Dairy Research Bulletin: Selected Articles from September 2023

Environmental Management and Sustainability

Influence of key factors on ammonia and nitrous oxide emission factors for excreta deposited by livestock and land-applied manure. van der Weerden TJ, Noble AN, Beltran I, Hutchings NJ, Thorman RE, de Klein CAM, Amon B. Sci Total Environ. 2023 Sep 1;889:164066.

  • Ammonia (NH3) and nitrous oxide (N2O) emissions from livestock manure management have a significant impact on air quality and climate change. There is an increasing urgency to improve our understanding of drivers influencing these emissions.
  • Therefore, researchers analyzed the DATAMAN (“DATAbase for MANaging greenhouse gas and ammonia emissions factors”) database to identify key factors influencing (i) NH3emission factors (EFs) for cattle and swine manure applied to land and (ii) N2O EFs for cattle and swine manure applied to land, and (iii) cattle urine, dung and sheep urine deposited during grazing.
  • Slurry dry matter (DM) content, total ammoniacal nitrogen (TAN) concentration and method of application were significant drivers of NH3EFs from cattle and swine slurry. Mixed effect models explained 14-59 % of the variance in NH3 Apart from the method of application, the significant influence of manure DM, manure TAN concentration or pH on NH3 EFs suggests mitigation strategies should focus on these.
  • Identifying key factors influencing N2O EFs from manures and livestock grazing was more challenging, likely because of the complexities associated with microbial processes and soil physical properties impacting N2O production and emissions.
  • Generally, significant factors were soil-related e.g. soil water content, pH, clay content, suggesting mitigations may need to consider the conditions of the receiving environment for manure spreading and grazing deposition. Total variability explained by terms in mixed effect model was on average 66 %, with the random effect ‘experiment identification number’ explaining, on average, 41 % of the total variability in the models.
  • This analysis has helped to improve our understanding of key factors of NH3and N2O EFs for inclusion within models. With more studies over time, insights into the underlying processes influencing emissions will be further improved.

Comparison of the use of life cycle assessment and ecological footprint methods for evaluating environmental performances in dairy production. Biagetti E, Gislon G, Martella A, Zucali M, Bava L, Franco S, Sandrucci A. Sci Total Environ. 2023 Sep 12;905:166845.

  • One popular methodology for assessing the environmental impact of livestock sector is Life Cycle Assessment (LCA), that quantifies the environmental impact of a product. Ecological Footprint (EF) performs an environmental sustainability assessment, by comparing the demand for natural capital by an economic activity with the offer of such capital within a certain territory.
  • The aim of the study was the comparison between LCA and EF in assessing the environmental performances of milk production, assuming as case study three cattle farms with increasing levels of production intensity.
  • Different metrics and functional units (FU) (i.e., fat and protein corrected milk, FPCM and hectare) were adopted for LCA analysis, considering some of the major impact categories. For greenhouse gases emissions, the Global Warming Potential (GWP) and the Global Temperature Potential (GTP) were considered. Both metrics were calculated assuming or not the distinction between biogenic and fossil methane.
  • Adopting GWP as a metric, the results per kg of FPCM provided by the LCA highlighted a different trade off compared to the EF method: the farm with the highest productive intensity produced the least impactful milk in terms of GWP but had the most negative Ecological Balance (EB). The same occurred for the other impact categories.
  • When GTP was adopted, or the hectare was considered as FU, the least intensive farm, characterized by greater feed self-sufficiency, became the one that produced the least impactful milk and had the least negative EB.
  • The study highlighted the scientific significance of the integration between the two approaches for creating a comprehensive representation of the effects of human activities on the environment.
  • The LCA method evaluates impacts intensity referred to a specific functional unit and its results are strongly influenced by productive efficiency; the EF method evaluates environmental sustainability of productions in relation to the territory that supports them.

A meta-analysis of methane mitigation potential of feed additives evaluated in vitro. Martins LF, Cueva SF, Lage CFA, Ramin M, Silvestre T, Tricarico J, Hristov AN. J Dairy Sci. 2023 Sep 12:S0022-0302(23)00649-5.

  • Decreasing enteric methane (CH4) emission to improve animal efficiency has been a research focus since early studies reported up to 12% of gross energy intake losses by CH4 production. More recently, the rising interest of governments and the society in climate change has directed researchers to better understand rumen methanogenesis and develop strategies to decrease greenhouse gas (GHG) emissions by livestock, especially enteric CH4 in ruminants. The effectiveness of mitigation strategies, however, is inconsistent and data are, in some cases, controversial.
  • Therefore, a systematic literature review of in vitro studies was performed to identify (CH4 mitigation interventions with a potential to reduce CH4emission in vivo.
  • Data from 277 peer-reviewed studies published between 1979 and 2018 were reviewed. Individual CH4mitigation interventions were classified into 14 categories of feed additives based on their type, chemical composition, and mode of action.
  • Response variables evaluated were absolute CH4emission (number of treatment means comparisons = 1,325); total volatile fatty acids (VFA; n = 1,007), acetate (n = 783), propionate (n = 792), and butyrate (n = 776) concentrations; acetate to propionate ratio (A:P; n = 675); digestibility of dry matter (DM; n = 489), organic matter (OM; n = 277), and neutral detergent fiber (NDF; n = 177).
  • In vitro CH4production was decreased by antibodies (-38.9%), chemical inhibitors (-29.2%), electron sinks (-18.9%), essential oils (-18.2%), plant extracts (-14.5%), plants inclusion (-11.7%), saponins (-14.8%), and tannins (-14.5%). Overall effects of direct fed microbials, enzymes, macroalgae, and organic acids supplementation did not affect CH4 production in the current meta-analysis.
  • When considering the effects of individual mitigation interventions containing a minimum number of 4 degrees of freedom within feed additives categories, Enterococcus spp. (i.e., direct fed microbial), nitrophenol (i.e., electron sink), and Leucaena spp. (i.e., tannins) decreased CH4production by 20.3, 27.1, and 23.5%, respectively, without extensively, or only slightly, affecting ruminal fermentation and digestibility of nutrients.
  • It should be noted, however, that although the total number of publications (n = 277) and treatment means comparisons (n = 1,325 for CH4production) in the current analysis were high, data for most mitigation interventions were obtained from less than 5 observations (e.g., maximum number of observations was 4, 7, and 22 for nitrophenol, Enterococcus spp., and Leucaena spp., respectively), because of limited data available in the literature. These should be further evaluated in vitro and in vivo to determine their true potential to decrease enteric CH4 production, yield, and intensity.
  • Some mitigation interventions (e.g., magnesium, Heracleum spp., nitroglycerin, β-cyclodextrin, Leptospermum pattersoni, Fructulus Ligustri, Salix caprea, and Sesbania grandiflora) decreased in vitro CH4production by over 50% but did not have enough observations in the database. These should be more extensively investigated in vitro, and the dose effect must be considered before adoption of mitigation interventions in vivo.

