Welcome to the September 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

Net reductions in greenhouse gas emissions from feed additive use in California dairy cattle. Feng X, Kebreab E.PLoS One. 2020 Sep 18;15(9):e0234289.

  • The livestock industry is one of the main contributors to greenhouse gas emissions and there is an increasing demand for the industry to reduce its carbon footprint. Several studies have shown that feed additives 3-nitroxypropanol and nitrate to be effective in reducing enteric methane emissions.
  • The objective of this study was to estimate the net mitigating effect of using 3-nitroxypropanol and nitrate on total greenhouse gas emissions in California dairy industry.
  • A life cycle assessment approach was used to conduct a cradle-to-farm gate environmental impact analysis based on dairy production system in California. Emissions associated with crop production, feed additive production, enteric methane, farm management, and manure storage were calculated and expressed as kg CO2 equivalents (CO2e) per kg of energy corrected milk.
  • The total greenhouse gas emissions from baseline, 3-nitroxypropanol and nitrate offered during lactation were 1.12, 0.993, and 1.08 kg CO2e/kg energy corrected milk, respectively. The average net reduction rates for 3-nitroxypropanol and nitrate were 11.7% and 3.95%, respectively. In both cases, using the feed additives on the whole herd slightly improved overall carbon footprint reduction compared to limiting its use during lactation phase.
  • Although both 3-nitroxypropanol and nitrate had effects on decreasing the total greenhouse gas emission, the former was much more effective with no known safety issues in reducing the carbon footprint of dairy production in California.

Genetic, farm, and lactation effects on behavior and performance of US Holsteins in automated milking systems. Dechow CD, Sondericker KS, Enab AA, Hardie LC.J Dairy Sci. 2020 Sep 24:S0022-0302(20)30754-2.

  • Selecting for favorable behavior and performance could enhance the efficiency of production in automated milking systems (AMS).
  • The objectives of this study were to describe AMS behavior and performance in Holsteins, estimate genetic parameters among AMS traits, and determine genetic relationships of AMS traits with other routinely recorded traits.
  • The edited data included 1,101,651 individual milking records and 394,636 daily records from 2,531 lactations and 1,714 cows that resided on 3 farms. Traits considered were individual milking and daily totals for milk yield, milking time, milk harvest rate (the ratio of milk yield to milking time), milk flow rate, electrical conductivity, machine kickoffs, incomplete milkings, and blood in milk.
  • Mature cows had higher milk harvest rates (2.05 kg/min) than first-lactation cows (1.73 kg/min) with larger differences in early lactation. First-lactation cows were more likely to kick off the machine (15.04%) than mature cows (8.62%), particularly in early lactation.
  • Udder conformation traits did not have favorable genetic correlations with AMS traits, with the exception that longer teats were correlated with fewer kickoffs and incomplete milkings; increased milk harvest rate and flow rate were unfavorably associated with genetic merit for udder health.
  • There is genetic variation for milking efficiency and behavioral traits, suggesting genetic selection to enhance efficiency in AMS systems is possible. Genetic associations with udder conformation indicate that selection for udder morphology is unlikely to substantially improve milking efficiency.

The influence of lameness on several automatic milking system variables and reproductive performance indicators in dairy cows. Urbonavicius G, Antanaitis R, Zilaitis V, Tusas S, Kajokiene L, Zymantiene J, Spancerniene U, Gavelis A, Juskiene V, Juozaitienė V.Pol J Vet Sci. 2020 Sep;23(3):383-390.

