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Methane, both enteric and from manure management, is the most important greenhouse gas from ruminant livestock, and its mitigation can deliver substantial decreases in the carbon footprint of animal products and potentially contribute to climate change mitigation. Although choices may be limited, certain feeding-related practices can substantially decrease livestock enteric CH 4 emission. These practices can be generally classified into 2 categories: diet manipulation and feed additives. Within the first category, selection of forages and increasing forage digestibility are likely to decrease enteric CH 4 emission, but the size of the effect, relative to current forage practices in the United States dairy industry, is likely to be minimal to moderate. An opportunity also exists to decrease enteric CH 4 emissions by increasing dietary starch concentration, but interventions have to be weighed against potential decreases in milk fat yield and farm profitability. A similar conclusion can be made about dietary lipids and oilseeds, which are proven to decrease CH 4 emission but can also have a negative effect on rumen fermentation, feed intake, and milk production and composition. Sufficient and robust scientific evidence indicates that some feed additives, specifically the CH 4 inhibitor 3-nitrooxypropanol, can substantially reduce CH 4 emissions from dairy and beef cattle. However, the long-term effects and external factors affecting the efficacy of the inhibitor need to be further studied. The practicality of mass-application of other mitigation practices with proven short-term efficacy (i.e., macroalgae) is currently unknown. One area that needs more research is how nutritional mitigation practices (both diet manipulation and feed additives) interact with each other and whether there is synergism among feed additives with different mode of action. Further, effects of diet on manure composition and greenhouse gas emissions during storage (e.g., emission trade-offs) have not been adequately studied. Overall, if currently available mitigation practices prove to deliver consistent results and novel, potent, and safe strategies are discovered and are practical, nutrition alone can deliver up to 60% reduction in enteric CH 4 emissions from dairy farms in the United States. [ABSTRACT FROM AUTHOR]

In the US, beef cattle feedlots commonly use antibiotic feed additives, such as tylosin and virginiamycin, to prevent liver abscesses, which can cause significant economic losses and animal welfare concerns. However, growing public and regulatory pressure to curb the proliferation of antibiotic resistant bacteria has prompted a need to reduce or eliminate their use. As an alternative, our group is working on a bacteriophage-based feed additive that targets Fusobacterium necrophorum, the primary cause of bovine liver abscesses, with the aim of reducing or eliminating the dependence on antibiotic feed additives. Using a combination of phage isolation techniques, we identified and characterized fifteen new F. necrophorum phages belonging to six genetically distinct groups. These phages exhibited a broad intraspecific host range and could infect various contemporary F. necrophorum strains isolated from different regions of the United States. All the phages were temperate, with dsDNA genomes ranging from around 36 kbp to 114 kbp. Almost all contemporary F. necrophorum isolates were found to have one or more active prophages upon bacterial genome sequencing and prophage induction. In vitro evolution resulted in the recovery of a potential virulent mutant, fBB37, which inhibited the growth of the high leukotoxin-producing F. necrophorum 8L1 strain for over 40 hours in vitro. Phage cocktails proved effective for up to 60 hours. After minimal optimization, most phages demonstrated high productivity (> 109 PFU/mL) and little yield variation during scale-up, highlighting their commercial potential. Unexpectedly, we discovered a previously unrecognized Fusobacterium species, Fusobacterium varium, is widely prevalent and frequently the most abundant member of the genus in cattle rumen. Previous studies on liver abscess control in cattle have almost exclusively focused on F. necrophorum, which may explain the lack of effectiveness observed. To elucidate the ecological role and potential pathogenicity of ruminal F. varium, we conducted genome sequencing and found these bovine strains to have multiple virulence factors and high similarity to human clinical isolates. However, phages with the ability to infect F. varium were plentiful in rumen fluid, with several demonstrating purely lytic activity. To assess the safety and in vivo dynamics of F. necrophorum and F. varium phage cocktails, a smallscale animal trial was recently conducted with ten cannulated cattle. [ABSTRACT FROM AUTHOR]

