Hello and welcome to the September 2019 DRB! 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

Composition and Toxicity of Biogas Produced from Different Feedstocks in California. Li Y, Alaimo CP, Kim M, Kado NY, Peppers J, Xue J, Wan C, Green PG, Zhang R, Jenkins BM, Vogel CFA, Wuertz S, Young TM, Kleeman MJ. Environ Sci Technol. 2019 Oct 1;53(19):11569-11579.

  • Biogas is a renewable energy source composed of methane, carbon dioxide, and other trace compounds produced from anaerobic digestion of organic matter. A variety of feedstocks can be combined with different digestion techniques that each yields biogas with different trace compositions. California is expanding biogas production systems to help meet greenhouse gas reduction goals.
  • The objective of this study was to report the composition of six California biogas streams from three different feedstocks (dairy manure, food waste, and municipal solid waste). The chemical and biological composition of raw biogas is reported, and the toxicity of combusted biogas is tested under fresh and photochemically aged conditions.
  • Results show that:
    • Municipal waste biogas contained elevated levels of chemicals associated with volatile chemical products such as aromatic hydrocarbons, siloxanes, and certain halogenated hydrocarbons.
    • Food waste biogas contained elevated levels of sulfur-containing compounds including hydrogen sulfide, mercaptans, and sulfur dioxide.
    • Dairy manure biogas generally had lower concentrations of trace chemicals, but the combustion products had slightly higher toxicity response compared to the other feedstocks.
  • No strong evidence of potential occupational health risk was detected at any of the five California biogas sites. This study also found no obvious differences between the toxicity of different biogas combustion exhaust streams after atmospheric dilution and aging.

Dairy producer perceptions of the Farmers Assuring Responsible Management (FARM) Animal Care Program. Rink KA, Turk P, Archibeque-Engle SL, Wilmer H, Ahola JK, Hadrich JC, Roman-Muniz IN. J Dairy Sci. 2019 Sep 25. pii: S0022-0302(19)30853-7.

  • Dairy farms producing 98% of the US milk supply participate in the Farmers Assuring Responsible Management (FARM) Animal Care Program. Producers who sell milk to cooperatives or processors participating in FARM must follow program standards.
  • The objectives of this study were to assess producer perceptions about the knowledge, experience, and value of FARM and to determine whether perceptions differ based on demographics.
  • Dairy producers from cooperatives or processors that participate in the FARM program were recruited via electronic and postal mail to participate in a 30-question survey. A total of 487 respondents from 40 states completed the survey.
  • Thematic analysis revealed 5 main themes: distrust of program, producers on the defense, anger, efficiency, and nostalgia. Of respondents, 73.6% reported being knowledgeable about the FARM Animal Care Program.
  • Greater level of formal education and larger herd size were associated with greater producer knowledge. More dairy producer input in the revisions of FARM was identified as a need by 83.3% of respondents. Although 89.3% of respondents reported positive experiences with evaluations and relationships with evaluators, 45.6% did not think that the program had value overall. Respondent age was positively associated with perceived value of FARM.
  • Results indicate that to increase buy-in and positive perceptions from producers, future versions of FARM should solicit producer input during the development of program standards, target specific producer demographics for program promotion, and address perceived communication deficits and program inequalities.

Effects of Dietary Forage Proportion on Feed Intake, Growth Performance, Nutrient Digestibility, and Enteric Methane Emissions of Holstein Heifers at Various Growth Stages. Dong L, Li B, Diao Q. Animals (Basel). 2019 Sep 26;9(10). pii: E725.

  • Enteric methane (CH4) emissions from young ruminants contribute to a substantial proportion of atmospheric CH4 Development of emission inventory and mitigation approaches needs accurate estimation of individual emission from animals under various physiological conditions and production systems.
  • This research investigated the effect of different dietary concentrate contents on feed intake, growth performance, nutrient digestibility and CH4emissions of heifers at various stages, and also developed linear or non-linear prediction equations using data measured by sulphur hexafluoride tracer technique.
  • Increasing dietary concentrate contents increased feed intake and growth rate, enhanced nutrient digestibility, and reduced enteric CH4 Heifers at the age of 9, 12, and 15 months with an average weight of 267.7, 342.1, and 418.6 kg produced 105.2, 137.4, and 209.4 g/day of CH4, and have an average value of CH4energy per gross energy intake (Ym) 0.054, 0.064, 0.0667, respectively.
  • Equations relating CH4emission values with animal and feed characteristics were developed with high determination coefficients for heifers at different growth stages. Dietary concentrate contents had significant influence on overall performance of heifers. These data can be used to develop regional or national emission inventories and mitigation approaches for heifers under various production regimes.