  • There is an increased interest in using automatic milking systems (AMS) to indirectly assess the welfare of dairy cows, but knowledge on analyzing the association between lameness, milk yield characteristics, and reproductive performance in cows is still insufficient.
  • The main aims of this study were to evaluate the influence of lameness on several AMS variables and reproductive performance indicators during the early stage of lactation and estrus, as well as to assess the associations between lameness, productivity and repro- ductive efficiency.
  • A total of 418 milking cows (~50 days postpartum) without any apparent reproductive disorder were monitored for hoof health status. Cows were assigned to two groups on the basis of visual locomotion scoring: “non-lame”cows and cows presenting “lameness”.
  • Productive and milking performances of dairy cows were recorded from 50 to 100 days in milk (DIM) and 1 day after the first estrus. The lameness was predominantly localized on the hind feet (79.60%) and less frequently – on the front feet (20.40%). Furthermore, the lameness had a tendency to decrease milk production (4.24%) and increase the difference in milk yield between rear and front quarters of the udder (1.20%).
  • The frequency of milking was 5.19% lower in lame cows. The lame cows during estrus showed a more pronounced decrement in milk yield and milking frequency, and also higher milk progesterone concentration values (1.55-1.76 time higher), and an increasing number of inseminations (11.69%) were observed.
  • The results highlighted that analysis of data from AMS programs can be a successful tool for reducing risk factors related to the effective management of reproductive performance and hoof health of dairy cows.

Perspectives of western Canadian dairy farmers on the future of farming. Ritter C, Mills KE, Weary DM, von Keyserlingk MAG.J Dairy Sci. 2020 Sep 17:S0022-0302(20)30717-7.

  • Similar to the situation in many countries, the dairy industry in Canada is challenged by the need to adapt to changing societal demands. An industry-led initiative (Dairy Farmers of Canada’s proAction Initative, known as proAction) was developed to respond to this challenge, providing mandatory national standards for on-farm practices. Farmers are more likely to follow such standards if they are aligned with their values and beliefs.
  • The aim of this study was to better understand farmers’ perspectives on the future of the Canadian dairy industry, with a focus on the role of mandatory policies such as those related to proAction.
  • Seven focus groups were conducted, with discussions based on the principles of appreciative inquiry. Participants were each asked to write down key words that represent the “must-haves” on dairy farms in 20 years from now. Although participants were encouraged to focus on aspects directly related to animal care, all answers were accepted. Key words were then used to facilitate a discussion and elicit ideas on how to achieve these must-haves.
  • Particular focus was on the direction that participants believed policy should take to meet these goals. Explorative qualitative analysis was used for the written key words, and transcripts of the audio-recorded focus group discussions were analyzed using thematic analysis.
  • Examples of farm-specific considerations that were raised as future must-haves of animal care on dairy farms included cow comfort, employee management, responsible health management, and use of advanced technologies.
  • Participants agreed that objectives can only be achieved through collaboration among farmers and between farmers and researchers, and they regarded citizen education as a promising approach to align differing expectations of the public and farmers.
  • Citizen trust in the dairy industry was considered a must-have, and participants believed that one of the benefits of mandatory policies for animal care is their potential to increase trust. These results may help guide the development of new animal care policies and increase understanding of the perceived legitimacy of new policies by dairy farmers.

The effects of bedding, stall length, and manger wall height on common outcome measures of dairy cow welfare in stall-based housing systems. McPherson SE, Vasseur E.J Dairy Sci. 2020 Sep 17:S0022-0302(20)30714-1.

  • Understanding and improving dairy cow welfare in stall-based housing systems is an important issue for the dairy industry, and one area of the stall that has a large impact on cow welfare is the stall bed. The stall bed is defined both by its size and by the material components of the stall bed (bedding depth, bedding type, and stall base type).
  • This review examines the current literature to determine how the material components of the stall bed, as well as bed length and manger wall/brisket board height (which together define the length of the stall bed) can affect cow welfare through lying time, injuries, lameness, and cow and stall cleanliness.
  • Of the material components of the stall bed, bedding depth appears to have the largest potential positive impact on dairy cow welfare, as deeper levels of bedding in stalls, regardless of the bedding type, can improve compressibility to the extent that the stall base type is negligible.
  • As such, deeper levels of bedding have been associated with increased lying time and a reduced likelihood of a cow developing injuries or becoming lame. Longer stall bed lengths have been shown to increase lying time and decrease the prevalence of injury and lameness. The effect of manger wall or brisket board height on cow welfare has not been studied extensively, but they may work in conjunction with other stall components to define the resting space available to the cow.
  • Overall, the material components of the stall bed, stall length, and manger wall/brisket board height, as well as their combination, all influence cow welfare and need to be taken in consideration to improve the overall welfare of cows in stall-based housing systems.