Effects of monensin supplementation on rumen fermentation, methane emissions, nitrogen balance, and metabolic responses of dairy cows: a systematic review and dose-response meta-analysis. Ahvanooei MRR, Norouzian MA, Piray AH, Vahmani P, Ghaffari MH. J Dairy Sci. 2023 Sep 12:S0022-0302(23)00650-1

  • Monensin, an ionophore antibiotic, affects the ion balance of gastrointestinal microorganisms by altering their membranes, leading to the promotion of certain bacterial species and resistance to antimicrobial agents. Monensin is widely used to improve feed efficiency by enhancing the efficiency of rumen fermentation. In addition, it can reduce methane emissions in ruminants leading to a reduced carbon footprint of ruminant-derived foods such as beef and dairy products.
  • The purpose of this report was to investigate the effects of supplemental monensin administration on the metabolic responses of dairy cows, a systematic review and dose-response meta-analysis was conducted.
  • After a 2-stage screening process, 51 articles with a total of 60 experiments were selected for meta-analysis based on criteria such as the study implementation date between 2001 and 2022, the presence of a control group that did not receive monensin supplementation, the reporting of at least one outcome variable, and the presentation of means and corresponding errors.
  • The results showed that the administration of monensin at a dosage of 19-26 ppm was inversely related to methane emissions and that the administration of monensin at a dosage of 18-50 ppm resulted in a significant decrease in dry matter intake (DMI).
  • Administration of monensin at doses of 13-28 and 15-24 ppm also resulted in a significant decrease in ruminal acetate proportion and an increase in propionate proportion, respectively, with no effects on ruminal butyrate, NH3, or pH levels.
  • There were no effects on blood parameters or nitrogen retention, but a significant negative correlation was observed between monensin supplementation and fecal nitrogen excretion.
  • Based on the analysis of all variables evaluated, the optimal dose range of monensin was estimated to be 19-24 ppm.

The Resilient Dairy Genome Project – a general overview of methods and objectives related to feed efficiency and methane emissions. van Staaveren N, Oliveira HR, Houlahan K, Baes CF, et al . J Dairy Sci. 2023 Sep 8:S0022-0302(23)00617-3.

  • The Resilient Dairy Genome Project (RDGP) is an international large-scale applied research project that aims to generate genomic tools to breed more resilient dairy cows. In this context, improving feed efficiency and reducing greenhouse gases from dairy is a high priority. The inclusion of traits related to feed efficiency (e.g., dry matter intake [DMI]) or greenhouse gases (e.g., methane emissions [CH4]) relies on available genotypes as well as high quality phenotypes.
  • Currently, 7 countries, i.e., Australia [AUS], Canada [CAN], Denmark [DNK], Germany [DEU], Spain [ESP], Switzerland [CHE], and United States of America [USA] contribute with genotypes and phenotypes including DMI and CH4. However, combining data is challenging due to differences in recording protocols, measurement technology, genotyping, and animal management across sources.
  • In this study, we provide an overview of how the RDGP partners address these issues to advance international collaboration to generate genomic tools for resilient dairy. Specifically, we describe the current state of the RDGP database, data collection protocols in each country, and the strategies used for managing the shared data.
  • As of February 2022, the database contains 1,289,593 DMI records from 12,687 cows and 17,403 CH4records from 3,093 cows and continues to grow as countries upload new data over the coming years.
  • No strong genomic differentiation between the populations was identified in this study, which may be beneficial for eventual across-country genomic predictions. Moreover, our results reinforce the need to account for the heterogeneity in the DMI and CH4phenotypes in genomic analysis.

In which US counties are anaerobic dairy digesters being implemented? O’Hara JK, Xiarchos IM. JDS Commun. 2023 Aug 12;4(5):349-353.

  • The United States is seeking to reduce greenhouse gas emission reductions from agriculture to comply with the Paris Agreement and seeking to cut CH4emissions specifically as part of the Global Methane Pledge. There has been limited research on the recent increase in US anaerobic dairy digesters.
  • In this study, researchers use panel data to estimate a double hurdle model that predicts both the probability that a county has a dairy digester and the number of digesters in counties that have them.
  • Dairy farms and retail electricity prices affect dairy digesters, although the parameter estimates are inelastic. Biogas-producing landfills, which reflect policies and infrastructure that enable renewable energy, also affect digesters. The findings on the conditions that are conducive to dairy digesters will help policymakers consider options for reducing manure methane emissions.
  • While past studies have focused on the profitability of installing a digester on one farm, regional-level manure management studies are needed as digesters increasingly aggregate manure or biogas from multiple farms and require pipeline accessibility for CNG/RNG production. Herein, researchers undertake one of the first studies to explore county-level characteristics that influence the installation of anaerobic digesters on US dairy farms.
  • To summarize, the researchers found that increases in smaller dairy farms, larger dairy farms, and electricity prices have a statistically significant effect on dairy digesters. Each of these effects are inelastic, with electricity prices exhibiting the greatest elasticity among the 3 variables. Food establishments have a negative effect on the number of digesters, while RNG landfills have a positive influence on the number of digesters. The pipeline density index coefficients were statistically insignificant.

