Salutations! Welcome to a curated collection of Dairy Research from the month of August! 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 Publications on Animal Health, Food Safety, and Sustainability

Metritis diagnosis and treatment practices in 45 dairy farms in California. Espadamala A, Pereira R, Pallarés P, Lago A, Silva-Del-Río N. J Dairy Sci. 2018 Aug 1. pii: S0022-0302(18)30687-8.

  • Minimizing the risk of antimicrobial-resistant organisms and antimicrobial residues in dairy and dairy beef products is a topic of nationwide interest. To design an effective outreach program on judicious use of antimicrobials, it is imperative to describe actual practices on dairies.
  • The study objective was to report current practices for metritis treatment in 45 dairies in California.
  • Data were collected using a survey tool that included questions on systemic antimicrobial treatments, intrauterine treatments, supportive treatments, and treatment records.
  • The surveys showed that there were inconsistent evaluation techniques and antimicrobial treatments across the dairies tested. Most dairies performed rectal exams for vaginal discharge, while some only detected abnormal vaginal discharge if visible on tail, vulva, or floor. Treatment decisions were generally based on the presence of abnormal discharge, fever, and/or results of rectal palpation, with some dairies using systemic antimicrobial treatment based on fever alone.
  • Systemic antimicrobials used were ceftiofur products (ceftiofur hydrochloride, ceftiofur sodium, and ceftiofur crystalline-free acid), penicillin procaine, and ampicillin. The antimicrobial drug of choice, the dose, and the treatment length for metritis varied across the study dairies.
  • Based on accepted industry best-management practices for metritis, a need exists to educate fresh cow evaluators on signs of health disorder indicative of metritis and on appropriate antimicrobial treatment regimens.

Review: Adaptation of ruminant livestock production systems to climate changes. Henry BK, Eckard RJ, Beauchemin KA. Animal. 2018 Aug 10:1-12.

  • There is growing evidence on the extent to which projected changes in climate, including increases in atmospheric levels of carbon dioxide, higher temperatures, changes in amount, seasonality and variability of precipitation and increases in extreme weather events, may affect future availability of ruminant animal products.
  • Elements of climate change affect livestock systems through direct impacts on animal physiology, behavior, production and welfare and indirectly through feed availability, composition and quality. These impacts may be positive or negative and will vary across geographical regions, animal species and with adaptive capacity.
  • Adverse impacts are likely to be greatest in tropical and sub-tropical regions including countries where both current need and future growth in demand for nutrition is greatest. The complexity of effects means that effective adaptation strategies to mitigate negative impacts on ruminant production systems to climate changes will need to be multi-dimensional.
  • Although predictions of future climate, particularly on regional and local scales, have a degree of uncertainty, adaptation planning is starting to be informed by changes already being observed and adjustments in management being made by farmers to maintain productivity and profitability.
  • Review of research on climate change impacts on ruminant livestock and effective adaptation together with evidence of practical adaptive management provide insights into potential strategies and gaps in knowledge to address challenges and improve future decisions.

Replacing human-edible feed ingredients with by-products increases net food production efficiency in dairy cows. Karlsson J, Spörndly R, Lindberg M, Holtenius K. J Dairy Sci. 2018 Aug;101(8):7146-7155.

  • Global demand for food is increasing, and use of large amounts of potentially human-edible feedstuffs for dairy cows is an important concern.
  • The present study examined whether feeding a by-product-based concentrate combined with high-quality grass silage to high-producing dairy cows affected feed intake and milk production compared with a conventional diet, as well as the effect on efficiency of human food production.
  • In a changeover experiment with four 21-day periods, 24 dairy cows in mid-lactation were offered 9.6 kg of dry matter per day with 1 of 4 concentrates and high-quality grass silage ad libitum. The control concentrate was based on cereal grain (wheat, oat, and barley) and soybean meal, whereas the 3 by-product-based concentrates contained sugar beet pulp in combination with mainly heat-treated rapeseed meal, distillers grain, or a mixture of both. All diets were formulated to be isoenergetic and isonitrogenous.
  • The cows had 10-fold higher starch intake when fed the control diet than when fed the by-product-based concentrates. Silage intake (13 kg of dry matter/d) and milk production (33 kg of energy-corrected milk/d) were not affected by the change in diet.
  • Therefore, replacing cereals and soybean meal with human-inedible by-products in a high-quality forage diet to dairy cows increased net food protein production substantially without lowering milk production.

