Effects of intravenous arginine infusion on inflammation and metabolic indices of dairy cows in early lactation

Identifying Predictive Biomarkers of Subclinical Mastitis in Dairy Cows through Urinary Metabotyping

Mastitis is a significant infectious disease in dairy cows, resulting in milk yield loss and culling. Early detection of mastitis-prone cows is crucial for implementing effective preventive measures before disease onset. Current diagnosis of subclinical mastitis (SCM) relies on somatic cell count assessment post-calving, lacking predictive capabilities. This study aimed to identify metabolic changes in pre-SCM cows through targeted metabolomic analysis of urine samples collected 8 wks and 4 wks before calving, using mass spectrometry. A nested case-control design was employed, involving a total of 145 multiparous dairy cows, with disease occurrence monitored pre- and postpartum. Among them, 15 disease-free cows served as healthy controls (CON), while 10 cows exclusively had SCM, excluding those with additional diseases. Urinary metabolite profiling revealed multiple alterations in acylcarnitines, amino acids, and organic acids in pre-SCM cows. Metabotyping identified 27 metabolites that distinguished pre-SCM cows from healthy CON cows at both 8 and 4 wks before parturition. However, only four metabolites per week showed significant alterations (p < 0.005). Notably, a panel of four serum metabolites (asymmetric dimethylarginine, proline, leucine, and homovanillate) at 8 wks prepartum, and another panel (asymmetric dimethylarginine, methylmalonate, citrate, and spermidine) at 4 wks prepartum, demonstrated predictive ability as urinary biomarkers for SCM risk (AUC = 0.88; p = 0.02 and AUC = 0.88; p = 0.03, respectively). In conclusion, our findings indicate that metabolite testing can identify cows at risk of SCM as early as 8 and 4 wks before parturition. Validation of the two identified metabolite panels is warranted to implement these predictive biomarkers, facilitate early intervention strategies, and improve dairy cow management to mitigate the impact of SCM. Further research is needed to confirm the efficacy and applicability of these biomarkers in practical farm settings.

L-arginine reduces injury from heat stress to bovine intestinal epithelial cells by improving antioxidant and inflammatory response

Heat stress (HS) has a negative impact on the health and performance of dairy cows, resulting in economic losses. Damage to the intestinal epithelium is the main cause of the adverse effects of heat stress on bovine health. This study investigated the repair capability of L-arginine (L-Arg) in reducing the adverse effects of HS on bovine intestinal epithelial cells (BIECs). BIECs were treated as follows: (1) control cells were cultured at 37 °C continuously and received no L-Arg; (2) cells in HS group were grown at 42 °C for 6 h followed by 12 h at 37 °C; and (3) the L-Arg group was cultured at 42 °C for 6 h, then treated with L-Arg at 37 °C for 12 h. HS disrupted redox homeostasis and reduced viability in BIECs, while treatment with L-Arg (6 mmol/L) for 12 h markedly reduced the negative effects of HS. L-Arg protected cells by preventing HS-induced changes in mitochondrial membrane-potential, inflammation, apoptosis-related gene expression and regulation of antioxidant enzymes. The above results indicated that L-Arg reduced the level of damage from HS in BIECs by lowering oxidant stress and inflammation, suggesting that L-Arg could be an effective dietary addition to protect cows from adverse intestinal effects caused by HS.

