fed concentrate-based diets achieved a higher mean CWG (P < 0.001), dressing proportion (P < 0.001) and carcass weight (P < 0.011), and were slaughtered up to 8.3 days earlier (P < 0.05) and at 1.2 kg lower (P < 0.05) live weight than pasture-fed lambs. However, carcasses from grass-fed lambs contained lower levels of perinephric and retroperitoneal fat (P < 0.05), and had less fat over the Iliocostalis thoracis (P < 0.001) and Obliquus internus abdominis (P < 0.05). Meat from grass-fed lambs also had lower levels of 18:2n-6 and total n-6 fatty acids compared with those finished indoors. The results of this study demonstrate that fish oil supplementation has some benefits for the health attributes of meat from lambs fed concentrate-based diets but not grass-based diets. Supplementing Se-deficient lambs with barium selenate will improve Se status of lambs fed zero-concentrate diets, but has no additional benefit when lambs are already consuming their daily Se requirement from concentrates or when fish oil-enriched diets are fed.     

Effect of selenium supplementation on thyroid hormone levels and selenoenzyme activities in growing lambs

The aim of the present study was to evaluate the effects of selenium supplementation on thyroid hormone metabolism and selenoenzyme activities in lambs. Twelve 20-d-old male lambs were assigned to one of two diets: A (0.11 ppm Se) and B (supplemented with 0.2 ppm selenium as sodium selenite). Blood samples were collected weekly for the determination of T₃, T₄, and selenium levels. The response to thyrotropin-releasing hormone (TRH) challenge was estimated at the 11th and 20th wk. Animals were slaughtered at wk 20 and tissues were collected for enzyme determination. Plasma selenium concentration was significantly higher in supplemented lambs (p<0.001). Plasma T₃ and T₄ levels remained similar in both groups. Type I deiodinase activity (ID-I) was decreased in the liver (p<0.05) and increased in the pituitary (p<0.01) of supplemented animals. No ID-I activity was detected in the thyroid. Pituitary type II deiodinase activity (ID-II) remained unchanged. The response to TRH challenge did not differ between the two groups for both challenges, but in group B, the second TRH challenge (20th wk) resulted in a significantly higher T₃ response compared to the first one (11th wk) (p<0.05). In conclusion, the lack of effects of Se supplementation on thyroid hormone metabolism demonstrates that enzyme activity is homeostatically controlled and selenium is incorporated in that order to ensure the maintenance of thyroid hormone homeostasis.     

Effect of individual and mixed live yeast culture feeding on growth performance,nutrient utilization and microbial crude protein synthesis in lambs

This study investigated effects of feeding three individual, and a mixed, yeast culture (Kluyveromyces marximanus NRRL3234, Saccharomyces cerevisiae NCDC42, Saccharomyces uvarum ATCC9080 all in a 1:1:1, ratio) on growth performance, nutrient utilization and microbial crude protein (CP) synthesis in feedlot lambs during the post-weaning phase of growth. Sixty weaner lambs (90 ± 3.5 d old and 15.9 ± 0.50 kg BW) were fed for 91 d in five equal groups. The control group of lambs received sterilized culture medium while the treatment groups were fed a yeast culture in addition to a ad libitum total mixed ration (TMR). The yeast culture, dosed at 1 ml/kg body weight (BW) had 1.5–2.0 × 10⁹ live cells/ml. Yeast culture supplementation did not influence intake and digestibility of organic matter (OM), CP, neutral detergent fiber (NDF), acid detergent fiber (ADF) and hemicellulose and the metabolizable energy (ME) level of the diets were similar between control and yeast supplemented lambs. Lambs in all groups were in positive N balance, but N intake and N voided in feces and urine, as well as N balance, did not change due to yeast culture supplementation. Urinary allantoin excretion was similar, but purine derivatives absorbed (mM/d) were higher (P<0.05) in yeast culture supplemented lambs. Yeast culture supplementation improved (P<0.05) microbial CP synthesis. Supplementation of SC and mixed yeast improved (P=0.002) BW gain of lambs by 21% and 16% respectively. All yeast culture supplemented lambs had higher feed efficiency in comparison to control lambs. Among the three yeast cultures used, S. cerevisiae had the most potential as a growth promoting feed additive in feedlot lamb production, and it may serve as an alternate to antibiotics and ionophores as a growth promoter of weaner lambs.     