Multi-criteria evaluation of dairy cattle feed resources and animal characteristics for nutritive and environmental impacts. van Lingen HJ, Fadel JG, Bannink A, Dijkstra J, Tricarico JM, Pacheco D, Casper DP, Kebreab E. Animal. 2018 Aug 24:1-11.

  • On-farm nutrition and management interventions to reduce enteric CH4 emission, the most abundant greenhouse gas from cattle, may also affect volatile solids and N excretion.
  • The objective was to jointly quantify enteric CH4 emissions, digestible volatile solids excretion and N excretion from dairy cattle, based on dietary variables and animal characteristics, and to evaluate relationships between these emissions and excreta.
  • Data derived from models using 520 individual North American dairy cow records indicated dry matter (DM) intake and dietary acid detergent fiber and crude protein to be the main predictors for production of enteric CH4 emissions and digestible volatile solids and nitrogen excreta (g/day).
  • Yields (g/kg DM intake) of enteric CH4 emissions and digestible volatile solids and nitrogen excreta were best predicted by dietary acid detergent fiber, dietary crude protein, milk yield and milk fat content. Intensities (g/kg fat- and protein-corrected milk) of enteric CH4, digestible volatile solids and nitrogen excreta were best predicted by dietary acid detergent fiber, dietary crude protein, days in milk and body weight.

Potential of anaerobic digestate of dairy manure in suppressing soil-borne plant disease. Pan Z, Qi G, Andriamanohiarisoamanana FJ, Yamashiro T, Iwasaki M, Nishida T, Tangtaweewipat S, Umetsu K. Anim Sci J. 2018 Aug 21.

  • Frequent use of pesticides to control soil-borne plant disease leads to environmental pollution and the development of pesticide resistance in phytopathogens. Soil amendment is considered to have the potential of suppressing plant disease because of its biological properties. However, information on anaerobic digestate is limited.
  • In this study, potential of antagonistic activities of anaerobic digestate against phytopathogens were investigated by detecting the amounts of antagonistic bacteria (Bacillus and Pseudomonas) in anaerobic digestates of dairy manure.
  • The results showed that anaerobic digestion increased the total amounts of Bacillus and Pseudomonas in digestate. Bacillus suppressed growth of phytopathogens, while Pseudomonas did not show any antagonistic activities. These results indicated that Bacillus was an effective antagonistic bacterium in digestate against phytopathogens.
  • Furthermore, two selected isolates, B11 (Bacillus subtilis) and B59 (Bacillus licheniformis), were applied in field experiments and showed significant reduction in percent infection of potato late blight (Phytophthora infestans). These results demonstrate the benefits of digestate in suppressing soil-borne plant diseases caused by antagonistic bacteria.

Carrier flies of multidrug-resistant Escherichia coli as potential dissemination agent in dairy farm environment. Alves TDS, Lara GHB, Maluta RP, Ribeiro MG, Leite DDS. Sci Total Environ. 2018 Aug 15;633:1345-1351.

