Biogenic amines in silage, apparent postruminal passage, and the relationship between biogenic amines and digestive function and intake by steers

Conditioner application improves bedding quality and bacterial composition with potential beneficial impacts for dairy cow's health

Recycled manure solids (RMS) is used as bedding material in cow housing but can be at risk for pathogens development. Cows spend several hours per day lying down, contributing to the transfer of potential mastitis pathogens from the bedding to the udder. The effect of a bacterial conditioner (Manure Pro, MP) application was studied on RMS-bedding and milk qualities and on animal health. MP product was applied on bedding once a week for 3 months. Bedding and teat skin samples were collected from Control and MP groups at D01, D51, and D90 and analyzed through 16S rRNA amplicon sequencing. MP application modified bacterial profiles and diversity. Control bedding was significantly associated with potential mastitis pathogens, while no taxa of potential health risk were significantly detected in MP beddings. Functional prediction identified enrichment of metabolic pathways of agronomic interest in MP beddings. Significant associations with potential mastitis pathogens were mainly observed in Control teat skin samples. Finally, significantly better hygiene and lower Somatic Cell Counts in milk were observed for cows from MP group, while no group impact was observed on milk quality and microbiota. No dissemination of MP strains was observed from bedding to teats or milk.

IMPORTANCE

The use of Manure Pro (MP) conditioner improved recycled manure solids-bedding quality and this higher sanitary condition had further impacts on dairy cows' health with less potential mastitis pathogens significantly associated with bedding and teat skin samples of animals from MP group. The animals also presented an improved inflammation status, while milk quality was not modified. The use of MP conditioner on bedding may be of interest in controlling the risk of mastitis onset for dairy cows and further associated costs.

Dynamic changes of rumen bacteria and their fermentative ability in high-producing dairy cows during the late perinatal period

Background

High-producing dairy cows face varying degrees of metabolic stress and challenges during the late perinatal period, resulting in ruminal bacteria abundance and their fermentative ability occurring as a series of changes. However, the dynamic changes are still not clear.

Aims/methods

Ten healthy, high-producing Holstein dairy cows with similar body conditions and the same parity were selected, and ruminal fluid from the dairy cows at postpartum 0, 7, 14, and 21 d was collected before morning feeding. 16S rRNA high-throughput sequencing, GC-MS/MS targeted metabolomics, and UPLC-MS/MS untargeted metabolomics were applied in the study to investigate the dynamic changes within 21 d postpartum.

Results

The results displayed that the structures of ruminal bacteria were significantly altered from 0 to 7 d postpartum (R = 0.486, P = 0.002), reflecting the significantly declining abundances of Euryarchaeota and Chloroflexi phyla and Christensenellaceae, Methanobrevibacter, and Flexilinea genera (P < 0.05) and the obviously ascending abundances of Ruminococcaceae, Moryella, Pseudobutyrivibrio, and Prevotellaceae genera at 7 d postpartum (P < 0.05). The structures of ruminal bacteria also varied significantly from 7 to 14 d postpartum (R = 0.125, P = 0.022), reflecting the reducing abundances of Christensenellaceae, Ruminococcaceae, and Moryella genera (P < 0.05), and the elevating abundances of Sharpea and Olsenella genera at 14 d postpartum (P < 0.05). The metabolic profiles of ruminal SCFAs were obviously varied from 0 to 7 d postpartum, resulting in higher levels of propionic acid, butyric acid, and valeric acid at 7 d postpartum (P < 0.05); the metabolic profiles of other ruminal metabolites were significantly shifted from 0 to 7 d postpartum, with 27 significantly elevated metabolites and 35 apparently reduced metabolites (P < 0.05). The correlation analysis indicated that propionic acid was positively correlated with Prevotellaceae and Ruminococcaceae (P < 0.05), negatively correlated with Methanobrevibacter (P < 0.01); butyric acid was positively associated with Prevotellaceae, Ruminococcaceae, and Pseudobutyrivibrio (P < 0.05), negatively associated with Christensenellaceae (P < 0.01); valeric acid was positively linked with Prevotellaceae and Ruminococcaceae (P < 0.05); pyridoxal was positively correlated with Flexilinea and Methanobrevibacter (P < 0.05) and negatively correlated with Ruminococcaceae (P < 0.01); tyramine was negatively linked with Ruminococcaceae (P < 0.01).

Conclusion

The findings contribute to the decision of nutritional management and prevention of metabolic diseases in high-producing dairy cows during the late perinatal period.