Modeling ammonia emissions from manure in conventional, organic, and grazing dairy systems and practices to mitigate emissions. Aguirre-Villegas HA, Besson C, Larson RA. J Dairy Sci. 2023 Sep 8:S0022-0302(23)00636-7.

  • Nearly 60% of all ammonia (NH3) emissions are from livestock manure. Understanding the sources and magnitude of NH3emissions from manure systems is critical to implement mitigation strategies.
  • This study models 13 archetypical conventional (5 farms), organic (5 farms), and grazing (3 farms) dairy farms to estimate NH3emissions from manure at the barn, storage, and after land application.
  • Mitigation practices related to management of the herd, crop production, and manure are subsequently modeled to quantify the change in NH3emissions from manure by comparing archetypical with these alternative practices. A mass balance of nutrients is also conducted.
  • Emissions per ton of excreted manure for the manure system (barn, storage, and land application) range from 3.0 to 4.4 g NH3for conventional farms, 3.5-4.4 g NH3 for organic farms, and 3.4-3.9 g NH3 for grazing farms.
  • For all farm types, storage and land application are the main sources of NH3emissions from manure. In general, solid manures have higher emission intensities due to higher pH during storage (pH = 7.4 for liquid, 7.8 for slurry, and 8.5 for solid manure) and lower infiltration rates after land application when compared with slurry and liquid manures.
  • The most effective management practices to reduce NH3emissions from manure systems are combining solid-liquid separation with manure injection (up to 49% reduction in NH3 emissions), followed by injection alone, and reducing of crude protein in the dairy ration, especially in organic and grazing farms that have grazing and forages as the main component of the dairy ration.
  • This study also shows that the intensity of NH3emissions from manure depends significantly on the functional unit and presents results per manure excreted, total solids in excreted manure, animal units, and fat and protein corrected milk.

Assessing the chronic toxicity of spreading organic amendments on agricultural soil: Tests on earthworms and plants. Roques O, Bayard R, Le Maux J, Patureau D, Nélieu S, Lamy I, Bedell JP. Ecotoxicol Environ Saf. 2023 Sep 22;265:115504.

  • Recycling organic wastes on agricultural soils improves the soil quality, but the environmental and health impact of these organic amendments closely depends on their origins, their bio-physicochemical characteristics and the considered organisms potentially affected.
  • The aim of this study was to assess the potential chronic ecotoxicity of spreading organic amendments on agricultural soils.
  • To do this, researchers characterized three different organic amendments: sewage sludge from an urban wastewater treatment plant, cow manure and liquid dairy manure. Their chronic ecotoxicity was studied through assays exposing earthworms of the species Eisenia fetida and two plants: Medicago sativa and Sinapis alba.
  • Of the three amendments, the sewage sludge presented the highest concentrations of micropollutants and a considerable fraction of available and biodegradable organic matter. The cow manure and liquid dairy manure had lower chemical contamination and similar characteristics with lower biodegradable fractions of their organic matter. No chronic phytotoxicity was evidenced: on the contrary, particularly with sewage sludge, the germination rate and aerial and root biomass of the two plants increased.
  • Considering earthworms, their biomass increased considerably during the reproduction assays in soil amended with sewage sludge, which contained the more bioavailable organic matter. Nonetheless, the earthworms presented an inhibition close to 78% of the production of juveniles when exposed to sewage sludge exceeding 20 g.kg-1DW (that means 2 times the agronomic dose). This reprotoxic effect was also observed in the presence of liquid dairy manure, but not with cow manure.
  • At the end of the assays, the glycogen and protein reserves in earthworms exposed to sewage sludge were inferior to that of control earthworms, respectively around 50% and 30%. For the earthworms exposed to liquid dairy manure, protein and lipid reserves increased. In the case of liquid dairy manure, this reprotoxic effect did not appear to be linked to the presence of micropollutants.
  • In conclusion, these results confirm the need to use several ecotoxicity assays at different biological levels and with different biological models to assess the ecotoxic impacts of soil amendments. Indeed, although certain organic wastes present a strong nutritional potential for both plants and earthworms, a not inconsiderable risk was apparent for the reproduction of the latter. An integrated ecotoxicity criterion that takes into account a weighted sum of the different results would guide the utilization of organic amendments while ensuring the good health of agricultural ecosystems.

Animal Health and Food Safety

How can better calf care be realized on dairy farms? A qualitative interview study of veterinarians and farmers. Wilson DJ, Saraceni J, Roche SM, Pempek JA, Habing G, Proudfoot KL, Renaud DL. J Dairy Sci. 2023 Sep 26:S0022-0302(23)00692-6.

  • Improving health and welfare outcomes for replacement and surplus dairy calves is important for the sustainability of the dairy industry. Dairy farmers and veterinarians hold expertise in calf management and have valuable perspectives on how to practically motivate improvements.
  • The objective of this study was to determine strategies that could improve the care calves receive on dairy farms from the perspective of dairy farmers and their herd veterinarians.
  • Two veterinary clinics specializing in dairy practice in British Columbia, Canada, and 21 of their client dairy farms participated in the project.
  • Interviews (n = 42) were transcribed and coded following inductive thematic analysis methodology. The themes identified included strategies for farmers, veterinarians and calf buyers, and contexts that influenced the dairy farmer’s internal motivation to provide good calf care.
  • Results indicated that farmers could optimize their calf management through fostering engagement of calf care personnel or enlisting technology. Veterinarians could provide support to farms by being actively involved in calf monitoring, assisting in developing operating protocols and setting goals, and especially using farm-specific data to guide their management recommendations. Calf buyers could communicate with and provide accountability to farmers and improve their purchasing strategies to encourage farms to raise more vigorous surplus calves.
  • Farmer personal values, social networks, and relationships to different dairy industry stakeholders influenced their concern about the standards of their calf care practices. These findings provide guidance on how dairy farmers could achieve or be prompted to achieve improvements in their calf care practices.

