Effect of administration of vitamin E and selenium during the dry period on mammary health and milk cell counts in dairy ewes

Effect of Milking Vacuum and the Supplementation of Vitamin E and Se in Milk Quantity, Quality, and Hygiene of Mammary gland in Mountainous Greek Sheep

The aim of this research was to study the effect of two machine milking vacuum levels on the quantitative and qualitative characteristics of milk and mammary gland hygiene of ewes, when vitamin E and Se were administrated supplementarily. The experiment was conducted at the Vlasti Research Station in the Greek province of West Macedonia. Ninety-six ewes of the Mountainous Greek sheep breed were used. Animals were separated in four equal groups of 24 ewes per group. A 2 × 2 factorial design was applied, with two milking vacuum levels (38 kPa and 46 kPa) and two rations, one supplemented with vitamin E (300 I.U.) and Se (3 mg/kg DM feed) and one without any vitamin E and Se supplementation. Six test days were assigned (evening and morning milkings) at 14-day intervals, from April to July. Following milk yield control, milk samples were collected for chemical composition and somatic cell count (SCC) determination. At the end of milking of each lot, the milk from the terminal receiver of the milking machine was received for the evaluation of total bacterial count (TBC). The results revealed that milk yield was improved considerably in the case of 46 kPa vacuum level. Moreover, the chemical composition of milk was not influenced by vacuum level; however, the administration of vitamin E and Se appeared to have a positive effect. Moreover, the addition of vitamin E and Se decreased somatic cell counts (number and log10) at the two assessed machine milking vacuum levels. In reference to TBC and their log10, significant differences were not observed at both milking vacuum levels, regardless of vitamin E and Se administration. Statistical analysis did not indicate any interactions between the factors that were studied. Therefore, it is concluded that the quantity of vitamin E and Se supplemented to the ration has a positive effect on decreasing SCC and consequent positive action in the hygiene of the mammary glands of machine milked ewes.

Feeding and Nutritional Factors That Affect Somatic Cell Counts in Milk of Sheep and Goats

The purpose of this quantitative review is to highlight the effects of feeding strategies using some mineral, vitamin, marine oil, and vegetable essential oil supplements and some agri-food by-products to reduce SCCs in the milk of sheep and goats. According to the results, only specific dietary factors at specific doses could reduce SCCs in the milk of dairy sheep and goats. The combination of Se and vitamin E in the diet was more effective in sheep than in goats, while the inclusion of polyphenols, which are also present in food matrices such as agro-industrial by-products, led to better results. Some essential oils can be conveniently used to modulate SCCs, although they can precipitate an off-flavoring problem. This work shows that SCCs are complex and cannot be determined using a single experimental factor, as intramammary inflammation, which is the main source of SC in milk, can manifest in a subclinical form without clinical signs. However, attention to mineral and vitamin supplementation, even in the most difficult cases, such as those of grazing animals, and the use of anti-inflammatory substances directly or through by-products, can improve the nutritional condition of animals and reduce their SCCs, offering undeniable benefits for the milk-processing sector as well.

Redox Status of Pregnant Ewes after Vaccination against Clostridial Diseases

The redox status shortly after the vaccination of pregnant ewes is rather unexploited. Thus, the present study was designed to evaluate the fluctuation of redox status after the administration of the annual booster dose of a polyvalent clostridial vaccine in pregnant ewes, 3 to 4 weeks before lambing, with or without a simultaneous injection of Vit E/Se. In total, 24 pregnant Lacaune ewes 3–4 weeks before lambing were randomly allocated into four equal groups: the V (vaccinated with a polyvalent clostridial vaccine), VE (vaccinated and injected IM with Vit E/Se), E (injected IM with Vit E and Se), and C (neither vaccinated nor injected with Vit E/Se). The study period lasted for 21 days, starting on the day of administration. Four redox biomarkers, the antioxidant capacity (TAC), the thiobarbituric acid reactive substances (TBARS), the reduced glutathione (GSH), and the catalase (CAT) were evaluated in blood samples collected from all ewes before the injections (0 h) and then at 12 (12 h), 24 (D1), and 48 h (D2), and thereafter on days 4 (D4), 6 (D6), 10 (D10), 14 (D14), and 21 (D21). The results reveal that the TAC was the only biomarker evaluated that was significantly affected by group and significantly lower in vaccinated animals (V and VE groups) compared to non-vaccinated (E and C groups). The absence of an increase in the TBARS values after vaccination in groups V and VE indicates the absence of significant oxidative stress. Overall, it can be assumed that annual booster immunizations against clostridial diseases do not impose acute oxidative stress on pregnant ewes in the last month of pregnancy.