High-Grain Diet Feeding Altered Blood Metabolites, Rumen Microbiome, and Metabolomics of Yaks

Currently, information available on the comprehensive changes in the rumen bacteria and metabolites of yaks fed high-grain diets is limited. This study aimed to investigate the effects of high-grain diet feeding on the blood metabolites, rumen microbiome, and metabolomics of yaks by using 16S rDNA gene sequencing and liquid chromatography–mass spectrometry (LC/MS). Here, fourteen healthy male yaks (body weight, 249.61 ± 8.13 kg) were randomly assigned to two different diets: a hay diet (0% grain, CON, n = 7), or a high-grain diet (70% grain, HG, n = 7). At the 74th day of treatment, blood and ruminal fluid samples were collected for the blood metabolites, rumen microbiome, and metabolomics analyses. The HG diet increased lipopolysaccharides (LPS), aspartate aminotransferase (AST), gamma-glutamyltransferase (GGT), haptoglobin (HPT), serum amyloid-A (SAA), interleukin-1β (IL1-β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) serum concentrations (p < 0.05). Compared with the CON diet, the HG diet decreased rumen pH (p < 0.05), and increased total volatile fatty acids concentration, and proportion of butyrate (p < 0.05). The relative abundance of Firmicutes and Saccharibacteria were higher (p < 0.05), while Bacteroidetes was lower (p < 0.05) in the HG group than those in the CON group. At the genus level, the relative abundance of Christensenelaceae_R-7_group, Ruminococcaceae_NK4A214_group, Lachnospiraceae_NK3A20_group, and Acetitomaculum were higher than in those in the HG diet (p < 0.05). Compared with the CON group, the HG diet increased the concentrations of biogenic amines (histamine, tyramine, and putrescine), common amino acids (phenylalanine, threonine, serine, etc.), and arachidonic acid (prostaglandin H2, prostaglandin E2, 12(S)-HPETE, etc.). Collectively, these findings demonstrate that the HG diet altered the microbiota and metabolites, as well as potentially damaged their rumen health and induced inflammation in yaks.

Effect of Temperature and Fermentation Time on Fermentation Characteristics and Biogenic Amine Formation of Oat Silage

Temperature is known to have a clear influence on the formation of biogenic amines during fermentation. To improve the quality of oat silage, the impact of ensiling temperature on the fermentation, microbiological and chemical characteristics, as well as biogenic amines (BAs) was investigated. Vacuum bag mini silos of oat forage were incubated at four different temperature levels (10, 20, 30 and 37 °C) and opened on day 0, 1, 3, 7, 15 and 60. All oat silages were sampled to evaluate the fermentation quality and biogenic amine production. Results showed that putrescine, cadaverine and tyramine were the most prevalent biogenic amines in oat silage, representing approximately about 90% of the total biogenic amines (TBAs) investigated. Ensiling increased the β–phenylethylamine, putrescine, cadaverine, histamine and tyramine accumulation in oat silage at the four incubation temperatures. On day 60, the β–phenylethylamine, cadaverine, histamine, tyramine and TBAs levels at a high temperature (37 °C) were significantly higher than those at a lower temperature (10, 20 and 30 °C); 10 °C fermentation increased the putrescine content in oat silage. A closed relationship between fermentation properties and BAs showed that the silages containing higher lactic acid, propionic acid and ammonia nitrogen and lower pH value had more BA content in oat silage. In conclusion, the ensiling process caused a significant increase in the amounts of BAs, except spermidine and spermine. The oat silage made in elevated temperature (30 and 37 °C) environments may accumulate more BAs than at a low temperature (10 °C), but low temperature (10 °C) fermentation may increase the putrescine levels in silage. The results suggested that ensiling at the proper temperature could retard BA formation and enhance the quality of oat silage.

Propionic Acid and Sodium Benzoate Affected Biogenic Amine Formation, Microbial Community, and Quality of Oat Silage

Investigating the microbial communities and biogenic amine (BA) formation in silage is of vital for improving the quality and safety of oat silage. The present study evaluated the effects of propionic acid (P) and sodium benzoate (SB) on the quality properties, microbial communities, and BA formation in oat silage. Oat was harvested at boot stage and ensiled using P and SB as additives in mini silos, followed by 14 days of aerobic exposure. The results showed that P and SB improved fermentation quality of oat silage, increased the lactic acid content, and decreased pH value and ammonia nitrogen content. Putrescine, cadaverine, and tyramine were the dominant BAs in oat silage; spermidine and spermine were not detected. The control silage had the highest content of total biogenic amine (TBA, 2506.7 mg kg^–1 DM), and decreased by 51.1 and 57.7% after adding P and SB, respectively. Moreover, a lower putrescine, cadaverine, and tyramine content and undesirable microbes, such as Caproiciproducens, Stenotrophomonas, Herbinix, and Enterobacter genera, were observed in P and SB silages, which was beneficial for oat silage quality. The fungal community of P silage was dominated by Monascus fuliginosus, and the temperature, pH and ammonia nitrogen content increased after exposure to air. Sedimentibacter, Herbinix, Caproiciproducens, Enterobacter, and Escherichia-Shigella were found to be positively correlated with BA formation in oat silage. Overall, P and SB effectively inhibit the undesirable microbes and BA formation in oat silage, the P silage exhibited lower aerobic stability than the SB silage.