Heat stress-associated changes in the intestinal barrier, inflammatory signals, and microbiome communities in dairy calves. Yu Z, Cantet JM, Paz HA, Kaufman JD, Orellano MS, Ipharraguerre IR, Ríus AG. J Dairy Sci. 2023 Sep 18:S0022-0302(23)00683-5.

  • Recent studies indicate that heat stress pathophysiology is associated with intestinal barrier dysfunction, local and systemic inflammation, and gut dysbiosis. However, inconclusive results and a poor description of tissue specific changes must be addressed to identify potential intervention targets against heat stress illness in growing calves.
  • Therefore, the objective of this study was to evaluate components of the intestinal barrier, pro- and anti-inflammatory signals, and microbiota community composition in Holstein bull calves exposed to heat stress.
  • Animals (mean age = 12-week-old, mean body weight = 122 kg) penned individually in temperature-controlled rooms were assigned to 1) thermoneutral conditions (constant room temperature at 19.5°C) and restricted offer of feed (TNR, n = 8), or, 2) heat stress conditions (cycles of room temperatures ranging from 20 to 37.8°C) along with ad libitum offer of feed (HS, n = 8) for 7 days.
  • Upon treatment completion, sections of the jejunum, ileum, and colon were collected and snap-frozen immediately to evaluate gene and protein expression, cytokine concentrations, and myeloperoxidase (MPO) activity. Digesta aliquots of the ileum, colon, and rectum were collected to assess bacterial communities. Plasma was harvested on d 2, 5, and 7 to determine cytokine concentrations.
  • Overall, results showed a section-specific impact of HS on intestinal integrity. Jejunal mRNA expression of TJP1 was decreased by 70% in HS relative to TNR calves. In agreement, jejunal expression of heat shock transcription factor-1 protein (HSF-1), a known tight junction protein expression regulator, decreased by 48% in HS calves. Jejunal analyses showed that HS decreased concentrations of interleukin-1 α by 36.6% and tended to decrease the concentration of interleukin-17A.
  • Conversely, HS elicited a 3.5-fold increase in jejunal concentration of anti-inflammatory interleukin-36 receptor antagonist. Plasma analysis of pro-inflammatory cytokines showed that interleukin-6 decreased by 51% in HS relative to TNR calves. Heat stress alteration of the large intestine bacterial communities was characterized by increased genus Butyrivibrio_3, a known butyrate-producing organism, and changes in bacteria metabolism of energy and amino acids. A strong positive correlation between the rectal temperature and pro-inflammatory Eggerthii spp. was detected in HS calves.
  • In conclusion, this work indicates that heat stress impairs the intestinal barrier function of jejunum. The pro- and anti-inflammatory signal changes may be part of a broader response to restore intestinal homeostasis in jejunum. The changes in large intestine bacterial communities favoring butyrate-producing organisms e.g., Butyrivibrio spp. may be part of a successful response to maintain the integrity of the colonic mucosa of HS calves. The alteration of intestinal homeostasis should be the target for heat stress therapies to restore biological functions.

Antibacterial activity of medicinal plants on the management of mastitis in dairy cows: A systematic review. Kaseke TB, Chikwambi Z, Gomo C, Mashingaidze AB, Murungweni C. Vet Med Sci. 2023 Sep 19.

  • Mastitis is a disease of economic importance in dairy production systems. The common management regime for mastitis is the use of synthetic antibiotics, giving a new problem of antibiotic resistance. There is, therefore, a need to prospect for alternatives to conventional antibiotics from herbal plants.
  • This systematic review evaluates the use of plants as alternatives for the control of mastitis in dairy cattle, focusing on the effectiveness of studied plants and plant-based products and possible implications on the use of these products in livestock health.
  • Data were extracted from 45 studies with 112 plant species from plant species belonging to 42 different families. The specific keywords were ‘mastitis’, ‘dairy cows’ and ‘medicinal plants’.
  • The most cited plant species included Allium sativum L., Azadirachta indica and Eucalyptus globulus Labill with the latter further exploring its components. Microbial species causing mastitis mainly were Staphylococcus aureus and Escherichia coli. The extraction methods used included maceration approach using ethanol, methanol and water as solvents for phytochemicals and chromatographic techniques for essential oils. A few studies explored the mode of action, and toxicities of the herbal extracts as well as evaluating their efficacy in clinical trials using animal models.
  • In conclusion, plants with defined levels of phytochemicals were essential sources of antibacterials.

Biofilm formation by heat-resistant dairy bacteria: multispecies biofilm model under static and dynamic conditions.
Diarra C, Goetz C, Gagnon M, Roy D, Jean J. Appl Environ Microbiol. 2023 Sep 21:e0071323.

  • In the food industry, especially dairy, biofilms can be formed by heat-resistant spoilage and pathogenic bacteria from the farm. Such biofilms may persist throughout the processing chain and contaminate milk and dairy products continuously, increasing equipment cleaning, maintenance costs, and product recalls.
  • Most biofilms are multispecies, yet most studies focus on single-species models. A multispecies model of dairy biofilm was developed under static and dynamic conditions using heat-resistant Bacillus licheniformis, Pseudomonas aeruginosa, Clostridium tyrobutyricum, Enterococcus faecalis, Streptococcus thermophilus,and Rothia kristinae isolated from dairies.
  • tyrobutiricumand R. kristinae were weak producers of biofilm, whereas the other four were moderate to strong producers. Based on cross-streaking on agar, P. aeruginosa was found to inhibit B. licheniformis and E. faecalis. In multispecies biofilm formed on stainless steel in a CDC reactor fed microfiltered milk, the strong biofilm producers were dominant while the weak producers were barely detectable.
  • All biofilm matrices were dispersed easily by proteinase K treatment but were less sensitive to DNase or carbohydrases. Further studies are needed to deepen our understanding of multispecies biofilms and interactions within to develop improved preventive strategies to control the proliferation of spoilage and pathogenic bacteria in dairies and other food processing environments.
  • The study of biofilm composition and bacterial interactions therein will lead to more effective means of suppressing bacterial growth on food processing equipment and contamination of products with spoilage and pathogenic bacteria, which represent considerable economic loss.

