University of Nebraska Extension beef specialist Rick Rasby, PhD, reminds ranchers heifers have different nutritional requirements from mature cows. The pounds of protein or energy needed by the first-calf female compared to a mature cow at the same stage of gestation or lactation are not all that different, he says, but because the heifer does not consume as much as a bigger cow, the ratio of protein and energy in the diet needs to be higher. Nebraska research shows a 17 percent decrease in feed intake in first-calf heifers within about three weeks of calving. For that reason, Rasby recommends managing and feeding first-calf heifers separately from mature cows beginning at least three weeks before calving. Intake typically returns to a more normal level about one week after calving. Rasby says the first-calf females post-calving need to consume a diet that is at least 62 percent total digestible nutrients and 10 to 11 percent crude protein.