Poultry act as a major reservoir host for Salmonella and Campylobacter spp., the 2 leading causes of foodborne illnesses globally and in the United States. Preharvest stage interventions to reduce foodborne pathogen carriage in poultry are increasingly informed by consumer preference for antibiotic-free poultry production. The in-feed inclusion of plant-derived antimicrobial compounds is a promising antibiotic alternative strategy to reduce foodborne pathogen load in the broiler chicken gut. Yet, the fate of these phytochemicals through the broiler chicken gastrointestinal tract is unknown. Likewise, while in-feed phytochemicals have been widely demonstrated in challenge models to reduce foodborne pathogen carriage, little is known regarding efficacy to curb natural routes of infection. As such, the aim of the present study was 2-fold. We sought to determine the concentrations of 2 phytochemicals, trans-cinnamaldehyde and caprylic acid, in each region of the chicken gastrointestinal tract following their in-feed inclusion over a 6-wk production period. In addition, we investigated how the in-feed provision of these phytochemicals may protect against environmental acquisition of Campylobacter jejuni and Salmonella spp. Trans-cinnamaldehyde and caprylic acid were detected in crop, gizzard, duodenal, jejunal, and ileal contents. Crop and gizzard concentrations were not significantly (P > 0.05) different. A significant (P < 0.05) decrease in phytochemical concentration was observed in intestinal regions compared to crop and gizzard. Trans-cinnamaldehyde was consistently identified in cecal and colon contents, while caprylic acid was not detectable in these regions. Trans-cinnamaldehyde and caprylic acid were found to reduce (P < 0.05) Salmonella load. Together, our data establish that the in-feed addition of trans-cinnamaldehyde and caprylic acid, 2 phytochemicals that have previously been shown to exert antimicrobial activity against poultry-associated foodborne pathogens, results in detectable concentrations in the broiler chicken gastrointestinal tract. By providing researchers with a gastrointestinal region-by-region map of phytochemical concentrations, the present study is expected to inform the choice of in-feed phytochemicals targeting foodborne pathogen carriage in the broiler chicken gastrointestinal tract. [ABSTRACT FROM AUTHOR]

Objective—To assess associations between herd management practices and herd-level rates of bovine respiratory disease complex (BRDC) in preweaned beef calves in US cow-calf operations. Design—Cross-sectional survey. Sample—443 herds weighted to represent the US cow-calf population. Procedures—Producers from 24 states were selected to participate in a 2-phase survey; 443 producers completed both survey phases and had calves born a ive during the study period. Data from those respondents underwent multivariable negative binomial regression analyses. Results—Bred heifer importation was associated with lower BRDC rates (incidence rate ratio [IRR], 0.40; confidence interval [Cl], 0.19 to 0.82), whereas wsaned steer importation was associated with higher BRDC rates [IRR, 2.62; Cl, 1.15 to 5 97). Compared with single-breed herds, operations with calves of 2-breed crosses (IRR, 2.36; Cl, 1.30 to 4.29) or 3-breed crosses (IRA, 4.00; Cl, 1.93 to 8.31) or composite-herd calves (IRA, 2.27; Cl, 1.00 to 5.16) had higher BRDC rates. Operations classified as supplemental sources of income had lower BRDC rates (IRR, 0.48; Cl, 0.26 to 0.87) than did operations classified as primary sources of income. Reported feed supplementation with antimicrobiEls was positively associated with BRDC rates (IRR, 3.46; Cl, 1.39 to 8.60). The reported number of visits by outsiders in an average month also was significantly associated with herd-level BRDC rates, but the magnitude and direction of the effects varied. Conclusions and Clinical Relevance—Management practices associated with preweaning BRDC rates may be potential indicators or predictors of preweaning BRDC rates in cow-calf production systems. [ABSTRACT FROM AUTHOR]

Consumer demand for nonconventional poultry products continues to increase in the United States. In pasture flock and organic poultry production, probiotics and prebiotic feed additives have potential advantages because they are thought to promote intestinal health and may offer a replacement for current intervention strategies that are not considered acceptable for these production systems. Prebiotics have been demonstrated to produce effects on the gastrointestinal tract including modulation of microflora by promoting selective increases in beneficial bacteria concomitant with decreases in undesirable bacteria. In-depth assessment of microbial community changes during host growth and development as well as the establishment of beneficial microbial species by adding biologicals such as probiotics and prebiotics is important to achieve predictable and consistent improvements in chicken health and productivity. To analyze microflora shifts and metabolites produced by bacteria in the gut as well as host responses to biological additives, sophisticated molecular techniques are now available and are becoming more widely used. Polymerase chain reaction assays, denaturing gradient gel electrophoresis, and temperature gradient gel electrophoresis offer approaches for detecting microbial shifts in the gut. Likewise, the employment of microarrays and molecular analysis of gut tissues can reveal insight into gut physiological and responses to dietary and other changes. Recent application of 16S rDNA sequencing and analysis utilizing basic local alignment search tool (BLAST) and FASTA databases on poultry gut samples have the potential to provide a much more in-depth assessment of the gut microbiome. Utilizing ultra pressure liquid chro-matography-mass spectroscopy profiling, metabolomic assessment of gut contents will also allow for parallel comparisons of changes in the gut contents with microbiome and physiological responses. Combining all these technologies will provide a plenary understanding of poultry gut health in alternative production systems. [ABSTRACT FROM AUTHOR]

