Welcome to the March 2020 Dairy Research Bulletin. 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

Review: Challenges for dairy cow production systems arising from climate changes. Gauly M, Ammer S. Animal. 2020 Mar;14(S1):s196-s203.

  • The so-called global change refers to changes on a planetary scale. The term encompasses various issues like resource use, energy development, population growth, land use and land cover, carbon and nitrogen cycle, pollution and health, and climate change.
  • This review paper deals with challenges for dairy cattle production systems arising from climate change as one part of global changes.
  • Global warming is increasing, and therefore ecosystems, plant and animal biodiversity, and food security and safety are at risk. It is already accepted knowledge that the direct and indirect effects of global warming in combination with an increasing frequency of weather extremes are a serious issue for livestock production, even in moderate climate zones.
  • The potential and already-measurable effects of climate change (including increase in temperature, frequency of hot days and heat waves), in particular the challenges on grassland production, fodder quality, nutrition in general, cow welfare, health as well as performance of dairy production, are reviewed.
  • Indirect and direct effects on animals are correlated with their performance. There are clear indications that with selection for high-yielding animals the sensitivity to climate changes increases. Cumulative effects (e.g. higher temperature plus increased pathogen and their vectors loads) do strengthen these impacts.
  • To cope with the consequences several possible adaptation and mitigation strategies must be established on different levels. This includes changes in the production systems (e.g. management, barn, feeding), breeding strategies and health management.

Review: Fifty years of research on rumen methanogenesis: lessons learned and future challenges for mitigation. Beauchemin KA, Ungerfeld EM, Eckard RJ, Wang M. Animal. 2020 Mar;14(S1):s2-s16.

  • Although ruminants have a unique advantage of being able to consume forages and graze lands not suitable for arable cropping, 2% to 12% of the gross energy consumed is converted to enteric CH4 during ruminal digestion, which contributes approximately 6% of global anthropogenic greenhouse gas emissions.
  • Thus, ruminant producers need to find cost-effective ways to reduce emissions while meeting consumer demand for food. This paper provides a critical review of the substantial amount of ruminant CH4-related research published in past decades, highlighting hydrogen flow in the rumen, the microbiome associated with methanogenesis, current and future prospects for CH4 mitigation and insights into future challenges for science, governments, farmers and associated industries.
  • Methane emission intensity, measured as emissions per unit of meat and milk, has continuously declined over the past decades due to improvements in production efficiency and animal performance, and this trend is expected to continue. However, continued decline in emission intensity will likely be insufficient to offset the rising emissions from increasing demand for animal protein. Thus, decreases in both emission intensity (g CH4/animal product) and absolute emissions (g CH4/day) are needed if the ruminant industries continue to grow.
  • Providing producers with cost-effective options for decreasing CH4 emissions is therefore imperative, yet few cost-effective approaches are currently available. Future abatement may be achieved through animal genetics, vaccine development, early life programming, diet formulation, use of alternative hydrogen sinks, chemical inhibitors and fermentation modifiers.
  • Individually, these strategies are expected to have moderate effects (<20% decrease). Therefore, it will be necessary to combine strategies to attain the sizable reduction in CH4 needed, but further research is required to determine whether combining anti-methanogenic strategies will have consistent additive effects.
  • Major constraints for decreasing global enteric CH4 emissions from ruminants are continued expansion of the industry, the cost of mitigation, the difficulty of applying mitigation strategies to grazing ruminants, the inconsistent effects on animal performance and the paucity of information on animal health, reproduction, product quality, cost-benefit, safety and consumer acceptance.

Different characteristics of greenhouse gases and ammonia emissions from conventional stored dairy cattle and swine manure in China. Zhuang M, Shan N, Wang Y, Caro D, Fleming RM, Wang L. Sci Total Environ. 2020 Mar 3;722:137693.

  • Livestock manure emits considerable amounts of greenhouse gases (GHGs) and ammonia (NH3), inducing climate change and air pollution. However, there remains a lack of knowledge in the literature related to GHGs and NH3emissions from the manure of various livestock species.
  • This study reports on a field observation conducted to analyze GHGs and NH3emissions of solid stored manure from dairy cattle and swine, which represent the two main livestock species raised in China.
  • Results showed that although dairy cattle manure emitted 521.9% more methane (CH4) than swine manure, they separately emitted 50.8% and 40.9% less nitrous oxide (N2O) and carbon dioxide (CO2) emissions, respectively. With respect to their global warming potential, the GHGs emission from dairy cattle manure was similar to that from swine manure.
  • NH3emissions from swine manure were significantly higher, namely, greater by a factor of 2.4 compared to dairy cattle manure. Differences in gas emissions between dairy cattle and swine manure can be explained by differences in the physicochemical characteristics of their manure and their associated microbiological, chemical, and physical processes that produce gas during storage periods.
  • Based on these results, this study highlights the necessity for prospective mitigation strategies to simultaneously decrease GHGs and NH3emissions from livestock manure. Our findings provide useful implications for understanding GHGs and NH3 emissions, which can be used to develop corresponding mitigation strategies for livestock manure management in China.