Multidrug-Resistant Escherichia coliKlebsiella pneumoniae and Staphylococcus spp. in Houseflies and Blowflies from Farms and Their Environmental Settings. Poudel A, Hathcock T, Butaye P, Kang Y, Price S, Macklin K, Walz P, Cattley R, Kalalah A, Adekanmbi F, Wang C. Int J Environ Res Public Health. 2019 Sep 25;16(19). pii: E3583.

  • Antimicrobial resistance is rising globally at an alarming rate. While multiple active surveillance programs have been established to monitor the antimicrobial resistance, studies on the environmental link to antimicrobial spread are lacking.
  • In this study, a total of 493 flies were trapped from a dairy unit, a dog kennel, a poultry farm, a beef cattle unit, an urban trash facility and an urban downtown area to isolate Escherichia coli, Klebsiella pneumoniae and Staphylococcus spp. for antimicrobial susceptibility testing and molecular characterization.
  • The results showed that E. coli, K. pneumoniae and coagulase-negative Staphylococcus were recovered from 43.9%, 15.5% and 66.2% of the houseflies, and 26.0%, 19.2%, 37.0% of the blowflies, respectively.
  • In total, 35.3% of flies were found to harbor antimicrobial-resistant bacteria and 9.0% contained multidrug-resistant isolates. Three Staphylococcus aureus isolates were recovered from blowflies while three extended spectrum beta lactamase (ESBL)-carrying E. coli and one ESBL-carrying K. pneumoniae were isolated from houseflies. Whole genome sequencing identified the antimicrobial resistance genes blaCMY-2 and blaCTXM-1 as ESBLs.
  • Taken together, the data indicate that flies can be used as indicators for environmental contamination of antimicrobial resistance. More extensive studies are warranted to explore the sentinel role of flies for antimicrobial resistance.

Effects of recycled manure solids bedding on the spread of gastrointestinal parasites in the environment of dairies and milk. Lasprilla-Mantilla MI, Wagner V, Pena J, Frechette A, Thivierge K, Dufour S, Fernandez-Prada C. J Dairy Sci. 2019 Sep 20. pii: S0022-0302(19)30832-X.

  • The introduction of bedding dairy cows on recycled manure solids (RMS) has led to concern that there could be an increased, unacceptable risk to animal and human health.
  • The primary aim of this work was to isolate common bovine digestive tract parasites in RMS, as well as to determine the ability of current RMS preparation procedures to eliminate these pathogens.
  • Other objectives were to assess whether any of the aforementioned parasites could be retrieved in bulk milk from dairies using RMS and to study whether the prevalence of these parasites differed among manure of cows housed on RMS versus on straw bedding.
  • For the study, 27 RMS farms and 61 control farms were recruited. Samples of manure from the pre-pit and milk from the bulk tank were recovered from straw-bedding farms and RMS-based farms. In addition, samples from the manure solid fraction after liquid extraction, RMS before use, and RMS currently in use were recovered from RMS herds.
  • Results revealed a high prevalence of Cryptosporidium spp. (C. parvum, C. andersoni, and C. meleagridis, identified by PCR) and Eimeria spp. (mainly E. bovis and E. zuernii) parasites in both types of farms, with a larger proportion of manure samples from RMS-bedded farms testing positive for Cryptosporidium parasites compared with manure from straw-bedded farms.
  • Both Cryptosporidium spp. and Eimeria spp. oocysts were found at every step of RMS preparation and transformation, showing that current RMS preparation strategies do not guarantee the destruction of protozoan parasites.
  • Cryptosporidium parvum, a potential zoonotic risk for professionals in close contact with livestock, was found to be present in 32 out of 61 straw-bedded and 24 of 27 RMS farms. No protozoan parasites were found in any sample derived from bulk milk, neither by microscopy analysis nor by molecular methods.

Economic and livestock health impacts of birds on dairies: Evidence from a survey of Washington dairy operators. Elser JL, Adams Progar AL, Steensma KMM, Caskin TP, Kerr SR, Shwiff SA. PLoS One. 2019 Sep 19;14(9):e0222398.