It is estimated that enteric methane (CH 4 ) contributes about 70% of all livestock greenhouse gas (GHG) emissions. Several studies indicated that feed additives such as 3-nitrooxypropanol (3-NOP) and nitrate have great potential to reduce enteric emissions. The objective of this study was to determine the net effects of 3-NOP and nitrate on farmgate milk carbon footprint across various regions of the United States and to determine the variability of carbon footprint. A cradle-to-farmgate life cycle assessment was performed to determine regional and national carbon footprint to produce 1 kg of fat- and protein-corrected milk (FPCM). Records from 1,355 farms across 37 states included information on herd structure, milk production and composition, cattle diets, manure management, and farm energy. Enteric CH 4 , manure CH 4 , and nitrous oxide were calculated with either the widely used Intergovernmental Panel on Climate Change Tier 2 or region-specific equations available in the literature. Emissions were allocated between milk and meat using a biophysical allocation method. Impacts of nitrate and 3-NOP on baseline regional and national carbon footprint were accounted for using equations adjusted for dry matter intake and neutral detergent fiber. Uncertainty analysis of carbon footprint was performed using Monte Carlo simulations to capture variability due to inputs data. Overall, the milk carbon footprint for the baseline, nitrate, and 3-NOP scenarios were 1.14, 1.09 (4.8% reduction), and 1.01 (12% reduction) kg of CO 2 -equivalents (CO 2 -eq)/kg of FPCM across US regions. The greatest carbon footprint for the baseline scenario was in the Southeast (1.26 kg of CO 2 -eq/kg of FPCM) and lowest for the West region (1.02 kg of CO 2 -eq/kg of FPCM). Enteric CH 4 reductions were 12.4 and 31.0% for the nitrate and 3-NOP scenarios, respectively. The uncertainty analysis showed that carbon footprint values ranged widely (0.88-1.52 and 0.56-1.84 kg of CO 2 -eq/kg of FPCM within 1 and 2 standard deviations, respectively), suggesting the importance of site-specific estimates of carbon footprint. Considering that 101 billion kilograms of milk was produced by the US dairy industry in 2020, the potential net reductions of GHG from the baseline 117 billion kilograms of CO 2 -eq were 5.6 and 13.9 billion kilograms of CO 2 -eq for the nitrate and 3-NOP scenarios, respectively., (© 2022, The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

Reports that excess dietary lysine does not cause lysine-arginine antagonism in adult cats according to researchers from Davis, California. Prevalence of feline herpesvirus type 1 (FHV-1) on different cat breeds; Development of severe upper respiratory tract and occular infection in kittens infected with FHV-1; Establishment of a lifelong neural latency with periodic reactivation of the virus; Propositions regarding the mechanisms of action of FHV-1.

The use of antimicrobial feed additives (AFAs) in animal rations has come under review recently in Europe and the US. A recent evaluation of the economic impact of a ban on AFAs on the US pork industry suggests that on average changes in productivity and fixed costs would result in increased costs and prices as producers adjust to the new regulation. These effects will vary among producers. Producers with high quality management and modern buildings would experience smaller costs from a ban. Also, new marketing technologies that support traceback of product to producers and additional compensation for pork produced without AFAs allow producers to capture price premiums to compensate for higher costs resulting from reduced use of AFAs. [Copyright &y& Elsevier]

Liver abscesses occur in finishing cattle fed highgrain, low-roughage diets. Cattle with abscessed livers do not show any clinical signs and are detected only at slaughter. Liver abscesses, which account for 67% of all liver abnormalities in cattle slaughtered in the United States, are of major economic concern to the beef industry. Fusobacterium necrophorum, Trueperella pyogenes, and Salmonella enterica, particularly the serotype Lubbock, are the main etiologic agents. Currently, the control of liver abscesses is based on in-feed use of antibiotics. The emergence and dissemination of antimicrobial resistance to antibiotics use in animals is a public health concern. Plant-based phenolic compounds, called phytophenols, are known to have antimicrobial properties. Our objectives were to evaluate antimicrobial activities of phytophenols on the liver abscess bacterial pathogens. Phytophenols extracted from rosemary, green tea, grapeseed, organic goji berry, and green coffee were selected for testing. The phytophenols were extracted using 75% aqueous acetone and total phenolic content was determined by a spectrophotometric analysis. Bacteria were cultured in Mueller-Hinton broth (S. Lubbock and T. pyogenes) or anaerobic brain-heart infusion broth (F. necrophorum with and without phytophenols, at 6, 12, 24, and 48 hours and bacterial concentrations were determined. If phytophenol was inhibitory, a microbroth dilution method was used to quantify the inhibition. Phytophenols from green tea, grape seed, and rosemary inhibited T. pyogenes. Further studies are ongoing to investigate different concentrations of phenolic compounds on the pathogens. Phytophenols that inhibit the pathogens may have the potential to be used as feed additives to prevent liver abscesses. [ABSTRACT FROM AUTHOR]

The article discusses the potential of roxarsone, a chicken feed additive, to contaminate groundwater and food crops in the U.S. Roxarsone, an organic arsenic compound, is commonly applied by most broiler-chicken farms as a feed additive to prevent disease and stimulate growth. However, research revealed that the compound is not absorbed by the tissue but is excreted in poultry manure which is usually applied as a fertilizer on the surrounding farmlands. The transformation of roxarsone into more toxic inorganic arsenic is influenced by Clostridium species through anaerobic respiration mechanism. The use of poultry manure, which contains toxic inorganic arsenic, in agriculture may affect drinking water and food crops.