Incidence of mastitis among cows of different genotypes in differing
nutritional environments
S.J. LACY-HULBERT, E.S. KOLVER, J.H. WILLIAMSON AND A.R. NAPPER
Dexcel Ltd., Private Bag 3221, Hamilton, NZ.
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NZSAP 2002 Abstract No. 8
Proceedings of the New Zealand Society of Animal Production 62: 24-29
Over three seasons (1998, 1999 and 2000) groups of
Holstein-Friesian cows of New Zealand (NZ) or overseas (OS) origin were
monitored for mastitis when managed in two contrasting systems. Cows
were fed either on pasture or total mixed ration (TMR) with cows on TMR
confined to small loafing paddocks or a concrete feedpad. All quarters
were sampled for bacteriology at calving, at dry off, in mid and late
lactation and when clinical mastitis was detected. Individual cow
somatic cell counts (SCC) were determined weekly throughout lactation.
In 1998, there was no difference in incidence of clinical mastitis but
in later seasons, cows on TMR experienced significantly more clinical,
and sub-clinical mastitis, than cows on pasture, probably reflecting
differences in bacterial challenge within the environment. Genotype
differences were less evident compared to dietary effects. Compared to
NZ cows, OS cows experienced more sub-clinical infections in 1998 and
more clinical infections in 1999 whilst in 2000, genotype effects were
confounded by diet. Seasonal SCC was higher for OS cows in 1999 and
2000, reflecting differences in incidence of sub-clinical mastitis among
treatment groups. Despite the strong influence of environment on
mastitis incidence, genotype differenceswere detectable between NZ and
OS cows.
Keywords: NZSAPAB;
mastitis; genotype; diet; Holstein-Friesian.
Last Updated 30/07/2002
