Tim and Steph bring you a spooky Halloween episode on the parasitic plants named dodders that have the ability to thrive by sucking their nutritional needs out of a host plant.
This week Tim and Steph discuss bacteriophages and their uses in health and food safety.
What is a bacteriophage?
Bacteriophages are viruses that invade bacterial cells and cause the bacterium to lyse, or split open, and subsequently die. Bacteriophages have a very specific relationship with bacteria; they ignore every cell but the strain of bacteria they have evolved to inhabit. That makes them harmless to mammalian cells and harmless even to bacteria they are not specific for. This is different from broad-spectrum antibiotics that can wipe out commensal flora in the intestinal tract along with the infectious bacteria of interest.
When were bacteriophages discovered?
Bacteriophages were discovered twice, independently, by a British and then a French scientist between 1915 and 1917 . The first study that was published regarding the use of phages in treating infectious diseases of humans was in 1921 where scientists were able to use bacteriophages successfully to treat staphylococcal skin infections.
Why aren’t bacteriophages used in medicine anymore?
In 1928 penicillin was discovered which would eventually dominate the way we treat infectious diseases. The miracle antibiotic that is produced from Penicillium chrysogenum fungus pushed phage therapy out of popular medicine before it became widely used. More and more antibiotics were discovered throughout the 1940’s and 50’s causing interest in phage therapy to decline in western medicine and nowadays it is not often discussed.
Why are we talking about phages today if they’re an old discovery?
In medicine, agriculture and other fields there is an increased interest in phages… this is due to fewer antibiotics being discovered and an alarming increase of multi-drug resistant pathogens. So while phages for medical therapy is not new, the use of phages in food safety is relatively new. In 2006, not that long ago, the FDA and USDA approved the first bacteriophage product that can come in contact with food; Listshield a cocktail of phages that target Listeria monocytogenes. Phage treatments are mixed usually with water and applied as a spray. Once on the food, the phages will inject their DNA material into their targeted bacterial cells, where they replicate until they burst the cell open thus controlling the pathogenic agent.
Recent research on bacteriophage use in E. coli O157:H7 illness prevention
For this episode topic we found a great scientific article from the Journal of Animal Sciences entitled “Development of bacteriophage treatments to reduce E. coli O157:H7 contamination of beef products and produce” by Hong et al., 2014. The paper is no longer open access but if you would like to read it you can find it here. The goal of Hong and colleagues in their paper was to determine whether the use of a phage-based treatments could limit pathogen contamination in food. First, they isolated phages specific for infecting E . coli O157:H7 and characterized them. Of the phages characterized, three potential phages were further tested for their ability to limit E. coli O157:H7 contamination in ground beef, spinach, and cheese. Lastly, they looked at the ability of E.coli to develop resistance to see whether this would be a problem for use of phages like it has been for antibiotics.
How does E. coli get in our food?
Ruminant animals (cows, goats, sheep) are the main reservoirs. 0157:H7 colonizes in the intestinal tract of, for instance, cattle and is passed to the environment through feces and then spread rapidly amongst the herd. It is during the processing step in the slaughterhouse where the pathogen can be transferred from the animal (from its hide, hooves or wherever the feces is located) to meat products. On vegetables such as spinach contamination can happen in field from bacteria in soils or irrigation water. Contamination can also occur during picking or at the packing house due to contaminated equipment or workers.
Selection of phage for use in the study
The environment is absolutely full of phages so you don’t need to look hard to find them but to find specific kinds it’s best to look where there is an abundance of their host bacteria. The researchers collected wastewater from wastewater treatment plants located throughout the state of Indiana and by using a series of laboratory methods (which we won’t bore you with here) isolated 16 different E. coli O157:H7 phages. Each phage was tested for its lytic abilities. What that means is each phage has its own ability to kill or ‘lyse’ bacteria. This is called its ‘lytic ability’. So, an E. coli O157:H7 phage with higher lytic ability would be more effective at killing an E. coli O157:H7 bacterium. What a ‘broad lytic range’ means is that it was able to lyse (or kill) greater than 95% of the bacteria). From this collection of 16 phages, they identified 3 optimal phages based on how well they infect the host and how fast, or slow, they grow (growth kinetics).
