title: Short communication: Preliminary investigation into the effect of freezing and a cryopreservant on the recovery of mastitis pathogens from ewe milk.
abstract: The objective of this study was to investigate the recovery of bacteria from ewe milk after freezing for 4 or 8 wk with and without the addition of glycerol as a cryopreservant. A total of 50 udder-half milk samples with a known range of bacterial species were selected, stored, and analyzed in 5 treatment groups: time zero; frozen for 4 wk with, and without, glycerol; and frozen for 8 wk with, and without, glycerol. A lower recovery was observed in all bacterial species studied after freezing. Samples containing fewer than 100 cfu/mL came from ewes with a lower somatic cell count and were more likely to be bacteriologically negative after freezing than those above this threshold. The addition of glycerol increased recovery of gram-negative bacteria after freezing, although this requires further study to draw strong conclusions. The effects on gram-positive species were inconsistent. We conclude that although the addition of glycerol had a small beneficial effect on the sensitivity of detection of bacteria from frozen sheep milk, sensitivity was highest in cultures from fresh milk.
authors.affiliation: University of Warwick, School of Life Sciences, Gibbet Hill Road, Coventry CV4 7AL, United Kingdom. edward.smith@warwick.ac.uk
authors.forename: E M
authors.initials: EM
authors.lastname: Smith
authors.forename: E M
authors.initials: EM
authors.lastname: Monaghan
authors.forename: S J
authors.initials: SJ
authors.lastname: Huntley
authors.forename: L E
authors.initials: LE
authors.lastname: Green
mesh_terms: D000818:Animals; D001419:Bacteria / Q000187:drug effects*; D018407:Bacterial Physiological Phenomena; D003451:Cryoprotective Agents / Q000494:pharmacology*; D005260:Female; D005511:Food Handling; D005615:Freezing; D005990:Glycerol / Q000494:pharmacology; D008413:Mastitis / Q000382:microbiology / Q000662:veterinary*; D008892:Milk / Q000382:microbiology*; D012756:Sheep; D013997:Time Factors
chemical_list: D003451:Cryoprotective Agents; D005990:Glycerol