Microbacterium represents an emerging microorganism of concern in microfiltered extended shelf-life milk products.
Lott TT, Martin NH, Dumpler J, Wiedmann M, Moraru CI. J Dairy Sci. 2023 Sep 5:S0022-0302(23)00615-X.

  • Growing interest in the manufacture of extended shelf-life (ESL) milk, which is typically achieved by a high temperature treatment called ultra-pasteurization (UP), is driven by distribution challenges, efforts to reduce food waste, and more.
  • Even though high temperature, short time (HTST) pasteurized milk has a substantially shorter shelf-life than UP milk, HTST milk is preferred in the United States because consumers tend to perceive UP milk as less desirable due to the “cooked” flavor associated with high-temperature processing.
  • While ESL beyond 21 days may be possible for HTST, the survival and outgrowth of psychrotolerant aerobic spore-forming bacteria can still be a limitation to extending shelf-life of HTST milk.
  • Microfiltration (MF) is effective for reducing vegetative microorganisms and spores in raw milk, but it is unclear what the effects of membrane pore size, storage temperature, and milk type (i.e., skim vs whole) are on the microbial shelf-life of milk processed by both MF and HTST pasteurization.
  • To investigate these factors, raw skim milk was MF using different pore sizes (0.8 μm or 1.2 μm), and then MF skim milk and standardized whole milk [MF skim with heat-treated (85°C for 20 s) cream] were HTST pasteurized at 75°C for 20 s. Subsequently, milk was stored at 3, 6.5, or 10°C and total bacteria counts were measured for up to 63 d.
  • Statistical analysis indicated that mean bacterial concentrations between storage temperatures were significantly different from each other, with mean maximum observed concentrations of 3.67, 5.33, and 8.08 log10cfu/mL for storage temperatures 3, 6.5, and 10°C, respectively. Additionally, a smaller difference in mean maximum bacterial concentrations throughout shelf-life was identified between pore sizes (<1 log cfu/mL), but no significant difference was attributed to milk type.
  • An unexpected outcome of this study was the identification of Microbacterium as a major contributor to the bacterial population in MF ESL milk. Microbacterium is a psychrotolerant, thermoduric gram-positive, non-spore forming rod with a small cell size (∼9 μm length and ∼0.3 μm width), which was able to permeate the membranes used in this study, survive HTST pasteurization, and then grow at refrigeration temperatures.
  • While spores continue to be a key concern for the manufacture of MF, ESL milk, our study demonstrates the importance of other psychrotolerant, thermoduric bacteria such as Microbacterium to these products. 

Human Health and Nutrition

Whole-Milk Dairy Foods: Biological Mechanisms Underlying Beneficial Effects on Risk Markers for Cardiometabolic Health. Torres-Gonzalez M, Rice Bradley BH. Adv Nutr. 2023 Sep 7:S2161-8313(23)01364-9.

  • Lifestyle modifications that include adherence to healthy dietary patterns that are low in saturated fat have been associated with reduced risk for cardiovascular disease, the leading cause of death globally.
  • Whole-milk dairy foods, including milk, cheese, and yogurt, are leading sources of saturated fat in the diet. Dietary guidelines around the world recommend the consumption of low-fat and fat-free dairy foods to obtain overall healthy dietary patterns that help meet nutrient recommendations while keeping within recommended calorie and saturated fat limitations.
  • A body of observational and clinical evidence indicates, however, that whole-milk dairy food consumption, despite saturated fat content, does not increase the risk for cardiovascular disease.
  • This review describes the proposed biological mechanisms underlying inverse associations between whole-milk dairy food consumption and risk markers for cardiometabolic health, such as altered lipid digestion, absorption, and metabolism; influence on the gut microflora; and regulation of oxidative stress and inflammatory responses.
  • The dairy food matrix, a term used to describe how the macronutrients and micronutrients and other bioactive components of dairy foods are differentially packaged and compartmentalized among fluid milk, cheese, and yogurt, may dictate how each affects cardiovascular risk.
  • Current evidence indicates consideration of dairy foods as complex food matrices, rather than delivery systems for isolated nutrients, such as saturated fatty acids, is warranted.

Cheese consumption and multiple health outcomes: an umbrella review and updated meta-analysis of prospective studies. Zhang M, Dong X, Huang Z, Li X, Zhao Y, Wang Y, Zhu H, Fang A, Giovannucci EL. Adv Nutr. 2023 Sep;14(5):1170-1186.

  • Cheese is generally a nutrient-dense and well-tolerated fermented dairy product consumed worldwide. However, the health effects of cheese consumption remain a matter of controversy.
  • On one hand, cheese is a rich source of high-quality protein (mainly casein), lipids, minerals (e.g., calcium, phosphorus, and magnesium), and vitamins (e.g., vitamin A, K2, B2, B12, and folate), and probiotics and bioactive molecules (e.g., bioactive peptides, lactoferrin, short-chain fatty acids, and milk fat globule membrane), which may provide various health benefits. On the other hand, cheese contains relatively high contents of saturated fat and salt, which are perceived as unfavorable dietary components for cardiovascular health.
  • This umbrella review aims to provide a systematic and comprehensive overview of current evidence from prospective studies on the diverse health effects of cheese consumption.
  • Researchers reanalyzed and updated previous meta-analyses and performed de novo meta-analyses with recently published prospective studies, where appropriate. They identified 54 eligible articles of meta-analyses/pooled analyses. After adding newly published original articles, they performed 35 updated meta-analyses and 4 de novo meta-analyses. Together with 8 previous meta-analyses, the researchers finally included 47 unique health outcomes.
  • Cheese consumption was inversely associated with all-cause mortality (highest compared with lowest category: RR = 0.95), cardiovascular mortality (RR = 0.93), incident cardiovascular disease (CVD) (RR = 0.92), coronary heart disease (CHD) (RR = 0.92), stroke (RR = 0.93), estrogen receptor-negative (ER-) breast cancer (RR = 0.89), type 2 diabetes (RR = 0.93), total fracture (RR = 0.90), and dementia (RR = 0.81).
  • According to the NutriGrade scoring system, moderate quality of evidence was observed for inverse associations of cheese consumption with all-cause and cardiovascular mortality, incident CVD, CHD, and stroke, and for null associations with cancer mortality, incident hypertension, and prostate cancer. These findings suggest that cheese consumption has neutral to moderate benefits for human health.

