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Cow factors affecting the risk of clinical mastitis
Berry, Donagh Meaney, William J
Berry, Donagh
Meaney, William J
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2005
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D.P. Berry, W.J. Meaney. (2005) Cow factors affecting the risk of clinical mastitis. Irish Journal of Agricultural and Food Research 44: 147–156
Abstract
The objective of the present study was to identify cow risk factors associated with
development of clinical mastitis (CM) in subsequent stages of lactation. A total of
3,309 lactations from spring-calving Holstein-Friesian cows were included in the
analysis; parity number ranged from one to three, inclusive. A generalised estimating
equations approach with a logit link function was used to account for the binary
nature of the data and the unequal number of repeated records per cow. The dependent
variable was the probability of developing CM in the subsequent stage of lactation.
Independent variables included in the model were chosen using stepwise selection;
herd, year of birth, month of calving, parity, period of lactation and previous CM history
significantly affected the probability of CM. Two-way interactions between parity
and period of lactation and between parity and incidence of CM in the previous lactation
were also included in the model. A greater probability of developing CM is
expected in cows that experienced CM in the previous lactation and/or previously
within the same lactation. The probability of CM occurring in cows that experienced
at least one case of CM in the previous lactation was 0.92 to 3.75 times that of a
cow that experienced no CM in the previous lactation. It is possible to predict the
probability of an animal developing CM in the subsequent stage of lactation when
information is available on the parity and month of calving of the animal and its previous
history of CM.