Critically important antimicrobials are generally not needed to treat nonsevere clinical mastitis in lactating dairy cows: Results from a network meta-analysis. Nobrega DB, Naqvi SA, Dufour S, Deardon R, Kastelic JP, De Buck J, Barkema HW.J Dairy Sci. 2020 Sep 4:S0022-0302(20)30655-X.

  • There is ongoing debate regarding whether critically important antimicrobials (CIA) should be used to treat infections in food-producing animals.
  • In this systematic review, we determined whether CIA and non-CIA have comparable efficacy to treat non-severe bovine clinical mastitis caused by the most commonly reported bacteria that cause mastitis worldwide.
  • The researchers screened CAB Abstracts, Web of Science, MEDLINE, Scopus, and PubMed for original epidemiological studies that assessed pathogen-specific bacteriological cure rates of antimicrobials used to treat non-severe clinical mastitis in lactating dairy cows.
  • A total of 30 studies met inclusion criteria. Comparisons of cure rates demonstrated that CIA and non-CIA had comparable efficacy for treatment of non-severe clinical mastitis in dairy cattle. Additionally, for cows with non-severe clinical mastitis caused by Escherichia coli and Klebsiella spp., bacteriological cure rates were comparable for treated versus untreated cows; therefore, there was no evidence to justify treatment of these cases with CIA.
  • These findings supported that CIA in general are not necessary for treating non-severe clinical mastitis in dairy cattle, the disease that accounts for the majority of antimicrobial usage in dairy herds worldwide. Furthermore, our findings support initiatives to reduce or eliminate use of CIA in dairy herds.


Selected Articles on Dairy Intake and Human Health

Energy and Nutrient Intake of Americans according to Meeting Current Dairy Recommendations. Hess JM, Cifelli CJ, Fulgoni Iii VL.Nutrients. 2020 Sep 30;12(10):E3006.

  • Most Americans do not meet dairy food recommendations from the 2015 Dietary Guidelines for Americans (DGA).
  • This study assesses differences in nutrient intake between Americans who meet recommendations for dairy intake and those who do not, using data from the National Health and Nutrition Examination Survey from 2013-2014 and 2015-2016 (n= 5670 children ages 2-18 years and n = 10,112 adults ages 19+ years).
  • Among children and adults, those meeting dairy food recommendations were significantly more likely to have adequate intake of calcium, magnesium, phosphorus, riboflavin, vitamin A, vitamin B12, and zinc and consume above the Adequate Intake (AI) for potassium and choline than Americans not meeting dairy recommendations, regardless of age, sex, or race/ethnicity.
  • Americans meeting dairy recommendations were also more likely to exceed recommendations for sodium and saturated fat but consume less added sugars.
  • Nearly 60% of Americans 2 years and older not meeting dairy recommendations consumed calcium and magnesium below the EAR. Only about 20% of Americans who did not meet dairy recommendations consumed above the AI for potassium.
  • Dairy foods make important and unique contributions to dietary patterns, and it can be difficult to meet nutrient needs without consuming recommended amounts of dairy foods.

Long-term consumption of non-fermented and fermented dairy products and risk of breast cancer by estrogen receptor status – Population-based prospective cohort study. Kaluza J, Komatsu S, Lauriola M, Harris HR, Bergkvist L, Michaëlsson K, Wolk A.Clin Nutr. 2020 Sep 17:S0261-5614(20)30469-6.