Ruminal epithelium: a checkpoint for cattle health

The reticulorumen, as the main fermentation site of ruminants, delivers energy in the form of short-chain fatty acids (SCFA) for both the animal as well as the ruminal wall. By absorbing these SCFA, the ruminal epithelium plays a major role in the maintenance of intraruminal and intraepithelial acid-base homoeostasis as well as the balance of osmolarity. It takes up SCFA via several pathways which additionally lead to either a reduction of protons in the ruminal lumen or the secretion of bicarbonate, ultimately buffering the ruminal content effectively. Nutrition of the epithelium itself is achieved by catabolism of the SCFA, especially butyrate. Catabolism of SCFA also helps to maintain a concentration gradient across the epithelium to ensure efficient SCFA uptake and stability of the epithelial osmolarity. Furthermore, the ruminal epithelium forms a tight barrier against pathogens, endotoxins or biogenic amines, which may emerge from ruminal microorganisms and feed. Under physiological conditions, it reduces toxin uptake to a minimum. Moreover, the epithelium seems to have the ability to degrade biogenic amines like histamine. Nonetheless, in high performance production animals like dairy cattle, the reticulorumen is confronted with large amounts of rapidly fermentable carbohydrates. This may push the epithelium to its limits, even though it possesses a great capacity to adapt to varying feeding conditions. If the epithelial limit is exceeded, increasing amounts of SCFA lead to an acidotic imbalance that provokes epithelial damage and thereby elevates the entrance of pathogens and other potentially harmful substances into the animal's body. Hence, the ruminal epithelium lays the foundation for the animal's health, and in order to ensure longevity and high performance of ruminant farm animals, it should never be overburdened.

The Ruminal Microbiome and Metabolome Alterations Associated with Diet-Induced Milk Fat Depression in Dairy Cows

Milk fat depression (MFD) syndrome represents a significant drawback to the dairy industry. The aim of this study was to unravel the ruminal metabolome-microbiome interaction in response to diet-induced MFD in dairy cows. Twelve healthy second parity Holstein dairy cows (days in milk (DIM) = 119 ± 14) were randomly assigned into control (CON, n = 6) group and treatment (TR, n = 6) group. Cows in TR group received a high-starch total mixed ration (TMR) designed to induce an MFD syndrome. Decreased milk fat yield and concentration in TR cows displayed the successful development of MFD syndrome. TR diet increased the relative abundance of Prevotella and decreased the relative abundance of unclassified Lachnospiraceae, Oribacterium, unclassified Veillonellaceae and Pseudobutyrivibrio in ruminal fluid. Metabolomics analysis revealed that the ruminal fluid content of glucose, amino acids and amines were significantly increased in TR cows compared with CON cows. Correlation analysis revealed that the concentration of amines and amino acids were highly correlated with the abundance of Oribacterium, Pseudobutyrivibrio, RC9_gut_group, unclassified BS11_gut_group and Selenomonas. In general, these findings revealed that TR diet reduced the rumination time and altered rumen fermentation type, which led to changes in the composition of ruminal microbiota and metabolites, and caused MFD.

Biogenic amines: Concentrations in serum and skeletal muscle from late pregnancy until early lactation in dairy cows with high versus normal body condition score

Biogenic amines (BA) are a class of nitrogenous compounds that are involved in a wide variety of physiological processes, but their role in transition cows is poorly understood. Our objectives were to describe the longitudinal changes of BA in serum and in skeletal muscle during the transition period and to characterize temporal responses of BA in relation to body condition score (BCS) of periparturient dairy cows. Fifteen weeks before calving, 36 multiparous Holstein cows were assigned to 2 groups (n = 18 per group) that were fed differently to reach either high [HBCS; net energy for lactation (NE_L) = 7.2 MJ/kg of dry matter (DM)] or normal BCS (NBCS; NE_L = 6.8 MJ/kg of DM) at dry-off. The targeted BCS and back fat thickness (BFT) at dry-off (HBCS, >3.75 and >1.4 cm; NBCS, <3.5 and <1.2 cm) were reached. Thereafter, both groups were fed identical diets. Blood samples and muscle (semitendinosus) biopsies were collected at d -49, +3, +21, and +84 relative to parturition. In serum and skeletal muscle, BA concentrations were measured using a targeted metabolomics assay. The data were analyzed as a repeated measure using the MIXED procedure of SAS. The serum concentrations of most BA (i.e., creatinine, taurine, carnosine putrescine, spermine, α-aminoadipic acid, acetylornithine, kynurenine, serotonin, hydroxyproline, asymmetric dimethylarginine, and symmetric dimethylarginine) fluctuated during the transition period, while others (i.e., spermidine, phenylethylamine) did not change with time. The muscle concentrations of BA remained unchanged over time. Creatinine had the highest concentrations in the serum, while carnosine had the highest concentration among the muscle BA. The serum concentrations of creatinine (d +21), putrescine (d +84), α-aminoadipic acid (d +3), and hydroxyproline (d +21) were or tended to be higher for HBCS compared with NBCS postpartum. The serum concentrations of symmetric dimethylarginine (d -49) and acetylornithine (d +84) were or tended to be lower for HBCS compared with NBCS, respectively. The serum kynurenine/tryptophan ratio was greater with HBCS than with NBCS (d +84). Compared with NBCS, HBCS was associated with lower muscle concentrations of carnosine, but those of hydroxyproline were higher (d -49). In both serum and muscle, the asymmetric dimethylarginine concentrations were greater with HBCS than with NBCS (d -49). No correlation was found between serum and skeletal muscle BA. This study indicates that overconditioning of dairy cows may influence serum and muscle BA concentrations in the periparturient period.