Fate of the nonsteroidal, anti-inflammatory veterinary drug flunixin in agricultural soils and dairy manure. Popova IE, Morra MJ. Environ Sci Pollut Res Int. 2020 Mar 28.

  • A large percentage of flunixin, a nonsteroidal anti-inflammatory drug widely used for treating livestock, is excreted in intact form and thus potentially available for environmental transport.
  • As the fate of flunixin in the environment is unknown, the objective of this study was to quantify sorption, desorption, and transformation in five agricultural soils and manure using batch equilibrium methods.
  • For all studied soils, sorption of flunixin exhibited linear character, with both linear and Freundlich models providing adequate fit. Linear sorption coefficients varied from 8 to 112 L kg-1. Desorption of the reversibly bound fraction (3-10% of total sorbed flunixin) from all five studied soils exhibited non-hysteretic character suggesting low affinity of this fraction of flunixin to soil.
  • Flunixin degradation in soils was relatively slow, exhibiting half-lives of 39-203 days, thus providing time for off-site transport and environmental contamination. The biological impacts of flunixin at environmentally relevant concentrations must be determined given its environmental behavior and extensive use as a nonsteroidal anti-inflammatory drug in livestock.

Shifts in microbial community, pathogenicity-related genes and antibiotic resistance genes during dairy manure piled up. Zhang X, Ma C, Zhang W, Li W, Yu J, Xue D, Wu X, Deng G. Microb Biotechnol. 2020 Mar 23.

  • The uncomposted feces of dairy cow are usually stacked on cow breeding farms, dried under natural conditions and then used as cow bedding material or they may be continuously piled up. However, no information is available to evaluate variations in the human and animal pathogen genes and antibiotic resistance during the accumulation of fresh feces of dairy cow to manure.
  • Here, the researchers present the metagenomic analysis of fresh feces and manure from a dairy farm in Ning Xia, showing a unique enrichment of human and animal pathogen genes and antibiotic resistance genes (ARGs) in manure.
  • The researchers found that manure accumulation could significantly increase the diversity and abundance of the pathogenic constituents. Furthermore, pathogens from manure could spread to the plant environment and enphytotic pathogens could affect the yield and quality of crops during the use of manure as a fertilizer.
  • Levels of virulence genes and ARGs increased with the enrichment of microbes and pathogens when feces accumulated to manure. Accumulated manure was also the transfer station of ARGs to enrich the ARGs in the environment, indicating the ubiquitous presence of environmental antibiotic resistance genes.
  • These results demonstrate that manure accumulation and usage without effective manure management is an unreasonable approach that could enrich pathogenic microorganisms and ARGs in the environment.

Impacts of Compost Bedded Pack Barns on the Welfare and Comfort of Dairy Cows. Fernández A, Mainau E, Manteca X, Siurana A, Castillejos L. Animals (Basel). 2020 Mar 4;10(3). pii: E431

  • The assessment of cow comfort on dairy farms is essential for strategies aimed at maintaining welfare, health, and production rates, or even to increase these rates.
  • In this study, three loose housing systems for lactating cows — compost bedded pack (CBP); conventional bedded pack (BP); and freestalls (FS) were assessed on one farm in terms of cow behavior and welfare.
  • An on-farm welfare assessment based on the Welfare Quality protocols was used four times every three months on 757 cows. Video recordings taken twice over four days were used to assess behavior patterns at resting areas.
  • Cows in CBP and BP were dirtier and had fewer integument alterations than those in FS. Cows in BP were quicker to lie down and stand up compared to those in CBP or FS.
  • Percentages of cows needing more attempts before rising were higher for FS. However, a higher frequency of kneeling was observed in CBP.
  • Overall, in this study, cows kept in bedded pack barns were dirtier but had fewer integument alterations and spent more time lying down in the resting area than cows housed in freestalls.

