The 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

Are dietary strategies to mitigate enteric methane emission equally effective across dairy cattle, beef cattle, and sheep? van Gastelen S, Dijkstra J, Bannink A. J Dairy Sci. 2019 May 9. pii: S0022-0302(19)30422-9.

  • The digestive physiology of ruminants is sufficiently different (e.g., with respect to mean retention time of digesta, digestibility of the feed offered, digestion, and fermentation characteristics) that caution is needed before extrapolating results from one type of ruminant to another.
  • The objectives of the present study were (1) to provide an overview of some essential differences in rumen physiology between dairy cattle, beef cattle, and sheep that are related to methane (CH4) emission; and (2) to evaluate whether dietary strategies to mitigate CH4emission with various modes of action are equally effective in dairy cattle, beef cattle, and sheep.
  • A literature search was performed using Web of Science and Scopus, and 94 studies were selected from the literature. Per study, the effect size of the dietary strategies was expressed as a proportion (%) of the control level of CH4emission, as this enabled a comparison across ruminant types.
  • Evaluation of the literature indicated that the effectiveness of forage-related CH4mitigation strategies, including feeding more highly digestible grass (herbage or silage) or replacing different forage types with corn silage, differs across ruminant types. These strategies are most effective for dairy cattle, are effective for beef cattle to a certain extent, but seem to have minor or no effects in sheep.
  • In general, the effectiveness of other dietary mitigation strategies, including increased concentrate feeding and feed additives (e.g., nitrate), appeared to be similar for dairy cattle, beef cattle, and sheep.
  • The researchers concluded that if the mode of action of a dietary CH4mitigation strategy is related to ruminant-specific factors, such as feed intake or rumen physiology, the effectiveness of the strategy differs across ruminant types, whereas if the mode of action is associated with methanogenesis-related fermentation pathways, the strategy is effective across ruminant types.

Dairy intensification: Drivers, impacts and alternatives. Clay N, Garnett T, Lorimer J. Ambio. pp 1–14. 2019 May 4. 

  • Dairy production systems have rapidly intensified over the past several decades. Dairy farms in many world regions are larger and concentrated in fewer hands. Higher productivity can increase overall economic gains but also incurs site-specific social and environmental costs.
  • In this paper, the researchers review the drivers and impacts of dairy intensification. They identify in the literature four prominent concerns about dairy intensification: the environment, animal welfare, socioeconomic well-being, and human health.
  • The researchers then critically assess three frameworks-sustainable intensification, multifunctionality, and agroecology-which promise win-win solutions to these concerns.
  • The researchers call for research and policy approaches that can better account for synergies and trade-offs among the multiple dimensions of dairy impacts. Specifically, they suggest the need to (1) consider dairy system transitions within broader processes of social-environmental change and (2) investigate how certain framings and metrics may lead to uneven social-environmental outcomes. Such work can help visualize transformations towards more equitable, ethical, and sustainable food systems.

Fecal Microbial Communities in a Large Representative Cohort of California Dairy Cows Jill V. Hagey, Srijak Bhatnagar, Jennifer M. Heguy, Betsy M. Karle, Patricia L. Price, Deanne Meyer, Elizabeth A. Maga. Front Microbiol. 2019; 10: 1093. Published online 2019 May 16. CDRF-Funded Research!

  • Improved sequencing and analytical techniques allow for better resolution of microbial communities; however, the agriculture field lacks an updated analysis surveying the fecal microbial populations of dairy cattle in California.
  • This study is a large-scale survey to determine the composition of the bacterial community present in the feces of lactating dairy cattle on commercial dairy operations.
  • For the study, 10 dairy farms across northern and central California representing a variety of feeding and management systems were enrolled. The farms represented three typical housing types including five freestall, two drylot and three pasture-based management systems. Fresh feces were collected from 15 randomly selected cows on each farm and analyzed using 16S rRNA gene amplicon sequencing.
  • This study found that housing type, individual farm, and dietary components significantly affected the alpha diversity of the fecal microbiota. While only one Operational Taxonomic Unit (OTU) was common among all the sampled individuals, 15 bacterial families and 27 genera were shared among 95% of samples.
  • The ratio of the families Coriobacteriaceaeto Bifidobacteriaceae was significantly different between housing types and farms with pasture fed animals having a higher relative abundance of Coriobacteriaceae. A majority of samples were positive for at least one OTU assigned to Enterobacteriaceae and 31% of samples contained OTUs assigned to Campylobacter. However, the relative abundance of both taxa was <0.1%.
  • The microbial composition displays individual farm specific signatures, but housing type plays a role. These data provide insights into the composition of the core fecal microbiota of commercial dairy cows in California and will further generate hypotheses for strategies to manipulate the microbiome of cattle.