Role of Selenium and Vitamins E and B9 in the Alleviation of Bovine Mastitis during the Periparturient Period

Mastitis (inflammation of the mammary gland) commonly occurs in dairy cattle during the periparturient period (transition period), in which dairy cattle experience physiological and hormonal changes and severe negative energy balance, followed by oxidative stress. To maintain successful lactation and combat negative energy balance (NEB), excessive fat mobilization occurs, leading to overproduction of reactive oxygen species (ROS). Excessive fat mobilization also increases the concentrations of nonesterified fatty acids (NEFA) and β-hydroxybutyric acid (BHB) during the periparturient period. In addition, the excessive utilization of oxygen by cellular respiration in the mammary causes abnormal production of oxidative stress (OS). OS impairs the immunity and anti-inflammatory efficiency of periparturient dairy cattle, increasing their susceptibility to mastitis. To alleviate oxidative stress and subsequent mastitis, antioxidants are supplemented to dairy cattle from an external source. Extensive studies have been conducted on the supplementation of selenium (Se) and vitamins E and B9 to mitigate mastitis during the transition period in dairy cattle. Altogether, in the current review, we discuss the research development on bovine mastitis and its major causes, with special emphasis on oxidative stress during the transition period. Moreover, we discuss the antioxidant, immunoregulatory, and anti-inflammatory properties of Se and vitamins E and B9 and their role in the control of bovine mastitis in periparturient dairy cattle.

The Antioxidant Properties of Selenium and Vitamin E; Their Role in Periparturient Dairy Cattle Health Regulation

Dairy cattle experience health risks during the periparturient period. The continuous overproduction of reactive oxygen species (ROS) during the transition from late gestation to peak lactation leads to the development of oxidative stress. Oxidative stress is usually considered the main contributor to several diseases such as retained placenta, fatty liver, ketosis, mastitis and metritis in periparturient dairy cattle. The oxidative stress is generally balanced by the naturally available antioxidant system in the body of dairy cattle. However, in some special conditions, such as the peripariparturient period, the natural antioxidant system of a body is not able to balance the ROS production. To cope with this situation, the antioxidants are supplied to the dairy cattle from external sources. Natural antioxidants such as selenium and vitamin E have been found to restore normal health by minimizing the harmful effects of excessive ROS production. The deficiencies of Se and vitamin E have been reported to be associated with various diseases in periparturient dairy cattle. Thus in the current review, we highlight the new insights into the Se and vitamin E supplementation as antioxidant agents in the health regulation of periparturient dairy cattle.

Impacts of heat stress on immune responses and oxidative stress in farm animals and nutritional strategies for amelioration

Heat stress is one of the greatest challenges for the global livestock industries as increased environmental temperature and humidity compromises animal production during summer leading to devastating economic consequences. Over the last 30 years, significant developments have been achieved in cooling and provision of shade and shelter to mitigate heat stress reducing some of the losses associated with heat stress in farm animals. However, the recent increase in the incidence of heat waves which are also becoming more severe and lasting longer, due to climate change, further accentuates the problem of heat stress. Economic losses associated with heat stress are both direct due to loss in production and animal life, and indirect due to poorer quality products as a result of poor animal health and welfare. Animal health is affected due to impaired immune responses and increased reactive oxygen species production and/or deficiency of antioxidants during heat stress leading to an imbalance between oxidant and antioxidants and resultant oxidative stress. Research over the last 20 years has achieved partial success in understanding the intricacies of heat stress impacts on oxidative stress and immune responses and developing interventions to ameliorate impacts of heat stress, improving immune responses and farm animal health. This paper reviews the body of knowledge on heat stress impacts on immune response in farm animals. The impacts of heat stress on both cell-mediated and humoral immune responses have been discussed identifying the shift in immune response from cell-mediated towards humoral response, thereby weakening the immune status of the animal. Both species and breed differences have been identified as influencing how heat stress impacts the immune status of farm animals. In addition, crosstalk signaling between the immune system and oxidative stress has been considered and the role of antioxidants as potential nutritional strategies to mitigate heat stress has been discussed.

