Alpha-tocopherol, selenium and polyunsaturated fatty acid concentrations in the serum and feed of spring-calving dairy heifers

Effects of selenium, vitamin E, and β-carotene administration on fertility of Awassi ewes synchronized for estrus in non-breeding season

The aim of this study was to evaluate the effect of selenium, β-carotene, and vitamin E administration on fertility of Awassi ewes synchronized in non-breeding season. A total of 80 multiparous Awassi ewes, aged 2 to 6 years were enrolled in the study. Intravaginal sponges containing flugeston acetate (20 mg cronolon) was inserted into vagina and allowed to remain in vagina for nine days. Ewes were randomly divided into two groups. Group I received intramuscular injections of 1 mg sodium selenite, 60 mg vitamin E, 75 mg β-carotene, and 100 mg DL-α-tocopherol acetate at sponge insertion, sponge removal, and 18 days after the introduction of ram. Group II remained as control group and received no treatment. On the removal of the sponges, 500 IU eCG and 0.075 mg D-cloprostenol were injected intramuscularly. Ram was introduced for 1 hr twice a day 24 hours after the sponge removal. Interval between sponge removal and estrus, estrus rates, conception rates, pregnancy rates, lambing rates, and fecundity rates in group I and group II were 45.30±1.71 and 43.94±1.72 hours, 79.1% and 86.6%, 66.66% and 72.41%, 54.05% and 58.33%, 100% and 100%, and 135% and 138%, respectively. There were no statistical differences between the groups (p>0.05). In conclusion, the administration of Se, β-carotene, and vitamin E in estrus synchronization protocols in non-breeding season had no positive effect on the fertility characteristics of Awassi sheep.

Stability of fatty acid composition of intramuscular fat from pasture- and grain-fed young bulls during the first 7 d postmortem

In order to study the effect of different amounts of concentrate feed and the effectiveness of natural antioxidants on the fatty acid stability of intramuscular fat during the first days postmortem, 75 young bulls of the Retinta breed were divided in three groups: 30 were grazed, 30 were fed on medium concentrate diets, and 15 were fed on high-concentrate diets. Young bulls were slaughtered at commercial weight, around a 500 kg final body weight. Samples from Longissimus lumborum muscle were assigned to two ageing periods (0 and 7 d) and were vacuum packaged in vacuum bags (O2 permeability: 9.3 mL O2/m2 per 24 h at 0 ∘C) using an EGARVAC® sealer. Beef from grass-fed bulls showed a higher polyunsaturated fatty acid content than concentrate-fed bulls. During the first 7 d postmortem, no changes in the fatty acids profile were observed, because α-tocopherol content was optimal to prevent lipid oxidation. The higher level of natural antioxidants in grass than in grain resulted in the stability of the fatty acid profile. This study shows that the anti-oxidative potential of natural antioxidants in meat plays an important role during the first 7 d postmortem.

Selenium requirements in grazing dairy cows: a review

In New Zealand, the recommended intake of Se for dairy cattle (0.03 mg/kg dry matter (DM)) is lower than in the United Kingdom and Australia (0.1 and 0.04 mg/kg DM, respectively), and much lower than in the United States of America (0.3 mg/kg DM). Advisors in New Zealand often suggest that New Zealand intake recommendations are far too low and that recommendations from the United States of America should be used. This has created confusion as farmers are given very different advice depending on which recommendations their advisor uses. In this review, we assess whether the published evidence supports the existing dietary requirements and associated Se status thresholds, or if change is required. We focus particularly on the evidence-base in cattle fed a primarily pasture-based diet, as it is critical that dietary recommendations are derived from data created using cows fed similar diets. Accordingly, we also consider whether the increased use of fodder crops, especially during the dry period, is likely to have altered the Se requirements of dairy cows in New Zealand. We report that the science behind the dietary requirements for Se is robust, being supported by factorial models validated using New Zealand data, and on-farm experimental studies. Published nutritional data suggest that the increased use of fodder crops is unlikely to have altered the dietary balance of pro- and antioxidant factors in New Zealand dairy cows in a way that would meaningfully affect Se requirements. However, the lack of specific data on the vitamin E and fatty acid content of the crops being fed in New Zealand means that more information is needed to confirm this conclusion. In general, the existing New Zealand recommendations for Se-status thresholds are supported, although studies are still lacking to properly characterise the upper threshold of the marginal range. Nevertheless many studies in New Zealand, of herds with marginal or low adequate Se status (using New Zealand recommendations), have failed to show an effect of Se supplementation on milk production, intramammary infection or reproductive performance, so it is highly unlikely that the upper threshold of the range is much higher than the current recommendation. Proponents of the hypothesis that Se intakes in New Zealand dairy cattle should be increased by at least 10 times the current recommendations are therefore not using the evidence base correctly.

