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PubMed1979

Trace element deficiencies and fertility in ruminants: a review.

Various minerals (copper, cobalt, selenium, manganese, iodine, zinc, and iron) can influence reproductive performance of ruminants. Reproductive failure may be induced by deficiencies of single or combined trace elements and by imbalances. This review is focused on maladjustments of trace elements leading to impaired breeding performance. Opinion is diverse as to the existence of various reproductive disturbances from either a severe copper depletion or a marginal dietary copper deficiency. Field experience suggests that administration of cobalt to ruminants on cobalt-deficient diets improves their impaired breeding performance. Selenium infertility in ewes is more prevalent in some areas and in some seasons, but the actual cause of this malady and the continuing role of additional factors are unknown. Manganese is necessary for normal fertility in ruminants, and feeding low-manganese rations depresses conception rates. Lack of iodine impairs thyroid activity and also ovarian function. Reproductive failure in the female and in spermatogenesis are manifestations of zinc deficiency. Despite forages rich in iron, low availability in certain instances could affect adversely ruminant reproduction. Knowledge of biochemical dysfunctions from trace element deficiencies is essential to determine the role which trace elements play in fertility of ruminant animals.

Abortion, Veterinary↗
PubMed2025

Unveiling novel antimicrobial peptides from the ruminant gastrointestinal microbiomes: A deep learning-driven approach yields an anti-MRSA candidate.

INTRODUCTION: Antimicrobial peptides (AMPs) present a promising avenue to combat the growing threat of antibiotic resistance. The ruminant gastrointestinal microbiome serves as a unique ecosystem that offers untapped potential for AMP discovery. OBJECTIVES: The aims of this study are to develop an effective methodology for the identification of novel AMPs from ruminant gastrointestinal microbiomes, followed by evaluating their antimicrobial efficacy and elucidating the mechanisms underlying their activity. METHODS: We developed a deep learning-based model to identify AMP candidates from a dataset comprising 120 metagenomes and 10,373 metagenome-assembled genomes derived from the ruminant gastrointestinal tract. Both in vivo and in vitro experiments were performed to examine and validate the antimicrobial activities of the AMP candidates that were selected through bioinformatic analysis and subsequently synthesized chemically. Additionally, molecular dynamics simulations were conducted to explore the action mechanism of the most potent AMP candidate. RESULTS: The deep learning model identified 27,192 potential secretory AMP candidates. Following bioinformatic analysis, 39 candidates were synthesized and tested. Remarkably, all synthesized peptides demonstrated antimicrobial activity against Staphylococcus aureus, with 79.5% showing effectiveness against multiple pathogens. Notably, Peptide 4, which exhibited the highest antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA), confirmed this effect in a mouse model with wound infection, exhibiting a low propensity for resistance development and minimal cytotoxicity and hemolysis towards mammalian cells. Molecular dynamics simulations provided insights into the mechanism of Peptide 4, primarily its ability to disrupt bacterial cell membranes, leading to cell death. CONCLUSION: This study highlights the power of combining deep learning with microbiome research to uncover novel therapeutic candidates, paving the way for the development of next-generation antimicrobials like Peptide 4 to combat the growing threat of MRSA would infections. It also underscores the value of utilizing ruminant microbial resources.

Animals↗
PubMed1979

Comparative lethal effects on mice of ruminal fluid from cattle fed hay or grain.

Strained ruminal fluid from cattle fed hay or grain was lethal to mice when injected intraperitoneally, but the fluid from grain-fed cattle was approximately 3.7 times more toxic than that from hay-fed cattle. The lethal factor(s) was not resistant to heat, was nondialyzable, was retained on Seitz and membrane filters, and was associated with the bacterial fraction of ruminal fluid. We concluded that death of the mice resulted from infection produced by facultative bacteria normally in ruminal fluid. Ruminal fluid from grain-fed cattle contained a greater number of facultative bacteria than did that from hay-fed cattle.

Animal Feed↗
PubMed2025

Genomic insights into Shigella species isolated from small ruminants and manure in the North West Province, South Africa.