A meta-analysis and meta-regression of the effects of vitamin E supplementation on serum enrichment, udder health, milk yield, and reproductive performance of transition cows

Vitamin E is an essential nutrient for cows, but the effect of vitamin E supplementation is often controversially discussed in the published literature. The main goal of this meta-analysis was to evaluate the effects of vitamin E supplementation on its serum and colostrum enrichment, milk yield (MY), and somatic cell counts (SCC), as well as on various reproductive variables of transition cows, by considering a large set of variables that might influence the responses to vitamin E supplementation. After a broad search in journals and databases with keywords related to transition cows supplemented with vitamin E and appropriate filtering of the results, 36 papers including 53 trials were selected, and their data were extracted into a database. A meta-analysis was conducted on the extracted data. The analysis showed enrichment of serum vitamin E both at parturition (effect size: 2.423) and postpartum (effect size: 0.473), but no effects of vitamin E supplementation on IgG concentration in colostrum (effect size: -0.05) were found. There was a tendency for supplemented cows to produce more milk (effect size: 1.29) during the first month of lactation. Because of large heterogeneity, a meta-regression was performed but none of the presumed influencing factors was identified as a potential variable affecting MY. Milk SCC, as an indicator of udder health, was unaffected by vitamin E supplementation. Vitamin E supplementation tended to decrease the calving to first estrus period (CFP), whereby supplementing Se and taking parity into account in the analysis significantly lowered the CFP. Cows receiving additional vitamin E had, on average, 6.1% fewer cases of retained placenta, whereby Se supplementation and breed were key factors improving the effect of vitamin E to reduce retained placenta. In this regard, breeds other than Holstein responded better and these cows showed a lower incidence of retained placenta. The supplemented cows showed fewer days open (effect size: -0.31), and this improvement was affected linearly by increasing the dosage administered. Also, cows showed fewer services per conception with increasing dosage of vitamin E. In conclusion, this analysis showed that supplementing vitamin E did not affect SCC or colostrum quality but improved reproductive performance of transition cows, an effect consistent with increased levels of serum vitamin E and, for some variables, being modulated by Se supplementation.

Predisposing factors for bacterial mastitis in ewes

Objective of this review paper is the appraisal of predisposing factors for bacterial mastitis in ewes. Factors that predispose ewes to mastitis can be classified into non-animal-related factors (environmental and climatological factors, housing, nutrition, milking practices) and animal-related factors (anatomic, genetic, litter size-ethological factors, number and stage of lactation period, health problems). There are clear management-environment-animal interactions in mastitis development in ewes, which underline its multifactorial nature. Research and studies regarding risk factors are important, in order to develop strategies for their elimination, control or correction. Control measures for bacterial mastitis, which attempt to eliminate predisposing factors for infection, can thus be developed and implemented.

Chemical-nutritional characteristics and aromatic profile of milk and related dairy products obtained from goats fed with extruded linseed

Objective

This study aimed to evaluate the effect of dietary integration with extruded linseed (EL) on fatty acid (FA) and aromatic profile of goat cheese after 60 (T₆₀) days of ripening.

Methods

Thirty goats were divided in two groups. The control group (CG) was fed with conventional diet, whereas the experimental group (EL+) was fed with conventional diet supplemented with 10% of EL. Milk samples were collected on 30 and 60 days of trial to determinate chemical-nutritional composition and FA profile. At the end of experiment, six cheese-making sessions (3 for each group) were carried out using a pooled milk sample obtained from the 15 goats of each group. At 60 days of ripening, cheeses were analyzed for chemical-nutritional composition, FA and aromatic profile.

Results

An increase in the milk production, protein, fat and lactose were evidenced in the EL+ goats. Conversely, a reduction of somatic cells was observed in the EL+ compared with the CG. However, no variation was observed for urea and casein levels content in milk samples, and no changes in protein and lipid content were found for cheeses in the two experimental groups. Dietary supplementation with EL modified the FA profile of milk. There was a decrease in saturated FAs and an increase in polyunsaturated FAs. Chemical composition of T₆₀ cheese did not differ between the two groups but a different FA profile was observed. In T₆₀ cheese obtained from EL+ milk, an increase in short-chain FA and a decrease in medium and long-chain FA were observed. The EL diet led to cheeses with butanoic acid 2 times higher compared to CG cheeses. Moreover, a greater presence of aldehyde compounds and alcohols were observed in the cheeses of experimental group.

Conclusion

The present study pointed out that EL supplementation may improve the chemical and physical qualities of goat milk and cheeses.