Practical implications of mineral and vitamin imbalance in grazing sheep

Rapid progress in research on mineral functions in biological systems over the past 20 years has provided new and unexplored implications for health and production in grazing livestock. The strong interaction among calcium (Ca), magnesium (Mg), phosphorus (P), sodium (Na), potassium (K) and vitamin D influences the absorption, utilisation and status of these nutrients, particularly Ca and Mg. An imbalanced intake of Ca, Mg, P, Na, K and vitamin D is common in ruminants grazing pastures and vegetative crops. The interaction may modify susceptibility to clinical hypocalcaemia, hypomagnesaemia and pregnancy toxaemia, or to subclinical and chronic deficiencies of Ca, Mg and Na. However, hypocalcaemia is also associated with endocrine failure. Whether this failure is susceptible to nutritional modulation or even whether supplements of Ca, Mg, Na and vitamin D reduce or exacerbate the risk of metabolic disease in sheep is unclear. Selenium, manganese, zinc, copper, sulfur, vitamin E and vitamin A play synergistic roles in the antioxidant defence mechanism and modulate the consequences of oxidative stress. In extensive grazing systems combined low intakes of these antioxidants are not unusual, particularly in seasonally dry environments and at a time coinciding with the increased oxidative stress that naturally occurs through the reproductive cycle. This oxidative stress is accentuated by heat stress and parasite infection. Oxidative stress in the short-term influences growth, reproduction, offspring survival and health. Long-term, oxidative damage to embryo DNA and changes in RNA expression, may influence lifetime performance of offspring. The high cost of providing mineral supplements to grazing sheep is a deterrence to addressing the implications of multiple mineral deficiencies. New herbaceous and shrub options to increase the botanical and nutritional diversity within pasture and crop-grazing systems may allow livestock to select a heterogeneous diet providing a more balanced mineral intake.

Lipid stability and meat colour of beef from pasture- and grain-fed cattle with or without vitamin E supplement

Meat from pasture-fed cattle can have high contents of α-tocopherol and other anti-oxidants originating from naturally occurring compounds present in grasses. However, meat from pasture-fed cattle may have an increased demand for endogenous anti-oxidants because of its high content of polyunsaturated fatty acids, which in turn, may affect its colour and lipid stability. In the work described, we evaluated the effects of pasture-feeding alone and with vitamin E supplementation and compared the findings with those obtained for grain-fed cattle (predominantly sorghum) with and without supplementation. Within each nutritional background, vitamin E supplementation did not alter meat colour or colour stability of fresh or 47-day aged muscle during 7-day aerobic storage. However, both control and supplemented grain-fed product had better meat colour (more redness) compared with meat from grass-fed cattle. These differences in redness between pasture- and grain-fed fresh beef were not apparent after ageing. The treatments did not affect the lipid stability of fresh meat during aerobic storage; however, supplementation reduced (P<0.01) lipid oxidation in grain-fed aged beef compared with pasture-fed aged beef, despite both having similar α-tocopherol contents. Pasture-fed beef had more linolenic acid, less linoleic acid and, overall, was more polyunsaturated than grain-fed beef (P<0.05). In summary, vitamin E supplementation of pasture-fed cattle did not alter muscle tocopherol contents but pasture-fed beef (both control and supplemented) was more susceptible to lipid oxidation following ageing than vitamin E supplemented grain-fed beef.

Monitoring of vitamin E status of dry, early and mid-late lactating organic dairy cows fed conserved roughages during the indoor period and factors influencing forage vitamin E levels

Analysis of blood plasma of 60 cows selected on six Flemish organic dairy farms revealed that on average 12% of all samples and on one farm up to 28% of the organic cows showed plasma vitamin E concentrations less than 3.0 μg/ml, which is considered the minimum level to avoid health risks due to vitamin E shortages. Furthermore, this study showed early lactating and dry cows to be more at risk in relation to animals in mid-late lactation. In European organic farming, vitamin supplements are only allowed if granted by the local authority to satisfy daily requirements. Therefore, the vitamin E content of the feedstuffs used on the farms was determined. Grass clover silage (GCS) and mixed silage had significantly more vitamin E than hay, maize or grain (p < 0.05) [mean (SD): 52 (35), 29 (20), 4.5 (1.7), 4.9 (4.4) and 7.1 (3.8) mg/kg DM, respectively]. Apparently, variation in the vitamin E content in the silage samples was huge. Hence, the vitamin E content of ryegrass, white and red clover was determined in a second lab scale experiment and the effects of wilting, DM content and supplementation of ensiling additives were investigated. Fresh ryegrass had a higher vitamin E content than white and red clover (p < 0.05) [156 (11.3), 49.3 (0.67) and 74.3 (5.73) μg/g DM, respectively]. These differences remained after the wilting or ensiling. Supplementation of formic acid or lactic acid bacteria at ensiling had no significant effect on the vitamin E content. Overall, it can be concluded that GCS is the most important source of vitamin E in organic dairy farming. A legal possibility for case-related supplementation should be retained in organic dairy farming as approximately 18% of all dry and early lactating cows were at risk of vitamin E shortage.