Effects of L-arginine and arginine-arginine dipeptide on amino acids uptake and αS1-casein synthesis in bovine mammary epithelial cells

Arginine (Arg), as an important functional amino acids (AA), is essential for milk protein synthesis in lactating ruminants. Arg shares transporters with cationic and neutral AA in mammary epithelial cells. Therefore, competitive inhibition might exist among these AA in uptake by mammary epithelial cells. In this study, cultured bovine mammary epithelial cells (BMEC) were used as the model to investigate whether the availability of L-Arg (0.7, 1.4, 2.8, 5.6, and 11.2 mM) affects the uptake of other AA and if this related to αS1-casein synthesis, and whether Arginine-Arginine (Arg-Arg) substituting part of free L-Arg can alleviate competitive inhibition among Arg and other AA, so as to promote αS1-casein synthesis. Our results showed that 2.8 mM L-Arg generated the greatest positive effects on αS1-casein synthesis and the activation of mammalian target of rapamycin (mTOR) signaling pathway (P < 0.01). With L-Arg supply increasing from 0.7 to 11.2 mM, the net-uptake of other AA (except Glu and Ala) decreased linearly and quadratically (Plinear < 0.01; Pquadratic < 0.01). Compared with 2.8 mM, the net-uptake of essential amino acids (EAA) and total amino acids (TAA) were lower at 11.2 mM L-Arg group, while greater at 1.4 mM L-Arg group (P < 0.01). Arg-Arg dipeptide replacing 10% free L-Arg increased αS1-casein synthesis (P < 0.05), net-uptake of EAA and TAA, as well as phosphorylation level of mTOR and p70 ribosomal protein S6 kinase (P70S6K) and mRNA expression of oligopeptide transporter 2 (PepT2; P < 0.01). These observations suggested that the increased αS1-casein synthesis by 10% Arg-Arg dipeptide might be related to the increase of AA availability and the activation of mTOR signaling pathway in BMEC.

Alterations in Skeletal Muscle mRNA Abundance in Response to Ethyl-Cellulose Rumen-Protected Methionine during the Periparturient Period in Dairy Cows

This study aimed to evaluate the effect of feeding ethyl cellulose rumen-protected methionine (RPM) on skeletal muscle mRNA abundance during the periparturient period. Sixty multiparous Holstein cows were used in a block design and assigned to either a control or RPM diet. The RPM was supplied from −28 to 60 days in milk (DIM) at a rate of 0.09% (prepartum) or 0.10% (postpartum) of dry matter (DM), ensuring a Lys:Met in the metabolizable protein of ~2.8:1. Muscle biopsies were collected at −21, 1, and 21 DIM. Thirty-five target genes associated with nutrient metabolism and biochemical pathways were measured via RT-qPCR. The mRNA abundance of genes associated with amino acid (AA) transport (SLC7A8, SLC43A2), carnitine transport (SLC22A5), insulin signaling (IRS1), and antioxidant response (NFE2L2) had diet × time effect (p < 0.05) due to greater abundance in RPM versus CON cows, especially at 1 and 21 DIM. Members of the AA transport (SLC7A8, SLC25A29, SCL38A9), fatty acid β-oxidation (ACADVL), vitamin transport (SLC5A6, SLC19A2), mTOR pathway (AKT1 and mTOR), antioxidant response (KEAP1, CUL3), CDP-Choline pathway and arginine metabolism had overall greater abundance (p < 0.05) in RPM versus CON cows. Overall, data indicate that RPM can alter nutrient metabolism in the skeletal muscle around parturition partly through alterations in mRNA abundance.

Arginine regulates inflammation response-induced by Fowl Adenovirus serotype 4 via JAK2/STAT3 pathway

Background

Fowl Adenovirus serotype 4 (FAdV-4) infection causes severe inflammatory response leading to hepatitis-hydropericardium syndrome (HHS) in poultry. As an essential functional amino acid of poultry, arginine plays a critical role in anti-inflammatory and anti-oxidative stress.