Mineral supplementation stimulates the immune system and antioxidant responses of dairy cows and reduces somatic cell counts in milk

The aim of this study was to evaluate whether the use of subcutaneous mineral supplementation would affect metabolic parameters, immunological response, milk quality and composition of dairy cows in the postpartum period. Twelve pregnant primiparous Holstein cows, were divided into two groups: six animals supplemented with the mineral complex (magnesium, phosphorus, potassium, selenium and copper), and six animals used as controls. Milk samples were collected every two other weeks postpartum up to sixty days of lactation to analyze composition and quality. Blood samples were collected, and the levels of ketone bodies, total proteins, glucose, albumin, and globulin were measured. The catalase and superoxide enzymes, reactive oxygen species, tumor necrosis factor, and interleukins were determined. Animals supplemented with minerals showed lower levels of ketone bodies and somatic cell counts on days 30, 45 and 60 of the experiment, without changes in milk composition compared to the control group. Supplemented cows had lower levels reactive oxygen species and increased superoxide enzymes activity. Total protein, globulin and cytokine levels were higher in cows supplemented with mineral complexes. Therefore, we can conclude that subcutaneous mineral supplementation improved the immune response and minimized the oxidative stress in dairy cows during lactation.

Effect of administration of vitamin E, selenium and antimicrobial therapy on incidence of mastitis, productive and reproductive performances in dairy cows

Administration of vitamin, mineral and antimicrobials at the end of lactation plays potential role in preventing mastitis in dairy cows. A total of 255 cows dividing into five groups (A = 50, B = 50, C = 50, D = 50 and E = 55) at their late gestation period were selected to explore the effect of vitamin E, selenium and antimicrobial therapy on mastitis incidence, their productive and reproductive performances. Each cow of group A received α-tocopherol + sodium selenite orally daily for last 30 days before calving, while each cow of group B, C and D was treated with α-tocopherol + sodium selenite intramuscular injection, procaine penicillin + neomycin sulfate, and dicloxacillin sodium intramammary infusions at Day 30-20 before calving, respectively. Group E cows served as untreated control. California mastitis test (CMT) revealed that 70.0%, 76.0%, 84.0% and 100.0% cows in group A, B, C and D, respectively were free from new intramammary infections (IMIs) during early lactation period. The bacteriological results showed highest IMIs rates (76.3%) in group E and lowest IMIs (2.0%) in group D (P < 0.05). Staphylococcus aureus and Escherichia coli were the most predominant udder pathogens in all groups except group D (only CNS). The mean IMIs incidence (20.5%) was significantly lower in treated cows (P < 0.001). The treated cows had higher cure rates (81.9%) than control cows (23.1%) and overall efficacy of treatments on cure rates was 71.8% for all mastitis pathogens (P < 0.0001). The productive and reproductive performances of the treated cows at postpartum and early lactation period remained always higher than their non-treated counterparts (P < 0.001). A number of cow and herd related factors were identified to be significantly associated with mastitis (P < 0.001). The results concluded that antimicrobial therapy had more beneficial effect in preventing mastitis over vitamin-mineral administration and intramammary infusion with dicloxacillin sodium remained as the best effective preventive strategies for mastitis in dairy cows.

Mastitis in sheep--The last 10 years and the future of research

Bacterial mastitis is a significant welfare and financial problem in sheep flocks. This paper reviews the recently published literature, including publications that highlight the significance and virulence factors of the causal agents, especially Staphylococcus aureus and Mannheimia haemolytica, the primary causes of the disease. Research has also contributed to the understanding of risk factors, including genetic susceptibility of animals to infections, supporting future strategies for sustainable disease control. Pathogenetic mechanisms, including the role of the local defenses in the teat, have also been described and can assist formulation of strategies that induce local immune responses in the teat of ewes. Further to well-established diagnostic techniques, i.e., bacteriological tests and somatic cell counting, advanced methodologies, e.g., proteomics technologies, will likely contribute to more rapid and accurate diagnostics, in turn enhancing mastitis control efforts.

Postpartum injection with vitamin E and selenium failed to improve the performance of Awassi ewes and their lambs

