If they have enough gras to eat, even relatively poor quality, they shouldn't need anything but monerals and water to go with the grass. This is the lowest nutrient requirement that they will have, unless they are very poor from having weaned a calf recently. Watch their condition, that's alwasy the key. Lots of grass doesn;t mean diddly if it's mostly water.
Kelly, They are 6-10 year old cows supposed to be early bred. Thanks