Abstract :
A case of unusually high (>94%) prevalence of mastitis in a flock of dairy sheep, which was caused by coagulase-negative
staphylococci (cnS) and associated with increased gossypol consumption, is presented. The animals were given a ration containing
25% cottonseed meal, whilst the farmer complained of significantly reduced milk yield. Various clinically detectable
abnormalities were found in the mammary glands; the California mastitis test (CMT) performed was always positive (≥1).
Bacterial species isolated from mammary secretion samples were cnS (n = 54), Staphylococcus aureus (n = 5), Bacillus
spp. (n = 5), Escherichia coli (n = 3) and Arcanobacterium pyogenes (n = 2). During the post mortem examination, pathological
findings characteristic of rumen acidosis were found in the mammary gland, macroscopic and histological lesions characteristic
of chronic mastitis were seen. Bacteria (cnS, n = 23; Bacillus spp., n = 3; S. aureus, n = 2; E. coli, n = 2) were also
isolated from mammary tissue samples. Gossypolwas detected in pooled milk samples collected from the ewes.Ahypothetical
model involving the high prevalence rate of staphylococcal mastitis with the increased dietary intake of gossypol is proposed.
© 2003 Elsevier B.V. All rights reserved.
