Influence of repeated mastitis on the milk production and metabolic status in the subsequent lactation period of dairy cattle.

Recurrent mastitis poses a common challenge on dairy farms. While the impact of repeated mastitis within the same lactation has been investigated, the difference from one lactation to the next, particularly concerning the change of milk and blood metabolites, remains unclear. This study aimed to examine the difference in milk yield, milk composition, and metabolic status in the subsequent lactation between healthy and repeated mastitis in the previous lactation. The study population comprised 50 cows chosen from 400 cows, with 25 having no history of mastitis and 25 experiencing mastitis more than three times during the last lactation. Following dry-off and calving, all cows initiated a new lactation, during which no mastitis was diagnosed until the sample collection period. In the group exposed to repeated mastitis, a significant decrease in milk fat levels was observed in the subsequent lactation, while no change was observed in milk somatic cell count (SCC). Milk collected from cows that had experienced repeated mastitis in the previous lactation exhibited significant increases in the levels of free amino acids, namely valine, proline, and alanine. However, no difference in plasma levels of these amino acids was noted. These results indicate that individuals exposed to repeated mastitis have persistent milk quality changes even after dry-off. Biomarker analysis suggested that the milk valine and proline showed a moderate biomarker potential on Kappa coefficients to characterize cows that have experienced repeated mastitis. Furthermore, the results of biomarker combinations for valine and proline provided the highest specificity (100 %), positive likelihood ratio (infinity), and substantial biomarker potential on kappa coefficients (0.68). These findings significantly enhance our understanding of the pathobiology and etiology of recurrent mastitis and provide a biomarker to characterize cows that have experienced repeated mastitis in the past.

Changes in fecal microbiota during estrous cycle in healthy thoroughbred mares.

Gut microbiota plays a crucial role in various physiological processes, including the regulation of the reproductive system and steroid sex hormones. Throughout the normal estrous cycle of healthy mares, the levels of estradiol-17ß (E2) and progesterone (P4) in the blood exhibit periodic changes. To investigate the relationship between cyclic changes in steroid sex hormones and the gut microbiome of mares, we analyzed the fecal microbiota composition in healthy mares during the typical estrous cycle. Blood and fecal samples from five healthy mares were collected, E2 and P4 levels in serum were analyzed using radioimmunoassay (RIA), and the gut microbiome was analyzed by 16S rRNA sequencing. The overall richness and composition of the gut microbiota remained relatively stable during the normal estrous cycle in mares. The Linear Discriminant Analysis Effect Size analysis of the microbial composition during the follicular and luteal phases identified the Rhodococcus genus as differentially abundant. These findings indicate that the mare's gut microbiota's significant composition remains consistent throughout the estrous cycle. At the same time, specific low-abundance pathogenic bacteria exhibit changes that align with sexual hormonal fluctuations.

L-amino acid oxidase-1 is involved in the gut-liver axis by regulating 5-aminolevulinic acid production in mice.

L-amino acid oxidase (LAAO) is a metabolic enzyme that converts L-amino acids into ketoacids, ammonia, and hydrogen peroxide (H2O2). The generated H2O2 has previously been shown to have antibacterial and gut microbiota-modulatory properties in LAO1 knock-out (KO) mice. Since most microbial metabolites reach the liver through the portal vein, we examined gut-liver interactions in LAO1 KO mice. We found lower total cholesterol levels, higher glutamic pyruvic transaminase (GPT) levels in the serum, and higher pro-inflammatory cytokine mRNA expression in the liver tissue. In wild-type (WT) mice, LAO1 was expressed in gut tissues (ileum and colon). Microbiome analysis revealed that the abundance of some bacteria was altered in LAO1 KO mice. However, short-chain fatty acid (SCFAs) levels in cecal feces and gut permeability did not change. Fecal microbiota transplantation (FMT) revealed that feces from LAO1 KO mice slightly stimulated pro-inflammatory cytokine expression in the liver. During metabolomic analysis, 5-aminolevulinic acid (5-ALA) was the only metabolite found to be significantly upregulated in the portal and abdominal veins of the LAO1 KO mice. Intraperitoneal administration of 5-ALA to WT mice significantly increased IL-6 mRNA expression in the liver. These observations suggest that gut LAO1 plays a role in regulating 5-ALA production and that a high level of 5-ALA stimulates the liver to increase pro-inflammatory cytokine expression by disrupting LAO1 in mice.

Accumulation of steroid hormones in the eggshells of Japanese quail (Coturnix coturnix japonica).

