Selenium biofortified alfalfa hay fed in low quantities improves selenium status and glutathione peroxidase activity in transition dairy cows and their calves

Invited review: Nutritional and management factors that influence colostrum production and composition in dairy cows

Colostrum is a rich source of nutritional and non-nutritional components and is recognized as essential to transfer passive immunity to newborn calves. Because of the individual and seasonal variability in colostrum yield and composition, maintaining an adequate supply of high-quality colostrum year-round remains a challenge for commercial dairy producers. In this narrative review, we described the individual, seasonal, and herd-level variability of colostrum production and summarized the association between individual animal factors such as parity, sex of the calf, calf birth weight, as well as indicators of the cow's metabolic status and the yield and composition of colostrum. Further, we reviewed the current knowledge on the influence of prepartum nutrition and management strategies on colostrum production. Research on the metabolizable energy and protein supplied in the prepartum diet as well as on the inclusion and source of vitamins, minerals, and feed additives suggests prepartum nutrition influences the yield, quality, and composition of colostrum. Furthermore, the prepartum environment and dry period length remain influential factors in the production of colostrum. However, additional research is needed to understand the mechanisms by which prepartum nutrition and management affect colostrum production. Finally, time from calving to colostrum harvest and oxytocin administration as well as the current knowledge on the effect of heat treatment and colostrum storage strategies on colostral components were discussed. To conclude, we identify critical gaps in knowledge for future focus of investigation in colostrum research.

Effects of selenium enrichment on fermentation characteristics, selenium content and microbial community of alfalfa silage

BACKGROUND

Selenium is essential for livestock and human health. The traditional way of adding selenium to livestock diets has limitations, and there is a growing trend to provide livestock with a safe and efficient source of selenium through selenium-enriched pasture. Therefore, this study was conducted to investigate the effects of selenium enrichment on fermentation characteristics, selenium content, selenium morphology, microbial community and in vitro digestion of silage alfalfa by using unenriched (CK) and selenium-enriched (Se) alfalfa as raw material for silage.

RESULTS

In this study, selenium enrichment significantly increased crude protein, soluble carbohydrate, total selenium, and organic selenium contents of alfalfa silage fresh and post-silage samples, and it significantly decreased neutral detergent fiber and acid detergent fiber contents (p < 0.05). Selenium enrichment altered the form of selenium in plants, mainly in the form of SeMet and SeMeCys, which were significantly higher than that of CK (p < 0.05). Selenium enrichment could significantly increase the lactic acid content, reduce the pH value, change the diversity of bacterial community, promote the growth of beneficial bacteria such as Lactiplantibacillus and inhibit the growth of harmful bacteria such as Pantoea, so as to improve the fermentation quality of silage. The in vitro digestibility of dry matter (IVDMD), in vitro digestibility of acid detergent fibers (IVADFD) and in vitro digestibility of acid detergent fibers (IVNDFD) of silage after selenium enrichment were significantly higher than those of CK (p < 0.05).

CONCLUSION

This study showed that the presence of selenium could regulate the structure of the alfalfa silage bacterial community and improve alfalfa silage fermentation quality. Selenium enrichment measures can change the morphology of selenium in alfalfa silage products, thus promoting the conversion of organic selenium.

Impacts of dairy cow nutrition precalving on calf health

This mini-review focuses on the effects of gestational dairy cow nutrition on calf health as mediated through colostrogenesis and calf immunity, morbidity, and mortality. The nutritional adequacy of the forage and supplementary diet and the metabolic status and body condition score of the dam can affect calf health. The mechanism of action of such impacts include maternal nutritional imbalances or deficiencies causing dyscolostrogenesis, nutritionally mediated calf ill health, and fetal programming impacts on calf health.

Effects of Pasture Type on Metabolism, Liver and Kidney Function, Antioxidant Status, and Plant Secondary Compounds in Plasma of Grazing, Jersey Dairy Cattle During Mid-lactation

Some pasture species are rich in phytochemicals, able to improve milk yield and quality and to reduce the environmental impacts of livestock farming. The phytochemicals interact with the different gene networks within the animal, such as nuclear factor erythroid 2-related factor 2 (NRF2), but their overall impact on animal health remains to be fully understood. The objective of this study was to identify the effects of pasture Legumes and non-leguminous Forbs containing high bioactive compounds on metabolism and activity of the liver, antioxidant response, kidney function, and inflammation of dairy cows using a large array of blood parameters associated with metabolism and the innate immune system. For this purpose, 26 parameters and the concentration of certain bioactive compounds were assessed in blood plasma, collected from the Jersey cows grazing either Grass, Legume, or Forb-based pastures. In addition, serum collected from all the cows was utilized to detect the changes in NRF2 activation in bovine mammary alveolar cells (MACT) and hepatocytes. Compared with Grass, the cows that grazed both Forb and Legume pastures had lower β-hydroxybutyric acid (BHB) and creatinine and larger vitamin E and the ferric reducing ability of the plasma, supporting an improved antioxidative status for these animals. Compared with both Grass and Legume, the cows that graze Forb pasture had lower urea and urea to creatinine ratio, and lower creatinine, indicating a better kidney function. The cows grazing Legume pasture had greater hematocrit, bilirubin, cholesterol, albumin, β-carotene, retinol, and thiol groups but lower ceruloplasmin, paraoxonase, and myeloperoxidase (MPO) than those grazed Grass and Forb pastures, indicating a positive effect of Legume pasture on the liver, oxidative stress, and red blood cells. The plasma of cows in the various pastures was enriched with various isoflavonoids, especially the cows grazed on Forb and Legume pastures, which likely contributed to improving the antioxidative status of those cows. However, this effect was likely not due to the higher activation of NRF2. Overall, these results indicate that Forb and Legume pastures rich in secondary metabolites do not strongly affect the metabolism but can improve the status of the liver and the kidney and improve the efficiency of N utilization and antioxidant response, compared with the Grass pasture.

