Yh. Schukken et al., A RANDOMIZED BLIND TRIAL ON DRY COW ANTIBIOTIC INFUSION IN A LOW SOMATIC-CELL COUNT HERD, Journal of dairy science, 76(10), 1993, pp. 2925-2930
The objective of the study was to evaluate the effect of administratio
n of antibiotics to cows at dry-off in a low SCC herd. Cows were infus
ed at dry-off with an intramammary antibiotic on the left or the right
side of the udder. Selection of the infused quarters was random, and
all people evaluating the occurrence of mastitis were unaware of which
half of the udder was infused. The quarters that were infused with an
antibiotic showed a significantly lower incidence of clinical mastiti
s in the dry period. Quarters that were uninfused had 10 cases of clin
ical mastitis versus 1 case in quarters that were infused with antibio
tics. The quarters that were infused showed a reduction of minor patho
gens at calving. The uninfused quarters showed little evidence of spon
taneous cure during the dry period. Milk leaking was frequent during t
he drying off period. Milk leaking was also associated with the occurr
ence of clinical mastitis later in the dry period. Cows that leaked mi
lk had a four times greater risk of clinical mastitis in the dry perio
d.