Evaluating the potential use of a dairy industry residue to induce denitrification in polluted water bodies: A flow-through experiment. Margalef-Marti R, Carrey R, Soler A, Otero N. J Environ Manage. 2019 May 27;245:86-94.

  • Improving the effectiveness and economics of strategies to remediate groundwater nitrate pollution is a matter of concern. In this context, the addition of whey into aquifers could provide a feasible solution to attenuate nitrate contamination by inducing heterotrophic denitrification, while recycling an industry residue.
  • Before its application, the efficacy of the treatment must be studied at laboratory-scale to optimize the application strategy in order to avoid the generation of harmful intermediate compounds.
  • To do this, a flow-through denitrification experiment using whey as organic C source was performed, and different C/N ratios and injection periodicities were tested. The collected samples were analyzed to determine the chemical and isotopic composition of N and C compounds.
  • The results proved that whey could promote denitrification. Nitrate was completely removed when using either a 3.0 or 2.0 C/N ratio. However, daily injection with C/N ratios from 1.25 to 1.5 seemed advantageous, since this strategy decreased nitrate concentration to values below the threshold for water consumption while avoiding nitrite accumulation and whey release with the outflow.
  • The isotopic results confirmed that nitrate attenuation was due to denitrification and that the production of Dissolved Inorganic Carbon (DIC) was related to bacterial whey oxidation. Furthermore, the isotopic data suggested that when denitrification was not complete, the outflow could present a mix of denitrified and non-denitrified water.
  • The calculated isotopic fractionation values (ε15NNO3/N2and ε18ONO3/N2) might be applied in the future to quantify the efficiency of the bioremediation treatments by whey application at field-scale.

Comparative study on the efficacy of sodium hypochlorite, aqueous ozone, and peracetic acid in the elimination of Salmonella from cattle manure contaminated various surfaces supported by Bayesian analysis. Megahed A, Aldridge B, Lowe J. PLoS One. 2019 May 23;14(5):e0217428.

  • Salmonella infection via foodborne transmission remains a major public health threat. Providing the dairy industry with an effective and safe disinfectant is considered a key step in improving the farm hygiene and biosecurity.
  • The main objective of this study was therefore to characterize and compare the decontamination power of NaOCl, aqueous-O3, and Peracetic acid against cattle manure based-Salmonella heavily contaminated various surfaces (plastic, nylon, rubber, and wood) using Bayesian analysis.
  • In a crossover design, 14 strips of each material were randomly assigned between 3 groups, treatment (n = 6), positive-control (contaminated with feces-Salmonella mixture, but not exposed to disinfectants, n = 6), and negative control (laboratory blank, inoculated only with sterile water, n = 2).
  • The strips were soaked in cattle manure inoculated with 107-108 of Salmonella Typhimurium-Choleraesuis and exposed to 50 mL of 200 ppm NaOCl, 9 ppm aqueous-O3, or 400 ppm Peracetic acid for 4 minutes.
  • On plastic and nylon surfaces, NaOCl, aqueous-O3, or Peracetic acid reduce Salmonella Typhimurium-Choleraesuis population to a safe level (>5.0-log10) within 4 minutes. On rubber surface, Peracetic acid and aqueous-O3 can produce a reduction in Salmonella Typhimurium-Choleraesuis population 50% and 30% higher than NaOCl. However, PAA can produce reduction factor on wood surface 40% higher than aqueous-O3 and NaOCl.
  • The researchers conclude that smooth surfaces were most effectively decontaminated. Peracetic acid of 400 ppm can provide an effective means for controlling Salmonella population heavily contaminated various surfaces in dairy operations. However, the safe residues and strong reactivity makes aqueous-O3 and Peracetic acid attractive alternative disinfectants for improving farm hygiene and biosecurity.

Proposed dairy calf birth certificate data and death loss categorization scheme. Lombard JE, Garry FB, Urie NJ, McGuirk SM, Godden SM, Sterner K, Earleywine TJ, Catherman D, Maas J. J Dairy Sci. 2019 May;102(5):4704-4712.