Effects of phage treatment on contaminated ground beef
Researchers gathered ground beef samples from local retail outlets and then inoculated them with the E. coli O157:H7. The three phages were mixed together in a cocktail in equal amounts and then applied to the meat. Phage treatment of E. coli O157:H7 contaminated beef was tested under 3 conditions (1) room temperature (2) refrigeration and (3) undercooking. Ground beef samples that were contaminated with E. coli O157:H7 but did not receive a phage treatment served as controls (always important in an experiment). After 24 hours of their testing conditions, the authors measured the amount of E. coli on the meat. Concentrations of E. coli O157:H7 in phage-treated ground beef were significantly less than those in untreated ground beef for both room temperature and refrigeration conditions. When contaminated beef samples were undercooked (internal temperature of 46°C), concentrations of E. coli O157:H7 in phage-treated ground beef were significantly less than those found in untreated, undercooked ground beef. However, there was no significant difference in E. coli O157:H7 concentrations between phage-treated and non-treated groups when contaminated beef was cooked to an internal temperature of 63°C.
Effect of phage treatment on contaminated spinach
Researchers choose three spinach leaves of similar sizes. Then they inoculated the leaves with E. coli by dropping a the E. coli mixture onto the leaves. There, of course, was a control group that was inoculated but did not receive any phage application. They then incubated the leaves at room temperature and measured the concentrations of E. coli at 24 h, 48 h, and 72 h post-treatment. They found that the application of the phage cocktail significantly reduced the concentration of viable E. coli O157:H7 on spinach surfaces and this was true for all three timepoints measured, after storage at room temperature for 24 h, 48 h and 72 h. So, phage treatment could potentially be very effective at reducing E. coli levels in our spinach.
Effect of phage treatment on cheese
When they did this same experiment as spinach only instead using E. coli contaminated cheese, there were no significant difference in concentrations of E. coli between cheese that had and had not been treated with the phage cocktail. We wondered if there was an antibacterial effect of cheese pH or possibly an effect on the phages.
Can bacteria become resistant to phages?
One of the concerns with any antimicrobial technology is the possibility for a bacteria, like E. coli, to develop resistance. While scientists hypothesize that phage resistance might be easier to overcome than resistance to antibiotics, it is still a concern and raises serious safety questions that must be researched. In previous studies, phage-resistant mutants of bacteria were detected within hours to days, especially when a single phage was used in an experiment. Hong and colleagues tested for phage resistance in their study. After a series of ‘spot inoculations’ and running other microbiological and biochemical assays, they did find resistance to some degree for all three phages. The mechanisms of phage resistance can be grouped into four major categories: adsorption prevention (the bacteria doesn’t allow the phage to attach), prevention of phage DNA entry (the bacteria doesn’t let phage DNA get in), degradation of phage nucleic acid (the bacteria degrades the phage DNA once it gets in), and abortive infection systems (the bacteria and phage both die). In this study, the authors determined that adsorption prevention was one of the main ways that bacteria were becoming resistant to the phage, however, it wasn’t the sole reason. Further studies are needed to determine the exact mechanisms of phage resistance.
Another concept that the authors investigated regarding phage resistance was something called Fitness Cost. Fitness is a central idea in evolution and describes the ability of, in this case bacteria, to survive and reproduce. Fitness cost is when some genetic change in the bacteria can cause decrease fitness. In this case, the question is, do bacteria that are resistant to phages have decreased fitness in the absence of phages compared to bacteria that do not have resistance. This phenomenon is also talked about a lot in regards to antibiotic resistant bacteria. Previous studies showed that when an antibiotic is taken out of the bacterial environment, the previously resistant bacteria have slow growth rates and more quickly to die compared to non-resistant bacteria; suggesting whatever made these bacteria resistant also decreases their overall fitness. So, the authors wanted to know ‘Do our phage-resistant mutants that we found have decreased fitness compared to the non-resistant mutants’. This is an important question because if phage treatment becomes mainstream in food safety and the issue of phage resistance becomes a problem, simply removing the phage treatment for a period of time may not solve the problem. The authors found that their phage-resistant mutants did not have decreased fitness compared to their non-resistant counterparts suggesting that if resistance developed, simply removing the phage treatment may not reverse resistance.
That’s all folks!
Thank you for listening to our show and/or reading the blog if you like it please go over to Our iTunes Page to subscribe and give us a star rating or a review so that we are more visible and more people can learn about the awesome science going on in agriculture. Be sure to listen in next week when we discuss biofuels and other energy related science . If you have any questions you would like answered on that topic please leave a comment below. If you’re new to AgSciToday check out our past blogs and podcasts and let us know what you think.
P.S. If you’re interested in the mucus surfaces and phage science Tim mentioned you can read about it here.