  • Birds are common pests on dairies, consuming and contaminating feed intended for cattle. As a result, dairy operators experience increased feed costs and increased pathogen and disease risk.
  • The survey described in this research paper aimed to investigate the economic and health impacts of birds on dairies.
  • The researchers surveyed dairy operators attending the 2017 Washington Dairy Conference to examine the impact of birds on dairies in Washington State.
  • Dairy operators reported feed losses valued at $55 per cow resulting in annual losses totaling $5.5 million in the Western region of the state and $9.2 million in the Eastern region of the state.
  • Shooting was the most commonly used bird management method and European starlings (Sternus vulgaris) were the most frequently implicated species statewide.
  • Bird abundance greater than 10,000 birds per day was associated with larger herd size and with self-reported presence of Johne’s disease and Salmonella.


Selected Articles on Dairy Intake and Human Health

Effects of Full-Fat and Fermented Dairy Products on Cardiometabolic Disease: Food Is More Than the Sum of Its Parts. Astrup A, Geiker NRW, Magkos F. Adv Nutr. 2019 Sep 1;10(5):924S-930S.

  • Current dietary recommendations to limit consumption of saturated fat are largely based on early nutrition studies demonstrating a direct link between dietary saturated fat, elevated blood cholesterol levels, and increased risk of cardiovascular disease. As full-fat dairy products are rich in saturated fat, these dietary guidelines recommend consumption of fat-free or low-fat dairy products in place of full-fat dairy.
  • However, dairy products vary greatly in both their nutrient content and their bioactive ingredients, and research increasingly highlights the importance of focusing on whole foods (i.e., the food matrix) as opposed to single nutrients, such as saturated fat.
  • In fact, the weight of evidence from recent large and well-controlled studies, systematic reviews, and meta-analyses of both observational studies and randomized controlled trials indicates that full-fat dairy products, particularly yogurt and cheese, do not exert the detrimental effects on insulin sensitivity, blood lipid profile, and blood pressure as previously predicted on the basis of their sodium and saturated fat contents; they do not increase cardiometabolic disease risk and may in fact protect against cardiovascular disease and type 2 diabetes.
  • Although more research is warranted to adjust for possible confounding factors and to better understand the mechanisms of action of dairy products on health outcomes, it becomes increasingly clear that the recommendation to restrict dietary saturated fat to reduce risk of cardiometabolic disease is getting outdated. Therefore, the suggestion to restrict or eliminate full-fat dairy from the diet may not be the optimal strategy for reducing cardiometabolic disease risk and should be re-evaluated in light of recent evidence.

Introduction to the Sixth Global Summit on the Health Effects of Yogurt: Yogurt, More than the Sum of Its Parts. Donovan SM, Goulet O. Adv Nutr. 2019 Sep 1;10(5):913S-916S.

  • Foods are not only a collection of individual components but are complex matrices. The food matrix is defined by the USDA as “the nutrient and nonnutrient components of foods and their molecular relations.”
  • The matrix of a food is an important factor in evaluating its nutritional and health contributions to the consumer. Dairy foods are a complex mix of various nutrients and other components, which together form the food matrix.
  • There are three main types of dairy food matrices: liquid (milk, some fermented milks), semi-solid (yogurt, some fresh cheeses), and solid (most cheeses). The nutritional value of dairy foods is determined by their nutrient composition and matrix structure, which can affect digestibility and the bioavailability of nutrients.
  • Additionally, a number of studies have shown that the health effects of dairy products, of similar nutrient content, vary by their matrix.

Dairy Foods, Obesity, and Metabolic Health: The Role of the Food Matrix Compared with Single Nutrients. Mozaffarian, D. Advances in Nutrition, Volume 10, Issue 5, September 2019, Pages 917S–923S.

  • In the 20th century, scientific and geopolitical events led to the concept of food as a delivery system for calories and specific isolated nutrients. As a result, conventional dietary guidelines have focused on individual nutrients to maintain health and prevent disease.
  • For dairy foods, this has led to general dietary recommendations to consume 2–3 daily servings of reduced-fat dairy foods, without regard to type (e.g., yogurt, cheese, milk), largely based on theorized benefits of isolated nutrients for bone health (e.g., calcium, vitamin D) and theorized harms of isolated nutrients for cardiovascular diseases (CVDs) and obesity (e.g., total fat, saturated fat, total calories).
  • However, advances in nutrition science have demonstrated that foods represent complex matrices of nutrients, minerals, bioactives, food structures, and other factors (e.g., phoshopholipids, prebiotics, probiotics) with correspondingly complex effects on health and disease.
  • The present evidence suggests that whole-fat dairy foods do not cause weight gain, that overall dairy consumption increases lean body mass and reduces body fat, that yogurt consumption and probiotics reduce weight gain, that fermented dairy consumption including cheese is linked to lower CVD risk, and that yogurt, cheese, and even dairy fat may protect against type 2 diabetes.
  • Based on the current science, dairy consumption is part of a healthy diet, without strong evidence to favor reduced-fat products; while intakes of probiotic-containing unsweetened and fermented dairy products such as yogurt and cheese appear especially beneficial.

