High milk production does not have a genetically related negative impact on immune function; however, high-producing cows tend to have more mastitis than lower-producing cows. This most likely can be explained by being more prone to negative energy and protein balance and the fact that higher-producing cows also have wider streak canals which makes them more prone to infections.
“Protein metabolism is equally important in the development of immune suppression around parturition,” Gorden states. “Cows are in negative energy balance for 45 to 75 days postpartum. They are also in negative protein balance for a similar period of time. The development of an immune response against an infection is not without expense to energy and protein metabolism.”
Chronic mastitis in the late dry period has been shown to decrease the volume of colostrum and the total IgG level compared to uninfected cows, but not the concentration of IgG/ml,
Help her regain balance
Prior to and after parturition maximizing dry matter intake by providing sufficient amounts of properly balanced feed can help the cow maintain proper energy balance. Gorden recommends providing the cow with adequate resting space and adequate bunk space (at least 30-in./cow) prior to calving, which is also important in the post-partum period. “In addition, minimizing pen changes prior to calving will promote better dry matter intake and lower incidence of metabolic problems,” he says. “It is extremely important to monitor dry matter intake to make sure the cows are actually eating what they are supposed to be. Measures to prevent hypocalcemia (subclinical and clinical) must be incorporated into transition cow program.”
Adequate levels of vitamins A and E as well as selenium are also needed to insure that the mammary gland immune system functions at its maximum capacity. The University of Pennsylvania New Bolton Center recommends that during lactation cows should receive 400–600 IU vitamin E and .3 ppm of selenium per day. During the dry period, cows should get 1000 IU vitamin E and .3 ppm selenium per day.
Gorden suggests that the most practical approaches for today’s dairyman include a combination of improving and maintaining cow hygiene, managing diets around the periparturient period to minimize dry matter intake and hypocalcemia, and implementing procedures to minimize cow stress. “It is inevitable that there will be a certain amount of immune suppression even in the best conditions,” he says. “However, implementing good management practices should help minimize this.”
Trace minerals and immunityIncreased severity of mastitis.
Deficiency:Decreased neutrophil killing capability. Increased susceptibility to bactericidal infection.
Function: Linked to proper immune function. Essential for integrity of skin, physiologic barriers.
Deficiency: Decreased leukocyte function. Increased susceptibility to bacterial infection. High calcium diets can exacerbate zinc deficiency problems.
Source: Lorraine Sordillo, PhD, The Pennsylvania State University, “Mastitis and Immunology,” Bovine Veterinarian, July–August 1998.