Awawdeh, M. S., Talafha, A. Q. and Obeidat, B. S. 2015. Postpartum injection with vitamin E and selenium failed to improve the performance of Awassi ewes and their lambs. Can. J. Anim. Sci. 95: 111–115. The objective of this study was to investigate the effect of vitamin E and Se injection of nursing Awassi ewes on the performance of ewes (body weight change, milk yield, and composition) and their lambs (growth rate and weaning weight). Twenty-eight Awassi ewes were randomly assigned upon lambing to one of two groups; Control (n=13) and Inject (n=15), where ewes received 0 (control) or 15 plus 0.05 mg kg−1 BW of vitamin E and Se, respectively (inject). Intramuscular injections were given at 1 and 4 wk postpartum. Body weight (BW) of ewes and their lambs were recorded at lambing and at 2, 4, 6, and 8 wk postpartum. Milk yield and composition were measured at 2, 4, and 6 wk postpartum and somatic cell count (SCC) was evaluated weekly (from lambing through 8 wk). Injecting nursing ewes with vitamin E and Se had no effects (P≥0.10) on BW change of ewes, milk yield and composition, composition yields, or milk SCC. Injecting nursing ewes with vitamin E and Se had no significant effects (P≥0.29) on weaning weight, BW gain, or growth rate of their lambs. Under conditions similar to the current study, injecting nursing Awassi ewes with vitamin E and Se at 1 and 4 wk postpartum was not effective in improving the performance of ewes and their suckling lambs. Such observations could be attributed to the time of supplementation (pre- or post-partum) and/or the adequate basal vitamin E status in ewes.

[Age-related changes in antioxidant parameters in healthy calves between the first day of life and the 18th month taking into consideration selected metabolic parameters]

OBJECTIVE

To follow the age-dependent development of anti-oxidative metabolic parameters in healthy cattle from birth until 18 months of age.

MATERIAL AND METHODS

Blood samples from healthy female cattle were collected at days 1 and 7 post natum (p. n.) and during the 1st, 3rd, 6th, 9th, 12th and 18th month p. n. The antioxidant parameters superoxide dismutase (SOD), glutathione peroxidase (GPX) and Trolox equivalent antioxidative capacity (TEAC), haematocrit (Hct) and the metabolic parameters total protein, albumin, bilirubin, calcium, inorganic phosphate, iron, urea, cholesterol, β-hydroxybutyrate, alkaline phosphatase, aspartate transaminase, glutamate dehydrogenase, creatine kinase and haptoglobin were determined.

RESULTS

All three antioxidant parameters displayed a comparable time-course, with a maximum at 6 months p. n. With the exception of the 9th month p. n., significantly positive correlations were found constantly. GPX activity increased continuously from 50-80 U/ml Hct on day 1 p. n. to 100-190 U/ml Hct in the 6th month p. n. The significantly lowest activities were found on the 1st and 7th day p. n. SOD activity at the 1st (4500-5600 U/g haemoglobin [Hb]) and 7th day p. n. were significantly lower than in the 1st and 3rd month p. n. Activi- ties at 12 and 18 months displayed significantly lower values com- pared to the 1st, 3rd and 6th (5000-9100 U/g Hb) month p. n. The increase in the TEAC concentration from 220-290 µmol/l on day 1 to 260-340 µmol/l in the 6th month p. n. was non-significant. Thereafter, a significant decrease in the concentrations (p>0.05) was found.

CONCLUSION

Parallel trends for SOD, GPX and TEAC found in this study indicate a fully functioning antioxidant defence system in the calf, which is well adjusted to and able to compensate the inevitable oxidative stress of birth, onset of respiration, haemoglobin remodelling, forestomach development and other physiological processes.

Vitamin and trace element supplementation in grazing dairy ewe during the dry season: effect on milk yield, composition, and clotting aptitude

A study was carried out to evaluate the influence of vitamin and trace mineral supplementation on milk production and composition in grazing dairy ewes during the dry season. Ewes (n = 50) were assigned at weaning to blocks and treatments. Ewes were daily conducted (8 h/day) on a pasture based on Italian ryegrass (Lolium multiflorum). At fold, ewes received a basal diet composed by ad libitum oat hay and a definite amount of a pelleted concentrate. Dietary treatments included: (1) the control concentrate containing background of vitamin and trace mineral only, and (2) the experimental concentrate containing the premix supplement (10 g/kg of dry matter). Vitamin and trace mineral supplementation did not affect ewes' body weight. Milk, fat- and protein-corrected milk, fat percentage, and clotting properties were improved in ewes fed supplemented concentrate. There was a week × treatment interaction (P < 0.05) for yield of milk and corrected milk that was greatest at peak production in ewes fed the premix. Our findings indicate that in grazing dairy ewe, the dietary vitamin and trace mineral supplementation during dry season led to an increase of milk production and quality, with positive improvement in milk clotting aptitude.