Milking time hygiene interventions on dairy farms reduce spore counts in raw milk. Evanowski RL, Kent DJ, Wiedmann M, Martin NH. J Dairy Sci. 2020 Mar 17. pii: S0022-0302(20)30208-3.

  • Spore-forming bacteria can survive High Temperature/Short Time (HTST) pasteurization in spore form and affect the quality of dairy products (e.g., spoilage in fluid milk). With the demand for higher quality finished products that have longer shelf lives, dairy processors are becoming interested in obtaining low-spore raw milk supplies.
  • Previous research has suggested that cow hygiene factors (e.g., udder hygiene, level of spores in milk from individual cows) are important for the transmission of spores into bulk tank raw milk, suggesting that one potential strategy to reduce spores in bulk tank milk should target cow hygiene in the parlor.
  • To that end, researchers conducted a study on 5 New York dairy farms over a 15-mo period to evaluate the effect of a combination of intervention strategies, applied together, on the levels of aerobic spores in bulk tank raw milk.
  • The combination of interventions included (1) training milking staff to focus on teat-end cleaning during milking preparation, and (2) implementing changes in laundered towel preparation (i.e., use of detergent, chlorine bleach, and drying).
  • A total of 355 bulk tank raw milk samples were collected with mean mesophilic and thermophilic spore counts of 2.1 and 2.4 cfu/mL, respectively, before interventions were applied, and 1.6 and 1.5 cfu/mL, respectively, after the interventions were applied. These reductions represent decreases of 37 and 40% in bulk tank raw milk mesophilic spores and thermophilic spores, respectively.
  • Further, when a higher proportion of very rough teat ends was observed, bulk tank milk thermophilic spore counts were significantly higher.
  • The intervention strategies tested here represent easy-to-execute cleaning strategies (e.g., focusing on teat-end hygiene and towel washing procedures) that can reduce bulk tank raw milk spore levels.

Consumer knowledge and perceptions of milk fat in Denmark, the United Kingdom, and the United States. Vargas-Bello-Pérez E, Faber I, Osorio JS, Stergiadis S. J Dairy Sci. 2020 Mar 11. pii: S0022-0302(20)30196-X.

  • This study examined the relationship between consumers’ country of origin: Denmark (DK), the United Kingdom (UK), and the United States (US) and their knowledge and perceptions of milk fat.
  • Adult participants answered a web-based survey, and data were collected online from December 2018 to April 2019, in DK, the UK, and the US. A total of 694 participants completed the online survey. Most respondents were between 18 and 39 years old, female, highly educated, and employed.
  • Most UK respondents consumed milk daily (73%), whereas in DK (56%) and the US (46%) consumption was significantly lower. Whole milk and semi-skim milk were consumed less by respondents in DK (20 and 36%, respectively) compared with the UK (50 and 49%, respectively) and the US (47 and 50%, respectively). Danish respondents (53%) consumed more skim milk than respondents from the UK (16%) and the US (19%).
  • Concern about milk fat was higher in DK (60%) than in the UK (34%) and the US (31%). More respondents considered milk fat to be “healthy” or “very healthy” in the UK (31 and 10%, respectively) and the US (37 and 19%, respectively), than in DK (23 and 6%, respectively).
  • Nutritional benefit was the most important reason for perceiving milk fat as healthy in the 3 countries. Awareness of milk saturated fat was higher among respondents from the UK (53%) than from DK (44%) and the US (38%). Results suggest that consumers in DK are different in their perceptions of milk fat, but consumers in the UK and the US share common characteristics.


Selected Articles on Dairy Intake and Human Health

Dairy versus other saturated fats source and cardiometabolic risk markers: Systematic review of randomized controlled trials. Duarte C, Boccardi V, Amaro Andrade P, Souza Lopes AC, Jacques PF. Crit Rev Food Sci Nutr. 2020 Mar 19:1-12.

  • Current dietary guidelines aim to limit the intake of saturated fats, but it is unclear as to the different health effects of different food sources of saturated fat.
  • The purpose of this study was to analyze the effects of dairy intake on cardiometabolic risk markers compared to other dietary fat sources in adults.
  • Literature database and gray literature were searched for studies published up to October 2018. Two independent authors selected and extracted data from articles. Summary tables were constructed to present data for all outcomes.
  • The intake of dairy appears to have a protective effect on some cardiovascular risk factors, or it is not worse than other saturated fat sources.
  • The higher intake of dairy can decrease total cholesterol and reduce waist circumference and increase HDL cholesterol. However, it can also increase LDL and triglycerides, although those were small changes.
  • It was observed that the effect of dairy on several serum lipids varied according to the type dairy product used on intervention. Dairy products seem to present a different effect on cardiometabolic risk factors than other fat sources, with evidence of improvement on metabolic parameters compared to another animal source of saturated fat.