  • The life cycle of synanthropic flies and their behavior, allows them to serve as mechanical vectors of several pathogens. Given that flies can carry multidrug-resistant bacteria, this study aimed to investigate the spread of genes of antimicrobial resistance in Escherichia coli isolated from flies collected in two dairy farms in Brazil.
  • Of 94 flies collected, Musca domestica was the most frequently found in the two farms. Researchers isolated 198 E. coli strains (farm A=135 and farm B=63), and >30% were multidrug-resistant E. coli. A high frequency (86%) of phylogenetic group B1 among multidrug-resistant strains and the lack of association between multidrug resistance and virulence factors suggest that antimicrobial resistance possibly is associated with the commensal bacteria.
  • Clonal relatedness of multidrug-resistant E. coli performed by Pulsed-Field Gel Electrophoresis showed wide genomic diversity. Different flies can carry clones, but with distinct antimicrobial resistance pattern.
  • In conclusion, in Brazil, multidrug-resistant E. coli is carried by flies in the milking environment. Therefore, flies can act as carriers for multidrug-resistant strains and contribute to dissemination routes of antimicrobial resistance.

Low quality rice straw forage increases the permeability of mammary epithelial tight junctions in lactating dairy cows. Wang D, Cai J, Zhao F, Liu J. J Sci Food Agric. 2018 Aug 24.

  • It is known that milking frequency and plasma hormones play important roles in regulating mammary permeability. However, whether nutritional factors can influence udder permeability is still unknown.
  • This study was conducted to investigate mammary epithelial tight junction permeability in lactating dairy cows fed different forage-based diets.
  • Twenty mid-lactating dairy cows were allocated into 10 blocks based on their parity and milk yield and then randomly assigned into rice straw-based diet and alfalfa-based diet groups. Both diets contained 15% of corn silage and 55% of concentrate (dry matter basis). In terms of forage source, rice straw-based diets contained 30% rice straw, whereas alfalfa-based diets contained 23% alfalfa hay plus 7% Chinese wild rye hay.
  • The concentrations of Na+, Na+ /K+ ratio, bovine serum albumin, and plasmin in the milk, plasma lactose concentration, and Insulin Like Growth Factor Binding Protein 5 in the mammary gland were greater in rice straw-fed cows than in alfalfa+hay fed animals.
  • Mammary expression of Proliferating Cell Nuclear Antigen and Occludin was lower in rice straw group compared with the alfalfa+hay group. The expressions of Growth Hormone Receptor was similar between the two diet groups.
  • The cows fed rice straw showed higher mammary alveolar permeability, likely through affecting proliferation/apoptosis rates of mammary epithelial cells.

Invited review: Roles of dietary n-3 fatty acids in performance, milk fat composition, and reproductive and immune systems in dairy cattle. Moallem U. J Dairy Sci. 2018 Aug 9. pii: S0022-0302(18)30731-8.

  • Mammals can synthesize all of the fatty acids necessary for proper health and functioning with the exception of those in the omega-3 and omega-6 families of polyunsaturated fatty acids, which should be supplied in the diet. The polyunsaturated fatty acids are the predominant type of lipid in dairy cattle diets; however, common feedstuffs are rich in omega-6 fatty acids, whereas the supply of omega-3 fatty acids in the intensive dairy industry is mainly limited to flaxseed and fish oils.
  • The purpose of this review was to provide a comprehensive description of different aspects and outcomes involved in dietary omega-3 fatty acid supplementation in dairy cattle.
  • The omega-3 fatty acids are involved in many biological systems and processes, and therefore their dietary supplementation is of special interest in dairy cattle. Furthermore, because milk, milk products, and meat are among the most important and widely used components in traditional and modern human diets, enrichment of these food products with omega-3 fatty acids is of special importance.
  • Selective uptake of omega-3 fatty acids has been demonstrated in the ovary compartments, as well as in bull sperm and in the unborn calf through the placenta. Incorporation of these unique fatty acid into the reproductive system influences many processes and exerts some positive effects on fertility. In addition, beneficial effects of feeding omega-3 fatty acids on the reproductive system of females and males can be achieved with supplementation of α-linolenic acid from flaxseed or from EPA and DHA from fish oil.
  • This work provides a broad perspective and demonstrates the importance and potential of omega-3 fatty acid dietary supplementation in dairy cattle on the animal itself, as well as its secondary effects, which are associated with human nutrition and health.


