Mengzhi Wang

Arginine Relieves the Inflammatory Response and Enhances the Casein Expression in Bovine Mammary Epithelial Cells Induced by Lipopolysaccharide

As one of functional active amino acids, L-arginine holds a key position in immunity. However, the mechanism that arginine modulates cow mammary inflammatory response in ruminant is unclear. Therefore, this study was conducted to investigate the effects of L-arginine on inflammatory response and casein expression after challenging the bovine mammary epithelial cells (BMECs) with lipopolysaccharide (LPS). The cells were divided into four groups, stimulated with or without LPS (10 μg/mL) and treated with or without arginine (100 μg/mL) for 12 h. The concentration of proinflammatory cytokines, inducible nitric oxide synthase (iNOS), mammalian target of rapamycin (mTOR), and Toll-like receptor 4 (TLR4) signaling pathways as well as the casein was determined. The results showed that arginine reduced the LPS-induced production like IL-1β, IL-6, TNF-α, and iNOS. Though the expression of NF-κB was attenuated and the mTOR signaling pathway was upregulated, arginine had no effect on TLR4 expression. In addition, our results show that the content of β-casein and the total casein were enhanced after arginine was supplemented in LPS-induced BMECs. In conclusion, arginine could relieve the inflammatory reaction induced by LPS and enhance the concentration of β-casein and the total casein in bovine mammary epithelial cells.

Effects of different dietary concentrate to forage ratio and thiamine supplementation on the rumen fermentation and ruminal bacterial community in dairy cows

A subacute ruminal acidosis (SARA) model was induced gradually by increasing the proportion of dietary concentrate to evaluate the effect of thiamine supplementation on the structure of bacterial community in dairy cows. Three Holstein dairy cows with rumen cannula were randomly assigned to a replicated 3 × 3 Latin square design trial and received three diets during three successive 21-day periods in each square. The three dietary treatments were as follows: a low-concentrate diet (control), a high-concentrate SARA-induced diet (SARA) and a high-concentrate SARA-induced diet with 180 mg thiamine/kg DM (SARA+thiamine). Real-time–polymerase chain reaction assay was used to quantify the population variation of SARA-related ruminal bacteria in these cows. The results showed that SARA was induced gradually when cows were fed with the high-concentrate diets. The mean ruminal pH value was higher in the control cows than in those of SARA and SARA+thiamine groups, the mean was decreased in cows fed on SARA diet, and the depression was alleviated by supplemented thiamine and the difference was significant (P 0.05). It was concluded that thiamine supplementation to high-concentrate diets at concentrations of 180 mg/kg DM could help alleviate SARA by increasing rumen pH and balancing the population of lactic acid-producing and -consuming bacteria.

The effects of the unsaturated degree of long-chain fatty acids on the rumen microbial protein content and the activities of transaminases and dehydrogenase in vitro

Abstract This study investigated the effects of the degree of unsaturation (unsaturity) of long-chain fatty acids on microbial protein content and the activities of transaminases and dehydrogenase in vitro using goat rumen fluid as the cultural medium. Six types of fatty acids, stearic acid (C18:0, group A, control group), oleic acid (C18:1, n-9, group B), linoleic acid (C18:2, n-6, group C), α-linolenic acid (C18:3, n-3, group D), arachidonic acid (C20:4, n-6, group E), and eicosapentaenoic acid (C20:5, n-3, group F), were tested, and the inclusion ratio of each fatty acid was 3% (w/w) in total of culture substrate. Samples were taken at 0, 3, 6, 9, 12, 18 and 24 h, respectively, during culture for analyses. Compared with stearic acid, linoleic acid, α-linolenic acid, and arachidonic acid increased the bacterial protein content, while oleic acid and eicosapentaenoic acid had no significant effects; the protozoal protein content was reduced for all the unsaturated fatty acids, and the magnitude of the reduction appeared to be associated with the degree of unsaturity of fatty acids. The total microbial protein content was dominantly accounted by the protozoal protein content (about 4–9 folds of the bacterial protein), and only increased by linoleic acid, but reduced by oleic acid, arachidonic acid and eicosapentaenoic acid. There were no significant effects in the activities of both glutamic oxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT) for all the other fatty acids, except for arachidonic acid which enhanced GOT activity and oleic acid which enhanced GPT activity. The total dehydrogenase activity was positively correlated with the degree of unsaturation of fatty acids. In conclusion, the inclusion of 3% of long-chain unsaturated fatty acids increased bacterial protein content, whereas reduced protozoal protein content and enhanced dehydrogenase activity. The fatty acids with more than three double bonds had detrimental effects on the microbial protein content. This work demonstrates for the first time the effect rule of the unsaturation degree of long-chain fatty acids on the rumen microbial protein in vitro.