Selenium persistency and speciation in the tissues of lambs following the withdrawal of dietary high-dose selenium-enriched yeast

The objective was to determine the concentration of total selenium (Se) and the proportion of total Se comprised as selenomethionine (SeMet) and selenocysteine (SeCys) in post mortem tissues of lambs in the 6 weeks period following the withdrawal of a diet containing high-dose selenised yeast (HSY), derived from a specific strain of Saccharomyces cerevisae CNCM (Collection Nationale de Culture de Micro-organism) I-3060. Thirty Texel × Suffolk lambs used in this study had previously received diets (91 days) containing either HSY (6.30 mg Se per kg dry matter (DM)) or an unsupplemented control (C; 0.13 mg Se per kg DM). Following the period of supplementation, all lambs were then offered a complete pelleted diet, without additional Se (0.15 mg Se per kg DM), for 42 days. At enrolment and 21 and 42 days later, five lambs from each treatment were blood sampled, euthanased and samples of heart, liver, kidney and skeletal muscle (longissimus dorsi and psoas major) tissue were retained. Total Se concentration in whole blood and tissues was significantly (P < 0.001) higher in HSY lambs at all time points that had previously received long-term exposure to high dietary concentrations of SY. The distribution of total Se and the proportions of total Se comprised as SeMet and SeCys differed between tissues, treatment and time points. Total Se was greatest in HSY liver and kidney (22.64 and 18.96 mg Se per kg DM, respectively) and SeCys comprised the greatest proportion of total Se. Conversely, cardiac and skeletal muscle (longissimus dorsi and psoas major) tissues had lower total Se concentration (10.80, 7.02 and 7.82 mg Se per kg DM, respectively) and SeMet was the predominant selenised amino acid. Rates of Se clearance in HSY liver (307 μg Se per day) and kidney (238 μg Se per day) were higher compared with HSY cardiac tissue (120 μg Se per day) and skeletal muscle (20 μg Se per day). In conclusion, differences in Se clearance rates were different between tissue types, reflecting the relative metabolic activity of each tissue, and appear to be dependent on the proportions of total Se comprised as either SeMet or SeCys.     

Serum and testis selenium concentrations and testis morphology in ram lambs of varying ages

Serum and testis selenium (Se) concentrations, body and testes weights, seminiferous tubule height and width measurements and percent of tubules containing luminal spermatozoa were determined in Se-treated (SSe) and control (NSe) crossbred ram lambs at 60, 90, 120, 150 and 180 days of age. With IM injections, SSe lambs received 3 mg of Se as selenite and NSe lambs received 0.9% saline at 30-day intervals throughout the study. For each age group, lambs were weighed, jugular vein blood collected and testes removed at the designated age. Serum and testis tissue samples for each lamb were assayed for Se, and testis tissue was also evaluated for histological parameters. For all parameters, only serum Se concentrations were affected (P<0.0001) by Se treatment; however, all other parameters were affected (P<0.0001) by age. For combined groups, mean testis Se concentration (0.33 ppm), testes weights, seminiferous tubule measurements and percent of tubules (82.2) containing luminal spermatozoa were greatest (P<0.05) at 180 days of age, and mean testis Se concentrations were significantly correlated with these testicular parameters. These data lend support to the hypothesis that the increase in concentration of testicular Se to adult concentrations (>0.3 ppm) around the time of puberty is associated with rapid testicular development and production of spermatozoa.     

The effects of sulphur supplementation on cellulose digestion in vitro and on nutrient digestion,nitrogen metabolism and rumen characteristics of lambs fed on good quality fescue and tropical star grass hays

Experiments were conducted in vitro and in vivo to determine the effects of sulphur (S) supplementation of a good quality fescue hay containing 0.27% total S and a tropical star grass hay containing 0.20% total S. Addition of S was on an isosulphurous basis of either sodium sulphate or D,L-methionine. Cellulose digestion in vitro was improved (P < 0.001) by the addition of 1% urea. Supplementation of forage with 0.05, 0.10 or 0.15% S from either sodium sulphate or methionine also stimulated cellulose digestion in vitro. There were no differences between S sources. The addition of 0.4 or 0.8% nitrate-nitrogen (nitrate-N) (potassium nitrate) depressed (P < 0.05) cellulose digestion in vitro of both hays. No effect of animal adaptation to nitrate was evident. Addition of S partially counteracted the depression in cellulose digestion due to nitrate. Trials were conducted in vivo in which 12 crossbred wether lambs (fescue experiment) or 12 crossbred intact male lambs (star grass experiment) were randomly assigned to one of three treatments: control (forage with no addition of S); forage plus 0.15% S as sodium sulphate; and forage plus 0.15% S as D,L-methionine. Lambs were housed in metabolism crates and each experiment was replicated twice. Dry matter intakes were highest for methionine-supplemented fescue and for S-supplemented star grass, regardless of S source. Dry matter digestibility tended to increase with S addition (fescue experiment) and was significantly higher for S-supplemented star grass. There was a significant increase (P < 0.05) in neutral detergent fibre (NDF) and acid detergent fibre (ADF) digestibility due to supplemental S, regardless of S source. Nitrogen retention, ammonia-N and ruminal volatile fatty acids were unaffected by S supplementation.     

