Dr. Lefeld speaks at National Mastitis Council
Dr. Andy presented in Dallas a Case Study of bacterial culture results in a large dairy. He outlined interventions and how effective they have been at reducing infectious mastitis.

What we are seeing Reviewing Vaccination Protocols
Many protocols are good, but can be better. Things we commonly see that can improve are: 1) We have largely replaced BoSe with Multimin 90. Multimin has the additional immune function minerals of zinc, copper, manganese, and selenium. Bose has Selenium and Vitamin E. Vitamin E is important for immune function but the amount in Bose only lasts a short time. The switch to Multimin seems to have helped. 2) We have switched from lnforce at birth to Nasalgen 3 PMH. We are seeing less respiratory. That dose at birth will last three months but most booster sooner while calves are easy to handle. The thought process of easy to handle does not follow with the Bovishield or Titanium vaccines in growing heifers. The better job you do with colostrum at birth, the later you want to give these vaccines because maternal antibodies from colostrums block some of the response to BVD and IBR fractions in the vaccine. We have seen a difference in disease when we have moved these vaccinations out to 7 and 8 months. We know that some facilities are not easy to vaccinate heifers in. Giving these vaccines earlier is better than none, but not as good as waiting until antibody block wanes.

Adult cows have reduced ability to respond to vaccines so waiting until 30 days fresh to vaccinate is recommended. There is pretty good research recommending moving vaccination away from pen moves at dry off and prefresh. This is especially important for prefresh cows on anionic diets as vaccination negates much of the effect of anionic salts for a week or more. Early calvers are at risk.
 

Drs. Stayduhar and Hardesty attend Ohio Dairy Vets
We had a great meeting in Columbus with a focus on "Transition Cow Immunology and Calcium Metabolism." Topics included Vaccination Guidelines and Protocols, Nutritional Immunology, Choline, NutriQuest Effects on Systemic Inflammation, Calcium Homeostais, and Molds and Mycotoxins.

Salmonella Dublin
Dr. Habing gave us an excellent review of Salmonella Dublin at our peer group meeting. To review, Salmonella Dublin is an invasive harmful bacteria that makes calves one week to two months old very sick with GI, Respiratory, septicemia, encephalitis, cardiac signs, and sudden death. It is quite common on farms and sale barns. It does not respond well to antibiotics and can spread from cattle to people. It has the ability to survive in the environment, but is not easily cultured from the environment including feces. The best source for diagnostics are lynph nodes from necropsy samples.

The salmonella Dublin cycle is difficult to break. Salmonella Dublin crosses the intestinal barrier to invade tissue. Latent carriers are a significant part of continuing the disease on a farm. These animals were infected, recovered, and now shed Dublin in the environment. One to two year old animals are the highest risk for becoming latent carriers. They are best identified by two serum ELISA tests a month apart with no salmonella vaccine in between. Dublin is transmitted from dam to calf in colostrums and contaminated maternity pens. In utero transmission is suspected.

Internal biosecurity after your herd already has Dublin focuses on reducing spread. Identifying latent carriers could be part of this. Practicing all in all out by area or group slows it down.. Prompt carcass disposal, restricting the number of 

personnel working with calves under two weeks of age, .Dublin is very good at creating biofilm, which means proper use of a good quality detergent helps. Load matters. Soap is not detergent. Vircon is the disinfectant of choice with 10 minute exposure at label level. Chlorine Dioxide is widely advocated, but it needs 3000 ppm and label dose is 500. Internal Biosecurity reduces spreading on farm and includes feeding youngest to oldest, wearing gloves, and working sick calves last. Vaccine, especially to the dry cows improves immunity in calves through colostrum and possibly intrauterine. Prevention includes colostrum, nutrition, vaccination and decreasing or separating stressors.

External biosecurity is designed to keep Dublin out if you don't have it. Farms that have introduced one animal in the last two years have a 2.3X chance of having Dublin compared to those that have not. Farms that have animals leave and come back have a 2.9X chance of having Dublin compared to those that do not. Limiting access to the farm, controlling animal movements and wildlife help. A routine of cleaning and disinfecting slows spread. Non vaccinated animals can be serum tested. However not all infected or vaccinated animals will be ELISA positive. Cultures are good for active disease.

Mycotoxins are created by molds on feeds. Jason Hartschuh gave an overview at Ohio Dairy Vets. There are 400 identified mycotoxins but we will focus on the DON and Zearelanone as the main issues in the Midwest.DON decrease performance in Dairy cattle at 3 ppm in the total diet and in beef at 5 ppm. Zearelanone decreases performance at .5 ppm. Coctail mixtures of multiple mycotoxins especially including T-2 are worse than individual contaminants. Fusarium molds make both of these toxins and it is common on corn ears and small grain heads during certain weather conditions. It is facilitated by insect feeding, stem rot and head scab. GMO varieties are more resistant. Corn silage that is not well packed and straw stored outside can increase pathogens through the year. Broad spectrum binders have been the common approach to toxin issues, but they are often not enough to resolve issues.

Decreased intake, digestive upsets, decreased conception, liver toxicity and short gestation can all be the result of mycotoxins. Short gestation is 255 to 269 days carried calf and results in lower milk production. The goal is less than 12% short gestation and mycotoxin feeding and DCAD fed longer than 40 days can result in 20 to 30% short gestations.

Rumen protozoas degrade 90 to 100% of DON but it influences rumen fermentation reduces protein synthesis, creates HBS fermentation, immunosuppression, decreases in colostrum quality and acidosis.  Fat and protein content of milk is decreased  and SCC and mastitis are increased and cheese yield is decreased.

Prevention is the obvious solution. Hybrid selection is the first step. GMO varieties with tight husk, dropped ears, and insect control are significant. Weather during pollination is critical from 15 days before silking to 15 days after. Rain increases canopy humidity and when relative humidity is greater than 80%, there is risk.

Fungicides can help but timing and application methods are important. Once pollinated, fungicide does not move down the silk. Once tassled, full silk is in 5 days. Method effects effectiveness as drop spraying the ear misses the top and plane application may not put the spray down on the plant. Helicopter or drone may be best.