  • The majority of dairy heifer calves in the United States are destined to be dairy replacements. However, many dairy heifer and bull calves die before 6 mo of age. Of these calves, about 6% (more than 500,000 calves) die at birth or shortly after (i.e., currently termed “stillbirth”). An additional 6% of dairy heifers die during the preweaning period. Death loss in dairy calves is primarily due to stillbirths, failure to adapt to extrauterine life, and infectious disease processes.
  • The reasons for preweaning heifer calf deaths caused by infectious diseases are generally categorized based on easily recognizable clinical signs such as digestive disease/scours or respiratory disease. Most causes of calf death can be mitigated by appropriate preventive care or well-tailored treatments, meaning that the typical death loss percentage could be decreased with better management. Producers could gather information on the circumstances near birth and at death if they had appropriate guidance on what details to record and monitor.
  • This paper provides recommendations on data to collect at the time of birth (i.e., calf birth certificate data). The recording of these critical pieces of information is valuable in evaluating trends over time in morbidity and mortality events in dairy calves. Ideally, necropsy examination would substantially improve the identification of cause of death, but even without necropsy, attribution of cause of death can be improved by more carefully defining death loss categories in on-farm record systems.
  • The authors propose a death loss categorization scheme that more clearly delineates causes of death. Recommendations are provided for additional data to be collected at the time of death. Recording and analyzing birth certificate and death loss data will allow producers and veterinarians to better evaluate associations between calf risk factors and death, with the goal of reducing dairy calf mortality.

Invited review: A systematic review of the effects of prolonged cow-calf contact on behavior, welfare, and productivity. Meagher RK, Beaver A, Weary DM, von Keyserlingk MAG. J Dairy Sci. 2019 May 15. pii: S0022-0302(19)30436-9.

  • Separation of calves from cows within hours or days of birth is common on dairy farms. Stakeholders have conflicting perspectives on whether this practice is harmful or beneficial for the animals’ welfare and production.
  • The objective of this study was to critically evaluate the scientific evidence for both acute and long-term effects of early separation versus an extended period of cow-calf contact.
  • The outcomes investigated were the behavior, welfare (excluding physical health), and performance (milk yield and growth, respectively) of dairy cows and calves.
  • The literature review results showed that early separation (within 24 h postpartum) was found to reduce acute distress responses of cows and calves. However, longer cow-calf contact typically had positive longer-term effects on calves, promoting more normal social behavior, reducing abnormal behavior, and sometimes reducing responses to stressors.
  • In terms of productivity, allowing cows to nurse calves generally decreased the volume of milk available for sale during the nursing period, but we found no consistent evidence of reduced milk production over a longer period.
  • Allowing a prolonged period of nursing increased calf weight gains during the milk-feeding period.

Short communication: Persistent contamination by Listeria monocytogenes of bovine raw milk investigated by whole-genome sequencing. Ricchi M, Scaltriti E, Cammi G, Garbarino C, Arrigoni N, Morganti M, Pongolini S. J Dairy Sci. 2019 May 15. pii: S0022-0302(19)30442-4.

  • Following the persistent detection of Listeria monocytogenes in raw bovine milk sold through a vending machine, the 120 lactating cows of the herd producing the milk were subjected to bacteriological investigation.
  • A single cow with subclinical mastitis (1.2-1.3 × 105somatic cells/mL) and persistent L. monocytogenes excretion was detected. The cow was subjected to antimicrobial therapy, but L. monocytogenes excretion remained high (>3.0 × 102 cfu/mL).
  • Following culling of the infected cow, L. monocytogenes disappeared from the tank milk, and further isolates were recovered from the mammary parenchyma and lymph nodes of the infected cow.
  • To investigate the clonal nature of the contamination, all isolates recovered in the study (n = 13) were analyzed by serogroup PCR, pulsed-field gel electrophoresis, and whole-genome sequencing.
  • These results demonstrated the clonal nature of the contamination. All isolates belonged to lineage II, serogroup IIa, sequence type 37, clonal complex 37 and harbored some virulence determinants.
  • This case showed that, although relatively rare, prolonged milk contamination by L. monocytogenes can originate from subclinical and persistently infected cows, posing a health risk to consumers.


Selected Articles on Dairy Intake and Human Health

Role of Calcium and Low-Fat Dairy Foods in Weight-Loss Outcomes Revisited: Results from the Randomized Trial of Effects on Bone and Body Composition in Overweight/Obese Postmenopausal Women. Ilich JZ, Kelly OJ, Liu PY, Shin H, Kim Y, Chi Y, Wickrama KKAS, Colic-Baric I. Nutrients. 2019 May 23;11(5). pii: E1157.