Selected Articles on Dairy Intake and Human Health

The collaborative effect of scientific meetings: A study of the International Milk Genomics Consortium. Kwok E1, Porter M1, Korf I1,2, Pasin G3, German JB4, Lemay DG1,5. PLoS One. 2018 Aug 22;13(8):e0201637.

  • Collaboration among scientists has a major influence on scientific progress. Such collaboration often results from scientific meetings, where scientists gather to present and discuss their research and to meet potential collaborators. However, most scientific meetings have inherent biases, such as the availability of research funding or the selection bias of professional societies that make it difficult to study the effect of the meeting per se on scientific productivity.
  • To evaluate the effects of scientific meetings on collaboration and progress independent of these biases, the researchers conducted a study of the annual symposia held by the International Milk Genomics Consortium (IMGC) over a 12-year period.
  • Using the number of co-authorships on published papers as a measure of collaboration, the analysis revealed that scientists who attended the symposium were associated with more collaboration than were scientists who did not attend.
  • Furthermore, the researchers evaluated the scientific progress of consortium attendees by analyzing publication rate and article impact. They found that IMGC attendees, in addition to being more collaborative, were also more productive and influential than were non-attendees who published in the same field.
  • The study results suggest that the annual symposium encouraged interactions among disparate scientists and increased research productivity, exemplifying the positive effect of scientific meetings on both collaboration and progress.

Identification and characterization of fluid milk consumer groups. Harwood WS, Drake MA. J Dairy Sci. 2018 Aug 9. pii: S0022-0302(18)30736-7.

  • Consumption of fluid milk has steadily declined over the last few decades. Understanding the attributes of fluid milk products that are attractive to specific consumer groups may provide a sound basis for education and marketing to encourage increased dairy consumption and reverse the downward trend.
  • The objective of this study was to identify the attributes of fluid milk that specific consumer groups find attractive and attributes that suggest a higher purchase likelihood. An adaptive choice-based conjoint (ACBC) survey was designed to assess attributes of fluid milk. The ACBC survey included Kano, importance, labeling identification, and beliefs questions to determine the key attributes that dictated consumer purchase and consumption.
  • Self-reported purchase habits and attitudes for organic food products were also collected. Attributes in the ACBC exercise included fat content, package type, shelf life, and label claims.
  • A total of 1,163 fluid milk consumers completed the survey, and of those, 434 were regular purchasers of organic milk. The ideal fluid milk from conjoint analysis was 2% milkfat, organic, packaged in a plastic jug, conventionally pasteurized, and contained no additives or label claims.
  • For all milk consumers, designation as organic was ranked as the 8th most important of 14 attributes. The belief that “organic milk is healthier” was the most important motivator for purchases of organic milk, followed by the beliefs that “organic milk production encourages ethical treatment of animals” and “organic milk production supports local farms and farmers.”
  • Conjoint importance scores of all fluid milk consumers showed that milkfat content was the most important attribute, followed by flavor, package size, and price.
  • Evaluation of these results on both aggregate and individual levels suggest that fluid milk consumers are not a homogeneous consumer group and that underlying consumer groups are led to purchase decisions by specific product features or expectations.

Dairy matrix effects: response to consumption of dairy fat differs when eaten within the cheese matrix-a randomized controlled trial. Feeney EL, Barron R, Dible V, Hamilton Z, Power Y, Tanner L, Flynn C, Bouchier P, Beresford T, Noronha N, Gibney ER. Am J Clin Nutr. 2018 Aug 11.