This study investigated Shigella species' antibiotic resistance patterns and genomic characteristics from small ruminants and manure collected in Potchefstroom, North West, South Africa. Whole genome sequencing was used to determine resistome profiles of Shigella flexneri isolates from small ruminants' manure and Shigella boydii from sheep faeces. Comparative genomics was employed on the South African 261 S. flexneri strains available from GenBank, including the sequenced strains in this study, by investigating the serovars, antibiotic resistance genes (ARGs), and plasmid replicon types. The S. flexneri strains could not be assigned to known sequence types, suggesting novel or uncharacterized lineages. S. boydii R7-1A was assigned to sequence type 202 (ST202). Serovar 2A was the most common among South African S. flexneri strains, found in 96% of the 250 compared human-derived isolates. The shared mdf(A) was the most prevalent gene, identified in 99% of 261 S. flexneri genomes, including plasmid replicon types ColRNAI_1 (99%) and IncFII_1 (98%). Both species share a core set of resistance determinants mainly involving β-lactams (ampC1, ampC, ampH), macrolides (mphB), polymyxins (eptA, pmrF), multidrug efflux pumps (AcrAB-TolC, Mdt, Emr, Kpn families), and regulatory systems (marA, hns, crp, baeRS, evgAS, cpxA, gadX). However, S. boydii possesses additional resistance genes conferring resistance to tetracyclines (tet(A)), phenicols (floR), sulphonamides (sul2), and aminoglycosides (APH(3'')-Ib, APH(6)-Id), along with the acrEF efflux pump components (acrE, acrF). In contrast, S. flexneri harboured unique genes linked to polymyxin resistance (ugd) and regulatory functions (sdiA, gadW) that were absent in S. boydii. These findings highlight Shigella strains' genomic diversity and antimicrobial resistance potential in livestock-associated environments. Moreover, S. boydii highlights the potential risk of multidrug-resistant bacteria in farming and environmental routes. KEY POINTS: • First whole genome study of Shigella from manure and small ruminants in South Africa. • Shigella boydii strain carried multiple resistance genes to β-lactams and tetracycline. • Multidrug efflux pump gene mdf(A) was detected in 99% of South African Shigella flexneri strains.

Animals↗
PubMed2026

A genetic manipulation tool based on the GP35 recombinase for targeted gene editing in mycoplasmas of ruminants.

Pathogenic ruminant mycoplasmas are major etiological agents in cattle and small ruminants and are responsible for substantial economic losses in the livestock industry. Progress in pathogenesis research and vaccine development has been hampered by a lack of effective genetic tools. The applicability of common genome editing platforms, such as CRISPR, is inherently restricted in these organisms owing to their minimal genomes, the absence of a cell wall, and low homologous recombination efficiency. Although transposon-mediated random mutagenesis and single-base editing are currently used in the editing of bovine mycoplasma, the stochastic nature of transposons, the risk of single-base random deamination, and limitations in editing window selection hinder the genetic manipulation of bovine mycoplasma. Here, we introduce a plasmid-based methodology that employs the GP35 recombinase from bacteriophage SPP1 to mediate long single-stranded DNA (ssDNA) recombineering, thereby enabling precise gene insertions and deletions in Mycoplasma bovis, with a positive-editing rate of 77.78% - 100%. This targeted system eliminates the risk of random deamination. Leveraging this tool, we generated a panel of M. bovis mutants affecting metabolic and virulence genes and obtained key insights into Mb0564, identified as a novel adhesin. The 192 to 287 aa region of GP35 is critical for interaction with SSB. Structural conservation analysis further suggested that this GP35-ssDNA editing system possesses a high potential for translation to other ruminant pathogens. Collectively, our approach expands the existing genetic toolkit for M. bovis, advances synthetic biology and M. bovis pathobiology, facilitates vaccine development, and strengthens the control of high-impact livestock diseases in line with the One Health framework.

Animals↗
PubMed1977

Protected proteins in ruminant nutrition. In vitro evaluation of casein derivatives.

Chemical treatment of proteins in feeds can, by crosslinking protein chains or other chemical effects, decrease their solubility and microbial degradation in the rumen. A need exists to modify proteins systematically under well-defined conditions with inexpensive reagents and to evaluate the treated products nutritionally for possible beneficial effects on wool growth and quality as well as production of meat and milk. As a first step toward this goal we evaluated many derivatives of casein treated at pH 9-10 with various acylating and alkylating agents. Initial tests indicate that all treatments decreased protein digestion by rumen microorganisms. Potentially crosslinking reagents are usually more effective than similar ones that cannot crosslink. A few treatments gave ruminal protection that approached or exceeded that obtained with formaldehyde. This result shows that systematic evaluation of ruminal in vitro digestibility of protein derivatives may disclose new products deserving tests of post-ruminal digestibility and practical nutritive value.

Amino Acids↗
PubMed1976

Effect of oxygen saturation on H+ and Cl- distribution across the red cell membrane in human and ruminant blood.