Effect of Isoenergetic Substitution of Cheese with Other Dairy Products on Blood Lipid Markers in the Fasted and Postprandial State: An Updated and Extended Systematic Review and Meta-analysis of Randomized Controlled Trials in Adults. Pradeilles R, Norris T, Sellem L, Markey O. Adv Nutr. 2023 Sep 15:S2161-8313(23)01376-5.

  • Consumption of fat as part of a cheese matrix may differentially affect blood lipid responses, when compared to other dairy foods.
  • This systematic review was conducted to compare the impact of consuming equal amounts of fat from cheese and other dairy products on blood lipid markers in the fasted and postprandial state.
  • Eligible human randomized controlled trials (RCTs) investigated the effect of isoenergetic substitution of hard or semi-hard cheese with other dairy products on blood lipid markers.
  • Of 1,491 identified citations, 10 articles were included. Pooled analyses of 7 RCTs showed a reduction in fasting total cholesterol, LDL-cholesterol and HDL-cholesterol concentrations following ≥ 14 days mean daily intake of 135 grams cheese relative to ∼52 grams/day butter.
  • The researchers found no evidence of a benefit from replacing cheese for ≥ 14 days with milk on fasting blood lipid markers (n = 2). Limited postprandial RCTs, described in narrative syntheses, suggested that cheese-rich meals may induce differential fed-state lipid responses compared to some other dairy matrix structures, but not butter (n ≤ 2).
  • In conclusion, these findings indicate that dairy fat consumed in the form of cheese has a differential effect on blood lipid responses relative to some other dairy food structures. However, owing to considerable heterogeneity and limited studies, further confirmation from RCTs is warranted.

Infant formula containing large, milk phospholipid-coated lipid droplets and dairy lipids affects cognitive performance at school age. Schipper L, Bartke N, Marintcheva-Petrova M, Schoen S, Vandenplas Y, Hokken-Koelega ACS. Front Nutr. 2023 Sep 5;10:1215199.

  • Breastfeeding has been positively associated with infant and child neurocognitive development and function. Contributing to this effect may be differences between human milk and infant formula in the milk lipid composition and milk fat globule structure.
  • The objective of this study wasto evaluate the effects of an infant formula mimicking human milk lipid composition and milk fat globule structure on childhood cognitive performance.
  • In a randomized, controlled trial, healthy term infants received until 4 months of age either a Standard infant formula (n= 108) or a Concept infant formula (n = 115) with large, milk phospholipid coated lipid droplets and containing dairy lipids. A breastfed reference group (n = 88) was included. Erythrocyte fatty acid composition was determined at 3 months of age. Neurocognitive function was assessed as exploratory follow-up outcome at 3, 4, and 5 years of age using the Flanker test, Dimensional Change Card Sort (DCCS) test and Picture Sequence Memory test from the National Institutes of Health Toolbox Cognition Battery.
  • The results showed that erythrocyte omega-6 to -3 long-chain polyunsaturated fatty acid ratio appeared to be lower in the Concept compared to the Standard group (P= 0.025). At age 5, only the Concept group was comparable to the Breastfed group in the highest reached levels on the Flanker test, and the DCCS computed score was higher in the Concept compared to the Standard group (P = 0.021).
  • Conclusion: In conclusion, these outcomes suggest that exposure to an infant formula mimicking human milk lipid composition and milk fat globule structure positively affects child neurocognitive development. Underlying mechanisms may include a different omega-3 fatty acid status during the first months of life.

Influence of dairy products consumption on oral cancer risk: A meta-analysis. Rodriguez-Archilla A, Gomez-Fernandez M. J Dent Res Dent Clin Dent Prospects. 2023 Winter;17(1):1-7.

  • The role of dairy product consumption on oral cancer risk is not yet fully clarified. Some studies have observed an inverse association between dairy consumption and oral cancer risk.
  • This study aimed to determine the influence of dairy product consumption (milk, cheese, yogurt, butter) on oral cancer risk.
  • A search for studies on dairy products and oral cancer was conducted in the following databases: PubMed (MEDLINE, Cochrane Library), Web of Science (WoS), and Scopus.
  • Twenty-one studies with 59,271 participants (8,300 oral cancer patients and 50,971 controls) were included in this meta-analysis. All dairy products significantly reduced oral cancer risk except butter (P=0.16). Milk intake reduced oral cancer risk by 27%; yogurt consumption by 25%, and cheese consumption by 21%.
  • In conclusion, regular consumption of dairy products reduces oral cancer risk between 21% and 27%.

Types of Dairy Foods and Risk of Fragility Fracture in the Prospective Nurses’ Health Study Cohort. Yuan M, Hu FB, Li Y, Cabral HJ, Das SK, Deeney JT, Zhou X, Paik JM, Moore LL. Am J Clin Nutr. 2023 Sep 28:S0002-9165(23)66162-3.