Effects of Glucose and Starch on Lactate Production by Newly Isolated Streptococcus bovis S1 from Saanen Goats.

ABSTRACT When ruminants are fed high-concentrate diets, Streptococcus bovis proliferates rapidly and produces lactate, potentially causing rumen acidosis. Understanding the regulatory mechanisms of the metabolism of this species might help in developing dietary strategies to alleviate rumen acidosis. S. bovis strain S1 was newly isolated from the ruminal fluid of Saanen dairy goats and then used to examine the effects of glucose and starch on bacterial metabolism and gene regulation of the organic acid-producing pathway in cultures at a pH of 6.5. Glucose or starch was added to the culture medium at 1 g/liter, 3 g/liter (close to a normal range in the rumen fluid), or 9 g/liter (excessive level). Lactate was the dominant acid produced during the fermentation, and levels increased with the amount of glucose or starch in a dose-dependent manner (P < 0.001). The production of formate and acetate in the fermentation media fluctuated slightly with the dose but accounted for small fractions of the total acids. The activities of lactate dehydrogenase (LDH) and α-amylase (α-AMY) increased with the starch dose (P < 0.05), but the α-AMY activity did not change with the glucose dose. The relative expression levels of the genes ldh, pfl (encoding pyruvate formate lyase), ccpA (encoding catabolite control protein A), and α-amy were higher at a dose of 9 g/liter than at 1 g/liter (P < 0.05). Expression levels of pfl and α-amy genes were higher at 3 g/liter than at 1 g/liter (P < 0.05). The fructose 1,6-diphosphate (FDP) concentration tended to increase with the glucose and starch concentrations. In addition, the S. bovis S1 isolate fermented glucose much faster than starch. We conclude that the quantities of glucose and soluble starch had a major effect on lactate production due to the transcriptional regulation of metabolic genes. IMPORTANCE This work used a newly isolated S. bovis strain S1 from the rumen fluid of Saanen goats and examined the effects of glucose and soluble starch on organic acid patterns, enzyme activity, and expression of genes for in vitro fermentation. It was found that lactate was the dominant product from S. bovis strain S1, and the quantities of both glucose and starch in the medium were highly correlated with lactate production and with the corresponding changes in associated enzymes and genes. Therefore, manipulating the metabolic pathway of S. bovis to alter the dietary level of readily fermentable sugar and carbohydrates may be a strategy to alleviate rumen acidosis.

Soybean oil suppresses ruminal methane production and reduces content of coenzyme F420 in vitro fermentation

This experiment examined which type of oils was a superior suppressor to methane mitigation in ruminants. Four oils, peanut, rapeseed, corn and soybean oils, varying in the contents of unsaturated fatty acids as indicated by their iodine values, were used to investigate their effects on methane production and on the content of the F420 enzyme of ruminal methanogens in an in vitro fermentation. The control group was added with calcium palmitate (100% saturated 16C fatty acid). The results showed that the total gas production over a period of 36 h varied from 20.61 mL to 39.67 mL, and were lower in rapeseed, corn and soybean oil treatments than the control (P < 0.05), but not in the peanut oil treatment. The methane concentration in the total gas differed significantly among groups (P < 0.05), and decreased with the increases of unsaturation degree of the oils. The coenzyme F420 content, as indicated by F420 fluorescence intensity in supernatant of the medium, was significantly lower in the oil treatments than in the control (P < 0.05), and the intensity values decreased with the increases of unsaturation degree of the oils, except for the rapeseed oil treatment. Furthermore, there was a close correlation between F420 content and methane production (r = 0.916). By comparison, soybean oil treatment had higher dehydrogenase activity and bacteria density than the other groups (P < 0.05); but was lower in methanogens and genus entodinium (P < 0.05), except for the rapeseed oil treatment. Overall, soybean oil contained a high level of unsaturated fatty acids, and could be used as an ingredient of ruminant diets for methane suppression.