In vitro–In vivo Hybrid Approach for Studying Modulation of NRF2 in Immortalized Bovine Mammary Cells

Nuclear factor erythroid 2-related factor 2 (NRF2) plays a key role in the response to oxidative stress. Diets containing known NRF2 modulators could be used to minimize oxidative stress in dairy cows. Currently, studies evaluating the activity of NRF2 in bovine have used the classical in vitro approach using synthetic media, which is very different than in vivo conditions. Furthermore, studies carried out in vivo cannot capture the short-term and dynamic response of NRF2. Thus, there is a need to develop new approaches to study NRF2 modulation. The aim of the present study was to establish an in vitro–in vivo hybrid system to investigate activation of NRF2 in bovine cells that can serve as an intermediate model with results closer to what is expected in vivo. To accomplish the aim, we used a combination of a gene reporter assay in immortalized bovine mammary cells, synthetic NRF2 modulators, and blood serum from periparturient cows. Synthetic agonist tert-butylhydroquinone and sulforaphane confirmed to be effective activators of bovine NRF2 with acute and large effect at 30 and 5 μM, respectively, with null response after the above doses due to cytotoxicity. When the agonists were added to blood serum the response was more linear with maximum activation of NRF2 at 100 and 30 μM, respectively, and the cytotoxicity was prevented. High concentration of albumin in blood serum plays an important role in such an effect. Brusatol (100 nM) was observed to be an effective NRF2 inhibitor while also displaying general protein synthesis inhibition and cytotoxicity when added to synthetic media. A consistent inhibition of NRF2 was observed when brusatol was added to the blood serum but the cytotoxicity was reduced. The synthetic inhibitor ML385 had no effect on modulation of bovine NRF2. Hydrogen peroxide activates NRF2 in bovine mammary cells starting from 100 μM; however, strong cytotoxicity was detected starting at 250 μM when cells were cultivated in the synthetic media, while blood serum prevented cytotoxicity. Overall, our data indicated that the use of synthetic media can be misleading in the study of NRF2 in bovine and the use of blood serum appears necessary.

Impacts of Bovine Trace Mineral Supplementation on Maternal and Offspring Production and Health

Nutritional status can have major implications for animal health and production. Energy balance is easily determined using a body condition scoring system. This allows producers to readily adjust diets to meet an animal's needs. Far less obvious is an animal's trace mineral status, which is typically not assessed until an animal's performance falls below expectation or illness is detected. Trace mineral toxicities and deficiencies can manifest as reduced thriftiness and/or poor reproductive performance, resulting in economic consequences for producers. Maternal mineral status not only impacts dam heath, but also the health of subsequent offspring. Both the oocyte and embryo are susceptible to changes in maternal mineral status. This susceptibility is maintained throughout fetal development via placental control of nutrient transfer to the fetal system. Furthermore, maternal mineral status continues to impact offspring health via colostrum and milk quality. Herein we discuss the roles of trace minerals in bovine reproductive performance, maternal health, colostrum and milk quality, and offspring health.

The interplay between non-esterified fatty acids and bovine peroxisome proliferator-activated receptors: results of an in vitro hybrid approach

Background

In dairy cows circulating non-esterified fatty acids (NEFA) increase early post-partum while liver and other tissues undergo adaptation to greater lipid metabolism, mainly regulated by peroxisome proliferator-activated receptors (PPAR). PPAR are activated by fatty acids (FA), but it remains to be demonstrated that circulating NEFA or dietary FA activate bovine PPAR. We hypothesized that circulating NEFA and dietary FA activate PPAR in dairy cows.

Methods

The dose-response activation of PPAR by NEFA or dietary FA was assessed using HP300e digital dispenser and luciferase reporter in several bovine cell types. Cells were treated with blood plasma isolated from Jersey cows before and after parturition, NEFA isolated from the blood plasma, FA released from lipoproteins using milk lipoprotein lipase (LPL), and palmitic acid (C16:0). Effect on each PPAR isotype was assessed using specific synthetic inhibitors.

Results

NEFA isolated from blood serum activate PPAR linearly up to ~ 4-fold at 400 μmol/L in MAC-T cells but had cytotoxic effect. Addition of albumin to the culture media decreases cytotoxic effects of NEFA but also PPAR activation by ~ 2-fold. Treating cells with serum from peripartum cows reveals that much of the PPAR activation can be explained by the amount of NEFA in the serum (R² = 0.91) and that the response to serum NEFA follows a quadratic tendency, with peak activation around 1.4 mmol/L. Analysis of PPAR activation by serum in MAC-T, BFH-12 and BPAEC cells revealed that most of the activation is explained by the activity of PPARδ and PPARγ, but not PPARα. Palmitic acid activated PPAR when added in culture media or blood serum but the activation was limited to PPARδ and PPARα and the response was nil in serum from post-partum cows. The addition of LPL to the serum increased > 1.5-fold PPAR activation.

Conclusion

Our results support dose-dependent activation of PPAR by circulating NEFA in bovine, specifically δ and γ isotypes. Data also support the possibility of increasing PPAR activation by dietary FA; however, this nutrigenomics approach maybe only effective in pre-partum but not post-partum cows.