This week Tim and Steph discuss colostrum, its importance to neonatal (baby) animals, and its role in extending the communication between mother and offspring outside of the uterus.
What is Colostrum?
It is the first milk an animal produces after giving birth and contains the nutrients and other things such as immune factors they need to start a healthy life. The processes that culminate in production of colostrum actually start weeks before parturition (birth) but colostrum cannot be obtained from an animal until after parturition.
Why do animals make colostrum?
Many animals have a very thick placenta so antibodies and other important factors in the blood stream aren’t able to pass through to the fetus. Because of this in order for the offspring to have a good immune system they have to get colostrum soon after birth for that transfer of maternal antibodies to occur and protect the calf or pig or whatever it might be. This inability for antibodies to cross the placenta isn’t universal but in some species colostrum is the sole way immunity is transferred from mother to offspring.
Why do calves and other animals need to get colostrum soon after birth?
Absorption of antibodies through the gut of an adult animal isn’t generally thought to be possible because they are fairly large particles. For a brief period after birth, around 12 hours, an animal’s intestinal epithelium is “leaky” allowing those antibodies to cross through to the blood stream. Within 24 hours the intestines have tightened up to keep pathogens out of the blood stream.
Colostrum testing and storage
Some cows give better colostrum than others and some just give straight up poor quality stuff. There are a few different ways to test the quality of cow colostrum. Colostrumeters and refractometers are two methods used to test the quality of colostrum. There are many different ways store colostrum but the big thing to keep in mind is proper labeling of colostrum when refrigerating or freezing to ensure it gets used in the proper amount of time depending on temperature it’s stored at. Spoilage of refrigerated colostrum can have a very large effect on the quality when it comes time to feed it to a calf.
What is lactocrine signaling?
The idea that the mother communicates with the developing fetus in the uterus seems common sense to most people but the idea that mothers continue to shape development of their offspring postpartum isn’t so obvious. Researcher Carol Bagnell from Rutgers University coined the term lactocrine to describe the many factors in milk that affect development of their offspring. The route through which milk transferred factors affect development is epigenetic programming or the turning on and off of genes. Young animals have many critical periods where things such as cells in their reproductive tract are still differentiating, developing the organs. Lactocrine signals can affect the development of those tissues.
Effect of feeding milk replacer instead of colostrum to pigs
In the paper by Bartol et. al. titled: “LACTATION BIOLOGY SYMPOSIUM: Lactocrine signaling and developmental programming” they test the hypothesis that factors contained in colostrum affect the reproductive tract tissue development of piglets. To test the hypothesis you fed piglets either colostrum or a milk replacer solution. They considered the milk replacer solution to be lactocrine null as it didn’t have the hormones and proteins that the colostrum had. They then looked at expression patterns of molecular markers and mediators of uterine and cervical development inluding the estrogen receptor, vascular endothelial growth factor and a special enzyme called matrix metalloproteinase 2 and 9. The results from this showed that the piglets who were fed normally from their mothers had higher levels of estrogen receptor in both the uterus and cervical tissues. Additionally, they had higher levels of vascular endothelial growth factor and matrix metalloproteinase2. However, matrix metalloproteinase 9 was not different between treatments suggesting not all neo- natal uterine and cervical protein expression is lactocrine sensitive.
A study measuring the antibody immunocrit levels in piglets blood which reflects colostrum intake in neonatal pigs. By analyzing approximately 380 animals, they found that lower immunocrit levels (equivalent to minimal colostrum consumption) were associated with reduced litter size. These data provide compelling support for the idea that lactocrine signaling affects uterine capacity and reproductive performance in adults.
That’s all folks!
Thank you for listening to our show and if you like it please go over to Our iTunes Page to subscribe and give us a star rating or a review so that we are more visible and more people can learn about the awesome science going on in agriculture. Be sure to listen in next week when we discuss bacteriophage and their applications in food safety. If you have any questions you would like answered on that topic please leave a comment below.
P.S. If you’re interested in the bone related discovery Tim mentioned you can read about it here.
A big thanks to Cargill’s @foodsecureworld twitter account for alerting us to this paper. It certainly was an interesting read and we were so lucky to get one of the authors to come on with us and share more insights into the research.
For this week’s blog on the episode we’ll just give you some of the questions and responses Amy gave. There is much more interesting discussion in the episode so please give it a listen but these are some of the highlights:
1. Give us an introduction of yourself (i.e. where you are now, where your previous degree(s) are from, etc).
Amy grew up in the pacific northwest and attended University of Washington earning a degree in biology. She completed a Masters in Vancouver BC at Simon Frasier University in resource management focused on humans in costal ecosystems. She currently resides in Seattle.
