The Dairy Research Bulletin delivers a brief synopsis of the most current Human, Animal, and Environmental dairy research that is going on in the World, and also that which is of special interest to California dairy producers and consumers alike.

If you would like to peruse the most pertinent dairy research from months past, then visit the Dairy Research Bulletin Archive


Selected Articles on Social Responsibility, Environmental Management, and Sustainability

Identification of rumen microbial biomarkers linked to methane emission in Holstein dairy cows. Ramayo-Caldas Y, Zingaretti L, Popova M, Estellé J, Bernard A, Pons N, Bellot P, Mach N, Rau A, Roume H, Perez-Enciso M, Faverdin P, Edouard N, Ehrlich D, Morgavi DP, Renand G. J Anim Breed Genet. 2019 Aug 16.

  • Mitigation of greenhouse gas emissions is relevant for reducing the environmental impact of ruminant production.
  • In this study, the rumen microbiome from Holstein cows was characterized through a combination of 16S rRNA gene and shotgun metagenomic sequencing.
  • Methane production (CH4) and dry matter intake (DMI) were individually measured over 4-6 weeks to calculate the CH4 yield (CH4 y = CH4/DMI) per cow.
  • Three ruminotype clusters (R1, R2 and R3) were identified, and R2 was associated with higher CH4 The taxonomic composition of this group had lower abundance of Succinivibrionaceae and Methanosphaera, and higher abundance of Ruminococcaceae, Christensenellaceae and Lachnospiraceae.
  • Overall, the researchers identified 86 discriminant bacterial operational taxonomic units (OTUs), notably including families linked to CH4emission such as Succinivibrionaceae, Ruminococcaceae, Christensenellaceae, Lachnospiraceae and Rikenellaceae. These selected OTUs explained 24% of the CH4 yield phenotypic variance, whereas the host genome contribution was ~14%.
  • In summary, the researchers identified rumen microbial biomarkers associated with the methane production of dairy cows; these biomarkers could be used for targeted methane-reduction selection programs in the dairy cattle industry provided they are heritable.

The effect of dietary forage to concentrate ratio and forage type on milk fatty acid composition and milk fat globule size of lactating cows. Jaakamo MJ, Luukkonen TJ, Kairenius PK, Bayat AR, Ahvenjärvi SA, Tupasela TM, Vilkki JH, Shingfield KJ, Leskinen HM. J Dairy Sci. 2019 Aug 14. pii: S0022-0302(19)30695-2.

  • Global demand for livestock products is rising, resulting in a growing demand for feed and potentially burdening freshwater resources to produce this feed. To offset this increased pressure on water resources, the environmental performance of livestock sector should continue to improve.
  • Over the last few decades, product output per animal and feedstuff yields in the US have improved, but before now it was unclear to what extent these improvements influenced the water productivity of the livestock products.
  • In this research, the researchers estimate changes in water productivity of animal products from 1960 to 2016. They considered feed conversion ratios (dry matter intake per head divided by product output per head), feed composition per animal category, and estimated the water footprint of livestock production following the Water Footprint Network’s Water Footprint Assessment methodology.
  • The current water productivity of all livestock products appears to be much better than in 1960. The observed improvements in water productivities are due to a number of factors, including increases in livestock productivity, feed conversion ratios and feed crop yields, the latter one reducing the water footprint of feed inputs.
  • Monogastric animals (poultry and swine) have a high feed-use efficiency compared to ruminants (cattle), but ruminants consume relatively large portion of feed that is non-edible for humans. Per unit of energy content, milk has the largest water productivity followed by chicken and pork. Per gram of protein, poultry products (chicken meat, egg and turkey meat) have the largest water productivity, followed by cattle milk and pork. Beef has the smallest.

Application of genome editing in farm animals: cattle. Van Eenennaam AL. Transgenic Res. 2019 Aug;28(Suppl 2):93-100.

  • Milk and meat from cattle and buffaloes contribute 45% of the global animal protein supply, followed by chickens (31%), and pigs (20%). In 2016, the global cattle population of 1.0 billion head produced 6.5 billion tons of cows’ milk, and 66 million tons of beef.
  • In the past century, cattle breeding programs have greatly increased the yield per animal with a resultant decrease in the emissions intensity per unit of milk or beef, but this has not been true in all regions.
  • Genome editing research in cattle to date has focused on disease resistance (e.g. tuberculosis), production (e.g. myostatin knockout; production of all-male offspring), elimination of allergens (e.g. beta-lactoglobulin knockout) and welfare (e.g. polled or hornlessness) traits.
  • Modeling has revealed how the use of genome editing to introduce beneficial alleles into cattle breeds could maintain or even accelerate the rate of genetic gain accomplished by conventional breeding programs, and is a superior approach to the lengthy process of introgressing those same alleles from distant breeds.
  • Genome editing could be used to precisely introduce useful alleles (e.g. heat tolerance, disease resistance) and haplotypes into native locally-adapted cattle breeds, thereby helping to improve their productivity.
  • As with earlier genetic engineering approaches, whether breeders will be able to employ genome editing in cattle genetic improvement programs will very much depend upon global decisions around the regulatory framework and governance of genome editing for food animals.