Alterations of red cell pH (pHc) and distribution ratios of H+ (gammaH+) and Cl (gammaCl-) between plasma and red blood cells with oxygenation of blood were studied in human blood (audult and fetal) and ruminant blood (bovine, goat and sheep). The experiments were carried out at a plasma pH of 7.0 to 7.7 and at 37 degrees C. In human blood pHc of fully oxygenated blood was 0.035 pH lower than that of fully deoxygenated blood in all ranges of plasma pH studied. In ruminant blood, however, the differences in pHc between oxygenated and deoxygenated blood were 0.011 in ox, and 0.003 in goat and sheep, all of them not being significant. The decreases in gammaH+ accompanying oxygenation were in fairly good agreement with those in gammaCl- in human blood and amounted to about 0.05. In ruminant blood, in spite of virtually zero changes in gammaH+ with oxygenation, the decreases in gammaCl- were slightly greater than those in human blood. There might be a species difference in the mechanisms of distribution of Cl- and H+ across the red cell membrane.

Animals↗
PubMed2026

Developmental block in ruminant embryos: Mechanisms, molecular insights and potential interventions.

Developmental block remains one of the major hurdles that makes it hard to develop embryos in vitro more efficiently. In ruminants, it is predominantly observed during the 8-16 cell stage, coinciding with the maternal-to-zygotic transition (MZT) and embryonic genome activation (EGA). In addition, reducing maternal transcripts and initiating embryonic transcription correctly is a major reason for developmental arrest. A broad array of molecular mechanisms has been implicated, encompassing incomplete epigenetic regulation, mitochondrial dysfunction, oxidative stress, improper cell cycle progression, and dysregulated apoptosis. During this process, several key genes, including ZAR1, NPM2, DPPA3, DNMTs, Cyclin B1, BCL2, and antioxidant enzymes (SOD1, GPX1, and CAT) have been recognized as essential regulators of the block. External factors, especially poor in vitro culture conditions, high oxygen levels, and the secretion of harmful metabolites, make developmental failure even worse. Recent research has underscored the significance of antioxidant supplementation, epigenetic modulators, and enhanced culture systems in mitigating developmental barriers. Therefore, the current review summarises the contemporary insights into the factors and molecular mechanisms responsible for ruminant embryonic developmental block, focusing on MZT, oxidative stress, and epigenetic regulation. It also addresses potential strategies to enhance the developmental competence of ruminant embryos in vitro.

Embryo↗
PubMed1977

[The effect of nutritional factors on the ruminal mucosa. 3. Condition of the mucosa after infusion of propionic acid, acetic acid and butyric acid].

Three non-lactating cows (Deutsches Schwarzbuntes Rind) with large ruminal fistulas were fed coarsely structured food. Within a trial period of 21 weeks infusion periods lasting 3 weeks alternated with equally long control periods (K). During the 3 infusion periods, 8.4 mMol of propionic acid (P), 14.8 mMol of acetic acid (E) and 4,5 mMol of butyric acid (B) per kg liveweight per day were administered through the fistula, the total quantity being 19 litres of solution. In the periods K1...4 the ruminal fluid contained an average of 68 Mol% E, 19 Mol% P, 13 Mol% B (maximum of 10.25 mMol free fatty acids (FFS) per 100 ml, minimum pH 6.4). In the course of the 10 hrs of infusion the Mol percentages of the particular acids infused increased to 27% P (maximum of 11.14 mMol FFS per 100 ml, minimum pH 6.4) or 79% E (maximum of 12,99 mMol FFS per 100 ml, minimum pH 6.0 (5.5)) or 25% B (maximum of 10.34 mMol FFS per 100 ml, minimum pH 6.0 (5.5)). Infusions of E and B had the most pronounced effect on the ruminal mucosa compared with the K periods. All fatty acids increased the process of keratinization and decreased the size of cell nuclei in the stratum basale. As specific effect, P infusions produced a thickening of the lamina propria; B infusions caused a thickening of the stratum germinativum (proliferative effect) while e infusions led to a drastically reduced thickness of villi (antiproliferative effect) due to reductions in the stratum germinativum and the lamina propria. According to the morphological situation high specific mucosal function is suggested during the B-period. The mucosa appeared quite normal during all periods investigated, with the exception of the E period, where hyperkeratosis, atrophy and necrosis were observed in 34% of the sample. Changes in the state of the mucosa appeared as early as 1 week after the beginning of the respective trial periods. Keratin consolidation was the primary cause for chemically induced keratosis. The development of hyperkeratosis seemed to be favoured if low pH values occurred in the rumen in combination with small amounts of metabolites inducing proliferation, both representing synergistic factors.

Acetates↗
PubMed1976

Inactivation of Clostridium botulinum toxin by ruminal microbes from cattle and sheep.

