Effect of prepartum selenium treatment on uterine involution in the dairy cow

The effect and mechanism of selenium supplementation on the proliferation capacity of bovine endometrial epithelial cells exposed to lipopolysaccharide in vitro under high cortisol background

Bovine endometritis severely inhibits uterine repair and causes considerable economic loss. Besides, parturition-induced high cortisol levels inhibit immune function, reduce cell proliferation, and further inhibit tissue repair. Selenium (Se) is an essential trace element for animals to maintain normal physiological function and has powerful antioxidant functions. This study investigated whether Se supplementation reduces endometrial damage and promotes tissue repair in cows with endometritis under stress and explored the underlying mechanism. Primary bovine endometrial epithelial cells were isolated and purified from healthy cows. The cells were treated with different combinations of lipopolysaccharide (LPS), cortisol, and various concentrations of Se. Data showed that LPS stimulation inhibited cell proliferation and increased cell apoptosis. High levels of cortisol further exacerbated these effects. Flow cytometry, scratch wound healing tests, and 5-ethynyl-2'-deoxyuridine (EdU) proliferation assays showed that Se supplementation promoted cell cycle progression, cell migration, and cell proliferation in the presence of LPS and cortisol. The quantitative PCR results showed that the expression of related growth factors was increased after Se supplementation. After administering various inhibitors, we further demonstrated that Se supplementation decreased the activity of glycogen synthetase kinase 3β (GSK-3β) through the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway to reduce the degradation of β-catenin except the Wnt signal to promote cell proliferation. In conclusion, Se supplementation attenuated the cell damage induced by LPS at high cortisol levels and increased cell proliferation to promote uterine repair by elevating the mRNA expression of TGFB3 and VEGFA and activating the PI3K/AKT/GSK-3β/β-catenin signaling pathway.

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.

The Technical and Financial Effects of Parenteral Supplementation with Selenium and Vitamin E during Late Pregnancy and the Early Lactation Period on the Productivity of Dairy Cattle

This study aimed to determine the effects of parenteral selenium (Se) and vitamin E supplementation on economic impact, milk yield, and some reproductive parameters in high-yield dairy cows in the dry period and in those at the beginning of lactation. At the beginning of the dry period, cows (n = 323) were randomly divided into three groups as follows: Treatment 1 (T1), Treatment 2 (T2), and Control (C). Cows in group T1 received this preparation 21 days before calving and on calving day, and cows in group T2 received it only on calving day. The cows in the control group did not receive this preparation. Supplementation with Se increased Se serum levels of cows treated at calving day (p<0.05). Differences in milk yield at all weeks and the electrical conductivity values at the 8th and 12th weeks were significant (p<0.05). Supplementation with Se and Vitamin E decreased the incidence of metritis, the number of services per conception and the service period, but had no effects on the incidence of retained fetal membrane. A partial budgeting analysis indicated that Se supplementation was economically profitable; cows in group T1 averaged 240.6$ per cow, those in group T2 averaged 224.6$ per cow. Supplementation with Se and Vitamin E has been found to increase serum Se levels, milk yield, and has positive effects on udder health by decreasing milk conductivity values and incidence of sub-clinical mastitis.

Effects of method of presynchronization and source of selenium on uterine health and reproduction in dairy cows

