(C) Week 3: What are the major factors that could interfere with immune potency of the animals in your system?

What are possible factors that could be immune potent to a dairy calf?

-Dystocia

-Insufficient colostrum uptake

-Poor colostrum quality

-Stress (removal of calf from mother, environment, housing)

-Diseases presented to calf after birth

What are the factors of "good colostrum"?

-From a cow that if healthy

-Donor is vaccinated

-Cow has been in a pre-fresh group for 2-3 weeks

-Udder is prepared

-Cow is milked within 4 hours of birthing

-If colostrum isn't fed right away it is put in the fridge

-If colostrum is older than five days it is thrown away

Colostrum intake is critical for the well being and survival of dairy calves. The calf relies on this colostrum to provide it with antibodies and immunoglobulins that will help protect it from disease while its immune system is still developing. Timing is essential to ensure that your dairy calf has received adequate colostrum and will be protected from the multitude of bacteria and pathogens that it will come in contact with in the upcoming days. Based on the Ontario ministry of agriculture, food, and rural affairs; if a dairy calf does not receive any colostrum within the first 12 hours after birth, it is unlikely to be able to absorb enough antibodies to have adequate immunity. It is also important to feed the correct amount of colostrum. Four liters of high quality colostrum is recommended to be given to Holstein calves within one hour of birth. A second feeding should be given sometime in the next 8 hours and should consist of 2-3 liters of colostrum.

This graph shows that as the hours after birth progress the smaller chance the calf has of immunoglobulin absorption. Therefore the smaller chance the calf has of survival because it has no passive immunity to protect it until its own immune system becomes active.

Success in providing adequate immune protection to calves can be monitored by taking blood samples from calves at 24 to 48 hours of age and measuring serum total protein. This measure of total protein in serum is highly correlated to IgG levels. If calves have received enough high quality colostrum, serum total protein will be 5.5 grams per deciliter (g/dl) or greater. When total protein falls between 5.0 and 5.5 g/dl, there is a marginal risk for mortality and morbidity. Total serum protein levels less than 5.0 g/dl put the calf at high risk for health problems.

 The “clinical threshold dose” (the level of exposure that results in disease) is considerable lower for colostrum-deprived calves than for colostrum-fed calves. The number of organisms needed to cause disease is much lower in calves that have not acquired immunity form colostrum antibodies.

 Beyond the clinical threshold dose, the greater the pathogen exposure is, the more severe the illness. Calves with colostrum-acquired immunity can be exposed to larger pathogen does yet suffer less severe illnesses than colostrum-deprived calves.
 This figure shows that colostrum affects both morbidity (illness) and mortality (death). Results of a national survey of heifer management practices showed mortality rates for calves with low antibody levels (less than 10 grams per liter) were more than twice that of calves with higher levels.

1. "Colostrum for the Dairy Calf." *Colostrum for the Dairy Calf*. N.p., n.d. Web. 26 Feb. 2017.

2. Jones , Dr. Hugh . "Colostrum ." *Colostrum*. Minnesota Dairy Team , 2009. Web. 26 Feb. 2017. <https://www.extension.umn.edu/agriculture/dairy/calves-and-heifers/colostrum-management.pdf>.