Toxin from Clostridium botulinum type C was rapidly inactivated during incubation in vitro with ruminal contents from either a cow or a sheep. Fractions of ruminal contents from which cells had been removed by high-speed centrifugation did not inactivate toxin. Inactivation was associated with fractions containing bacteria, whereas fractions containing protozoa and relatively few bacteria were much less active. This activity may help explain the relatively greater tolerance by ruminants to oral doses of botulinum toxin than to toxin administered by other routes. The results are also pertinent to assays for botulinum toxin from gastrointestinal samples obtained postmortem.

Animals↗
PubMed1979

Histochemical localization of adenosine triphosphatase activity in bovine ruminal epithelium.

A fine-structural histochemical technique was used to localize magnesium-dependent adenosine triphosphatase (Mg-ATPase) activity in ruminal mucosa. Precipitate appeared on the cytoplasmic surface of the plasmalemma in cells of the upper stratum spinosum, the stratum granulosum, and the deepest layer of the stratum corneum. This ATPase activity was sensitive to glutaraldehyde fixation and possibly to ouabain, but was unaffected by sodium and potassium. The preponderance of Mg-ATPase activity in bovine ruminal epithelium may make it impossible to detect sodium-potassium-activated adenosine triphosphatase ((Na + K)-ATPase) activity histochemically. A Mg-ATPase activity also occurred in mitochondria of the stratum spinosum and stratum granulosum. None of the ruminal sections hydrolyzed adenosine diphosphate, inosine triphosphate, or beta-glycerophosphate when these compounds were used as substitute substrates for adenosine triphosphate. When adenosine-5'-monophosphate was the available substrate, a reaction product appeared in the same layers as Mg-ATPase activity, but the reaction product was confined to the intercellular space.

Adenosine Triphosphatases↗
PubMed1979

Blood and ruminal fluid profiles in carbohydrate-foundered cattle.

The relationships of acetylhistamine and histamine to the clinical signs of carbohydrate-induced acidosis were investigated in beef steers. Blood pH and plasma L-lactic acid decreased and serum sodium, serum potassium, ruminal fluid L-lactic acid, ruminal fluid histamine, and ruminal fluid and blood acetylhistamine increased in carbohydrate-engorged steers as compared with the changes in the steers while feeding on pasture (forage-fed steers). Twelve to 14 hours after the steers had become engorged, clinical signs of laminitis ("feedlot founder") were observed in three of six steers. These signs appeared 4 to 6 hours after blood acetylhistamine attained maximal concentration (2.9997 +/- 1.7054 microgram of histamine base/ml of blood) and blood pH decreased to 7.260 +/- 0.026 at 8 hours after engorgement. Blood histamine value reached 0.1298 +/- 0.1095 microgram of histamine base/ml 4 hours after engorgement (8 to 10 hours before the appearance of clinical illness), but had reached maximal concentration 32 hours after engorgement (0.3300 +/- 0.028 microgram of histamine base/ml of blood).

Animals↗
PubMed1977

Effect of ruminal lactic acid-utilizing bacteria on adaptation of cattle to high-energy rations.

Heifers, unadapted to a concentrate ration, were intraruminally inoculated (1 dose) with cultures of ruminal lactic acid-utilizing bacteria or with ruminal fluid from a steer adapted to a concentrate ration. Inoculation with cultures (1 L) of Selenomonas ruminantium or Megasphaera elsdenii did not produce better average daily weight gains or feed efficiency of heifers fed a high-energy ration for 21 days, if these values were compared with the performance of noninoculated heifers. Average daily weight gain and feed efficiency of heifers inoculated with 1 L of Peptococcus asaccharolyticus culture or with 1 L of adapted ruminal fluid and fed a high-energy ration for 21 days were better if these values were compared with the performance of noninoculated heifers.

Animal Feed↗
PubMed1976

The site of magnesium absorption from the ruminant stomach.