The effect of long-acting injectable selenium formulations on blood and liver selenium concentrations and liveweights of red deer (Cervus elaphus)

AIM

To evaluate the efficacy of a new long acting injectable selenium ( Se ) formulation to increase the Se status and prevent Se deficiency in red deer.

METHODS

Groups of weaned red deer (four stags and six hinds/group) grazing pastures containing <30 mg Se/kg DM were injected subcutaneously with either 0.5, 1.0 or 2.0 mg Se/kg as a new formulation of BaSeO4 (Deposel Multidose), 1.0mgSe/kg of a current formulation (Deposel), or not treated. Blood Se concentrations and liveweight were measured nine times at intervals over 377 and 270 days, respectively.

RESULTS

Both formulations of Se elevated blood Se concentrations from 105 nmol/l pre-injection for at least 377 days with peak levels of 1894, 1395 and 818 nmol/l for high, medium and low doses of Deposel Multidose, respectively, at 73141 days, and 1508 nmol/l at 73-141 days for the medium dose of Deposel, which persisted at similar levels for the duration of the study. Deposel Multidose produced fewer and less severe subcutaneous tissue reactions than Deposel. Pastures contained 10 to 30 mg Se/kg DM. There was no significant difference in growth rate between treated and control deer. There was a significant (p<0. 01) linear relationship (y = 1.25x + 71.6, R2=0.86) between blood (x) and liver (y) Se concentrations in the range of 120 - 2100 nmol/l for blood concentrations, and 200 - 3000 nmol/kg for liver concentrations.

CONCLUSION

Injections of BaSeO4 in both formulations studied were effective in increasing the Se status of deer but the new formulation produced fewer and less-severe tissue reactions. Young growing red deer appear less sensitive to Se deficiency as measured by weight gain, than sheep and cattle, suggesting that reference ranges for those species are not appropriate for deer. There was a linear correlation between blood and liver selenium concentrations.

Barium selenate supplementation and its effect on intramammary infection in pasture-based dairy cows

A significant proportion of cattle receive inadequate dietary Se because of its low content in soils and pastures of various regions of the world. Several economically important diseases in dairy cows, such as mastitis, have been associated with Se deficiency. The objective of this study was to evaluate the effect of a single injection of a long-acting form of Se at drying off on the risk and incidence rate of new intramammary infections and on milk somatic cell count in the subsequent lactation in pasture-based dairy cows. Forty-nine Chilean Holstein-Friesian cows were fed a diet containing <0.05 mg of Se/kg of ration dry matter. During the dry period, cows were allocated to 1 of 2 groups, a supplemented (n=24) group treated with a single subcutaneous injection of barium selenate 2 mo before calving and a control group (n=25) that remained unsupplemented. Duplicate foremilk samples were aseptically collected within 6 d after calving and every 2 wk until drying-off for bacteriological culture. Milk samples were also collected monthly for somatic cell count evaluation. Blood samples were collected before treatment and at 30, 90, 180, and 270 d after treatment for analysis of blood glutathione peroxidase (GPx) activity. The activity of glutathione peroxidase was higher in supplemented cows 30 d after the injection until the end of the study. The risk and incidence rate of new intramammary infections was not affected by supplementation. A progressive increase in somatic cell count was observed throughout lactation, but there was no effect of supplementation. In conclusion, a one-time injection of barium selenate 2 mo before calving in these pasture-based dairy cows did not affect udder health in the subsequent lactation, indicating that Se basal intake was adequate for preventing subclinical mastitis in pasture-based cows in southern Chile.