Whole-Fat or Reduced-Fat Dairy Product Intake, Adiposity, and Cardiometabolic Health in Children: A Systematic Review. O’Sullivan TA, Schmidt KA, Kratz M. Adv Nutr. 2020 Mar 2. pii: nmaa011

  • Dietary guidelines commonly recommend that children aged >2 years consume reduced-fat dairy products rather than regular- or whole-fat dairy. In adults, most studies have not found the consumption of whole-fat dairy products to be associated with increased cardiometabolic or adiposity risk. Associations in children could differ due to growth and development.
  • In this study, the researchers systematically reviewed the literature in indexed, peer-reviewed journals to summarize pediatric studies (children aged from 2 to 18 years) assessing associations between whole- and reduced-fat dairy intake and measures of adiposity as well as biomarkers of cardiometabolic disease risk, including the serum lipid profile, blood pressure, low-grade chronic inflammation, oxidative stress, and measures of glucose homeostasis.
  • A total of 29 journal articles met the criteria for inclusion. The majority were conducted in the United States and were prospective or cross-sectional observational studies, with only 1 randomized controlled trial.
  • Studies were consistent in reporting that whole-fat dairy products were not associated with increased measures of weight gain or adiposity. Most evidence indicated that consumption of whole-fat dairy was not associated with increased cardiometabolic risk, although a change from whole-fat to reduced-fat dairy improved outcomes for some risk factors in 1 study.
  • Taken as a whole, the limited literature in this field is not consistent with dietary guidelines recommending that children consume preferably reduced-fat dairy products. High-quality randomized controlled trials in children that directly compare the effects of whole-fat compared with reduced-fat dairy intake on measures of adiposity or biomarkers of cardiometabolic disease risk are needed to provide better quality evidence in this area.

Dairy and Fruit Listed as Main Ingredients Improve NRF8.3 Nutrient Density Scores of Children’s Snacks. Drewnowski A, Richonnet C. Front Nutr. 2020 Mar 10;7:15.

  • The US Food and Drug Administration has modified its regulations on nutrient content claims by considering healthy dietary ingredients as well as nutrients.
  • The objective of this study was to assess the relation between dairy and fruit as main ingredients in children’s snacks and the Nutrient Rich Food (NRF8.3) nutrient density score. Methods:
  • Commonly consumed children’s snacks in the United States, Canada, France, and the United Kingdom (n= 261) were assigned into USDA What We Eat in America (WWEI) categories. Nutrient composition data came from industry websites, open-source government databases, and back-of-pack food labels.
  • The study found that nutrient density scores were higher for snacks listing dairy or fruit as main ingredients. Dairy or fruit when listed as the first ingredient were associated with higher percent daily values of protein, fiber, calcium, vitamin A, vitamin C, and vitamin D, lower saturated fat content and a 30-point increment in NRF8.3 scores.
  • In conclusion, the correspondence between back-of-pack food ingredients and the nutrient based NRF8.3 scores suggests that ingredients can also be used to communicate the nutritional value of foods to the consumer. Dairy and fruit, when listed as first ingredients, were an important component of the NRF8.3 nutrient density score.

Effects of dairy products, calcium, and vitamin D on ovarian cancer risk: a meta-analysis of 29 epidemiological studies. Liao MQ, Gao XP, Yu XX, Zeng YF, Li SN, Naicker N, Joseph T, Cao WT, Liu YH, Zhu S, Chen QS, Yang ZC, Zeng FF. Br J Nutr. 2020 Mar 19:1-28

  • The findings for the roles of dairy products, calcium, and vitamin D on ovarian cancer risk remain controversial.
  • In this study, researchers aimed to assess these associations by using an updated meta-analysis. Five electronic databases (e.g., PubMed and Embase) were searched from inception to December 24, 2019.
  • A total of 29 case-control or cohort studies were included. For comparisons of the highest vs. lowest intakes, higher whole milk intake was associated with increased ovarian cancer risk, whereas decreased risks were observed for higher intakes of low-fat milk, dietary calcium, and dietary vitamin D.
  • Additionally, for every 100-g/d increment, increased ovarian cancer risks were found for total dairy products and for whole milk; however, decreased risks were found for a 100-g/d increased intakes of low-fat milk, cheese, dietary calcium, total calcium, dietary vitamin D, and increased levels of circulating vitamin D.
  • These results show that whole milk intake might contribute to a higher ovarian cancer risk, whereas low-fat milk, dietary calcium, and dietary vitamin D might reduce the risk.