Dairy Fat Consumption and the Risk of Metabolic Syndrome: An Examination of the Saturated Fatty Acids in Dairy. Unger AL, Torres-Gonzalez M, Kraft J. Nutrients. 2019 Sep 12;11(9).

  • Lifestyle is a key modifiable risk factor involved in the manifestation of metabolic syndrome and, in particular, diet plays a pivotal role in its prevention and development.
  • Current dietary guidelines discourage the consumption of saturated fat and dietary sources rich in saturated fat, such as dairy products, despite data suggesting that full-fat dairy consumption is protective against metabolic syndrome.
  • This narrative review assessed the recent epidemiological and clinical research that examined the consumption of dairy-derived saturated fatty acids (SFA) on metabolic syndrome risk. In addition, this review evaluated studies of individual SFA to gain insight into the potential mechanisms at play with intake of a diet enriched with these dairy-derived fatty acids.
  • This work underscores that SFA are a heterogenous class of fatty acids that can differ considerably in their biological activity within the body depending on their length and specific chemical structure.
  • In summary, previous work on the impact of dairy-derived SFA consumption on disease risk suggests that there is currently insufficient evidence to support current dietary guidelines which consolidate all dietary SFA into a single group of nutrients whose consumption should be reduced, regardless of dietary source, food matrix, and composition.

Association of Dairy Product Consumption with Metabolic and Inflammatory Biomarkers in Adolescents: A Cross-Sectional Analysis from the LabMed Study. Abreu S, Agostinis-Sobrinho C, Santos R, Moreira C, Lopes L, Gonçalves C, Oliveira-Santos J, Sousa-Sá E, Rodrigues B, Mota J, Rosário R. Nutrients. 2019 Sep 21;11(10). pii: E2268.

  • Coupled with other factors such as age, sex, weight status, physical activity, smoking, and alcohol habits, diet can influence the regulation of inflammation. In parallel with a growing body of evidence on the role of diet, research has emerged on the association of dairy products with inflammation.
  • Low-grade systemic inflammation has been associated with the development and progression of a number of chronic non-communicable diseases. Several inflammation markers are used due to their clinical relevance, including C-reactive protein (CRP) and interleukin-6 (IL-6).
  • This study aimed to investigate the association between dairy product consumption and metabolic and inflammatory biomarkers in Portuguese adolescents, and whether the association differed by weight status.
  • A cross-sectional study was conducted during the school year 2011/2012 with 412 Portuguese adolescents (52.4% girls) in 7th and 10th grade (aged 12 to 18 years old). The World Health Organization cutoffs were used to categorize adolescents as non-overweight (NW) or overweight (OW).
  • The majority of adolescents were NW (67.2%). NW adolescents had lower IL-6, CRP, and leptin concentration than their counterparts. Higher levels of total dairy product and milk intake were inversely associated with IL-6 in NW adolescents, but not in OW adolescents. NW adolescents in the second tertile of yogurt consumption had lower level of IL-6 compared to those in the first tertile.
  • These results suggest an inverse association between total dairy product and milk intake and serum concentrations of IL-6 only among NW adolescents.

Dairy consumption during adolescence and endometriosis risk. Nodler JL, Harris HR, Chavarro JE, Frazier AL, Missmer SA. Am J Obstet Gynecol. 2019 Sep 14. pii: S0002-9378(19)31115-9.