  • Fragility fractures present enormous health challenges for women. Dairy products provide many bone-beneficial nutrients such as calcium and vitamin D. Individual dairy foods may exert different association on bone health.
  • The purpose of the study wasto investigate the associations between total dairy, yogurt, milk, and cheese and fragility fracture risk among females in the prospective Nurses’ Health Study (NHS) in the US.
  • There were 103,003 females with mean age of 48 in the current analysis who were followed from 1980-2004. Proportional hazards models were used to estimate risk of first fracture (of the wrist, hip, or vertebrae) by intakes of dairy foods (total dairy, milk, yogurt, or cheese) obtained from food frequency questionnaire (FFQ). Fractures that were caused by high-trauma events were not included. We relied on self-reported data for wrist and hip fractures while for vertebral fractures, medical records were used to confirm cases.
  • The results showed a total of 5,495 incident fracture cases were documented during follow-up. After controlling for relevant confounding variables, consumption of ≥2 servings per day (servings/d) of total dairy (compared with <1 servings/d) was associated with lower fracture risk [hazard ratio (HR): 0.74]. More than 2 servings of milk per day (compared with <1 servings/d) were associated with a lower fracture risk (HR: 0.85).
  • Intakes of calcium, vitamin D, and protein from non-dairy sources did not modify the effects of total dairy or milk on fracture risk. There was no association between yogurt intake and fracture risk. Intake of cheese (≥1 servings/d compared with < 1 servings per week) was weakly associated with a lower fracture risk (HR: 0.89).
  • Overall, higher total dairy, milk and cheese intakes were associated with lower risks of fracture in females in NHS.

Innovation, Economics, and Dairy Alternatives

Milk Beverage Base with Lactose Removed with Ultrafiltration: Impact of Fat and Protein Concentration on Sensory and Physical Properties. Hernandez AJ, Truong T, Barbano DM, Drake MA. J Dairy Sci. 2023 Sep 8:S0022-0302(23)00632-X.

  • Milk and dairy products are among the most versatile foods on the market, ranging from indulgent to nutritional depending on the many ways they can be processed. A major issue that limits the consumption of dairy products is lactose intolerance.
  • The study’s objectives were to determine the impact of fat (skim to whole milk) and protein (3.4 to 10.5%) concentration on the sensory and physical properties of milk beverage base that had lactose and other low molecular components removed by ultrafiltration.
  • In experiment 1, a matrix of 16 treatments was produced to achieve 4 levels of lactose removal (0, 30,70, and 97%) at each of 4 fat levels (skim, 1%, 2% and whole milk). In experiment 2, a matrix of 12 treatments was produced to achieve 4 levels of lactose removal (0, 30, 70, and 97%) at each of 3 protein concentrations (3.4, 6.5, and 10.5% protein).
  • Physical and sensory properties of these products were determined. Removal of >95% of milk lactose by UF required a diafiltration volume of approximately 3 times the milk volume. Lactose and low molecular weight solute removal increased whiteness across the range from skim to whole milk while decreasing viscosity and making milk flavor more bland. In addition, lactose (and other low molecular weight solute) removal by UF decreased titratable acidity by more than 50% and increased milk pH at 20°C to > 7.0.
  • Future work on milk and milk-based beverages with lactose removed by UF needs to focus on interaction of the remaining milk solids with added flavorings, changing casein to whey protein ratio before removal of lactose by UF, and the impact of lactose and low molecular weight solute removal on heat stability, particularly for neutral-pH, shelf-stable milk-based beverages.

Review: Linking animal health measures in dairy cows to farm-level economic outcomes: a systematic literature mapping. Af Sandeberg A, Båge R, Nyman AK, Agenäs S, Hansson H. Animal. 2023;17(10):100971.

  • Farm animal health is an area of increasing interest to both the public and industry stakeholders. There is an ongoing debate on whether improving animal health, and thereby increasing welfare, is profitable or not. Improving animal health often requires investments in the farm or increases labor costs. As a result, the impact of animal health on farm economy is particularly interesting.
  • This study systematically maps and assesses the available evidence in the published scientific literature regarding the link between farms’ economic outcomes on dairy cow health, with the aim of identifying knowledge gaps in this field of research. In total, 59 peer-reviewed articles were included using a broad range of animal health variables and economic outcomes.
  • Researchers found a heterogeneous body of evidence in terms of both methods, animal health measures (AHMs) and economic outcome measures used. None of the included studies makes explicit causal claims between AHMs and economic outcomes.
  • The results suggest that common production diseases such as clinical mastitis and lameness, which are painful and affect cow health and welfare, are costly for farmers. The researchers also found a knowledge gap and lack of evidence on the impact of animal health interventions on farms’ economic outcomes, as well as the long-term effects of such interventions. Future research should aim to investigate the causal links between animal health and economic outcomes.

CDRF-Funded Research Geographical trends for automatic milking systems research in non-pasture-based dairy farms: A scoping review. Marques TC, Lage CFA, Bruno DR, Fausak ED, Endres MI, Ferreira FC, Lima FS. J Dairy Sci. 2023 Aug 23:S0022-0302(23)00496-4.

  • Automatic milking system (AMS) adoption in the United States is trending upward, with issues such as lower availability and increased cost of labor being factors frequently listed as motives for AMS implementation. In addition, more interest in precision dairy farming by the new generation of farmers may also help increase AMS adoption.
  • The objective of this scoping review was to characterize the nature of the literature investigating non-pasture-based AMS and the opportunities and challenges for future research.
  • The eligibility criteria included studies published in or after the year 2000, with full text in English, of at least 500 words, examining various outcomes related to AMS in non-pasture-based dairy farms.
  • The review focused on studies with objectives, characteristics, farms, and AMS information. A total of 4,292 titles and abstracts were screened, and 536 studies were finally included. Most of the studies were conducted in Europe (73.5%), among commercial herds (67.9%), comprising Holstein cows (57.7%), using Lely and DeLaval brands (45.4% vs. 39.7%), with free-flow traffic (52.7%).
  • The main research topics investigated were milk production, milk composition, and AMS efficiency, followed by behavior and welfare, health disorders (especially mastitis), and nutrition in Europe and other regions. At the same time, in the United States, trends were similar, except for nutrition.
  • Since 2016 there has been an increased interest in studies on energy and water consumption, technological development, environment (enteric emissions), reproduction, genetics, and longevity or culling. However, the small number of studies and unclear characterization of what is optimum for reproductive management, other health disorders, economics, and water and energy consumption suggest a need for future research.