Silage review: Animal and human health risks from silage

Silage may contain several agents that are potentially hazardous to animal health, the safety of milk or other animal food products, or both. This paper reviews published literature about microbial hazards, plant toxins, and chemical hazards. Microbial hazards include Clostridium botulinum, Bacillus cereus, Listeria monocytogenes, Shiga toxin-producing Escherichia coli, Mycobacterium bovis, and various mold species. High concentrations of C. botulinum in silage have been associated with cattle botulism. A high initial concentration of C. botulinum spores in forage in combination with poor silage fermentation conditions can promote the growth of C. botulinum in silage. The elevated pH level that is generally associated with aerobic deterioration of silage is a major factor influencing concentrations of L. monocytogenes, Shiga toxin-producing E. coli, and molds in silage and may also encourage survival and growth of M. bovis, the bacterium that causes bovine tuberculosis. Soil is a major source of B. cereus spores in silage; growth of this bacterium in silage appears to be limited. Hazards from plant toxins include pyrrolizidine, tropane and tropolone alkaloids, phytoestrogens, prussic acid, and mimosine, compounds that exist naturally in certain plant species that may contaminate forages at harvesting. Another group of toxins belonging to this category are ergot alkaloids, which are produced by endophytic fungal species in forages such as tall fescue grass, sorghum, and ryegrass. Varying effects of ensiling on the degradation of these plant toxins have been reported. Chemical hazards include nitrate, nitrite, and toxic oxide gases of nitrogen produced from nitrate and high levels of butyric acid, biogenic amines, and ammonia. Chemical and microbiological hazards are associated with poorly fermented silages, which can be avoided by using proper silage-making practices and creating conditions that promote a rapid and sufficient reduction of the silage pH and prevent aerobic deterioration.

Supplementing phytogenic compounds or autolyzed yeast modulates ruminal biogenic amines and plasma metabolome in dry cows experiencing subacute ruminal acidosis

Subacute ruminal acidosis (SARA) causes ruminal dysbiosis, thereby increasing the risk of systemic metabolic disorders in cattle. We recently showed that supplementation with phytogenic compounds (PHY) or autolyzed yeast (AY) counteracted negative effects of SARA by improving ruminal pH and microbiome. This study investigated the effects of an intermittent SARA challenge on the ruminal concentration of biogenic amines (BA) and lipopolysaccharides (LPS), as well as on the blood metabolome. We also evaluated effects of PHY and AY on the latter variables. Eight rumen-cannulated nonlactating Holstein cows were arranged in an incomplete 4 × 3 Latin square design with 4 experimental runs and 3 treatment groups. During each run, cows were switched from an all-forage diet (baseline) to an intermittent concentrate-challenge diet with a forage:concentrate ratio of 35:65 (dry matter basis) to induce SARA for 1 (SARA1) or 2 (SARA2) wk, separated by 1 wk of forage-only feeding. The 3 treatment groups were no additive as control, PHY, or AY. During baseline, SARA1 and SARA2 rumen fluid samples were collected for analysis of BA and LPS. Blood samples were taken during baseline and SARA1 for a targeted metabolomics approach. High-concentrate feeding caused a 9-fold increase in ruminal LPS during SARA1 and an 11-fold increase in SARA2 compared with the baseline. Elevated concentrations of ruminal BA were found during both SARA periods, with histamine showing the strongest increase during SARA1. Moreover, a decrease in phosphatidylcholines, lysophosphatidylcholines, sphingomyelines, and several AA in the blood during SARA1 were detected. Supplementation of PHY decreased concentrations of LPS (-43%), histamine (-66%), pyrrolidine (-38%), and spermine (-54%) in SARA1 and cadaverine in SARA2 (-50%). Moreover, cows that received PHY had higher concentrations of cholesterol (+26%), several AA, and phosphatidylcholines in SARA1 compared with control cows. For AY, decreases in ruminal ethanolamine (-21%), methylamine (-52%), histamine (-54%), spermidine (-44%), and spermine (-80%) in SARA1 were observed, whereas in the blood an increase in tryptophan was noticed. In conclusion, the SARA was associated with markedly increased concentrations of LPS and BA in the rumen fluid and undesirable shifts in the plasma metabolome. Supplementation of PHY and AY counteracted some of these changes and therefore may help in attenuating negative effects of high-concentrate feeding in dairy cattle.