Efeito da suplementação de selênio e vitamina E sobre a incidência de mastite clínica em vacas da raça holandesa

Oitenta e quatro vacas da raça holandesa foram distribuídas em quatro tratamentos (grupos): o grupo A recebeu 5mg Se/dia, o B recebeu 1000 UI vit. E/dia, o C 5mg Se + 1000 UI vit. E/dia e o D foi usado como controle. A suplementação foi iniciada 30 dias antes da provável data de parição, prolongando-se até o parto. Amostras do volumoso e do concentrado foram colhidas quinzenalmente para análise bromatológica completa e levantamento dos níveis de Se e de vit. E. O sangue foi colhido antes do início da suplementação, ao parto, aos 30 e aos 60 dias após o parto para determinação dos níveis de Se no soro sangüíneo das vacas. O teste de Tamis foi realizado semanalmente para detecção dos casos clínicos de mastite e iniciado logo após o parto, prolongando-se até a 12ª semana da lactação. Um mês após a suplementação, as vacas que receberam selênio apresentaram níveis séricos de Se superiores (P<0,05) aos do grupo-controle. A administração de vitamina E (P<0,05) e de selênio (P<0,08) diminuiu a incidência de mastite clínica nas 12 primeiras semanas de lactação.

The influences of dietary intakes and supplementation with selenium and vitamin E on reproduction diseases and reproductive efficiency in cattle and sheep

Retained placenta, endometritis, cystic ovaries and low conception rates are often considered as interconnected conditions in cattle. Wide ranges in amounts of selenium and vitamin E supplements have been advised in late-pregnancy diets and, frequently, they can be synergistically beneficial. Animals at grass or with other green foods should be of adequate vitamin E status, but dietary selenium deficiencies are both more frequent and severe. Selenium status is important for super-ovulation in cattle and multiple births in ewes because of its importance in sperm transport and establishment of ova. However, the potential toxicity of selenium-enriched feed supplements restricts their use on a free-access basis. Giving sodium selenite or selenate by injection provides only a short-term response in the plasma. Barium selenate given in oil by injection provides a more durable response but has potential tissue residue problems. Compressed metallic selenium powder with iron powder in high-density reticulo-ruminal pellets gives sustained release, but uncertainties regarding possible surface coating and the variable effects of selenium particle size may require additional grinders to ensure prolonged release. Neither reticulo-ruminal pellets of such composition nor barium selenate by injection may be used worldwide because only sodium selenite and selenate have general regulatory approval. A sustained-release multi-trace element/vitamin rumen bolus system effective for several months has increased lambing percentages in ewes, and increased herd conception rates and reduced the spread of calving for herds of beef cattle.

The influences of dietary selenium and vitamin E intakes on milk somatic cell counts and mastitis in cows

Dietary supplements of selenium and vitamin E in greater amounts than are required for nutritional adequacy can have complementary functions in reducing somatic cell counts and both the severity and duration of clinical mastitis. Selenium inadequacy is geographically widespread and can frequently be a year-round problem. In contrast, an adequate intake of fresh grass and quality grass silage or other green, leafy material should provide adequate vitamin E. Many observations indicate that in farm situations where there is good udder hygiene and where long-acting antibiotic treatment is given at drying off, significant correlations are found between the mean bulk milk somatic cell counts and the blood selenium concentration or glutathione peroxidase activity in the blood, even where plasma vitamin E concentration is fully adequate. The accompanying reduced incidence of clinically affected quarters diminishes the need for corrective antibiotic treatment during lactation. Presentation of selenium and vitamin E within a sustained-release rumen bolus system during the dry period and into the succeeding lactation is a convenient means of supplementation to avoid over- or under-consumption by individual cows within a group. Adequate hygiene of the environment, the milking equipment and the udder are essential.

A review of selenium deficiency in grazing ruminants Part 1: New roles for selenium in ruminant metabolism

SELENIUM AVAILABILITY: Selenium deficiency has been an important source of loss to the pastoral industries of New Zealand. About 30% of farmed land in New Zealand is considered to be selenium-deficient and continued development of soils and pasture will tend to further decrease the concentration of selenium in pasture.

BIOLOGICAL FUNCTIONS

Formerly it was believed that all biological functions of selenium in animals could be attributed to the antioxidant activity of the enzyme glutathione peroxidase. More recently, it has been shown that selenoproteins have roles in immune function and thyroid hormone metabolism.

RESPONSES TO SUPPLEMENTATION

Following supplementation of ruminants grazing pastures deficient in selenium, milk production and growth responses are likely to occur in cattle, while in sheep improvements in growth and fertility are most likely. Reproductive dysfunction may not be as important as previously thought in cattle grazing pasture moderately deficient in selenium. The relationship between selenium intake and disease resistance deserves further study.

CLINICAL RELEVANCE

Management of selenium deficiency will continue to be important in grazing ruminants. Veterinarians should be aware that many selenoenzymes exist, some with functions quite distinct from the antioxidant role of glutathione peroxidase.