Risk of Kidney Stones: Influence of Dietary Factors, Dietary Patterns, and Vegetarian-Vegan Diets. Ferraro PM, Bargagli M, Trinchieri A, Gambaro G. Nutrients. 2020 Mar 15;12(3). pii: E779.

  • Nephrolithiasis is a common medical condition influenced by multiple environmental factors, including diet. Since nutritional habits play a relevant role in the genesis and recurrence of kidney stones disease, dietary manipulation has become a fundamental tool for the medical management of nephrolithiasis.
  • Dietary advice aims to reduce the majority of lithogenic risk factors, reducing the supersaturation of urine, mainly for calcium oxalate, calcium phosphate, and uric acid. For this purpose, current guidelines recommend increasing fluid intake, maintaining a balanced calcium intake, reducing dietary intake of sodium and animal proteins, and increasing intake of fruits and fibers.
  • In this review, the researchers analyzed the effects of each dietary factor on nephrolithiasis incidence and recurrence rate.
  • Available scientific evidence agrees on the harmful effects of high meat/animal protein intake and low calcium diets, whereas high content of fruits and vegetables associated with a balanced intake of low-fat dairy products carries the lowest risk for incident kidney stones.
  • Furthermore, a balanced vegetarian diet with dairy products seems to be the most protective diet for kidney stone patients.

Effects of kefir or milk supplementation on zonulin in overweight subjects. Pražnikar ZJ, Kenig S, Vardjan T, Bizjak MČ, Petelin A. J Dairy Sci. 2020 Mar 11. pii: S0022-0302(20)30199-5.

  • Zonulin is a protein that affects gut health by modulating the permeability of tight junctions between cells of the wall of the digestive tract.
  • Increased intestinal permeability has been shown to be involved in several diseases associated with low-grade chronic inflammation, including obesity and metabolic syndrome. In the last decade, growing evidence shows the beneficial effects of probiotic-containing food supplementation on these conditions.
  • In this crossover intervention study on 28 asymptomatic overweight adults, the researchers tested the effects of a 3-wk kefir supplementation compared with a 3-wk milk supplementation on serum zonulin levels. The effects on serum glucose, triacylglycerols, low-density lipoproteins, high-density lipoproteins, total cholesterol, markers of inflammation (C-reactive protein and adiponectin), anthropometric variables, mood, and appetite were also determined.
  • Kefir supplementation resulted in a greater improvement of serum zonulin levels, whereas a significant yet similar improvement in lipid profile and serum glucose levels was found in both supplementations.
  • Positive mood was slightly but significantly enhanced with kefir supplementation, and reduced with milk supplementation. The C-reactive protein, adiponectin, and appetite were unaffected.
  • In conclusion, supplementation with both dairy products had health beneficial effects, but only kefir showed an effect on the intestinal barrier dysfunction marker.

Association between dairy consumption and prevalence of obesity in adult population of northeast China: An internet-based cross-sectional study. Song X, Li R, Guo L, Guo P, Zhang M, Feng R. Asia Pac J Clin Nutr. 2020;29(1):110-119.

  • Dairy has been shown to reduce the risk of obesity in many epidemiological studies. However, few studies have been fully conducted in China in this respect.
  • In this study, researchers aimed to investigate the association between dairy consumption and prevalence of obesity in an adult Chinese population.
  • A cross-sectional study was performed in an adult population of 5,598 in northeast China, aged ≥18 years. Intakes of dairy products were obtained by internet-based dietary questionnaire for the Chinese (IDQC).
  • A total of 3,871 participants, including 1,700 men and 2,171 women, were eligible for analysis. Men who consumed ≥100 g/day of yogurt had lower risks of abdominal obesity (multivariate-adjusted OR=0.41) than men who did not consume yogurt.
  • Women who consumed ≥200 g/day of milk had lower risks of overall obesity (multivariate-adjusted OR=0.47) than women who did not consume milk.
  • In conclusion, increased fermented dairy consumption was associated with lower risk of obesity in adult population in northeast China. Further studies are needed to explain the observed gender-specific difference.