The aim of this cross-sectional study was to test whether there is an
association between clinical mastitis incidence and variations in dry
matter intake in lactating dairy cows. Data were collected and analyzed
from two voluntarily participating dairy herds (1,000 -1,200 cows)
between 2017 and 2018. Lactating cows were assigned to seven “effective”
husbandry groups (HGeff), considering important performance
parameters such as lactation number, lactation day, reproductive
status, and health status. The average daily dry matter intake of a cow
in a husbandry group was determined once a week. Dry matter was
determined using dehydration equipment that dried the fresh masses
of the total mixed ration (TMR) in a standardized way. The incidence
of clinical mastitis was calculated for different aetiological groups
(environment associated mastitis pathogens, cow-associated mastitis
pathogens, NAS (non-aureus staphylococci) and no growth cases). Dry
matter intake (DMI) per individual cow was calculated as the averaged
value plus the associated standard deviation (DMI (sd)) from weekly
examinations of each husbandry group (HGeff). The average dry matter
intake per cow per day was 23.6 kg +/- 3.7 kg. Environment associated
pathogens were found in about half of all clinical mastitis cases (49.4
%). Cow-associated pathogens were found in 4.8 % of clinical mastitis
cases. In all models, the different clinical incidences of mastitis
studied were significantly associated with HGeff. In most cases, the
incident rates were significantly higher in the fresh milking and high
milking groups compared to the other groups. The incidence of clinical
non severe mastitis cases (only mild and moderate cases) caused by
environment associated microorganisms was further associated with
variation in dry matter intake, with higher variation related to higher
clinical mastitis incidence. Further studies are needed to verify this
association.