Oviparous mother transfer significant amounts of steroid to egg yolk during oviposition and the amounts may vary throughout the embryonic development. Eggshell may contain steroid hormones and the amounts could be different during embryonic development inside the egg. This study was designed to quantify the steroid concentrations in the eggshells of Japanese quail. We hypothesized that the steroids would be accumulated in the eggshells in a sex-dependent manner. Eggshells were obtained from three different stages (after laying, 15 days of incubation, and after hatching). The internal contents of the shells were carefully removed, completely dried and pulverized. The steroid contents of the eggshells were then measured by RIA. Physiologic variations in steroids were analyzed according to the amounts accumulated in the eggshells with the different embryonic stages. Results indicate that eggshell testosterone concentrations were high after laying. However, the concentrations were decreased during embryonic development and hatching and no difference was found in eggshell testosterone levels between male and female. However, eggshell estradiol concentrations were undetectable at laying time and the amounts were significantly increased at 15 days of incubation and slightly after hatching. Eggshell estradiol levels were significantly high in female eggshells than male during embryonic development. In contrast, eggshell corticosterone levels were significantly higher in males than in females after hatching. These results clearly demonstrated that eggshells accumulated steroid hormones, and the amounts varied during embryonic development concomitant with changes the internal contents of the eggs.

Steroidogenic enzyme expression in estrogen production in the goat gastrointestinal (GI) tract and the effect of castration.

Extragonadal tissues are known to produce estrogens. At these sites, the C19 precursor is important for aromatase expression for the production of estrogen. Aromatase expression is tissue-specific and is controlled by hormones. Recent studies have shown that rat gastric parietal cells expressed aromatase. Our first objective was to investigate steroidogenic enzyme expression in estrogen biosynthesis; the second objective was to investigate which site(s) of the GI tract expressed steroidogenic enzymes; and the third objective was to assess the effects of castration on steroidogenic enzyme expression. CYP19A1, 17ß-HSD3, CYP17A1, 3ß-HSD and P450scc were quantified in the GI tract by real-time PCR. CYP19A1 was detected mainly in the body and pyloric regions of the abomasum, while we detected weak expression of CYP19A1 in other parts of GI tract. In addition, the expression of 17ß-HSD3 and CYP17A1 was detected in abomasum. 3ß-HSD expression was observed in duodenum and jejunum, while P450scc was not detectable in any part of GI tract. Immunohistochemical results showed immunolocalization of aromatase in parietal cells. Aromatase expression was observed to increase after castration. Furthermore, immunohistochemical results demonstrated that parietal cells also produced luteinizing hormone receptor (LHR). These results indicate steroidogenic enzymes required for the biosynthesis of estrogen were expressed, and the abomasum appeared to be the responsible organ for estrogen biosynthesis in the goat GI tract. In addition, parietal cells were responsible for estrogen production and the expression of LHR. Castration increased aromatase expression in abomasum through LH mediation.

The effects of phytosterols on the sexual behavior and reproductive function in the Japanese quail (Coturnix coturnix japonica).

Phytosterols (PS) are plant origin sterols naturally found in many foods and added as food additives. Since 1950, PS have attracted considerable attention due to their ability to lower serum cholesterol and inhibit cardiovascular disease (CVD). However, recent studies have found that PS act as endocrine-disrupting chemicals in laboratory animals. Therefore, this study was aimed at finding the mechanism(s) for PS effects on the sexual behaviors and reproductive functions in male Japanese quails (Coturnix coturnix japonica). At 15 d of age, 30 male Japanese quails were randomly assigned to 3 groups for the chronic in-vivo experiment. Animals were gavaged daily with single dose of PS suspension (PS dissolved in medium chain triglyceride [MCT]) into the crop sac from 15-100 d of age. Following maturation, a sexual behavior test, semen collection, and test of fertilization ability were performed. Blood was collected by cervical dislocation at 100 day of age for hormones analysis. To observe the direct effects of PS on the testis, interstitial cells of the normal testes were cultured for 24 h. Ovine-LH (O-LH) was used for half of each group to stimulate interstitial cells for testosterone production. The results showed that chronic doses of PS reduced (P < 0.01) mount and copulation behavior in male quails (primarily in the group receiving 800 mg/kg BW). Both acute in vitro and chronic in vivo experiments revealed a reduction in testosterone (P < 0.05) after PS treatments; concomitantly, Leydig cell numbers were also low (P < 0.05) at a dose of 800 mg/kg BW. Real-time PCR results showed lower expression of 17ß-hydroxysteroid dehydrogenase (17ß-HSD) at the same dose. The results suggested that feeding large amounts of PS reduced testosterone levels and sexual behavior by affecting Leydig cell proliferation, and cholesterol trafficking, 17ß-HSD expression in the testes of male Japanese quail.