  • Dairy fat consumed as cheese has different effects on blood lipids than that consumed as butter. It is unknown whether the effect is specific to fat interaction with other cheese nutrients (calcium, casein proteins), or to the cheese matrix itself.
  • The researchers aimed to test the effect of 6 weeks of daily consumption of ∼40 g dairy fat, eaten within macronutrient-matched food matrices, on markers of metabolic health, in overweight adults aged ≥50 years. The study was a 6-week randomized parallel intervention; 164 volunteers (75 men) received ∼40 g of dairy fat/day, in 1 of 4 treatments:
    • (A) 120 g full-fat Irish cheddar cheese (n = 46); no “run-in” period
    • (B) 120 g reduced-fat Irish cheddar cheese + butter (21 g) (n = 45);
    • (C) butter (49 g), calcium caseinate powder (30 g), and Ca supplement (CaCO3) (500 mg) (n = 42);
    • (D) 120 g full-fat Irish cheddar cheese (n = 31); With a 6-week “run-in” period, where the participants excluded all dietary cheese before commencing the intervention.
  • There was no difference in anthropometry, fasting glucose, or insulin between the groups at pre- or postintervention. However, a stepwise-matrix effect was observed between the groups with significantly lower postintervention total cholesterol (5.23 ± 0.88 mmol/L) and LDL cholesterol (2.97 ± 0.67 mmol/L) when all of the fat was contained within the cheese matrix (Group A), compared with butter matrix (Group C).
  • Dairy fat, eaten in the form of cheese, appears to differently affect blood lipids compared with the same constituents eaten in different matrices, with significantly lower total cholesterol observed when all nutrients are consumed within a cheese matrix.

Effect of milk protein intake and casein-to-whey ratio in breakfast meals on postprandial glucose, satiety ratings, and subsequent meal intake. Kung B, Anderson GH, Paré S, Tucker AJ, Vien S, Wright AJ, Goff HD. J Dairy Sci. 2018 Aug 16. pii: S0022-0302(18)30742-2.

  • Whey and casein proteins differentially affect postprandial blood glucose and satiety mechanisms, with relevance for type 2 diabetes and obesity.
  • The purpose of this work was to investigate the effect of the casein-to-whey protein ratio and total protein concentration of milks consumed with cereal on postprandial blood glucose, appetite ratings, and subsequent food intake in a randomized, controlled, double-blinded study with healthy young adults.
  • Fasted participants consumed milk (250 mL) with either 80:20 or 40:60 (modified) casein-to-whey protein ratios at commercially normal (3.1%, wt) or high protein (9.3%, wt) concentration, or control (water with whey permeate), each along with 2 servings of oat-based breakfast cereal.
  • Blood glucose concentrations were determined from finger prick blood samples and appetite was assessed using visual analog scales. Participants consumed a measured ad libitum pizza lunch at 120 min and blood glucose determination and appetite assessment continued following the lunch meal (140-200 min) to observe the second meal effect.
  • Protein ratio showed a modest effect in that modified (40:60) protein ratio lowered pre-lunch blood glucose change from baseline but not iAUC, and normal (80:20) protein ratio lowered pre-lunch appetite change from baseline but not tAUC. Therefore, high-carbohydrate breakfast meals with increased protein concentration (9.3%, wt) could be a dietary strategy for the attenuation of blood glucose and improved satiety ratings after the second meal.

Diet as a risk factor for antimicrobial resistance in community-acquired urinary tract infections in a middle-aged and elderly population: a case-control study. Mulder M, Kiefte-de Jong JC, Goessens WH, de Visser H, Ikram MA, Verbon A, Stricker BH. Clin Microbiol Infect. 2018 Aug 9. pii: S1198-743X(18)30560-3.