Effects of different selenium sources on tissue selenium concentrations,blood GSH-Px activities and plasma interleukin levels in finishing lambs

Thirty-two wether lambs of Tan sheep were randomly assigned into four dietary treatment groups (eight per group) for an 8-wk study and then fed a basal diet deficient in Se (0.06 mg/kg) or diets supplemented to provide 0.10 mg/kg Se from sodium selenite, selenized yeast, and selenium-enriched probiotics, respectively. Blood samples were collected at d 0, 28, and 56 of the experiment and tissue samples were collected at experiment termination. Tissue and blood Se concentrations, blood glutathione peroxidase (GSH-Px) activities, and plasma interleukin levels were analyzed. The results showed that the concentrations of Se in the kidney, liver, and muscle increased in all of the supplemented groups (p<0.01) compared with the control group. However, the Se concentrations in the kidney, liver, and muscle in the groups supplemented with Se yeast and Se-enriched probiotics were higher than those in the group supplemented with sodium selenite (p<0.01). The activities of GSH-Px and the concentrations of Se in blood also increased in all of the supplemented groups during the period of supplementation (p<0.01) compared with the control group. The activities of GSH-Px and the concentrations of Se in the whole blood of the lambs fed with selenized yeast and Se-enriched probiotics were higher than those of lambs fed with sodium selenite (p<0.01 or p<0.05). The concentrations of interleukin-1 and interleukin-2 in plasma significantly increased in all of the supplemented groups during the entire period of experiment (p<0.01) compared with the control group, but had no significant differences among all of the supplemented groups. In conclusion, a diet supplemented with Se for finishing lambs was able to increase the concentrations of Se in tissue and blood, activities of GSH-Px in blood, and levels of interleukins in plasma. Organic Se sources (selenized yeast and Se-enriched probiotics) were more effective than the inorganic Se source (sodium selenite) in increasing tissue and blood Se concentrations and blood GSH-Px activities of lambs. However, there were no significant differences in plasma interleukin levels of lambs between organic and inorganic Se sources.     

Influence of sodium selenite on203Hg absorption,distribution, and elimination in male mice exposed to methyl203Hg

To study the effects of long-term selenium supplementation on absorption, distribution, and elimination of methylmercury (MeHg) in mice, three groups of male mice (Balb/c CA) were exposed for 7 wk to 0, 0.6, and 3 ppm sodium selenite in tap water. They were then given a single oral dose of Me²⁰³Hg (2 μmol/kg) by gastric intubation, and elimination of²⁰³Hg was followed by whole-body counting for 49 d at the same Se exposure as previously. Twenty-four hours and 49 d after dosage, 6–7 animals/group were sampled for analysis of²⁰³Hg distribution in the body. Glutathione peroxidase (GSH-PX) activity in blood and selenium levels in the liver were used as measures of selenium status. Gastrointestinal absorption of Me²⁰³Hg was not influenced by the Se status of the animals. Selenium supplementation of MeHg-exposed mice caused an enhanced whole-body elimination of Hg, but selenium-supplemented animals did not have lower Hg levels in the brain and kidney than nonsupplemented animals. The effect of selenium on the accumulation, of Hg in the brain was dose-dependent, a high dose (3 ppm Se) causing a higher initial accumulation of Hg. The intracellular distribution of²⁰³Hg in the liver and kidney was not affected by Se. The results indicate that selenium treatment of MeHg-exposed mice may have a positive effection the health of the animals by decreasing the total body burden of MeHg.     

Influence of dietary culture material containing aflatoxin and T<Subscript>2</Subscript> toxin on certain serum biochemical constituents in Japanese quail

Forty newly hatched unsexed Japanese quail (Coturnix coturnix japonica) chicks were fed diets containing 3 ppm aflatoxin (AF) and 4 ppm T₂ toxin either singly and in combination for 35 days. Sera samples were collected from six birds in each group at the end of the trial to study the effect of certain serum biochemical parameters. Highly significant (P < 0.01) differences were observed for serum total protein, albumin, globulin, glucose, cholesterol, aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP) and gamma glutamyl transferase (GGT) between control and toxin treated groups. Toxin treated groups did not reveal any significant difference for serum urea nitrogen, creatinine, uric acid, calcium, phosphorus, sodium and potassium. There was a reduction in the levels of serum total protein, albumin, globulin, glucose, cholesterol, ALT and elevation of AST and GGT and variable ALP levels observed in toxin treated groups. Forms part of M.V.Sc. thesis of first author approved by the Tamil Nadu Veterinary and Animal Sciences University, Chennai 600 051, India.