The objectives of this study were to evaluate the effects of method of presynchronization and source of supplemental Se on uterine health and reproductive performance of lactating dairy cows. Holstein cows (n = 512) were assigned randomly to 2 methods of presynchronization, Presynch (2 PGF(2a) given 14 d apart) or CIDR-PS (controlled internal drug releasing inserted for 7 d with an injection of PGF(2a) at removal) and 2 sources of Se, sodium selenite (SS) or selenized yeast (SY) supplemented at 0.3 mg/kg from 25 d before calving to 80 d in milk (DIM) arranged in a 2 x 2 factorial. Cows were inseminated following the Ovsynch protocol (d 0 GnRH, d 7 PGF(2a), d 9 GnRH, timed artificial insemination (AI) 12 h after the final GnRH) starting at 12 and 3 d after Presynch and CIDR-PS, respectively. Cows were diagnosed for pregnancy at 28, 42, and 56 d after AI. Source of Se did not influence uterine health and resumption of cyclicity, but fewer CIDR-PS than Presynch cows were cyclic at the beginning of the Ovsynch, although differences in the proportion cyclic may have been caused by the timing when corpus luteum evaluations were performed in the different pre-synchronization treatments. Ovulatory responses were not influenced by source of Se. However, the CIDR-PS increased ovulation to the first GnRH, double ovulation to the final GnRH, and size of ovulatory follicle at PGF(2a) and final GnRH of the Ovsynch, but did not influence ovulation at the final GnRH of the Ovsynch. Concentrations of estradiol during the Ovsynch increased with follicle diameter and were greater for cows receiving CIDR-PS than Presynch, but they were not influenced by source of Se. Pregnancy per AI on d 28 (32.7%), 42 (28.5%), and 56 (25.9%) after AI, and pregnancy loss (20.5%) from 28 to 56 d were not influenced by source of Se or method of presynchronization. Although cows receiving CIDR-PS had an increased incidence of ovulation to the first GnRH (73.2 vs. 57.8%) and double ovulation to the final GnRH of the Ovsynch (18.7 vs. 9.0%), both of which enhanced pregnancy, the CIDR-PS protocol did not improve pregnancy per AI or reduce pregnancy loss compared with presynchronization with PGF(2a) alone.

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.

Effect of injection of beta-carotene or vitamin E and selenium on fertility of lactating dairy cows

Experiments tested whether supplemental antioxidants improved fertility. To test effects of beta-carotene, cows in a hot environment were injected with prostaglandin F2 alpha (PGF2 alpha) and were given 3 injections, i.m., of 800 mg beta-carotene or saline at Days -6 and -3 before the anticipated date of insemination and at insemination (n = 37-41 inseminated cows/group). There was no effect of beta-carotene on the proportion of cows detected in estrus following PGF2 alpha, timing of estrus after PGF2 alpha injection or pregnancy rate in inseminated cows. In a second trial, cows in a temperate climate received intramuscular injections of vitamin E (500 mg) and selenium (50 mg) at 30 d post partum (n = 97) or were untreated controls (n = 89). Treatment did not affect interval from calving to first insemination or the proportion of cows pregnant at first service, but it increased the pregnancy rate at second service (69.8 vs 52.1%; P = 0.07) and reduced services per conception (1.7 vs 2.0; P < 0.05) and interval from calving to conception (84.6 vs 98.1; P < 0.05). Thus, injection of vitamin E and selenium increased fertility in cattle that did not become pregnant at first service.

Effect of dietary selenium supplementation on the plasma progesterone concentration in cows

ABSTRACT. The effect of selenium (Se) supplementation to the diet on the plasma progesterone concentration was investigated in non-lactating and non-pregnant cows. Italian ryegrass wafers and concentrates, with or without 0.5 ppm of Se, were fed to cows at a maintenance level. The plasma Se concentrations in the each treatment were 0.047 ppm (-Se) and 0.081 ppm (+Se), respectively. Se supplementation did not affect the length of the estrous cycle, but it did increase the concentration of plasma progesterone in the estrous cycle (P<0.001). These results suggest the possibility that Se contributes to the progesterone production of corpus luteum.

The use of oxytocin for the reduction of cow placental retention, and subsequent endometritis

Oxytocin was administered to reduce incidence of retained placenta and uterine infections that could delay subsequent conception. Three hundred and fifty multiparous Friesian cows, each with spontaneous delivery of a single calf were divided randomly into two groups. Some (n = 175) were injected with 30 IU of oxytocin immediately after delivery and again 2-4 h later, while the remainder formed an untreated control group. The placental retention 24 h after parturition was 24.6% and 10.9% in control and treated animals respectively (P < 0.01). Endometritis occurred in 51.6% of the animals following placental retention as compared to 10.4% of those with normal expulsion of the fetal membranes (P < 0.001). A comparison of reproductive indices showed a statistically significant improvement of fertility in treated cows with the average interval from calving to conception being reduced from 124.4 d to 93.7 d (P < 0.0001).

