Recipient Organization
NORTH CAROLINA STATE UNIV
(N/A)
RALEIGH,NC 27695
Performing Department
College of Vet Medicine
Non Technical Summary
Molds can produce poisons called mycotoxins that affect animals when they consume mycotoxin contaminated feeds. Worldwide it is estimated that about 25% of crops are affected annually with mycotoxins. There are hundreds of different mycotoxins which are diverse in their chemistry and effects on animals. In nature, it is unlikely that one mycotoxin will occur in a feed without the presence of several other mycotoxins.Mycotoxins can increase the incidence of disease and reduce production efficiency in cattle. They can be the primary agent causing acute health or production problems in a dairy herd, but more likely, mycotoxins are a factor contributing to chronic problems including a high incidence of disease, poor reproductive performance or suboptimal milk production. They exert their effects through four primary mechanisms: (1) a reduction in feed intake or increased feed refusal, (2) alteration in nutrient content of feed, and nutrient absorption and metabolism; (3) alterations in the endocrine and exocrine systems; and (4) suppression of the immune system. Recognition of the impact of mycotoxins on animal production has been limited by the difficulty of diagnosis. The symptoms are often nonspecific and the result of a series of effects, making a diagnosis difficult or impossible because of the complex clinical results.The impact of mycotoxins on the immune system is extremely important in dairy cattle but has not been studied extensively. Therefore the goal of this study is to evaluate the effects of moderate levels of mycotoxin exposure on immune function in lactating dairy cattle. A further goal is to determine whether or not the inclusion of OmniGen-AF™ (Prince Agri Products, Inc., Quincy, IL) is able to partially or completely counteract any immunosuppression or immune dsyfunction identified.
Animal Health Component
33%
Research Effort Categories
Basic
33%
Applied
33%
Developmental
34%
Goals / Objectives
To determine whether short-term exposure to mycotoxins has an adverse effect on immune function in mid-lactation dairy cows. An additional goal is to evaluate whether or not feeding Omni-Gen-AF is able to partially or completely reverse any immunosuppression or immune dysfunction that might be observed.
Project Methods
Forty mid-lactation Holstein cattle will be identified for this study. The cows may range from 60 to 150 days in milk at the start of the trial and will be at least 2nd lactation. All cattle will be housed on the Piedmont Research station in Salisbury, NC, and will be milked twice a day throughout the duration of the study. Personnel on this dairy have extensive experience conducting mycotoxin and nutrition trials. The 40 cows will be divided into 4 groups of 10 cows each, grouped by lactation number, milk production and somatic cell count. Two groups of 10 cows will remain on a diet free of mycotoxins for the duration of the trial. One of these groups (group 1; n=10) will be fed OmniGen-AF during the 12-week feeding period while the other group (group 2; n=10) will not receive OmniGen-AF. After an initial acclimation period of 6 weeks, the other 2 groups will be fed a diet containing mycotoxins for 6 weeks. The mycotoxins will come from naturally contaminated sources of grain and ideally will include deoxynivalenol (at 2-5 ppm of the total TMR) and T-2 toxin. An important part of this study will be finding contaminated grain and agreeing on what mycotoxin inclusion levels are appropriate. This is to be agreed upon jointly between the investigators and Prince AgriProducts. However we believe the best chance of identifying a significant degree of immunosuppression in this study will be the inclusion of T-2 toxin in the ration.During the 6-week acclimation period (prior to the inclusion of mycotoxins in the diet), one group of cattle (group 3; n=10) will received OmniGen-AF at a rate of 56 grams/day. This will continue for at least 42 days prior to start of mycotoxin feeding and will also continue throughout the mycotoxin feeding period. The fourth group of cattle (group 4; n=10) will be exposed to mycotoxins after the acclimation period, but will not receive OmniGen-AF at any point in the study. All cattle will be fed individually through Calan® gates where their daily feed intake can be controlled and feed intake measured. Diets (TMR) will be formulated by Dr. Lon Whitlow and the exact composition will depend on what mycotoxin-contaminated feedstuffs are identified for the trial. However all diets will meet or exceed the recommendations set forth by the NRC.Parameters to be measured include dry matter intake and daily milk production. Milk samples will be taken every 2 weeks beginning on day 42 to determine somatic cell count. On days 42, 63, 84 and 91 serum will be submitted for evaluation of hepatic enzymes. We also plan to measure immune function in these cattle by several different methods.1) Streptococcus uberis challenge - From samples collected on days 0, 42, 84 and 91, neutrophils will be harvested from whole blood and exposed to Streptococcus uberis in vitro.2) Blood samples collected on days 0, 28, 42, 49, 56, 70, 84 and 91 will also be analyzed for expression of L-selectin, interleukin 8 receptor (IL8-R) and other markers (TBD by Prince Agri. scientists). These samples will be collected as whole blood (0.5 ml.) and transferred to RNA Protect tubes provided by the Prince Agri-OmniGen Research Laboratory (OGR), maintained at room temperature for two hours and shipped on ice to OGR (1767 NW Kings Blvd., Corvallis, OR, 97330).3) We will also collect blood on days 0, 42, 84 and 91 to monitor neutrophil function (ie. phagocytic activity) to determine any potential deleterious effects of mycotoxins exposure (Prince Agri. scientists will assist).4) On day 42 all cattle will be given a 2 mL dose of Salmonella Newport Bacterial Extract (SRP®) - a Salmonella newport vaccine which has never been used on this dairy. On day 63 a 2nd dose will be given. Serum samples will be collected at day 42 (prior to vaccination) and on day 84. ELISAs will be run (by Epitopix, Willmar MN) to determine antibody concentrations to S. newport (ie. response to vaccination).4) On day 42 all cattle will also receive a 2 mL dose of Spirovac L5 (which contains inactivated serovars of Leptospira borgpetersenii serovar hardjo-bovis, L. pomona, L. grippotyphosa, L. canicola and L. icterohaemorrhagiae). Cattle will be revaccinated at day 63 and serum from days 42 and 84 will be collected to measure the antibody response to vaccination. Antibody titers will be performed by the Michigan State Veterinary Diagnostic Laboratory The above approach will allow us to evaluate any potential effect on either the cell mediated or humoral branch of the immune system. Additional blood can be collected and/or saved for other assays if requested. Following the end of the 12-week study all cows will be returned to their regular diet3) We will also collect blood on days 0, 42, 84 and 91 to monitor neutrophil function (ie. phagocytic activity) to determine any potential deleterious effects of mycotoxins exposure (Prince Agri. scientists will assist).4) On day 42 all cattle will be given a 2 mL dose of Salmonella Newport Bacterial Extract (SRP®) - a Salmonella newport vaccine which has never been used on this dairy. On day 63 a 2nd dose will be given. Serum samples will be collected at day 42 (prior to vaccination) and on day 84. ELISAs will be run (by Epitopix, Willmar MN) to determine antibody concentrations to S. newport (ie. response to vaccination).4) On day 42 all cattle will also receive a 2 mL dose of Spirovac L5 (which contains inactivated serovars of Leptospira borgpetersenii serovar hardjo-bovis, L. pomona, L. grippotyphosa, L. canicola and L. icterohaemorrhagiae). Cattle will be revaccinated at day 63 and serum from days 42 and 84 will be collected to measure the antibody response to vaccination. Antibody titers will be performed by the Michigan State Veterinary Diagnostic Laboratory The above approach will allow us to evaluate any potential effect on either the cell mediated or humoral branch of the immune system. Additional blood can be collected and/or saved for other assays if requested. Following the end of the 12-week study all cows will be returned to their regular diet