1. A low-magnesium diet was fed to four sheep, each of which had been surgically prepared with a rumen fistula, a tube into the cranial one-third of the omasum, a tube to the cranial one-third of the abomasum and a re-entrant duodenal cannula. Mg, as gluconate or acate or acetate, was continuously infused for 12-14 d in turn into (1) the caudal duodenal cannula, (2) the abomasum, (3) the omasum, (4) the rumen. A continuous infusion of the chromium-ethylenediaminetetraacetic acid complex (CrEDTA) was maintained to the rumen. The abomasal effluent which flowed through the cranial duodenal cannula was continually sampled and the flow of Mg calculated from the concentrations of Mg and CrEDTA. Blood and rumen fluid samples were taken and urine and faeces collected during each period of Mg infusion. 2. The Mg infused to either the abomasum or omasum was completely recovered at the duodenum, indicating a lack of net absorption of Mg from these stomach compartments. In contrast, 13-7-18-7 mmol (36-61%) of the Mg infused to the rumen was not recovered at the duodenum which suggested that a substantial net absorption of the infused Mg occurred from the reticulo-rumen. Absorption of Mg caudal to the pylorus was not related to the site of Mg infusion and averaged 3-28 +/- 0-56 (SEM) mmol/d. 3. Compared with the intraruminal infusion, the post-ruminal infusion of Mg was associated with decreased plasma and rumen fluid Mg concentrations, decreased urinary Mg exretion, decreased Mg balance and increased faecal Mg excretion. 4. It is concluded that no significant absorption of Mg occurs from either the omasum or abomasum in sheep and that the reticulo-rumen is the principal site of Mg absorption before the pylorus. Absorption of Mg post-ruminally is insufficient to maintain normal Mg status in the animal.

Abomasum↗
PubMed1977

Evidence of a specific nidation site in ruminants.

The site of umbilical cord attachment in ruminants indicates the limited segment of the uterus where the blastocyst attachment occurs and could have potential significance for locating presumptive nidation sites. Measurements of the site of cord attachment were made on impala (Aepyceros melampus) and common duiker (Sylvicapra grimmia) at several stages of gestation. Both implant only in the right uterine horn although they ovulate from either ovary. Relative to uterine length, cord attachment in impala is somewhat closer to the cervix than it is in common duiker. As pregnancy advances in common duiker, the relative position of cord attachment becomes closer to the tubal end. This relationship was not seen in impala and may perhaps to be attributed inadequate data. Upon extrapolation of the data from common duiker, a presumptive attachment area is suggested for this species. This region is located at about 41% of the distance from the internal cervical os to the uterotubal junction. Similar cord attachment data could be used in any ruminant species to indicate the existence and location of a specific nidation site.

Animals↗
PubMed1976

[Determination of urea in the ruminal fluid of sheep].

Low values for urea were found in samples of ruminal fluid of sheep fed concentrate rations if urea determination was carried out by the urease method. The present paper describes a both simple and sensitive colorimetric method of analysis using diacetyldioxime. The method is suitable for determining urea in coloured solutions such as ruminal fluid or silage extracts.

Animals↗
PubMed1977

[Estimation of the net energy using volatile acids produced in the process of in-vitro digestion with ruminal fluid].

47 types of green feeds and roughages were subjected to an in-vitro fermentation with dilute ruminal fluid. The volatile fatty acids produced in this process were determined quantitatively in accordance with the method of digestibility estimation proposed by Tilley and Terry (1963). An average of 5 Mol FFS (FFS=volatile fatty acids) was found per kg of dried feed, a value is also reported in the literature. The ratios of acetate to propionate to n-butyrate to iso-butyrate to n-valerianate were 64.2 : 25.4 : 6.6 : 0.8 : 1.5 : 1.5. In this ratio, propionic acid predominated so that acetic acid and n-butyric acid were misrepresented compared with the data of in-vivo measurements made for the corresponding foodstuffs. Consequently, it is only within certain limits that values of FFS concentrations obtained in vitro may be used for estimating net energy data, disregardful of the fact that the FFS are the main source of metabolizable energy in ruminants. The reliability index for an estimation of Starch Equivalents and NEFr based on the above-mentioned method was found to be considerable lower (0.71 and 0.80) than that based on in-vitro digestibility measurements (0.86).

Animal Feed↗
PubMed1979

Effects of life span feeding of ruminant-derived human diets to rats.

A freeze-dried human diet, based on linoleic acid-enriched food stuffs derived from ruminants, was evaluated and compared with a similarly-prepared diet based on conventional ruminant-derived foodstuffs, using Porton rats in a whole-of-life study. A cereal-based stock diet was used for comparison. Serum biochemical and histopathological examinations were carried out at 0.25, 1.1 and 2.1 years of age and other rats were left until they died of natural causes. Although some diet-specific biochemical differences were noted, triglyceride and cholesterol levels showed changes which were more age-specific than diet-specific. Longevity did not seem to be influenced by quantity or quality of dietary fat. The most common cause of death was a bronchopneumonia at about 2 years of age. Dietary fat also did not affect incidence of tumors. The most common tumor was a pituitary adenoma which occurred most often in females. Only minor causes of death were specific to diet with waxy intra-cardial plaques occurring in less than 5% of rats fed both of the high-fat diets and severe systemic hypertension occurring in rats fed the low-fat stock diet at the same frequency. No deleterious changes were noted that were unique to the linoleic acid-enriched diet.

Animals↗