Analysis of Jersey versus Holstein breed profitability on north central US dairies. Olthof LA, Domecq JJ, Bradford BJ. JDS Commun. 2023 Jul 21;4(5):344-348.

  • With over 9 million cows in the United States, Holstein is the dominant breed in the US dairy population; however, the US Jersey population is growing.
  • The objective of this study was to determine the profitability of Holstein and Jersey cows managed similarly on the same farms. Holstein and Jersey economic performance was compared within 3 north central US dairies, each milking more than 500 cows.
  • The herds’ average distribution was 21% Jersey (27 ± 0.67 kg/d milk, 4.92% ± 0.24 fat, 3.72% ± 0.03 protein) and 79% Holstein (37 ± 1.98 kg/d milk, 3.85% ± 0.21 fat, 3.17% ± 0.17 protein). A comparative budget approach was used to assess economic factors that differed between the breeds on a per cow annual basis, based on the assumption that an existing farm would be constrained by stalls and parlor to an equal number of Jersey and Holstein cows.
  • Data from 2020 were gathered from farm management software, on-farm evaluations, and producer interviews. Sensitivity analysis was performed to determine which conditions would lead to different conclusions. Factors considered in the analysis included milk and component production, milk bonuses, ration prices, and dry matter (DM) intake.
  • In a 2021 price scenario, Holstein cows ranged from $345 to $601 more profitable than Jersey cows on a per cow annual basis. Although Jersey cows had an advantage in component concentration, Holstein cows produced 13 ± 4.7% more fat and 22 ± 6.6% more protein annually due to greater milk yield. This accounted for most of the profitability advantage for Holsteins; 78% of the revenue advantage for Holstein cows came from increased component production.
  • Few health and reproductive differences were found. The sensitivity analysis revealed, if all other factors remained the same, Jersey profitability would equal that of Holstein if any of the following changes occurred (assuming no change in Holstein metrics): mean Jersey milk production increased to 31 kg/d; milk price adjustments decreased from -$0.008 to -$0.11 per kg fluid milk; lactating cow ration price increased from $0.27 per kg DM to $0.53 per kg DM; or Jersey DM intake decreased from 20 to 15 kg/d. The study did not consider crossbred profitability or new infrastructure investments.
  • In conclusion, Holstein cows were more profitable than Jersey cows on these 3 north central US dairies.

How animal milk and plant-based alternatives diverge in terms of fatty acid, amino acid, and mineral composition. Moore SS, Costa A, Pozza M, Vamerali T, Niero G, Censi S, De Marchi M. NPJ Sci Food. 2023 Sep 16;7(1):50.

  • The decline in fresh milk in the Western world has in part been substituted by an increased consumption of plant-based beverages (PBB). These are often marketed as healthy and sustainable alternatives to milk and dairy foodstuff, although studies have suggested PBB to be of lower nutrient quality.
  • The current study considered different brands of almond-, oat-, rice-, coconut- and soya-based beverages for a comparative analysis and found that they indeed presented lower contents of total protein, lipids, amino acids, and minerals than cow and goat milk. The only exception was given by soya-based beverages which approximated the protein content (3.47% vs. 3.42 and 3.25% in cow and goat milk, respectively) and amino acid composition of animal milk, and also demonstrated high mineral content.
  • The natural presence of phyto-compounds in PBB characterized as antinutrients and their potential to exacerbate the issue of low nutrient quality by lowering bioavailability have been discussed.

Levels and types of microbial contaminants in different plant-based ingredients used in dairy alternatives. Kyrylenko A, Eijlander RT, Alliney G, de Bos EL, Wells-Bennik MHJ. Int J Food Microbiol. 2023 Sep 9;407:110392.

  • In this study levels and types of microbial contaminants were investigated in 88 different plant-based ingredients including many that are used to manufacture dairy alternatives. Studied ingredients encompassed samples of pulses (pea, faba bean, chickpea, and mung bean), cereals/pseudocereals (oat, rice, amaranth and quinoa) and drupes (coconut, almond and cashew).
  • The microbial analysis included: i) total viable count (TVC), ii) total aerobic mesophilic spore count (TMS), iii) heat resistant aerobic thermophilic spore count (HRTS), iv) anaerobic sulfite reducing Clostridium spore count (SRCS), and v) Bacillus cereus spore count (BCES).
  • Many of the investigated ingredients showed a high proportion of spores as part of their total aerobic mesophilic counts. In 63 % of the samples, the difference between TVC and TMS counts was 1 Log10unit or less. This was particularly the case for the majority of pea isolates and concentrates, faba bean isolates, oat kernels and flakes, and for single samples of chickpea isolate, almond, amaranth, rice, quinoa, and coconut flours.
  • Concentrations of TVC ranged between <1.0 and 5.3 Log10CFU/g in different samples, and TMS varied between <1.0 and 4.1 Log10 CFU/g. Levels of HTRS, BCES and SRCS were generally low, typically around or below the LOD of 1.0 Log10 CFU/g. In total, 845 individual bacterial colonies were isolated belonging to 33 different genera.
  • Bacillus licheniformis and B. cereus group strains were most frequently detected among Bacillus isolates, and these species originated primarily from pea and oat samples. Geobacillus stearothermophilus was the main species encountered as part of the HRTS.
  • Among the Clostridium isolates, Clostridum sporogenes/tepidum were predominant species, which were mostly found in pea and almond samples. Strains with potential to cause foodborne infection or intoxication were typed using the PCR-based method for toxin genes detection.
  • In the B. cereus group, 9 % of isolates contained the ces gene, 28 % contained hbl, 42 % cytK, and 69 % were positive for the nhe gene. Absence of the boNT-A and -B genes was confirmed for all isolated C. sporogenes/tepidum strains. Nearly all (98 %) B. licheniformis isolates were positive for the lchAA gene.
  • Insight into the occurrence of microbial contaminants in plant-based ingredients, combined with knowledge of their key inactivation and growth characteristics, can be used for the microbial risk assessment and effective design of plant-based food processing conditions and formulations to ensure food safety and prevent spoilage.