Results

In this study, the differential expression genes (DEGs) were screened by transcriptomic techniques, and the DEGs in gene networks of inflammatory response-induced by FAdV-4 in broiler’s liver were analyzed by Kyoto encyclopedia of genes and genomes (KEGG) enrichment. The results showed that the cytokines pathway and JAK/STAT pathway were significantly enriched, in which the DEGs levels of IL-6, IL-1β, IFN-α, JAK and STAT were significantly up-regulated after FAdV-4 infection. It was further verified with real-time fluorescence quantitative polymerase chain reaction (Real-time qPCR) and Western blotting (WB) in vitro and in vivo. The findings demonstrated that FAdV-4 induced inflammatory response and activated JAK2/STAT3 pathway. Furthermore, we investigated whether arginine could alleviate the liver inflammation induced by FAdV-4. After treatment with 1.92% arginine level diet to broilers or 300 μg/mL arginine culture medium to LMH cell line with FAdV-4 infection at the same time, we found that the mRNA levels of IL-6, IL-1β, IFN-α and the protein levels of p-JAK2, p-STAT3 were down-regulated, compared with FAdV-4 infection group. Furthermore, we confirmed that the inflammation induced by FAdV-4 was ameliorated by pre-treatment with JAK inhibitor AG490 in LMH cells, and it was further alleviated in LMH cells treatment with AG490 and ARG.

Conclusions

These above results provide new insight that arginine protects hepatocytes against inflammation induced by FAdV-4 through JAK2/STAT3 signaling pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03282-9.

N-Carbamoylglutamate Supplementation on the Digestibility, Rumen Fermentation, Milk Quality, Antioxidant Parameters, and Metabolites of Jersey Cattle in High-Altitude Areas

This study aimed to assess the impact of the dietary supplementation of N-carbamoylglutamate (NCG) on nutrient digestibility, rumen fermentation, milk quality, oxidative stress, and metabolites in the plasma and feces of Jersey cattle under high altitude with the hypoxic condition. A total of 14 healthy lactating Jersey dairy cows with similar body conditions were selected and randomly divided into 2 groups. The control group (CON group, N = 6 replicates) was fed with a conventional complete diet, whereas the experimental group (NCG group, N = 8 replicates) received 20 g/d per head NCG supplementation. The experiment lasted for 60 days, the adaptation period was 12 days, and the formal experiment period was 48 days. Except that the NCG group showed an upward trend in dry matter intake (DMI) (p = 0.09) and the fermentation parameters, the molar proportion of butyric acid tended to decrease (p = 0.08); the two groups had no significant differences (p > 0.05) in nutrients digestibility, plasma immunity, and antioxidant ability. However, compared with the CON group, the milk fat rate and blood oxygen saturation of the NCG group showed an upward trend (p = 0.09). For indexes associated with altitude stress, the contents of thyroxine, transferrin, and endothelin both decreased significantly (p < 0.05) in the NCG group. Meanwhile, heat shock protein (p = 0.07) and aldosterone (p = 0.06) also showed a downward trend. A total of 114 different metabolites were identified from feces and plasma, 42 metabolites were derived from plasma that mainly included 5 kinds of Super Class, and 72 metabolites were derived from feces that mainly included 9 kinds of Super Class. The significantly increased plasma differential metabolites were 2,5-dihydroxybenzoate and salicyluric acid, and the significantly increased fecal differential metabolites were Butenafine (fold change > 2). Pathway analysis showed that after applying NCG as a feed additive, the changes of the Jersey dairy cows mainly focused on amino acid metabolism and lipid metabolism. These results indicated that adding NCG to the diet can prevent the hypoxic stress state of lactating Jersey cows in high-altitude areas and has a tendency to improve milk quality.

Dietary rumen-protected L-arginine or N-carbamylglutamate attenuated fetal hepatic inflammation in undernourished ewes suffering from intrauterine growth restriction