  • Several studies have investigated the possibility of dairy foods and calcium mediating weight and body composition, but a consensus has not been reached.
  • This study aimed to investigate weight-loss-related outcomes during intervention with low-fat dairy foods or calcium + vitamin D supplements, both as complements to hypocaloric diets.
  • Overweight/obese Caucasian, early-postmenopausal women (n= 135) were recruited for a 6 month energy-restricted weight loss study complemented with either:
    • Low-fat dairy foods (4-5 servings/day)
    • Calcium + vitamin D supplements
    • Placebo pills
  • Participants on average lost ~4% of body weight, ~3% total fat, and ~2% of lean tissue. The significantly better outcomes were noticed in participants in the Low-fat dairy group regarding body composition (fat loss/lean tissue preservation), and in participants in the calcium and vitamin D supplement group regarding the bone mineral density outcomes, compared to those in the placebo group.
  • Therefore, increasing low-fat dairy foods to 4-5 servings/day and/or increasing calcium and vitamin D intake by supplements (in those who are at the borderline dietary intake) may be beneficial for weight loss/maintenance and may lead to more favorable bone and body composition outcomes in postmenopausal women during moderate weight loss.

The Impact of Dairy Products in the Development of Type 2 Diabetes: Where Does the Evidence Stand in 2019? Guo J, Givens DI, Astrup A, Bakker SJL, Goossens GH, Kratz M, Marette A, Pijl H, Soedamah-Muthu SS. Adv Nutr. 2019 May 24. pii: nmz050.

  • The prevalence of type 2 diabetes (T2D) has increased rapidly. Adopting a heathy diet is suggested as one of the effective behaviors to prevent or delay onset of T2D. Dairy consumption has been recommended as part of a healthy diet, but there remains uncertainty in both the scientific community and the public about the effect of different dairy products on T2D risk.
  • In a recent workshop, the evidence on dairy products and T2D risk was presented and discussed by a group of experts. The main conclusions from the workshop are presented in this position paper and are as follows.
    • 1) Available evidence from large prospective cohort studies and limited randomized controlled trials (RCTs) suggests that total dairy consumption has a neutral or moderately beneficial effect on T2D risk.
    • 2) Increasing evidence from prospective cohort studies indicates that yogurt is most strongly associated with a lower T2D risk, but evidence from RCTs is scarce.
    • 3) Fatty acids from dairy (medium-chain, odd, and very long-chain SFAs as well as trans-palmitoleic acid) are associated with lower T2D risk and improved metabolic health.
    • 4) The food matrix can be a stronger determinant of health effects than SFA content.
  • This review further identifies research gaps in the existing knowledge and highlights key research questions that need to be addressed to better understand the impact of dairy consumption on future T2D risk.

Effect of ingesting yogurt fermented with Lactobacillus delbrueckii ssp. bulgaricus OLL1073R-1 on influenza virus-bound salivary IgA in elderly residents of nursing homes: a randomized controlled trial. Yamamoto Y, Saruta J, Takahashi T, To M, Shimizu T, Hayashi T, Morozumi T, Kubota N, Kamata Y, Makino S, Kano H, Hemmi J, Asami Y, Nagai T, Misawa K, Kato S, Tsukinoki K. Acta Odontol Scand. 2019 May 16:1-8.

  • The purpose of this study was to clarify the influence of consuming yogurt fermented with Lactobacillus delbrueckii ssp. bulgaricus OLL1073R-1 (1073R-1-yogurt) on influenza virus-bound salivary immunoglobulin A (IgA) levels, in the elderly residents of nursing homes.
  • A double-blind, parallel-group, randomized controlled trial was conducted with 96 elderly volunteers residing in 2 nursing homes. During the trial, participants consumed 100 g of 1073R-1-yogurt every morning for 12 weeks, whereas the control participants consumed yogurt fermented with a different Lactobacillus strain (control yogurt).
  • Saliva was collected before the trial and after 4, 8 and 12 weeks of yogurt ingestion. The data indicated that consumption of 1073R-1-yogurt affected influenza A virus subtype H3N2-bound IgA levels in saliva. In addition, saliva flow rate and total IgA levels increased in response to the yogurt intake period in both the 1073R-1 and control yogurt groups.
  • These results suggest that continuous daily ingestion of 1073R-1-yogurt may help prevent infection with influenza A virus subtype H3N2 in elderly subjects with weakened immunity, by increasing the production of influenza A virus subtype of H3N2-bound salivary IgA.