  • There is an ongoing debate to which extent antimicrobial resistance (AMR) can be transmitted from animals to humans via the consumption of animal products. Because epidemiological data on the role of diet on AMR in humans are lacking, we investigated this association between diet and AMR to different antimicrobial drugs in E. coli in urinary tract infections (UTIs).
  • Susceptibility of E.coli in urinary cultures and information on diet (with food frequency questionnaires) were obtained from participants of the Rotterdam study, a population-based prospective cohort study. The association between intake of several food groups (meat, sea food, eggs, dairy products, crops) and resistance of E. coli to several antimicrobial drugs (amoxicillin, amoxicillin-clavulanic acid, trimethoprim, sulfamethoxazole-trimethoprim, first-generation cephalosporins, cefotaxime, nitrofurantoin, norfloxacin) was studied.
  • Urinary cultures with E.coli were obtained from 612 individuals, of whom 481 (78.6%) were women. Resistance rates varied from 246/611 (40.3%) for amoxicillin and 167/612 (27.3%) for trimethoprim to only 29/612 (4.7%) for nitrofurantoin and 16/462 (3.5%) for cefotaxime.
  • A higher intake of chicken was associated with cefotaxime resistance (OR 2.18; 95%CI 1.05-4.51 per tertile increase); a higher intake of pork was associated with norfloxacin resistance (OR 1.42; 95%CI 1.04-1.95 per quartile increase). In contrast, a higher intake of cheese was associated with lower AMR to amoxicillin (OR 0.84; 95%CI 0.72-0.99 per quartile increase) and amoxicillin-clavulanic acid (OR 0.67; 95%CI 0.53-0.86 per quartile increase).
  • These findings support the hypothesis that diet may play a role in AMR of E.coli in UTIs, and that cheese consumption may be associated with lower levels of anti-microbial resistance.

Most children who are allergic to cow’s milk tolerate yogurt. Küçükosmanoğlu E, Özen E, Eltan SB, Özkars MY, Keskin Ö. J Int Med Res. 2018 Aug 9:300060518790430.

  • Objective Cow’s milk allergy is the most common food allergy in childhood. Changes occur in the protein structure of milk during yogurt fermentation.
  • This study aimed to determine whether children who are diagnosed with a cow’s milk allergy can tolerate yogurt.
  • The researchers performed a yogurt challenge test on 34 children who were diagnosed with a cow’s milk allergy in a Pediatric Allergy Outpatient Clinic. The mean age of the children was 24 ± 13 months.
  • A reaction was observed in 17 (50%) patients, whereas no reaction was observed in the other 17 (50%) during an oral yogurt challenge test that was performed in all of the 34 patients with a cow’s milk allergy. Cow’s milk-specific immunoglobulin E levels were significantly lower in the group of children who could tolerate yogurt than in the group of children who could not tolerate yogurt.
  • Yogurt is tolerated by approximately half of children with a cow’s milk allergy when subjected to a challenge test performed with yogurt.

Biological sex and glucoregulation modulate postprandial cognition following dairy milk and fruit juice in healthy school-age children. Anderson JR, Gunstad J, Updegraff J, Sato A, Hagerdorn PL, Spitznagel MB. Nutr Neurosci. 2018 Aug 10:1-10.

  • Recent work suggests potential postprandial benefits for cognition and on-task behavior in children, depending on the macronutrients consumed, as well as individual differences such as sex and glucoregulation.
  • The researchers examined the effects of 1% milk versus apple juice on cognition and on-task behavior among healthy school-age children, predicting that milk would promote better performance and a greater presence of on-task behavior compared to juice. The researchers also examined how biological sex and glucoregulation influenced cognition and behavior following each beverage.
  • Eighty-four English-speaking children ages 8-12 (45 female, 39 male) attended two testing sessions after fasting overnight in a crossover design. Participant sessions were counterbalanced to include 237 mL of 1% milk or apple juice. Behavioral measures and complex attentional and executive function tasks were assessed at baseline, 30, 90, and 120 min post-ingestion.
  • Participants with fasting glucose levels above 89.91 mg/dL responded more quickly in an inhibitory control paradigm following milk. Females performed faster on a vigilance task, but less accurately in a working memory paradigm after milk versus juice.
  • Results demonstrated modulatory effects of glucoregulation and sex on postprandial cognition. Milk may improve cognitive performance in school-aged children with higher fasting glucose, and may be the optimal choice for speed among females, whereas juice may be better for accuracy.