Risk Factors for the Occurrence of Methicillin-Resistant Staphylococcus aureus in Dairy Herds: An Update. Schnitt A, Tenhagen BA. Foodborne Pathog Dis. 2019 Aug 21.

  • In dairy cows, Staphylococcus aureus is a major mastitis pathogen and methicillin-resistant S. aureus (MRSA) has been reported from dairy farms around the world. The risk of foodborne zoonotic infections with bovine MRSA strains seems to be low since MRSA prevalence is low in dairy herds and milk is commonly heat treated before consumption.
  • However, bovine mastitis caused by MRSA is an important issue in veterinary medicine since treatment options with non-β-lactam antibiotics are limited. For the development of effective MRSA prevention strategies, it is necessary to know which factors increase the risk for MRSA transmission into and within dairy herds.
  • Therefore, the aim of this review is to summarize the risk factors for the occurrence of MRSA in dairy herds and to identify the respective knowledge gaps.
  • MRSA was more frequently detected in conventional dairy farms than in organic farms and in larger farms than in smaller farms. Dairy farms housing pigs along with cattle are more frequently affected by MRSA. Moreover, humans carrying MRSA can probably infect dairy cows. Consequently, pigs and humans may introduce new MRSA strains into dairy herds.
  • MRSA transmission within dairy herds was associated with improper milking hygiene procedures. Furthermore, methicillin-resistant coagulase-negative staphylococci (MR-CoNS) were repeatedly isolated from dairy farms. This is an important issue since MR-CoNS may transfer resistance genes to S. aureus. The role of antimicrobial exposure as a risk factor for the occurrence of MRSA within dairy herds needs to be further investigated.

Bacterial spore levels in bulk tank raw milk are influenced by environmental and cow hygiene factors. Martin NH, Kent DJ, Evanowski RL, Zuber Hrobuchak TJ, Wiedmann M. J Dairy Sci. 2019 Aug 22.

  • Sporeforming bacteria are responsible for the spoilage of several dairy products including fluid milk, cheese, and products manufactured using dried dairy powders as ingredients.
  • Sporeforming bacteria represent a considerable challenge for the dairy industry because they primarily enter the dairy product continuum at the farm, survive processing hurdles, and subsequently grow in finished products.
  • The goal of the current study was to investigate sources of spores in the farm environment and survey farm management practices that affect the presence and levels of spores in bulk tank raw milk.
  • Environmental samples including feed, bedding, manure, soil, water, and bulk tank raw milk were collected twice from 17 upstate New York dairy farms over a 19-mo period and the presence and levels of various spore types (e.g., psychrotolerant, mesophilic, thermophilic, highly heat resistant thermophilic, specially thermoresistant thermophilic, and anaerobic butyric acid bacteria) were assessed.
  • Manure had the highest level of spores for 4 out of 5 aerobic spore types with mean counts of 5.87, 5.22, 4.35, and 3.68 log cfu/g of mesophilic, thermophilic, highly heat resistant thermophilic, and specially thermoresistant thermophilic spores, respectively. In contrast, bulk tank raw milk had mean spore levels below 1 log cfu/mL across spore types.
  • Further analyses indicated that variables of importance for more than one spore type included the residual level of spores in milk from individual cows after thorough teat cleaning and forestripping, udder hygiene, clipping or flaming of udders, spore level in feed commodities, spore level in parlor air, how often bedding was topped up or changed, the use of recycled manure bedding, and the use of sawdust bedding.
  • These results improve our understanding of how spores transfer from environmental sources into bulk tank raw milk and provide information that can be used to design intervention trials aimed at reducing spore levels in raw milk.

Production, economic viability and risks associated with switching dairy cows from drylots to compost bedded pack systems. Marcondes MI, Mariano WH, De Vries A. Animal. 2019 Aug 14:1-10.

