The most important time to feed a beef cow is 2 to 4 months after calving. This determines how fast her calf grows and how soon she gets back in calf. Cows need to be gaining weight when they are with the bull to optimise cycling. In a trial performed where the only difference between groups was high (20kgDM/day) versus low (8kgDM/day) the empty rates were 0% and 22% respectively. In reality we want to be feeding somewhere around 12kgDM/day from calving to mating. Any reduction in this and the cow will sacrifice her body weight first to maintain milk production. With only 85 days for a cow to get back in calf to maintain a 365 day calving interval cows need to be cycling when the bull goes in. Make sure selenium levels are adequate. Yearlings and 2 year olds can benefit from a drench.