  • The impact of dairy consumption on breast cancer development is unclear.
  • Researchers sought to examine associations between long-term consumption of milk and fermented dairy products and risk of breast cancer by estrogen (ER) and progesterone receptor (PR) status and assess whether these associations varied by body weight.
  • The population-based Swedish Mammography Cohort included 33,780 women (88.2% postmenopausal), with no history of cancer or diabetes at baseline (1997).
  • During 16.6 years of follow-up (559,286 person-years), 1870 total breast cancer cases were diagnosed (1162 ER+/PR+; 195 ER-/PR-). High long-term non-fermented milk consumption was associated with increased ER+/PR+ breast cancer incidence, HR = 1.30, for the average of 1987 and 1997 intake ≥2 vs. 0 servings/day and this increased risk was limited to women with BMI<25 kg/m2HR = 1.55, while no significant associations with milk consumption were observed with ER-/PR- breast cancer.
  • In contrast, consumption of fermented dairy products was inversely associated with ER-/PR- breast cancer (for consistently high intake ≥3 vs. <1 servings/day HR = 0.28), but not clear association was observed for ER+/PR+ (HR = 0.89).
  • In this cohort of mainly postmenopausal women, high long-term consumption of milk was associated with increased risk of ER+/PR+ breast cancer. In contrast, high long-term consumption of fermented dairy products was associated with decreased risk of ER-/PR- breast cancer.

Replacement of Red and Processed Meat With Other Food Sources of Protein and the Risk of Type 2 Diabetes in European Populations: The EPIC-InterAct Study. Ibsen DB, Forouhi NG, Wareham NJ, et al. Diabetes Care. 2020 Aug 31:dc201038.

  • There is sparse evidence for the association of suitable food substitutions for red and processed meat on the risk of type 2 diabetes.
  • Researchers modeled the association between replacing red and processed meat with other protein sources and the risk of type 2 diabetes and estimated its population impact.
  • The European Prospective Investigation into Cancer (EPIC)-InterAct case cohort included 11,741 individuals with type 2 diabetes and a subcohort of 15,450 participants in eight countries. Researchers modeled the replacement of self-reported red and processed meat with poultry, fish, eggs, legumes, cheese, cereals, yogurt, milk, and nuts. Country-specific hazard ratios (HRs) for incident type 2 diabetes were estimated.
  • There was a similar lower hazard for type 2 diabetes for the modeled replacement of red and processed meat (50 g/day) with cheese (30 g/day), yogurt (70 g/day), nuts (10 g/day), or cereals (30 g/day) but not for replacements with poultry, fish, eggs, legumes, or milk.
  • If a causal association is assumed, replacing red and processed meat with cheese, yogurt, or nuts could prevent 8.8%, 8.3%, or 7.5%, respectively, of new cases of type 2 diabetes.
  • Replacement of red and processed meat with cheese, yogurt, nuts, or cereals was associated with a lower rate of type 2 diabetes. Substituting red and processed meat by other protein sources may contribute to the prevention of incident type 2 diabetes in European populations.

Dairy intake and bone health across the lifespan: a systematic review and expert narrative. Wallace TC, Bailey RL, Lappe J, O’Brien KO, Wang DD, Sahni S, Weaver CM.Crit Rev Food Sci Nutr. 2020 Sep 14:1-47.