  • The use of compost bedded pack systems (CBS) has increased over the past 5 years in tropical countries, and studies associating production traits with economical outcomes of this system are warranted.
  • The study objectives were to evaluate productive traits, economic outcomes and the risks of losses of dairy farms that switched from a drylot system (DLS) to a CBS and to compare these with similar farms that did not change their system.
  • The researchers collected data from 18 farms over 36 consecutive months (August 2014 to July 2017). All farms started the study as DLS, and six farms switched to CBS in the second year. The other 12 farms kept their DLS during the 36 months of evaluation. Annual technical and economic indexes per farm were collected and calculated.
  • Milk fat, milk total solids, and somatic cell count did not change when farms switched from DLS to CBS, and averaged 3.80%, 12.04%, and 256 500 cells/ml, respectively. However, milk protein (%) decreased in CBS farms. The majority of milk production variables were not affected. Nevertheless, farms that switched to CBS increased milk production per cow by 13.3% compared with DLS farms.
  • Total operation costs (296 076.83 $/year) were not affected by the system, and neither were the costs of concentrates, roughage, labor or medicines. Net margin per liter (0.09 $/l), operating profit (14.95%), assets per liter (398.68 $/l per day) and return on assets (10.27%) did not change when farms switched from DLS to CBS. Net margin ($/l and $/cow) and asset turnover rate increased in CBS farms. Risk analysis indicated that the risk was reduced by 38% in CBS farms.
  • In conclusion, this study demonstrates that CBS systems might be promising for producers in tropical countries who are looking for a more productive and less risky system. We did not observe improvements in animal health as previously reported in the literature.

Relationships among bedding materials, bedding bacteria counts, udder hygiene, milk quality, and udder health in US dairy herds. Patel K, Godden SM, Royster E, Crooker BA, Timmerman J, Fox L. J Dairy Sci. 2019 Aug 22. pii: S0022-0302(19)30732-5.

  • Bedding is an important source of teat end exposure to environmental mastitis pathogens. To better control environmental mastitis, we need an improved understanding of the relationships among bedding selection and management, bedding bacteria counts, and udder health.
  • The objectives of this cross-sectional observational study were to:
    • Describe BBC, bedding characteristics, udder hygiene scores, bulk tank milk quality, and udder health in US dairy herds using 1 of 4 bedding materials;
    • Describe the relationship between BBC and herd measures of udder health;
    • Identify benchmarks for monitoring bedding hygiene.
  • Local dairy veterinarians and university researchers enrolled and sampled 168 herds from 17 states. Herds were on a Dairy Herd Improvement Association testing program and used 1 of 4 bedding types for lactating cows: new sand, reclaimed sand, manure solids, or organic non-manure materials.
  • Each herd was sampled twice (winter and summer) in 2016. Samples and data collected included unused and used bedding, bulk tank milk samples, udder hygiene scores, Dairy Herd Improvement Association test data, and descriptions of facilities and herd management practices.
  • Although much variation existed within and among bedding types, the results showed the use of manure solids bedding to be generally associated with higher bedding bacteria counts, dirtier udders, increased coliform and SSLO counts in bulk tank milk, and poorer udder health measures compared with organic non-manure materials, reclaimed sand, or new sand bedding materials.
  • While controlling for important farm traits and management practices, mixed linear regression showed that increased counts of coliforms, Klebsiella spp., SSLO, and Staphylococci spp. in both unused and used bedding were associated with poorer values for 1 or more herd-level measures of udder health.

Review: Associations among goods, impacts and ecosystem services provided by livestock farming. Dumont B, Ryschawy J, Duru M, Benoit M, Chatellier V, Delaby L, Donnars C, Dupraz P, Lemauviel-Lavenant S, Méda B, Vollet D, Sabatier R. Animal. 2019 Aug;13(8):1773-1784.

  • Livestock is a major driver in most rural landscapes and economics, but it also polarizes debate over its environmental impacts, animal welfare and human health. Conversely, the various services that livestock farming systems provide to society are often overlooked and have rarely been quantified.
  • The aim of analyzing bundles of services is to chart the coexistence and interactions between the various services and impacts provided by livestock farming, and to identify sets of ecosystem services that appear together repeatedly across sites and through time.
  • At a local scale, farming practices interact with landscape heterogeneity in a multi-scale process to shape grassland biodiversity and ecosystem services. Production and various ecosystem services provided by grasslands to farmers, such as soil fertility, biological regulations and erosion control, benefit to some extent from the functional diversity of grassland species, and length of pasture phase in the crop rotation.
  • Livestock management also appeared to be a key driver of bundles of services in prospective scenarios. These scenarios simulate a breakaway from current production, legislation (e.g. the use of food waste to fatten pigs) and consumption trends (e.g. halving animal protein consumption across Europe).
  • Overall, strategies that combine a reduction of inputs, of the use of crops from arable land to feed livestock, of food waste and of meat consumption deliver a more sustainable food future. Livestock as part of this sustainable future requires further enhancement, quantification and communication of the services provided by livestock farming to society, which calls for the following: (i) a better targeting of public support, (ii) more precise quantification of bundles of services and (iii) better information to consumers and assessment of their willingness to pay for these services.