Recent advances on the circadian gene PER2 and metabolic rhythm of lactation of mammary gland

Due to regulation by circadian rhythm, the lactation of the mammary gland has rhythmicity. As one of prominent members of period protein family which regulates biological rhythms, PER2 plays an important role in developing the milk duct and maintaining the polarity and the morphology of the mammary epithelium; at the same time, it is also closely related with the metabolism of milk protein and milk fat. This paper summarized recent researches on PER2 gene and related researches on mammary gland development and metabolism to provide some information for the studies of the theory and technology on physiological functions of the mammary gland and milk quality control.

Impact of dietary carbohydrate balance on rumen fermentation, eating behaviour, growth and development of 8–10-month-old heifers

The present study was undertaken to determine an optimal balance between the amount of physically effective fibre and rumen readily fermentable carbohydrates in the diets of heifers. The dietary carbohydrate balance index (CBI) was expressed as the ratio of physically effective neutral detergent fibre (g/kg of DM) to rumen degradable starch (g/kg of DM). Twenty-four Chinese Holstein heifers aged ~8 months were randomly divided into four groups of six. The length and content of Chinese wild-rye hay and the content of rumen degradable starch in diets were used to adjust dietary CBI, and treatment diets consisted of the following four CBI levels: 1.21 (Treatment A), 1.53 (Treatment B), 1.86 (Treatment C) and 2.29 (Treatment D). The feeding trial lasted 75 days, with 15 days for adaptation. DM intake of heifers was not influenced by different treatments (P > 0.10). Average daily gain of heifers varied (0.86 ± 0.10, 1.03 ± 0.06, 1.12 ± 0.08 and 0.98 ± 0.04 (mean ± s.d.) kg/day among groups respectively), with significant (P 0.10). In addition, the abdominal girth of heifers in Treatments C and D was significantly (P < 0.05) greater than that in Treatment A. With the increment of CBI, eating and chewing time increased significantly (P < 0.05), while eating frequency decreased significantly (P < 0.05). Rumen fluid pH increased significantly (P < 0.05) with the increasing of CBI level, while there was little difference in total volatile fatty acid concentration, and propionate, butyrate and valerate concentrations. Acetate concentration was significantly (P < 0.05) higher in Treatments C and D than in Treatment A. Moreover, ammonia-nitrogen concentration of Treatments B and C was significantly (P < 0.05) higher than that of Treatment D. These results indicated that 1.86 is the optimal CBI in diets for 8–10-month-old heifers in the present study.

Impacts of the unsaturation degree of long-chain fatty acids on the volatile fatty acid profiles of rumen microbial fermentation in goats in vitro

Abstract This study investigated the impacts of the degree of unsaturation (unsaturity) of long-chain fatty acids on volatile fatty acid (VFA) profiles of rumen fermentation in vitro. Six types of long-chain fatty acids, including stearic acid (C18:0, control group), oleic acid (C18:1, n-9), linoleic acid (C18:2, n-6), α-linolenic acid (C18:3, n-3), arachidonic acid (C20:4, n-6) and eicosapentaenoic acid (C20:5, n-3), were tested. Rumen fluid from three goats fitted with ruminal fistulae was used as inoculum and the inclusion rate of long-chain fatty acid was at 3% (w/w) of substrate. Samples were taken for VFA analysis at 0, 3, 6, 9, 12, 18 and 24 h of incubation, respectively. The analysis showed that there were significant differences in the total VFA among treatments, sampling time points, and treatment×time point interactions (P 0.05). In contrast, the molar proportion of propionate did not differ among treatments during the whole incubation (P>0.05). However, for butyrate molar proportions, significant differences were found not only among sampling time points but also among treatments and treatment×time point interactions (P 0.05), even the treatments stearic acid and α-linolenic acid were numerically higher than the others. The inclusion of 3% long-chain unsaturated fatty acids differing in the degree of unsaturation brought out a significant quadratic regression relation between the total VFA concentration and the double bond number of fatty acid. In conclusion, the α-linolenic acid with 3 double bonds appeared better for improving rumen microbial fermentation and the total VFA concentration.