2. Tell us about your research
Amy admittedly didn’t know much about clam garden before participating in this research. She now knows a great deal and shared with us what they are and how they are constructed. Clam gardens are intertidal terraces. Rocks are rolled to the bottom of the beach to build a wall and backfilled with sediment to create a more gently sloping beach. They were built by first peoples to raise littleneck and butter clams. Amy tells us what a midden heap is and why they are valuable as a living record of life to research how first peoples ate and lived.
3. How did the subject of ancient clam gardens come about to be something of interest for you to research?
Amy had Read book by Judith Williams called ancient mariculture. We couldn’t find that book but here is a link to a similar book by her about clam gardens. Through some stroke of luck her advisor Dr. Anne Salomon was contacted by Dr. Dana Lepofsky who invited Amy to take part in this clam garden research.
4. Give us an introduction on the clam industry (from a food perspective)
Today’s clam farming techniques are much different than old gardens in that they remove other species than the ones being cultivated and done on a far larger scale on larger beaches than the type they studied. There are a number of cultivation methods currently employed by commercial clam farming.
5. What were your results?
Research team wanted to know if clam beds increased number of clams raised and if so how? They tested the hypothesis by studying walled beaches (clam gardens) and unmodified beaches. They did surveys of the beaches and transplanted some clams as tests. Clams grew twice as fast in clam gardens and higher survival rates of young clams. 4X the butter clam and 2X more littleneck clam populations in the clam gardens compared to unmodified beaches. They also found clam gardens increase the area of the beach that is at the ideal water depth for clams by flattening grade out.
6. Tell us a bit about clams and their life cycle. How do they reproduce, migrate to new areas, etc.?
Clams reproduce through releasing gametes into the water similar to fish and other aquatic breeding species. Clams’ only opportunity to migrate to new beaches is when they are spawned and floating around as plankton in the ocean currents. They eventually settle out on a beach and grow a small shell.
7. Do you think the results would have been different if the gardens were being actively tended to through methods noted in the paper such as adding gravel, shells, turning rocks, and thinning larger clams?
Amy predicted that if gardens had been tended in traditional ways they would have been more productive. Tending was largely a practice of thinning out competing things such as larger clams and a species of seaweed that grows on the beaches.
8. In the paper, you mention the difficulty of these types of studies because of the lack of adequate controls. Can you discuss that and things you would do in the future to when considering studying ancient resource management in contemporary areas.
Amy said that working with first peoples to deconstruct a clam garden and reconstruct one would be a valuable experience for researchers.
9. What are some other examples of ancient ecosystem modifications people may not know about?
Fish weirs used for the trapping or holding of fish are a common ancient modification along coasts. Stone modifications to salmon bearing rivers to make it easier to catch them are also common. Transplanting of bushes and starchy root plants was common in areas that mariculture was practiced.
10. What are your thoughts on whether total biomass production is increased by ecosystem modification or a shifting of biomass production to one or more desired species?
At first glance it seems that clam gardens studied increase biomass but its really unclear without further study what might be missing or other things that could be there but aren’t seen. Tim brought up an interesting bit of research he heard about that seashell picking could be a problem for beaches you can follow this link to the paper he was thinking of. Amy mentioned that shells are a signal for recruitment of new clams to settle there and therefore important for beaches that house clams.
11. If you could leave our listeners with something to remember from your research in relation to agriculture and food production, what would that be?
Amy’s message was that people have been managing and tending seascapes for millennia and they can offer techniques and strategies for cultivation that can inform how we produce food today. Traditional practices are very relevant today from a food security standpoint looking at the populations they managed to provide for in the past.
This week Tim and Steph talk about Staphylococcus Aureus which is a major pathogen for both humans and animals. We discuss briefly how it is handled in a human medicine setting as well as in agriculture, primarily from a dairy farming perspective. The remainder of the episode is a discussion of the paper “Phagocytosis Escape by a Staphylococcus aureus protein that connects complement and coagulation proteins at the bacterial surface” by Ko and colleagues. The paper can be read for free at PLOS Pathogens by following this link.