Biogenic amines and mycotoxins concentrations in baled silage from organic and conventional farms

ABSTRACT The aim of the current study was to investigate biogenic amines and mycotoxins concentrations in baled silage (mainly Poaceae family grasses) prepared in organic and conventional farms and to relate these parameters to fermentative parameters. The mean dry matter (DM) content was 364.10±93.31 and 424.70±95.93g/kg in the silage from organic and conventional farms respectively. The silage samples from organic farms had 17.00% higher (P≤ 0.05) tyramine (TY) than the silage from conventional farms. Conventional farm samples were characterized by 46.00% higher histamine (HIS) (P≤ 0.05), 9.80% higher putrescine (PUT) (P≤ 0.05), 17.30% higher cadaverine (CAD) (P≤ 0.05). Aflatoxins (AFL) (total) and zearalenone (ZEN), T-2/HT-2 concentrations were higher respectively 16.00% (P≤ 0.05) and 13.40% (P≤ 0.05), 1.80% (P≤ 0.05) in the silage prepared in organic farms. Deoxynivalenol (DON) concentration was higher 42.40% (P≤ 0.05) in silage from conventional farms. Volatile fatty acids (VFA), lactic acid, ethanol, pH and ammonia nitrogen showed that the silage samples from organic and conventional farms were of good quality. Our study suggests differences in biogenic amine formation or mycotoxins content in silage from organic and conventional farming, but, overall, the measured values are too low to be relevant for animal health. Furthermore, these differences might as well be due to the difference in dry matter content and plant maturity between the organic and conventional silage samples.

The effects of intradermal injections of spermidine on the growth rate of fibres and mitosis of wool follicles in Merino lambs

Polyamines (putrescine, spermidine and spermine) are required for optimal growth in all cells, and are essential for cell proliferation and growth of cultured wool follicles, with an optimal concentration of spermidine required for the fibre elongation. The effects of a local supply of exogenous spermidine on the rate of cell division in the wool follicles, the length growth rate and diameter of fibres were therefore examined in Merino lambs. Three groups of eight lambs (40 kg) were given food at 1·2 ✕ maintenance. Spermidine was injected intradermally into a small patch (3 ✕ 3 cm) on the left flank three times per day for 7 days at one of three concentrations: 1·38, 2·75 or 4·58 џmol in 0·8 ml volume. The same volume of saline was injected into the contralateral side as a control. The concentration of spermidine in the skin patch 3 h after injection on day 7 increased by proportionately 018, 0·33 or 0·41 (P < 0001) respectively. The rates of cell division in the follicle bulb 3 h after the spermidine injection were proportionately 0104, 0184 and 0·283 higher compared with the contralateral side (P = 0078 overall) for the low, medium and high doses of spermidine respectively and differed between the three doses (P < 005). The fibre length growth rate, as measured using autoradiography, was proportionately 0099, 0117 and 0156 higher than that of the contralateral side (P < 0001 overall) for the low, medium and high doses of spermidine respectively, but differences between doses were not significant (P > 005). Spermidine injection did not result in a significant change in fibre diameter during the treatment period. The ratio of fibre length growth rate to fibre diameter was increased by the injection of spermidine (P < 0001). The results suggest that injecting extra spermidine into the skin altered spermidine homeostasis in the skin, stimulated cell proliferation and resulted in increased fibre growth.

Effect of Soybean Meal and Soluble Starch on Biogenic Amine Production and Microbial Diversity Using In vitro Rumen Fermentation