Diversification not specialization reduces global and local environmental burdens from livestock production. Soteriades AD, Foskolos A, Styles D, Gibbons JM. Environ Int. 2019 Aug 23;132:104837.

  • Milk and beef production generates environmental burdens globally and locally. Across many regions a typical dairy intensification pathway is for dairy farms to specialize on milk production and reduce the co-production of beef (i.e. ‘dairy-beef’).
  • Dairy-beef thus reduces and beef needs to be produced elsewhere if beef production is to be maintained. Life Cycle Assessment (LCA) studies quantifying the environmental implications of dairy and beef production have largely focused on the farm level and not captured system connections. This research presents comprehensive LCA results for multiple environmental burdens based on a large panel dataset for commercial dairy and suckler-beef farms.
  • The researchers present a 15-year LCA assessment of a total of 738 dairy (3624 data points in 15 years) and 1887 suckler-beef (10,340 data points in 15 years) UK farms for five major LCA footprints. They also explore the footprint implications of compensating for reduced dairy-beef through producing this ‘displaced’ beef on suckler-beef farms.
  • The researchers found that dairy-beef was much more efficient than beef produced on suckler-beef farms in terms of footprints per unit of beef output. Reducing dairy-beef and replacing it on a suckler-beef farm generally significantly increased environmental burdens.
  • A reduction in carbon footprint was also associated with a reduction in other burdens suggesting no trade-off between local and global emissions. Increasing dairy farm diversification via higher dairy-beef output per unit of milk reduced burdens by up to 11-56%, on average, depending on burden and sensitivity run.
  • In conclusion, overspecialization of dairy farms in milk production increases the combined burdens from beef and milk, and that more intensive beef systems that make more efficient use of forage land play a crucial role in mitigating these burdens.


Selected Articles on Dairy Intake and Human Health

Associations of dairy product consumption with mortality in the European Prospective Investigation into Cancer and Nutrition (EPIC)-Italy cohort. Pala V, Sieri S, Chiodini P, Masala G, Palli D, Mattiello A, Panico S, Tumino R, Frasca G, Fasanelli F, Ricceri F, Agnoli C, Grioni S, Krogh V. Am J Clin Nutr. 2019 Aug 21.

  • The relation of dairy product consumption to health and mortality is controversial.
  • Researchers investigated associations of consumption of various dairy products with mortality in the Italian cohort of the European Prospective Investigation into Cancer and Nutrition (EPIC)-Italy study.
  • Dairy product consumption was assessed by validated semiquantitative FFQs. Multivariable Cox models stratified by center, age, and sex and adjusted for confounders estimated associations of milk (total, full fat, and reduced fat), yogurt, cheese, butter, and dairy calcium consumption with mortality for cancer, cardiovascular disease, and all causes.
  • After a median follow-up of 14.9 years, no significant association of consumption of any dairy product with mortality was found in the fully adjusted models. A 25% reduction in risk of all-cause mortality was found for milk intake from 160 to 120 grams/day but not for the highest (>200 grams/day) category of intake compared with non-consumption. Associations of full-fat and reduced-fat milk consumption with all-cause and cause-specific mortality were similar to those for milk as a whole.
  • In this Italian cohort characterized by low to average milk consumption, the researchers found no evidence of a dose-response association between milk consumption and mortality and also no association of consumption of other dairy products investigated with mortality.

Dairy fat intake and risk of type 2 diabetes in 3 cohorts of US men and women. Ardisson Korat AV, Li Y, Sacks F, Rosner B, Willett WC, Hu FB, Sun Q. Am J Clin Nutr. 2019 Aug 14. pii: nqz176.