Effects of dietary n-6/n-3 polyunsaturated fatty acid ratios on the mass, and histological and ultrastructures of liver, spleen and thymus of 70-day-old Yangzhou goslings.

The objective of this study was to determine the effects of dietary n-6/n-3 polyunsaturated fatty acid (PUFA) ratios on the organ indexes, and histological and ultrastructures of organs including liver, spleen and thymus in 70-day-old Yangzhou goslings. One-hundred and sixty 21-day-old Yangzhou goslings were randomly divided into 4 groups and fed 4 diets varying in the n-6/n-3 PUFA ratio from 3:1 up to 12:1. After 1-week acclimation, the feeding experiment lasted for 6 weeks. At the end of the experimental period, goslings were slaughtered and the liver, spleen and thymus were weighed, and their histological and ultrastructures were examined. The results showed that the organ indices in the 3:1 group were remarkably higher than in the other three groups, whereas the mitochondrial square did not differ among four groups. The histological and ultrastructures of the liver, spleen and thymus were not affected by the diets with the lower n-6/n-3 PUFA ratios (3:1 and 6:1). However, feeding diets with the higher n-6/n-3 PUFA ratios (9:1 and 12:1), the nuclear chromatin was concentrated and marginalized; the cell membrane was contracted inwardly and disrupted; the mitochondrial membrane was damaged to some degree. In conclusion, the diet containing higher content of n-3 PUFA might improve immune capacity of goslings the animal by accelerating the growth and maintaining cellular structures of organs like liver, spleen and thymus.

Effects of different dietary ratio of physically effective neutral detergent fiber and metabolizable glucose on rumen fermentation, blood metabolites and growth performance of 8 to 10-month-old heifers

Objective The present study was undertaken to determine an optimal balance between the amount of physically effective neutral detergent fiber (peNDF) to metabolizable glucose (MG) on rumen fermentation, blood metabolites and growth performance of 8 to 10-month-old heifers. Methods A total of 15 healthy Holstein heifers weighing an average of 256 kg (8 month of age) were randomly assigned to three groups of five. Treatment diets consisted of the following three peNDF8.0/MG levels: 1.46 (Treatment A), 1.74 (Treatment B), and 2.08 (Treatment C). Results The results showed that the ratio of peNDF8.0/MG affected rumen fermentation, blood metabolites and growth performance of heifers. The average daily gain of heifers tended to decrease as the ratio of peNDF8.0/MG increased (p = 0.07). The concentrations of blood urea nitrogen, triglyceride, and cholesterol increased significantly (p<0.05), while the high-density lipoprotein concentration decreased (p<0.05). After feeding 2 h and 4 h, insulin concentration in Treatment A was greater than Treatment C (p<0.05). Propionate concentration had decreasing trend (p = 0.07); acetate to propionate ratio and non-glucogenic to glucogenic volatile fatty acid (NGR) increased significantly (p<0.05). In addition, the digestibility of dry matter, crude protein, neutral detergent fiber, and acid detergent fiber decreased significantly (p<0.05). Conclusion The present investigation indicated that dietary peNDF8.0/MG ratio can affect the growth and development, blood metabolites, rumen fermentation and apparent digestibility of heifers, and the optimal dietary peNDF8.0/MG ratio for 8 to 10-month-old heifers in the present study was 1.46.