THE BACTERICIDAL PROPERTY OF COW'S MILK

Area of Science:

• Veterinary Medicine
• Microbiology
• Dairy Science

Background:

• Raw milk possesses natural inhibitory properties against certain bacteria.
• Mastitis streptococcus is a common pathogen affecting dairy cows.
• Understanding milk's antibacterial activity is crucial for udder health and milk quality.

Purpose of the Study:

• To investigate the bactericidal activity of raw cow's milk against mastitis streptococcus.
• To characterize the nature and origin of the inhibitory substance in milk.

Main Methods:

• Testing fresh raw milk against non-hemolytic mastitis streptococcus.
• Ruling out agglutinin as the inhibitory factor.
• Assessing inhibition periods and the effect of B. bovisepticus inoculation.
• Analyzing whey for inhibitory activity and heat resistance.

Main Results:

• All tested raw milk samples inhibited streptococcus growth for 4-8 hours.
• Inhibitory action was observed in milk from both young and old cows.
• The inhibitory substance could be absorbed by B. bovisepticus and was heat-resistant.
• Whey showed similar inhibition, suggesting an udder origin.

Conclusions:

• Raw cow's milk contains a heat-resistant antibacterial substance originating in the udder.
• This substance is distinct from blood alexin and is not influenced by artificial immunization or natural infection.
• The findings have implications for understanding natural resistance to mastitis.