Staph aureus is an important bacterium from a disease and economic standpoint costing billions of dollars per year in the United States alone due to costs incurred by hospitals all the way down to things like milk yield loss in cows with mastitis caused by it. It is so prevalent in the world avoiding it isn’t possible and it is even a common organism to have growing peacefully on our skin and some mucous membranes. The issues come about when S. aureus gets introduced to somewhere it doesn’t belong such as a wound or during a medical procedure.
Many people have heard of MRSA or Methicillin Resistant Staph Aureus which is a major problem in human health, causing hospital acquired infections that are very hard to cure. Hospitals take serious steps to prevent infection by S. aureus and slow spread if someone admitted to the hospital has it. Tim tells a story about his family’s close brush with what could have been a staph infection in one of his children and the steps doctors took to ensure the safety of the other patients. MRSA isn’t just an issue in hospitals but has been found on many farms. Treating antibiotic resistant bacteria in animals is just as frustrating as it is in humans and can be deadly for the animals if the right therapy isn’t found soon enough.
Staph aureus mastitis in dairy cattle
The paper we discuss today “Phagocytosis Escape by a Staphylococcus aureus protein that connects complement and coagulation proteins at the bacterial surface” by Ko and colleagues is introduced which can be read for free at PLOS Pathogens by following this link. Tim talks about his experience with Staph aureus mastitis on his farm and how bulk tank cultures are one way to monitor for levels of S. aureus in a herd. A nice factsheet about S. aureus prevention and control can be found here for those interested in reading more on this.
Steph talks about vaccine development for Staph aureus and discusses some of the ways it is able to persist so well in cows’ udders even when treating them with antibiotics. She then talks about her time working in the lab of Dr. Isis Kanevsky-Mullarky a professor in the Dairy Science Department at Virginia Tech who does S. aureus vaccine research. Recently Dr. Kanevsky-Mullarky was awarded the Presidential Early Career Award for Scientists and Engineers and we congratulate her on that achievement.
Extracellular Fibrinogen Binding Protein
Tim introduces everyone to a protein called Extracellular Fibrinogen binding protein or “Efb” that Staph aureus is able to produce and talks about its potential as a vaccine candidate. Some immunological concepts needed to be laid down to understand the next content: We talk about phagocytosis or the “eating” of particles by neutrophils which are an important immune cell for combating potential infections. Next Steph explains opsonization which is when small proteins in the blood that are part of the body’s immune system bind to the bacteria and “flag” it for neutrophils to destroy. Coagulation which is generally thought of in blood clotting is discussed in its role of a way for immune system to trap foreign particles for clearing by immune cells.
Results of Initial Efb Experiments
The researchers first put staph aureus, human neutrophils, the Efb protein, complement into a culture system together and then measured how much bacteria could be phagocytized (broken down). With this combination (the staph, the neutrophils, the Efb and the complement) the phagocytosis by neutrophils was not altered. However, when they added coagulation proteins, in particular fibrinogen, they found that phagocytosis was inhibited. Now they needed to further proof that Efb can also block phagocytosis in a more natural environment. So, they repeated the experiment we just described but instead they tested Efb with staph aureus in whole blood. Similarly, they found that neutrophil phagocytosis was dependent on Efb. Then they tested it in a mouse. They infused the mice with fluorescent Staph aureus with or without Efb. They sacrificed the mice and then looked for the fluorescent Staph aureus inside the neutrophils and found the mice that the neutrophils from mice treated with Efb did not phagocytose the bacteria (phagocytosis was inhibited)
More Experiments to Prove How Staph Tricks the Neutrophils
The next thing the authors wanted to know was whether Efb might bind to the bacteria and then attract fibrinogen to the surface. They wanted to test whether Efb might bind to one of those complement proteins, C3b to help bring in fibrinogen. To do this, they coated specialized plates with the C3b protein and found that the Efb actually binds both C3b and Fg and needed both C3b and Fg to bind. To see if Efb actually attracts fibrinogen Staph aureus was “pre-opsonized” and all that means if before adding any Efb they added the complement protein C3b to pre-flag the bacteria. Then they added the Efb and then the fibrinogen and with microscopy saw that Efb and fibrinogen covered the entirety of the bacteria. When they added Efb that in the lab had been manipulated to lack bindings sites for C3b or fibrinogen you did not see the binding. So now by the authors can suggest that the order of things goes binding of the flag protein C3b to the bacteria to say “hello” I’m here. Then the Efb binds to the C3b follow by the fibrinogen to build a protective shield, kind of a cloak of invisibilty, around the bacteria.