  • Over the past 30-years, the U.S. Dietary Guidelines for Americans have included recommendations around dairy consumption, largely based on meeting recommendations for calcium intake with the intended purpose of osteoporosis prevention. Although dairy products provide more bone-beneficial nutrients (e.g., calcium, magnesium, potassium, zinc, phosphorus, and protein) per unit of energy than any other food group, the relevance of dairy products for long-term bone health and fracture prevention has resurged as some observational studies have suggested consumption to be associated with a greater risk of fractures.
  • Given this controversy, we sought to synthesize the evidence on dairy consumption and bone health across the lifespan. We searched the PubMed, EMBASE, Web of Science, and Cochrane Central Register of Controlled Trials databases for English-language publications through June 2, 2020. Case-controlled, cross-sectional, prospective cohort or nestled case-control (or case cohort), and clinical trials reporting the effect of dairy products on bone mineral density, bone mineral content, and/or fractures were included in the systematic review.
  • Data from 91 publications, including 30 RCTs, 28 prospective cohorts, 23 cross-sectional studies, and 10 case-control studies were included in the systematic review.
  • Researchers assigned a “D” grade or “insufficient evidence” for the effect of dairy in infants and toddlers (0- to <36-months), children (3- to <10-years), and young adults (19- to <50-years).
  • Researchers assigned a “C” grade or “limited evidence” for the effect of dairy in adolescents (10- to <19-years), and a “B” grade or “moderate” evidence was assigned for the effect of dairy in middle aged to older adults (≥50-years).
  • Research on bone mass in adults between the ages of 20- to 50-years and individuals from other ethnic groups apart from Chinese females and Caucasians is greatly needed. Daily intake of low or nonfat dairy products as part of a healthy habitual dietary pattern may be associated with improved BMD of the total body and at some sites and associated with fewer fractures in older adults.

Effects of whey protein on glycemic control and serum lipoproteins in patients with metabolic syndrome and related conditions: a systematic review and meta-analysis of randomized controlled clinical trials. Amirani E, Milajerdi A, Reiner Ž, Mirzaei H, Mansournia MA, Asemi Z.Lipids Health Dis. 2020 Sep 21;19(1):209.

  • This systematic review and meta-analysis aimed to assess the effects of whey protein on serum lipoproteins and glycemic status in patients with Metabolic Syndrome and related disorders.
  • Online databases, such as Web of Science, Cochrane Library, PubMed and Scopus were systematically searched for randomized clinical trials investigating the efficacy of whey protein administration in subjects with Mets or related conditions on the parameters of glycemic and lipid control compared to certain control.
  • Twenty-two studies were selected to be included in this meta-analysis. Consumption of whey protein resulted in significant reduction of Hemoglobin A1c, insulin, and homeostasis model assessment-estimated insulin resistance (HOMA-IR).
  • A significant reduction in triglycerides levels, total cholesterol, LDL-cholesterol levels, and total cholesterol/HDL-cholesterol ratio was found as well.
  • This meta-analysis suggests that supplementation with whey protein had beneficial effect on several indicators of glycemic control and lipid parameters in patients with Metabolic Syndrome and related conditions.

Dairy products, surrogate markers, and cardiovascular disease; a sex-specific analysis from the ATTICA prospective study. Kouvari M, Panagiotakos DB, Chrysohoou C, Georgousopoulou EN, Yannakoulia M, Tousoulis D, Pitsavos C; ATTICA study Investigators.Nutr Metab Cardiovasc Dis. 2020 Jul 31:S0939-4753(20)30312-4.

  • Dairy products are a very diverse food group with multiple effects on the cardiac health of men and women.
  • The aim of this work was to evaluate the sex-specific association between dairy products (total and subtypes) and 10-year first fatal/nonfatal cardiovascular disease (CVD) incidence.
  • In 2001-2002, n = 1514 men and n = 1528 women (>18 years old) from greater Athens area, Greece, were enrolled. Dairy product consumption was examined in relation to 10-year CVD incidence.
  • Follow-up (2011-2012) was achieved in n = 2020 participants (n = 317 CVD cases). Ranking from lowest (<1 serving/day) to highest (>2 servings/day) total dairy intake, CVD incidence in men was 17.8%, 15.0%, and 10.9%, while in women it was 14%, 6.0%, and 5.7%.
  • Additional analysis revealed that total dairy intake protected against CVD only in women, irrespective of the fat content. Further analysis revealed that only fermented products (yogurt and cheese), protected against CVD. For per 200 g/day yogurt consumption, CVD risk was 20%-30% lower with this claim being more evident in women, while for per 30 g/day cheese intake, about 5% lower risk was observed particularly in men.
  • These associations were mainly retained in the case of hepatic steatosis, insulin resistance, and systemic inflammation. This work provides incentives for researchers to elucidate the diversity of ingredients and mechanisms through which dairy products exert their effect on cardiac health separately for men and women.