This study was conducted to investigate the effect of soybean meal (SM) and soluble starch (SS) on biogenic amine production and microbial diversity using in vitro ruminal fermentation. Treatments comprised of incubation of 2 g of mixture (expressed as 10 parts) containing different ratios of SM to SS as: 0:0, 10:0, 7:3, 5:5, 3:7, or 0:10. In vitro ruminal fermentation parameters were determined at 0, 12, 24, and 48 h of incubation while the biogenic amine and microbial diversity were determined at 48 h of incubation. Treatment with highest proportion of SM had higher (p<0.05) gas production than those with higher proportions of SS. Samples with higher proportion of SS resulted in lower pH than those with higher proportion of SM after 48 h of incubation. The largest change in NH3-N concentration from 0 to 48 h was observed on all SM while the smallest was observed on exclusive SS. Similarly, exclusive SS had the lowest NH3-N concentration among all groups after 24 h of incubation. Increasing methane (CH4) concentrations were observed with time, and CH4 concentrations were higher (p<0.05) with greater proportions of SM than SS. Balanced proportion of SM and SS had the highest (p<0.05) total volatile fatty acid (TVFA) while propionate was found highest in higher proportion of SS. Moreover, biogenic amine (BA) was higher (p<0.05) in samples containing greater proportions of SM. Histamines, amine index and total amines were highest in exclusive SM followed in sequence mixtures with increasing proportion of SS (and lowered proportion of SM) at 48 h of incubation. Nine dominant bands were identified by denaturing gradient gel electrophoresis (DGGE) and their identity ranged from 87% to 100% which were mostly isolated from rumen and feces. Bands R2 (uncultured bacterium clone RB-5E1) and R4 (uncultured rumen bacterium clone L7A_C10) bands were found in samples with higher proportions of SM while R3 (uncultured Firmicutes bacterium clone NI_52), R7 (Selenomonas sp. MCB2), R8 (Selenomonas ruminantium gene) and R9 (Selenomonas ruminantium strain LongY6) were found in samples with higher proportions of SS. Different feed ratios affect rumen fermentation in terms of pH, NH3-N, CH4, BA, volatile fatty acid and other metabolite concentrations and microbial diversity. Balanced protein and carbohydrate ratios are needed for rumen fermentation.

Effect of dietary forage sources on rumen microbiota, rumen fermentation and biogenic amines in dairy cows

BACKGROUND

Fifteen lactating Holstein dairy cows were assigned to three diets in a 3 × 3 Latin square design to evaluate the effects of dietary forage sources on rumen microbiota, rumen fermentation and biogenic amines. Diets were isonitrogenous and isocaloric, with a forage/concentrate ratio of 45:55 (dry matter basis) but different main forage sources, namely cornstalk (CS), Leymus chinensis (LC) or alfalfa hay (AH).

RESULTS

Pyrosequencing of the V3-V6 hypervariable coding region of 16S rRNA revealed that the rumen microbiota was significantly affected by forage sources. AH feeding increased the proportion of genera Prevotella and Selenomonas compared with the CS diet, while CS feeding increased the proportion of genera Anaerotruncus, Papillibacter, Thermoactimoyces, Bacillus and Streptomyces compared with the LC or AH diet. AH and LC feeding both increased the propionate concentration compared with the CS diet. AH feeding decreased the concentrations of tyramine, putrescine and histamine compared with the LC diet.

CONCLUSION

These results indicate that a high proportion of alfalfa hay in the ration is beneficial for milk yield and a healthy and balanced rumen microbiota in lactating cattle. This can be attributed to the higher degradation of rumen organic matter and the more balanced carbohydrates and proteins for optimal rumen microbial growth.

A metabolomics approach to uncover the effects of grain diets on rumen health in dairy cows

Dairy cows fed high-grain diets during early lactation have a high incidence of metabolic disorders. However, the precise mechanism(s) of how grain feeding causes disease is not clear. In an effort to understand how this diet transition alters the rumen environment and potentially leads to certain metabolic disorders in dairy cattle, we undertook a comprehensive, quantitative metabolomic analysis of rumen fluid samples from dairy cows fed 4 different diets. Using a combination of proton nuclear magnetic resonance spectroscopy, gas chromatography-mass spectrometry, and direct flow injection tandem mass spectroscopy, we identified and quantified 93 metabolites in rumen samples taken from 8 dairy cows fed graded amounts of barley grain (i.e., 0, 15, 30, and 45% of diet dry matter). We also studied temporal changes in the rumen by studying metabolite concentration differences between the first day and the last day of each diet phase following the diet adaptation period. Multivariate analysis showed that rumen metabolites arising from the diet containing 45% barley grain were clearly different from those containing 0, 15, and 30% barley grain. Likewise, a clear separation of the metabolic composition of the ruminal fluid was evident at the beginning and at the end of each diet phase-contrary to the belief that 11 d are suitable for the adaptation of cows to high-grain diets. High-grain diets (>30%) resulted in increased rumen fluid concentrations of several toxic, inflammatory, and unnatural compounds including putrescine, methylamines, ethanolamine, and short-chain fatty acids. Perturbations in several amino acids (phenylalanine, ornithine, lysine, leucine, arginine, valine, and phenylacetylglycine) were also evident. The present study confirms and greatly extends earlier observations on dietary effects on rumen fluid composition and shows that the use of multiple metabolomic platforms permits a far more detailed understanding of metabolic causes and effects. These results may improve our understanding of diet-related rumen metabolism and the influence of grain on the overall health of dairy cattle.