Effects of monensin on the metabolism of periparturient dairy cows

The effects of monensin on plasma concentrations and changes in plasma concentrations of energy metabolites and minerals over time were investigated using 24 multiparous Holstein cows. Cows were paired according to farm, predicted date of calving, and body condition score and were randomly allocated to two groups. Treated cows were given a ruminal bolus containing 32 g of monensin at 50 +/- 7 d before predicted calving. Treated cows had lower plasma concentrations of glucose, free fatty acid (FFA), and beta-hydroxybutyrate (BHBA) than did control cows before calving, indicating that monensin influenced energy metabolism. However, no significant differences in plasma concentrations of glucose, FFA, and BHBA were found between groups after calving. Plasma BHBA concentrations increased more before calving in control cows, and plasma FFA and urea concentrations increased significantly before calving in all cows. No significant differences in body weight, plasma concentrations of urea, or whole blood concentrations of glutathione peroxidase were detected between groups before or after calving. Plasma ceruloplasmin activity did not differ between groups before calving, but was significantly higher in treated cows after calving. Plasma concentrations of Ca did not significantly differ between groups before or after calving. Monensin altered both energy and mineral metabolism and has the potential to improve the health and production of dairy cows.

Effect of selenium and a-tocopherol supplementation on postpartum reproductive function of dairy heifers at pasture

The objective of this study was to investigate the effects of selenium (Se) and alpha-tocopherol supplementation on uterine involution and ovarian function in dairy heifers fed a prepartum diet containing low concentrations of Se and alpha-tocopherol. Twenty-four pregnant Friesian heifers were randomly allocated to one of four experimental groups in a 2 x 2 design balanced for age and body weight. Prepartum treatments consisted of supplementation with either 2 intraruminal Se pellets or 3600 mg of alpha-tocopherol p.o. 4 times per wk, or both. Control animals received no supplementation. For 8 wk before calving, the heifers were fed exclusively on pasture hay which contained less than 10 microg/kg of Se and 19 mg/kg of alpha-tocopherol. After calving, the heifers grazed perennial ryegrass and white clover pasture. Concentrations of Se and alpha-tocopherol in serum for the prepartum heifers of the control group were 10 ng/ml and 1.3 microg/ml, respectively, indicating deficiencies of these nutrients. Treatment with Se and alpha-tocopherol increased prepartum serum concentrations of Se and alpha-tocopherol to 74 ng/ml and 5 microg/ml, respectively (P < 0.001). However, treatment with Se, alpha-tocopherol, or both, failed to enhance uterine involution, hasten resumption of postpartum ovarian activity or reduce the incidence of clinical postpartum abnormalities. These findings suggest that postpartum reproductive dysfunction is not a primary feature of moderate Se or vitamin E deficiency of cattle at pasture.

Effect of prepartum injection of vitamin E and selenium on postpartum reproductive function of dairy cattle

A total of 198 cows were randomly assigned to treatment with a single intramuscular injection of 10 ml of a preparation containing vitamin E and selenium or placebo 3 wk before expected parturition. Incidence of retained fetal membranes was 3.0% for the treated group and 10.1% for the control group (P=0.06). Administration of MU-SE also increased the percentage of cows pregnant to the first service (41.2 vs 25.3%; P=0.02), reduced the number of services per conception (2.3 vs 2.8; P=0.03), and reduced the interval from calving to conception (121 vs 141 days; P=0.06). The effect of MU-SE on fertility was apparent in cows with and without retained fetal membranes. There was no effect of MU-SE on the interval from calving to the first estrus. In conclusion, prepartum supplementation with vitamin E and selenium can decrease the incidence of retained fetal membranes, increase pregnancy rates and, thereby, reduce the interval from calving to conception in lactating dairy cows.

Recent developments in the roles of vitamins and minerals in reproduction

Vitamins and minerals affect reproductive function. Vitamin A deficiency has long been known to affect reproductive function in cattle. More recently, a role has been proposed for the vitamin A percursor, beta-carotene, in reproductive efficiency. Dietary supplementation with vitamin E and selenium may reduce the incidence of retained placenta, but these nutrients may also affect reproductive function in other ways. Calcium and phosphorus deficiencies affect reproduction in cattle, and vitamin D may directly affect reproductive function in addition to its role in calcium and phosphorus metabolism. Dietary manipulation of a number of other vitamins and minerals also influences reproductive function. However, the specific roles of nutrients in reproductive tissues are not well-defined in dairy cattle, and nutrient requirements for optimal reproductive efficiency in modern dairy cattle deserve careful reevaluation. This review provides a background of the effect of vitamins and minerals on reproduction and it attempts to provide a basis for further investigation of specific mechanisms by which reproductive function is affected. The interface between nutritional science and reproductive physiology provides considerable potential for optimizing reproductive efficiency in dairy cattle.