Respiratory effects of acute milk consumption among asthmatic and non-asthmatic children: a randomized controlled study. Koren Y, Armoni Domany K, Gut G, Hadanny A, Benor S, Tavor O, Sivan Y.BMC Pediatr. 2020 Sep 12;20(1):433.

  • A commonly held public belief is that cow’s milk products increase mucus production and respiratory symptoms. Dietary milk elimination is often attempted despite lack of evidence.
  • The study’s objective was to investigate whether a single exposure to cow’s milk is associated with respiratory symptoms and changes in pulmonary functions in asthmatic and non-asthmatic children.
  • Researchers conducted a prospective double blind, placebo-controlled trial on non-asthmatic and asthmatic children aged 6-18 years evaluated at a pediatric pulmonology unit. The children were randomly challenged with cow’s milk or soy milk substitute.
  • Fifty non-asthmatic children (26 assigned to the cow’s milk group and 24 to the soy substitute group), and 46 asthmatic children (22 in the cow’s milk group and 24 in the soy substitute group) were enrolled.
  • No changes in symptoms, spirometry, FeNO, or oxygen saturation measurements were observed following challenge in any of the participants in both groups, at any time point compared to baseline. A single exposure to cow’s milk is not associated with symptoms, bronchial inflammation, or bronchial constriction in both non-asthmatic and asthmatic children.
  • These findings do not support the strict elimination of dairy products from a child’s diet for the prevention of respiratory symptoms.

Children and adults should avoid consuming animal products to reduce the risk for chronic disease: Debate Consensus. Barnard ND, Leroy F.Am J Clin Nutr. 2020 Oct 1;112(4):937-940.

NO.   Leroy F, Barnard ND.Am J Clin Nutr. 2020 Oct 1;112(4):931-936.

    • Excessive attention to the animal versus plant binary food choice reflects society’s moral views on eating right. To claim that avoidance of animal products is required to prevent chronic disease is not supported by evidence, makes little sense from an evolutionary perspective, and distracts policy makers from common-sense approaches to achieve adequate nutrition. Animal products provide highly bioavailable nutrients, some of which are not easily obtained from plants, and can play a key role in meeting the nutritional challenges of populations in both high- and low-income countries. This role goes beyond the need for protein and relates to vitamins, minerals, and numerous often-overlooked nutrients, such as long-chain fatty acids, taurine, and choline. Restrictive dietary prescriptions that exclude animal products complicate the quest for optimal nutrition by undermining dietary diversity and flexibility, and by introducing a dependency on fortification and supplementation. Thus, a vegan diet may put the general population at increased risk of poor nutrition, a problem of particular concern for those with special nutritional requirements.

YES.  Barnard ND, Leroy F.Am J Clin Nutr. 2020 Oct 1;112(4):926-930.

    • The consumption of animal products exposes humans to saturated fat, cholesterol, lactose, estrogens, and pathogenic microorganisms, while displacing fiber, complex carbohydrates, antioxidants, and other components needed for health. In the process, consumption of animal products increases the risk for cardiovascular disease, cancer, diabetes, obesity, and other disorders. This dietary pattern also promotes the growth of unhealthful gut bacteria, fostering, among other things, the production of trimethylamine N-oxide, a proinflammatory compound associated with cardiovascular and neurological diseases. When omnivorous individuals change to a plant-based diet, diet quality as measured by the Alternate Healthy Eating Index improves, and the risk of these health problems diminishes. Planning for nutrient adequacy is important with any diet. However, a diet based on vegetables, fruits, whole grains, and legumes, supplemented with vitamin B-12, is nutritionally superior to diets including animal products and is healthful for children and adults.