  • Previous studies have examined dairy products with various fat contents in relation to type 2 diabetes (T2D) risk, although data regarding dairy fat intake per se are sparse.
  • This research aimed to evaluate the association between dairy fat intake and risk of T2D in 3 prospective cohorts. The researchers also examined associations for isocalorically replacing dairy fat with other macronutrients. The researchers prospectively followed 41,808 men in the Health Professionals Follow-Up Study (HPFS; 1986-2012), 65,929 women in the Nurses’ Health Study (NHS; 1984-2012), and 89,565 women in the NHS II (1991-2013).
  • The results showed that dairy fat was not associated with risk of T2D when compared with calories from carbohydrates. Replacing 5% of calories from dairy fat with other sources of animal fat or carbohydrate from refined grains was associated with a 17% and a 4% higher risk of T2D, respectively. Conversely, a 5% calorie replacement with carbohydrate from whole grains was associated with a 7% lower risk of T2D.
  • Dairy fat intake was not associated with T2D risk in these cohort studies of US men and women when compared with calories from carbohydrate. Replacing dairy fat with carbohydrates from whole grains was associated with lower risk of T2D. Replacement with other animal fats or refined carbohydrates was associated with higher risk.

High calcium intake from fat-free milk, body composition and glycaemic control in adults with type 2 diabetes: a randomised crossover clinical trial. Gomes JMG, de Assis Costa J, Ribeiro PVM, Alfenas RCG. Br J Nutr. 2019 Aug 1:1-8.

  • Adequate calcium consumption seems to improve glucose homeostasis in adults with type 2 diabetes (T2D) particularly among low habitual consumers (<600 mg/d). That effect seems to be mainly due to the consumption of fat-free dairy products associated with energy-restricted diets.
  • The researchers evaluated the effects of high-calcium fat-free milk compared to low calcium control diet on adiposity and on glycemic control. Fourteen adult subjects with T2D with low habitual calcium consumption (<600 mg/d)) were included in this randomized, crossover clinical trial.
  • Subjects participated in two 12-week experimental sessions (high-calcium fat-free milk or low-calcium control) separated by 8-week washout. Energy-restricted diets containing 800 mg of dietary calcium/day were prescribed.
  • There was a greater reduction in body weight, body fat mass, waist circumference and waist:hip ratio after high calcium intake. Serum 25-hydoxyvitamin D and homeostatic model assessment-2 β-cell function (HOMA2-%B) increased, and serum uric acid, parathormone (PTH) and glycated Hb (HbA1c) concentrations reduced after high calcium.
  • In addition, changes from baseline in terms of serum uric acid, glucose, HbA1c and PTH concentrations were lower, and those of HOMA2-%B, serum calcium and 25-hydoxyvitamin D were higher after the high calcium than after low calcium intake. The consumption of approximately three servings of fat-free milk and 1200 mg of dietary calcium per day enhanced weight loss, improved body composition and promoted glycemic control in subjects with type 2 diabetes and low habitual calcium consumption.

Association of Lactase Persistence Genotypes (rs4988235) and Ethnicity with Dairy Intake in a Healthy U.S. Population. Chin EL, Huang L, Bouzid YY, Kirschke CP, Durbin-Johnson B, Baldiviez LM, Bonnel EL, Keim NL, Korf I, Stephensen CB, Lemay DG. Nutrients. 2019 Aug 10;11(8). pii: E1860. CDRF-Funded Research

  • Lactase persistence (LP) is a trait in which lactose can be digested throughout adulthood, while lactase non-persistence (LNP) can cause lactose intolerance and influence dairy consumption.
  • One single nucleotide polymorphism (SNP ID: rs4988235) is often used as a predictor for dairy intake, since it is responsible for LP in people in European descent and can occur in other ethnic groups.
  • The objective of this study was to determine whether rs4988235 genotypes and ethnicity influence reported dairy consumption in the United States. A food frequency questionnaire (FFQ) and multiple Automated Self-Administered 24-h recalls (ASA24®) were used to measure habitual and recent intake, respectively, of total dairy, cheese, cow’s milk, plant-based alternative milk, and yogurt in a multi-ethnic U.S. cohort genotyped for rs4988235.
  • The results showed that within Caucasian subjects, LP individuals reported consuming more recent total dairy and habitual total cow’s milk intake. For subjects of all ethnicities, LP individuals consumed more cheese and recent total dairy. For both dietary assessments, Caucasians consumed more cheese than all non-Caucasians independent of genotype, as well as more recent intake of yogurt. Fluid milk and alternative plant-based milk consumption were not associated with genotypes or ethnicity.
  • These results show that both LP genotype and ethnicity influence the intake of some dairy products in a multi-ethnic U.S. cohort, but the ability of rs4988235 genotypes to predict intake may depend on ethnic background, the specific dairy product, and whether intake is reported on a habitual or recent basis. Therefore, ethnicity and the dietary assessment method should also be considered when determining the suitability of rs4988235 as a proxy for dairy intake.