Before purchase that cow, here is what you have to out for;
Viewed from the side, a cow with a deep, long body with wide, well-sprung ribs is said to have a large body capacity, associated with good milk production.
A dairy cow with little body capacity is not a great milk producer. A broad muzzle implies the ability to get the food into her mouth and chew cud effectively.
Cows with a narrow chest as determined by the width between the fore-legs are not normally good producers.
Also if at least two fingers can be placed between the ribs of a dairy cow, then it has great capacity.
The udder should be your main priority. It must be pliable, silky in texture and sack-like in nature.
When viewed from the side it should not hang below the cow’s hock but should be close to the body, giving an appearance of support rather than swinging loosely.
It should be full and firm with no hard spots, redness, or swelling. Remember that a large udder is not always a sign that the cow is a good producer.
The teats should be even, medium-sized and centrally placed on each quarter of the udder. Over/undersized teats show the cow is not a good milk-producer.
Teats of older cows appear fuller than those of young ones. A teat that is not functional will look smaller than the others.
Mastitis is a common disease on most farms. Before buying a cow, find out whether the farm has a history of mastitis and what the actions they have taken to control it.
Feet and leg
A good cow should have strong legs because cows may have to walk long distances to feed. From the side view, the hind leg should be slightly sickle-shaped.
Any cow which is unable to stand up and/or walk with ease is useless. The legs should be clean, blemish-free and it should walk without signs of lameness.
Avoid temperamental cows. The cow should have a calm disposition. You can find out by observing the people working around it. This should tell you a lot.
Many cows with a chronic disease will show symptoms, but others will not.
If the cow is thin and rough-coated, it could need deworming and feeding. Or it could be suffering from a number of diseases, in which case it will probably never look any better and may even infect other livestock. Ask for assistance from a veterinary doctor.