Ultrasonographic evaluation of reticular motility during rest, eating, rumination and stress in 30 healthy cows

A 3.5 MHz linear transducer was used to assess the motility of the reticulum in 30 healthy, standing, non-sedated cows while they were at rest, eating, ruminating and under stress. The ultrasonographic examinations were made over periods of nine minutes and video recorded for analysis. The reticulum contracted in a biphasic pattern while the cows were resting, eating or stressed. The first contraction was incomplete and was followed by a period of incomplete relaxation. A complete second contraction occurred immediately afterwards, followed by an interval of complete relaxation and the return of the organ to its original position. When the cows were ruminating, a regurgitation contraction, which was incomplete, occurred immediately before the biphasic contraction. The number of reticular contractions in a nine-minute period was largest when the cows were eating (13.9 contractions, or approximately 1.5 per minute) and smallest when they were stressed (9.3 contractions, or approximately 1 per minute). The duration of the first reticular contraction was shortest during rumination (2.4 seconds) and longest when the cows were eating (3.0 seconds). The interval between two biphasic contractions was shortest when the cows were eating (31.6 seconds) and longest when they were stressed (53.8 seconds).

Biogenic amine production in grass, maize and total mixed ration silages inoculated with Lactobacillus casei or Lactobacillus buchneri

AIMS

To investigate the effects of inoculating Lactobacillus casei or Lacobacillus buchneri on the production of biogenic amines (BA) in silage.

METHODS AND RESULTS

Wilted festulolium (Lolium perenne x Festuca pratensis), whole crop maize or a total mixed ration, consisting of wet brewer grains, lucerne hay, cracked maize, sugarbeet pulp, soyabean meal and molasses, was ensiled with or without the inoculation of either L. casei (>10(6) CFU g(-1)) or L. buchneri (>10(6) CFU g(-1)). Silages were opened after 60 days of storage, and the concentrations of histamine, tyramine, putrescine and cadaverine were determined. The inoculation of L. casei decreased all the BA regardless of the silage type. The effects of L. buchneri varied between the three silages; the tyramine and putrescine were increased in maize but were lowered in festulolium. Histamine was reduced in festulolium and the by-products, whereas no change was found in the maize silage. None of the inoculant strains produced the four BA in a synthetic medium, accounting for the actual ensiling except for tyramine and putrescine in maize.

CONCLUSIONS

Wide variation would be found in the production of BA owing to the ensiling materials. The inoculation of L. casei can lower the BA concentration, while the effects of L. buchneri may vary considerably. The screening of BA-producing activity may help to reduce the risk of BA contamination in inoculated silage.

SIGNIFICANCE AND IMPACT OF THE STUDY

Strains of decarboxylase-negative L. buchneri can enhance the aerobic stability of silage without a concern regarding the large production of putrefactive BA.

The effect of fermentation quality on the voluntary intake of grass silage by growing cattle fed silage as the sole feed1

This study was designed to separate the effect of fermentation quality on voluntary intake of grass silage from other feed factors affecting intake. Variations in DMI were quantified, and the impact on intake was modeled. The relationships between individual silage components and intake were examined. A partially balanced changeover experiment with 30 Norwegian Red steers (137 +/- 16.4 kg of BW) was carried out to determine the intake of 24 silages and of hay harvested from the same parent crop within 60 h. Five forages were fed at a time in each of five 3-wk periods. Every 3-wk period was preceded by 2 wk of feeding a standard silage. Silage DMI ranged from 1.79 to 2.65, with a mean of 2.38 kg x 100 kg of BW(-1) x d(-1). Hay DMI averaged 2.43 kg x 100 kg of BW(-1) x d(-1). Ranges (mean) for the composition of silages were as follows: DM, 166 to 237 (213) g/kg; water-soluble carbohydrates, 16.3 to 70.9 (33.0) g/kg of DM; acetic acid, 11.5 to 64.7 (28.6) g/kg of DM; propionic acid, 0 to 5.2 (1.0) g/kg of DM; butyric acid, 0 to 25.1 (6.0) g/kg of DM; lactic acid, 2.2 to 102 (49.3) g/kg of DM; and NH3-N (not corrected for additive-derived N), 89.3 to 255 (153) g/kg of total N. Silage DMI was closely (P < 0.05) related to DM, ADL, VFA, lactic acid, total acids, the lactic acid:total acids ratio, ADIN, NH3-N (not corrected), histamine, tryptamine, cadaverine, and the total sum of amines (the explained variation in intake ranged from 14 to 53%). The 2 best models describing silage DMI included concentrations in the silage of propionic acid, butyric acid, and lactic acid, and these models explained 75 and 84% of the variation in DMI. The strong correlation (r = 0.84, P < 0.05) between total NH3-N and butyric acid concentrations in silages indicates that these variables described the same variation pattern. The inclusion of NH3-N in the equations describing the effect of fermentation quality on DMI of low-DM grass silage was less useful than that of butyric acid. This was due to the confounded relationship between the NH3-N concentration in silages and the use of ammonium-containing preservatives and to difficulties in correcting for the added ammonium.