This study aimed to explore whether dietary rumen-protected L-arginine (RP-Arg) or N-carbamylglutamate (NCG) supplementation to feed-restricted pregnant ewes counteracts fetal hepatic inflammation and innate immune dysfunction associated with intrauterine growth retardation (IUGR) in ovine fetuses. On d 35 of pregnancy, twin-bearing Hu ewes (n = 32) were randomly assigned to 4 treatment groups (8 ewes and 16 fetuses per group) and fed diets containing 100% of the NRC requirements (CON), 50% of the NRC requirements (RES), RES + RP-Arg (20 g/d) (RESA), or RES + NCG (5 g/d) (RESN). At 08:00 on d 110 of gestation, fetal blood and liver tissue samples were collected. The levels of triglyceride, free fatty acid, cholesterol and β-hydroxybutyrate in the fetal blood of RESA and RESN groups were lower (P < 0.05) than those of the RES group, but were higher (P < 0.05) than those of the CON group. The interleukin (IL)-6 and IL-1 levels in fetal blood and liver tissue as well as the myeloid differentiation primary response 88 (MyD88), transforming growth factor β (TGFβ), and nuclear factor kappa B (NF-κB) mRNA levels in the fetal liver were decreased (P < 0.05) by the NCG or RP-Arg supplementation compared to the RES treatment. Similarly, the toll-like receptor (TLR)-4, MyD88, TGFβ, and p-c-Jun N-terminal kinase (JNK) protein levels in the fetal liver were reduced (P < 0.05) in the NCG and RP-Arg -supplemented groups compared to the RES group. These results showed that dietary supplementation of RP-Arg or NCG to underfed pregnant ewes could protect against IUGR fetal hepatic inflammation via improving lipid metabolism, down-regulating the TLR-4 and the inflammatory JNK and NF-κB signaling pathways, and decreasing cytokine production in ovine fetal blood and liver tissue.

Effect of alfalfa hay and starter feed supplementation on caecal microbiota and fermentation, growth, and health of yak calves

The caecum is the primary site where microbial fermentation and acidosis occurred. The supplementation of starter feed and alfalfa hay has the potential to influence caecal microbiota and then affect caecal fermentation. This study aims to investigate the effect of starter feed and alfalfa hay supplementation on caecal microbiota, immune homeostasis, and growth of preweaning yaks. Twenty 30-day-old male yak calves were randomly assigned to four groups, which separately fed with milk replacer (CON group), milk replacer with alfalfa hay (A group), milk replacer with starter feed (S group), and milk replacer with starter feed plus alfalfa hay (SA group) throughout the trial. Growth performance and plasma physiological and biochemical indicators were measured every 30 days. Calves were sacrificed at 120 days of age. The caecal contents were collected for measuring pH and contents of volatile fatty acids (VFAs) and lipopolysaccharide (LPS) and for characterizing caecal microbiota. The results indicated that individual or simultaneous supplementation with alfalfa hay and starter feed all significantly increased the BW, body height, body length, and chest girth of yak calves. However, supplementation with starter feed significantly increased plasma cortisol, nitric oxide, tumor necrosis factor-α, and interferon-γ concentrations and the ratio of aspartate aminotransferase to alanine aminotransferase of yak calves when compared with the control and alfalfa hay feeding groups, while the co-supplementation of starter feed and alfalfa hay could significantly decrease these inflammation-related indices when compared with the starter feeding group. Sequencing of the 16S rRNA gene showed that starter feed and alfalfa hay separately stimulated the proliferation of starch-decomposing and cellulose- or hemicellulose-decomposing bacteria. This also significantly increased the levels of acetate, propionate, butyrate, valerate, isobutyrate, and isovalerate in the caecal contents. Furthermore, compared with the S and CON groups, the significantly increased genera of Desulfobulbus, Olsenella, Pseudoflavonifractor, and Stomatobaculum in the SA and A groups were beneficial to the immune homeostasis, and the significantly decreased Blautia, Clostridium IV, Bacteroides, Eubacterium, Clostridium XVIII, and Mogibacterium in the SA and A groups were related to the reduced caecal lactate and LPS contents, the decreased inflammatory reaction, and the improved healthy hepatic condition of yak calves. In conclusion, milk replacer supplemented with alfalfa hay and starter feed is recommended during preweaning to improve yak calf health and growth because this regimen promotes the growth and maintains the immune homeostasis of yak calves.