Masters Theses

Date of Award

6-1988

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

S.P. Oliver

Committee Members

P.M. Davidson, F.M. Hopkins

Abstract

An in vitro microassay was used to evaluate growth of eight Staphylococcus strains representing five species and five strains of Corynebacterium bovis in skims from mammary secretions collected from quarters of five Holstein cows during the nonlactating and peripartum periods. Significant variation in growth among different strains of Staphylococcus species andCorynebacterium bovis and among cows was observed. All Staphylococcus species evaluated followed similar patterns of growth in mammary secretion skims. Mammary secretion skims obtained at 14 and 28 days of involution were poor media for growth of Staphylococcus species. Conversely, mammary secretion skims collected at cessation of milking, parturition, and during early lactation supported growth of all species evaluated. Staphylococcus hyicus and Staphylococcus chromogenes growth was greatest followed by Staphylococcus epidermidis, Staphylococcus xylosus, and Staphylococcus hominis. Similarly, Corynebacterium bovis grew well in mammary secretion skims obtained at cessation of milking, at parturition, and 14 days after parturition. However, growth of 4 strains in mammary secretion skims obtained at 14 and 28 day of involution was significantly lower compared to the 5th strain. Growth of Staphylococcus species in whey followed a similar pattern, but increased growth was observed in manimary secretions obtained during involution. Variation in growth of Corynebacterium bovis in mammary secretion skims and whey obtained during involution and peripartum period was not observed. However, growth of Corynebacterium bovis was reduced in whey. Mammary secretion skims were passed through S-200 gel filtration column. Four protein peaks were obtained from each skim sample. Peaks were characterized by two-dimensional polyacrylamide gel electrophoresis. The majority of proteins eluted in peak 1 and 2 from S-200 columns. Protein peaks were evaluated with respect to growth of Staphylococcus species and Corynebacterium bovis. In general, growth of Staphylococcus species and Corynebacterium bovis was reduced in peak 1 and 2 of mammary secretion skims collected during involution. These data suggest that mammary secretion skims support growth of Staphylococcus species and Corynebacterium bovis during lactation but inhibit their growth during the nonlactating period. The presence of high molecular weight biochemical components in mammary secretions are inhibitory to the growth of Staphylococcus species and Corynebacterium bovis.

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