Effect of whey protein on blood pressure in pre- and mildly hypertensive adults: A randomized controlled study. Yang J, Wang HP, Tong X, Li ZN, Xu JY, Zhou L, Zhou BY, Qin LQ. Food Sci Nutr. 2019 Apr 21;7(5):1857-1864.

  • In China, the frequency of mild hypertension cases remains prevalently high. Meanwhile, diets containing functional ingredients that control blood pressure have received considerable attention.
  • In this randomized, controlled intervention study, 54 participants were randomly assigned to consume 30 g of whey protein or maltodextrin daily for 12 weeks.
  • Blood pressure, body composition, biochemical analysis in plasma, and flow-mediated dilation, an index for evaluating endothelial function, were measured.
  • The increase in flow-mediated dilation was significantly higher in the whey protein group than in the control group.
  • In the overweight and obese participants, the systolic blood pressure was significantly lower in the whey protein group than in the control group, and body fat, fat percentage, and waist circumference significantly decreased in the whey protein group.
  • In conclusion, whey protein significantly decreased systolic blood pressure in pre- and mildly hypertensive adults, who are also overweight and obese. Whey protein also improved endothelial function. The lowering effect of blood pressure was probably related to body fat loss in these participants.

Dairy Food Consumption is Inversely Associated with the Prevalence of Periodontal Disease in Korean Adults. Lee K, Kim J. Nutrients. 2019 May 9;11(5). pii: E1035.

  • Dairy food consumption is known to be inversely associated with periodontal disease. However, there are conflicting results depending on the type of dairy foods.
  • The aim of this study was to determine the relationship between individual dairy food consumption and periodontal disease.
  • A total of 9798 Korean adults, aged ≥30 years, who participated in the fifth and sixth Korea National Health and Nutrition Examination Survey were included in this study’s analysis. Dairy food consumption was measured by the semi-quantitative food frequency questionnaire. Periodontal disease was defined as Community Periodontal Index score ≥3 in more than one of six sextants.
  • Frequent intake of dairy foods (≥7 servings/week) was associated with a 24% lower prevalence of periodontal disease compared with never consumers after adjustment for age, gender, income, education, smoking, alcohol consumption, body mass index, diabetes mellitus status, calcium intake, tooth brushing frequency, and use of dental floss.
  • Also, frequent intake of milk (≥7 servings/week) was associated with a 26% lower prevalence of periodontal disease after adjustment for potential confounders.
  • In conclusion, frequent consumption of dairy food including milk may have a beneficial effect on periodontal disease in the Korean adult population.

Full-Fat Dairy Food Intake is Associated with a Lower Risk of Incident Diabetes Among American Indians with Low Total Dairy Food Intake. Kummer K, Jensen PN, Kratz M, Lemaitre RN, Howard BV, Cole SA, Fretts AM. J Nutr. 2019 May 9. pii: nxz058.

  • Diet plays a key role in development of diabetes, and there has been recent interest in better understanding the association of dairy food intake with diabetes.
  • This study examined the associations of full-fat and low-fat dairy food intake with incident diabetes among American Indians — a population with a high burden of diabetes.
  • The study included participants from the Strong Heart Family Study (SHFS), a family-based study of cardiovascular disease in American Indians, free of diabetes at baseline (2001-2003) (n = 1623). Participants were 14 to 86 years old at baseline. Dairy serving sizes were defined as 250 mL for milk and 42.5 g for cheese.
  • After a follow-up of 11 years: Reported intake of dairy foods was low, but interestingly, participants who reported the highest full-fat dairy food intake had a lower risk of diabetes compared to those who reported the lowest full-fat food dairy intake.
  • Low-fat dairy food intake was not associated with diabetes.
  • In conclusion, participants who reported higher full-fat dairy food intake had a lower risk of diabetes than participants who reported lower intake. These findings may be of interest to populations with low dairy food intake.

SUPPLEMENT—ROLE OF MILK AND DAIRY PRODUCTS IN HEALTH AND PREVENTION OF NONCOMMUNICABLE CHRONIC DISEASES: A SERIES OF SYSTEMATIC REVIEWS – Advances in Nutrition, Volume 10, Supp 2, May 2019 The present supplement aims to assess and summarize scientific evidence regarding the impact of dairy intake on health and all-cause mortality, and on the prevention of diverse chronic diseases, mainly from meta-analyses of observational studies and randomized controlled trials (RCTs). The systematic reviews and meta-analyses of the present supplement support adequate milk consumption at various stages of life and in the prevention/control of various noncommunicable chronic diseases.