These bacteria can spread rapidly through a herd, so it is better not to introduce them in the first place.
Replacement cows may be purchased to increase the size of the herd, to assemble a new herd, or to maintain cow numbers after culling. You should carefully consider the disease history of cows before buying as replacements or assembling a herd from mixed-age cows or from multiple sources.
Guideline 21 and Technote 21 provide practical and technical information on:
- buying heifers rather than cows
- Not buying cows unless bulk milk SCC and mastitis records are available
- Checking udders and collecting milk samples before buying the cows
- Milking bought-in cows last
- Not milking other people's cows with your herd
- Assembling new herds