The effects of lactic acid bacteria inoculants and formic acid on the formation of biogenic amines in grass silages

Silages were prepared in six laboratory experiments from four direct-cut grassland swards and pure swards of perennial ryegrass and false oat with dry matter contents ranging between 180 and 325 g/kg. Grass was fermented at 22 degrees C and silages were stored at the same temperature for 4 months. Untreated silages (negative control) and silages preserved with 3 g/kg of formic acid (positive control) were compared with silages inoculated with commercial strains of Lactobacillus plantarum, Lactobacillus buchneri and a mixed preparation Microsil. The inoculants were applied at a dose of 5.10(6) CFU/g of grass. Seven biogenic amines were extracted from silages with perchloric acid and determined as N-benzamides by micellar electrokinetic capillary chromatography. Common chemical quality parameters of silages were also determined. Tyramine, cadaverine and putrescine were the amines occurring at the highest concentration. As compared to untreated silages, formic acid was most effective to suppress formation of the main amines. Also the inoculants often decreased amine contents significantly (P < 0.05). The inoculants decreased levels of polyamine spermidine more efficiently than formic acid. Contents of histamine, tryptamine and polyamine spermine were very low, commonly below the detection limits.

Effects of particle size of alfalfa-based dairy cow diets on site and extent of digestion

Effects of ratio of alfalfa silage to alfalfa hay and forage particle size on nutrient intakes, site of digestion, rumen pools, and passage rate of ruminal contents were evaluated in a 4 x 4 Latin square design with a 2 x 2 factorial arrangement of treatments. The diets consisted of 60% barley-based concentrate and 40% forage made up either of 50:50 or 25:75 of alfalfa silage:alfalfa hay and alfalfa hay was either chopped or ground. Lactating dairy cows surgically fitted with ruminal and duodenal cannulas were used and offered ad libitum access to a total mixed ration. Intakes of nutrients were increased by increasing ratio of silage to hay but were not affected by particle size of forage. Change in ratio of silage to hay of diets did not affect site and extent of digestion. However, increased forage particle size of the diets improved digestibility of fiber and N in the total tract, and as well as digestibility of organic matter, starch, and acid detergent fiber in the intestine. There was a shift of starch digestion from the rumen to the intestine when forage particle size was increased, although total digestion of starch was not changed. Ruminal microbial protein synthesis and microbial efficiency also improved with increasing forage particle size. Cows fed ground hay versus chopped hay had significantly lower rumen wet mass regardless of the ratio of silage to hay. Reduced forage particle size also lowered ruminal nutrient pool size for cows fed the high silage diet. Ruminal passage rates of liquid and solid were decreased by reducing the ratio of silage to hay, and retention time of solids in the total tract was shortened by reducing forage particle size. These results indicate that manipulating ratio of silage to hay in the diets of dairy cows changed feed intake but had little effect on digestion. In contrast, increased forage particle size in dairy cow diets improved fiber digestion and microbial protein synthesis in the rumen, and shifted starch digestion from the rumen to the intestine. Dietary particle size, expressed as physically effective neutral detergent fiber, was a reliable indication of ruminal microbial protein synthesis and nutrient digestion.

Feeding oleamide to lactating Jersey cows. 2. Effects on nutrient digestibility, plasma fatty acids, and hormones

Six lactating Jersey cows were used in a 6 x 6 Latin square with 14-d periods to evaluate different ratios of canola oil and oleamide on nutrient digestibility, plasma fatty acids, and plasma hormones. The control diet contained no added fat. All other diets contained 3.5% added fat consisting of 0, 25, 50, 75, and 100% as oleamide and the remainder as canola oil. Data were collected during the final 4 d of each period. Dry matter intake was reduced by the addition of canola oil to the diet, and further reduced by replacing canola oil with oleamide. Milk yield was not affected by diet but increasing oleamide proportion in the fat supplement caused linear increases in cis-C18:1 and linear decreases in C4 to C16 fatty acids in milk. Adding canola oil reduced total tract digestibilities of fiber and fatty acids, but had no effect on the digestibilities of dry matter or protein. Replacing canola oil with oleamide increased protein digestibility linearly, and increased digestibility of fiber (quartic relationship) and fatty acids (quadratic relationship). Oleic acid concentration in plasma increased by adding canola oil to the diet, and was further increased by replacing canola oil with oleamide. Diet had no effect on plasma concentrations of insulin or IGF-I. Oleamide fed to Jersey cows in this study was highly digestible and had no deleterious effects on total tract digestility of fiber or protein. Increasing oleic acid concentration in plasma lipids while maintaining a constant level of added fat in the ration had no effect on circulating concentrations of insulin or IGF-I in Jerseys.