Applicability of the Research
The research we reviewed in this show really illustrates why it is so hard to control a Staph aureus infection. Until we get an effective vaccine for S. aureus the best way to deal with infections is still going to be preventing them. Culturing of microbes causing an infection can help us know what the best plan of attack to deal with an infection is because what particular microbe is causing the problem plays a huge role in determining the correct management practices or antibiotics that will have the biggest impact.
That’s all folks!
Thank you for listening to our show and if you like it please go over to Our iTunes Page or click on the link to sticher in our sidebar to subscribe and give us a rating or a review so that we are more visible and more people can learn about the awesome science going on in agriculture. Be sure to listen in next week when we discuss aquaculture and in particular ancient clam beds. If you have any questions you would like answered on that topic please leave a comment below.
Agriculture Science Today Episode 008
This week Tim and Steph talk about group housing dairy calves and some new research that suggests the practice may help them be smarter cows better able to deal with change. We had the pleasure of interviewing Dr. Rebecca Meagher a coauthor on the paper who gave us some great insight into the animal behavior research field.
Random Chatter About Our Week
Steph noted that she helped out at the Intercollegiate Dairy Challenge this past week. You can learn more about that great learning and networking opportunity afforded to college students here.
Tim talked about going to the Organic Valley annual meeting and receiving a milk quality award. To see the other farms who won awards you can view the press release here.
Short Preview of the Study and Results
Steph started off mentioning some calf behavior research she had done as an undergrad but unfortunately we don’t have a link to the paper if it has even been published. If we do find it we will post it on here for you all to read.
The first test they did on the two groups of calves was in a Y-maze with two choices associated with black or white colored square and a full or empty bottle of milk. After the calves were able to correctly associate the side of the maze with the full bottle reward they switched it. The side that previously had the full bottle was now empty and vice versa. They then measured the number of correct choices the calves made. The results of the test were the same during initial training for both groups but after switching the bottles around the group housed calves adapted to the change quicker.
The second test they did was a novel object test. They put a plastic bin in the pen with each calf and measured the amount of time the calf spent interacting with the object. The results of the test were that individually housed calves spent significantly greater amounts of time interacting with the novel object compared to the group housed calves.
Interview with Dr. Meagher
Dr. Meagher has done previous work studying behavior of mink raised in a production setting for fur and tells us a bit about that type of farming. She then described the increase in animal welfare and behavior research due to many factors including a general public interest and Dr. Temple Grandin.
Dr. Meagher next described the study construction and why they chose to use the two tests they did for testing the cognitive ability of calves. The two tests have been used in rats and other animals in the past for cognitive ability testing so they picked those tests based on them being accepted in this type of research.
Applicability of the Research
The benefit of calves being housed together is that they could be less stressed by changes in their environment in the future. Providing social contact for calves and more variability in their environment seems to cause a biological change in the calves’ brains but more research will be needed to confirm this. Cows that are able to handle change well may be more ideal for automatic feeding, milking, etc which are all pretty big changes to a cow. Dr. Meagher noted that see is looking into anxiety in animals and the relationship between that and cognitive development.
That’s all folks!
Thank you for listening to our show and if you like it please go over to Our iTunes Page to subscribe and give us a star rating or a review so that we are more visible and more people can learn about the awesome science going on in agriculture. Be sure to listen in next week when we discuss aquaculture. If you have any questions you would like answered on that topic please leave a comment below.
Agriculture Science Today Episode 007
PEDv “The Sticky Virus”
This week Tim and Steph talk about the pig disease Porcine Epidemic Diarrhea Virus or PEDv with Dr. Bob Morrison of the University of Minnesota. The virus is highly pathogenic, spreading and has caused over 5 million pig deaths in 27 states.
History of PEDv
It was found first in April 2013 on an Ohio hog farm. It is a devastating virus for baby pigs causing diarrhea which is deadly because they have little reserves to live on. There is a strain in Europe that has been around since the 70’s but not as virulent as the strain that showed up in Asia 2-4 years ago and in the U.S. in 2013.There aren’t any theories of how PEDv came to arrive in the U.S.
Possibility of Zoonosis for PEDv
Despite being a Coronavirus which is a common virus type to many species Dr. Morrison knew of no potential for spread to humans or other domesticated animals at the present time. Bats being the potential initial source of PEDv was discussed but not enough is known currently about it to speculate. Dr. Morrison also mentioned the Delta Virus which causes similar symptoms to PEDv although not the extreme death losses.
University of MN role in PEDv research
The University’s diagnostic lab is providing diagnostics services and development of new tests to test for PEDv. Dr. Morrison is working on the epidemiology of the virus focusing and incidence, impact, spread, and rate of infection.