Effect of selenium and vitamin E supplementation during the late pregnancy on reproductive indices and milk production in heifers

A trial was performed to determine the effects of supplementation of selenium (Se) and vitamin E (VE) on reproductive indices and milk production in Holstein heifers. Sixty heifers at the late stage of gestation were randomly assigned into three groups. Heifers were balanced for age, weight and time of calving. Four and 2 weeks before expected calving the heifers were injected 0 ml (C), 20 ml (T1), and 40 ml (T2) Se and VE supplements. Each ml contained 0.5mg Se and 50 IU of D, L-alpha-tocopheryl acetate. Blood samples were collected from heifers 4 weeks before expected calving and at calving day. Se concentrations in serum and colostrums were measured. The reproductive parameters were recorded. The effects of Se and VE supplements on somatic cell count (SCC) and milk yield also were measured. Supplementation of Se increased the level of Se in serum of treated heifers at calving day (P<0.05). Se concentration of colostrums were affected by the treatments (P<0.05). Concerning reproductive performance of treated heifers; gestation length was similar among groups but in comparison with controls, T1 and T2 had no incidence of retained fetal membrane (i.e., beyond 12h.). In addition, open days were fewer in T1 and T2 heifers and the number of services per conception was fewer in T2 compared with controls (P>0.05). Daily milk production at 8 weeks lactation was significantly increased in T2 compared with controls (P<0.05). Likewise, the milk SCC decreased in treated heifers compared with controls (P<0.05).

Prevention of clinical mastitis with barium selenate in dairy goats from a selenium-deficient area

Mastitis is one of the most negative factors involved in the economy of dairy goat farms. The effect of selenium on mammary gland resistance to infectious diseases has been demonstrated. This work evaluates the efficacy of a slow-release Se salt (barium selenate) to reduce the incidence of clinical mastitis in goats reared on Se-deficient areas. Six hundred milking goats of the Malagueña breed, from 4 commercial dairy farms located in a Se-deficient area, were randomly allotted to 2 groups: treated group (given a subcutaneous injection of barium selenate at a dose of 1 mg of Se/kg of body weight 15 d before mating) and control group (no supplement). During the lactation the does were monitored to assess the occurrence of clinical mastitis by physical examination, California Mastitis Test performance, and microbiological study. The Se content of the ration consumed previously by the animals did not meet the requirements for dairy goats. The Se injection significantly increased glutathione peroxidase activity in the treated group and had evident beneficial effects in the subsequent lactation. The somatic cell count and the incidence of clinical mastitis were significantly lower in the treated group than in the control group. However, no significant differences were found for milk composition. Thus, in Se-deficient areas, the supplementation with Se of any source in programs for prevention of clinical mastitis and improvement of milk quality is strongly recommended.

How minerals may influence the development and expression of immunity to endoparasites in livestock

This review attempts to explain how dietary mineral intake may affect the immune system, with particular reference to gastrointestinal nematode infestations of livestock, and considers its significance for other gut infections as well as for other species. Of the 56 minerals found in mammalian tissues, 16 are currently considered to be essential, and a further 13 probably essential, for cell and tissue function. To date, eight of these have been shown to affect the function of the mammalian immune system directly. Nine others have roles in physiological pathways such as neurological or endocrine function, or protein or carbohydrate metabolism, which in turn regulate the immune system. The remainder may in the future be shown to have immunologically specific roles. The pathogenesis of mineral effects on immunity involves a number of pathways and molecular mechanisms. Major areas requiring further investigation are the relationship between deficiency of minerals and in vivo immune-mediated protection against disease, in particular diseases of the mucosa, and the mechanisms by which the minerals or their deficiency exert their effect on immunity. Research is also required into the possibility that animals in the process of acquiring gut immunity have higher requirements for minerals.

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.

Mastitis of sheep and goats

This article presents an overview of the recent research into ovine and caprine mastitis. The common clinical presentations of mastitis in these species are reviewed, as are the important etiologic agents and their significance. The interpretation of somatic cell counts and surrogate tests, factors that affect somatic cell count levels, and association of somatic cell count levels with productivity are reviewed. Investigations into the treatment and prevention of mastitis and milking equipment function are discussed, and comments are made on the public health implications of extra label drug use and the consumption of unpasteurized milk.

Selenium and vitamin E

Deficiency of selenium and vitamin E has recently been identified as a major health concern of sheep producers in certain regions of the United States, and familiarity with published data on these nutrients seems to be of value to small ruminant practitioners. This article begins with a description of the biochemical roles and metabolism of selenium and vitamin E. A literature review follows in which the influence of these nutrients on the musculoskeletal, reproductive, and immune systems, as well as on flock productivity, is discussed. Methods for detection of deficiency and supplementation strategies are also described.