Concurrent falls in milk production and electrical resistance of composite milk were examined in Israeli Holstein @entity291 . The @entity291 were milked three times a day by a system that recorded yield and the lowest electrical resistance in the composite milk from the four glands. The study included two groups: @entity291 that experienced on day 0 a decline in resistance and milk production > or = 20% from the mean of the previous 9 d (62 @entity291 , case group) and @entity291 that experienced no such episodes over 9 d before and after a fixed day (118 @entity291 , control group). Bacteriological status and somatic cell count (SCC) or @entity1271 test scores were assessed on the fixed day in the control group, and on days 0, 1 and 2 in the case group. @entity1271 test scores greater than 2 and SCC thresholds of 5 x 10(5) cells/ml were used to create two classes of leucocytosis. There was no statistically significant difference between the two groups in frequency distributions of pathogens and their types: in 30% of @entity291 infection was not detected, 33% were infected by major pathogens (95% of which were @entity794 ), and 53.5% by minor pathogens (80% Micrococcus spp.). @entity291 in the case group had lower milk production during the 8 d following day 0. Mean electrical resistance was lower in infected @entity291 and particularly in @entity291 infected by Staph. aureus. High leucocytosis was associated with reduced electrical resistance in both groups, and was found in 93% of @entity291 in the case group v. 25% in the control group. The results suggest that falls in electrical resistance of milk and in milk production were not linked to a specific pathogen, and were followed by 3-8 d of reduced milk production and electrical resistance. The study suggests that there are episodic aggravations in mammary health that do not evolve into clinical @entity1271 but may induce significant losses in milk yield and quality.

Subclinical XXXX assessed by deviations in milk yield and electrical resistance.

@entity291 :: ('9913', 'Species') :: ['Cows', 'cows'] @entity794 :: ('1280', 'Species') :: ['Staphylococcus aureus'] @entity1271 :: ('MESH:D008413', 'Disease') :: ['California mastitis', 'mastitis']
@entity1271 :: (MESH:D008413,Disease) :: ['mastitis']