The incidence project he is running has 680 sow farms (1/3 of industry) they are monitoring for incidence of PEDv infection. The information gleaned helps track how the epidemic is taking place. First zone of infection was in Oklahoma followed by the Southeast and now the third phase that is currently happening is in the Midwestern states.
The estimate of impact project they are doing is finding out what to expect on average if the disease strikes on a farm. 18 farms data showed that for first 3 weeks 100% of piglets were lost and on average it takes 6 weeks to get back to normal after it has gone through. Some recent data is showing that the losses may be getting worse.
The third project they are just starting now is researching how long it takes to eliminate the virus after a farm has gotten it. Preliminary data suggests that it will take around 4 month to eliminate the virus but there is concern that it is persisting longer than previously thought.
The last major project is quantifying risk posed by a neighboring farm being infected. The national pork board funded it. Having PEDv in a region definitely increases likelihood of it infecting another farm. The more traffic a farm has the higher the risk of disease. Rodents were a risk factor as well as how deadstock are disposed of. There is a cumulative effect of those factors so the more of them a farm has the higher their risk of a PED outbreak.
How to prevent spread of PEDv
First off farmers are encouraged to let others know the status of their farm so they don’t visit and track the disease back to their farm. Dr. Morrison compared the virus to honey in that it’s a very sticky virus and stays on equipment, people, clothes way better than other viruses seem to. He mentioned visiting the National Pork Board website for educational resources for farmers on how to prevent and handle PEDv outbreaks. Another good source we found for information was the AASV website which had a ton of info on the disease and good practices to prevent it. Limiting traffic on a farm seemed to be one of the most important factors a farm can control he mentioned while discussing his lab’s research.
Feedbacks and vaccines as measures to control PEDv
Vets and farmers are using intestines of pigs which died of disease and fecal matter from diseased pigs to get widespread immunity in the sow herd and to make sure there will be no lingering infection because of naive individuals. This may sound gross but is among the few options available to farmers currently to try to save their herd.
The only vaccine currently available is a killed vaccine which is not thought to be effective in a naive sow herd to build immunity to levels needed to prevent disease. Companies are working on attenuating a modified live virus but this will take time to complete. Killed virus vaccine can however be used in an infected herd with some success along the same lines as feedbacks to increase herd immunity.
How to keep employee moral up during PEDv outbreak
Farmers need to help keep employee moral up because as Dr. Morrison says “working with healthy pigs is so fun but working with diseased or dying pigs is so not fun”. He provided some great advice that owners or supervisors need to acknowledge the tough times and work that goes into trying to keep pigs healthy and thank employees for their efforts. Another tip not mentioned on the show but seems like a good idea Tim’s friends the Roelofs mentioned is to hire an outside crew to do feedback making and inoculation if that’s a tool a farm decides to implement to fight an ongoing infection.
That’s all folks!
Thank you for listening to our show and if you like it please go over to Our iTunes Page to subscribe and give us a star rating or a review so that we are more visible and more people can learn about the awesome science going on in agriculture. Be sure to listen in next week when we discuss why “Grouped Calves are Smarter” and we’ll be reviewing a paper in PLOS one by Charlotte Gaillard “Social Housing improves Dairy Calves Performance in two cognitive tests”.
Sexy Male Goats
Today Tim and Steph discuss male goats and their unique (lady goats may say sexy) scent, also known as pheromones. They note the first pheromone discovered in moths in 1959 named bombykol and stink fights among lemurs and ant foraging behavior. The possibility of human pheromones was discussed in regards to studies of menstrual cycle syncing in women. You can read about that here and here. Interestingly related by being smell mediated but not pheromone as far as scientists know MHC research on sweaty mens tshirts was discussed which you can read about here.
Male Effect in Goats
Steph laid out what the “male effect” was as seen in sheep and goats and noted the title and author of paper being discussed “Identification of an Olfactory Signal Molecule that Activates the Central Regulator of Reproduction in Goats” by Murata and colleagues published in the recent edition of “Current Biology” a Cell Press journal publication. Tim talked about the difference between polyestrous cows and seasonal goats and sheep and brought up research from the 1980s that first noted the “male effect phenomina”
Steph discussed the unique cap they made for the goats to collect the volatile compounds (smells) emitted from the the goats’ heads and the reason they thought that the place to search for pheromones. Tim talked about how the researchers tested the volatiles collected in the goat headwear to identify potential pheromone compounds. 7 compounds were identified testing castrated male goats against intact male goats.