  • Modifiable risk factors such as diet may be important in both the etiology and progression of endometriosis as well as the prevalence of pain symptoms and infertility associated with this condition.
  • In adults, higher intake of dairy has been associated with lower risk of endometriosis diagnosis. There is currently no literature on whether dairy intake during adolescence – a potentially critical window of exposure – influences endometriosis risk.
  • The study’s objective was to evaluate the association between consumption of dairy foods in adolescence and risk of endometriosis.
  • A prospective cohort study, the Nurses’ Health Study II (NHSII), which has prospectively collected data since 1989.
  • Among women who completed the HS-FFQ in 1998, 581 cases of endometriosis were diagnosed among 32,868 premenopausal women from 1998 to 2013. Women who consumed more than four servings/day of dairy foods during adolescence had a 32% lower risk of endometriosis during adulthood compared to women consuming one or fewer servings/day.
  • The association was similar for low-fat and high-fat dairy foods. Yogurt and ice cream consumption, specifically, were associated with a lower risk of endometriosis. Those who consumed two or more servings of yogurt per week as an adolescent had a 29% lower risk of endometriosis diagnosis compared to those consuming less than one serving per week.
  • In addition, women who consumed one or more servings/day of ice cream per day during adolescence had a 38% lower risk of endometriosis diagnosis compared to those consuming less than one serving per week.
  • These findings suggest that dairy consumption, specifically yogurt and ice cream intake, in adolescence may reduce the risk of subsequent endometriosis diagnosis. Future studies in adolescent populations are needed to confirm these results.

Effects of Regular Kefir Consumption on Gut Microbiota in Patients with Metabolic Syndrome: A Parallel-Group, Randomized, Controlled Study. Bellikci-Koyu E, Sarer-Yurekli BP, Akyon Y, Aydin-Kose F, Karagozlu C, Ozgen AG, Brinkmann A, Nitsche A, Ergunay K, Yilmaz E, Buyuktuncer Z. Nutrients. 2019 Sep 4;11(9). pii: E2089.

  • Several health-promoting effects of kefir have been suggested, however, there is limited evidence for its potential effect on gut microbiota in metabolic syndrome.
  • This study aimed to investigate the effects of regular kefir consumption on gut microbiota composition, and their relation with the components of metabolic syndrome.
  • In a parallel-group, randomized, controlled clinical trial setting, patients with metabolic syndrome were randomized to receive 180 mL/day kefir (n= 12) or unfermented milk (n = 10) for 12 weeks.
  • Fasting insulin, HOMA-IR, TNF-α, IFN-γ, and systolic and diastolic blood pressure showed a significant decrease by the intervention of kefir. However, no significant difference was obtained between the kefir and unfermented milk groups.
  • Gut microbiota analysis showed that regular kefir consumption resulted in a significant increase only in the relative abundance of Actinobacteria. No significant change in the relative abundance of Bacteroidetes, Proteobacteria or Verrucomicrobiaby kefir consumption was obtained. Furthermore, the changes in the relative abundance of sub-phylum bacterial populations did not differ significantly between the groups.
  • Kefir supplementation had favorable effects on some of the metabolic syndrome parameters, however, further investigation is needed to understand its effect on gut microbiota composition.

Whey Protein Supplementation Compared to Collagen Increases Blood Nesfatin Concentrations and Decreases Android Fat in Overweight Women: A Randomized Double-Blind Study. Giglio BM, Schincaglia RM, da Silva AS, Fazani ICS, Monteiro PA, Mota JF, Cunha JP, Pichard C, Pimentel GD. Nutrients. 2019 Sep 2;11(9). pii: E2051.

  • Protein supplements are usually used to control body weight, however, the impact of protein quality on body fat attenuation is unknown.
  • This study investigated the effects of isocaloric isoproteic supplementation of either whey protein (WG) or hydrolysed collagen supplementation (CG) on dietary intake, adiposity and biochemical markers in overweight women.
  • In this randomized double-blind study, 37 women (mean age 40 years; BMI of 31), consumed sachets containing 40 g/day of concentrated whey protein (25 g total protein, 2.4 leucine, 1.0 valine, 1.5 isoleucine) or 38 g/day of hydrolysed collagen (26 g total protein, 1.02 leucine, 0.91 valine, 0.53 isoleucine) as an afternoon snack.
  • After eight weeks, there were no differences in caloric intake or protein, carbohydrate and lipids intakes. BMI increased in the CG (0.2 ± 1.1 kg/m2) but did not change in WG. WG decreased the android fat (−0.1 ± 0.3 kg) and increased nesfatin concentrations (4.9 ± 3.2 ng/mL) compared to CG.
  • In conclusion, whey protein supplementation in overweight women increased nesfatin concentrations and could promote increase of resting metabolic rate as part of body composition improvement programs compared to collagen supplementation for 8 weeks. Additionally, these findings suggest that collagen may not be an effective supplement for overweight women who are attempting to alter body composition.