Lady Goat Response
Steph discussed hormones in female goats associated with estrus focusing on GnRH pulse generation and LH which were the two main things looked at in the study. Tim talked about the findings from the experiment the researchers carried out first measuring hormone response in female goats to male goat hair then Steph laid out the response of hormone levels to synthesized compounds based on the ones found to be different between intact and male goats. Tim spoke on the response of LH and how levels of it followed the increase in GnRH pulsation. Steph finished out the discussion on hormones revealing that the synthesized compound found to have greatest effect on hormone levels was 4-ethyloctanal.
Pheromones to replace hormones in livestock reproduction?
Tim and Steph summarize the findings of the paper and discuss possible applications namely in reproductive management of livestock and possibility of finding pheromones in polyestrous animals such as cattle.
That’s all folks!
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Effects of landscape on bumblebees to ensure crop pollination
This week we review a paper on the effects of different land use types surrounding squash fields on the ability of bumblebees in conjunction with honey bees to pollinate the crop. The researchers asked 4 questions about pollinators in this paper. 1)The amount of pollen each type of bee can carry and efficiency with which bees can transfer pollen to plants? 3)Can honey bees or bumblebees alone pollinate plants at high enough rates for maximum yields? 3)What is the effect of surounding land cover on pollenation by honey or bumble bees? 4)What is the overall relationship between land use and pollination of plants?
Colony collapse disorder
We discuss the need for pollinator research in the context of the problem posed to our domesticated bee populations by colony collapse disorder. You can read more about CCD here.
New problem for bees, a plant virus?
We discuss the recent research suggesting that a plant virus, tobacco ringspot virus, may have jumped kingdoms into bees. This finding is new and we have our reservations about blaming it for the plight of honey bees but it is very interesting so we included it in this episode. You can read about it here.
You can also listen here to the recent This Week in Virology Episode on the topic of the potential new bee virus. They do a great job discussing the background and potential shortfalls of the research that exposed this new potential reason for bee problems.
Methods of assessing pollinator efficiency
We review and explain the ways the researchers of our main paper quantified and recorded the efficiency of honey bees and bumblebees in pollinating squash.
Results of the paper
The researchers found that asian honey bees while not being very efficient at carrying pollen did make a high number of visits to blossoms vs. the high efficiency pollen carrying bumblebees who made many less visits per blossom. They found that neither species had the ability to fully pollinate plants alone but with above 13% natural habitat surrounding fields bumblebee populations were high enough in conjunction with honeybees to sufficiently pollinate plants.
Comparison with research by Kennedy et. al.
Steph compares the research of Xie and An with that done by Kennedy and others published in Ecology Letters. They found that diversity of plants in an area as well as organic management practices favored bee richness. Tim noted new funding available in the upper midwest through USDA for bee habitat planting. You can find out how to get involved by clicking here.
Thank you for listening to our show and if you like it please go over to Our iTunes Page to subscribe and give us a star rating or a review so that we are more visible and more people can learn about the awesome science going on in agriculture.
A final link for you to the Plant Pathology Podcast we noted at the end of the show. Just go to www.theplantpathologypodcast.wordpress.com/ to check out her podcast and learn about plant diseases.
Phytase and Nutrient Management
This week we discuss the enzyme phytase mostly as it relates to dairy nutrition but with a few nods to pigs and chickens. Nutrient management on farms and water pollution is a concern we discuss as it is part of the justification for the need of researching phosphorus in animal feeds and manure. We discuss some of the ways phosphorus can get to waterways and the concerns
Animal Nutrition Research
The study design was discussed with a brief note on animal research regulation and concerns if you’re curious and want to learn more about animal research regulations and IACUC the University of Wisconsin Madison has a good explanation here.
Byproduct Feeds Phytate Percentages
Through research for this show and our interview with Dr. Jarrett we discovered that processing of feed grains such as distilling or heat treatment can affect the percentages of total phosphorus and amount occuring as phytate. Here are some papers on distillers grains and phosphorus:
Interview with Dr. Jamie Jarrett
We finish the second half of the podcast with an interview of Dr. Jamie Jarrett who tells us more about her research on phosphorus along with why she believes they saw no difference in milk production when phytase was added to the rations.
Thank you for listening to our show and if you like it please go over to Our iTunes Page and give us a star rating or a review so that we are more visible and more people can learn about the awesome science going on in agriculture.