Performance during first lactation is the best indicator that a successful rearing program has been implemented. The typical guidelines to consider are (i) optimum age at first calving should be around 22–24 months of age; (ii) excessive rate of weight gain prior to puberty directly affects performance, reproductively and productively; and (iii) never underestimate the costs associated with rearing programs.

There are many alternatives with regard to housing and delivery of feed to recently weaned heifers. From pasture to confinement, it is imperative to avoid overcrowding, and to move heifers out of the hutches in small groups of 5–10 head at a time.^1,2 This is the beginning of a system where the heifers experience the most stressful time as a group. The main advantage of having a small group is that this allows the heifers the opportunity to adjust to diet change, pathogen challenges, and proper growth. Ultimately, the goal is to raise healthy heifers that reach the breeding group as homogeneous and balanced as possible; however it is imperative to keep in mind that when calves are grouped, the risk of diseases such as respiratory conditions and diarrhea, specifically coccidiosis in this age group (>30 days old), increases.

A palatable concentrate diet (same as that being fed in the hutch) should continue to be offered during the first 2–3 weeks after grouping, followed by a change to a heifer grower ration with inclusion of a coccidiostat product, either an ionophore or a sulfonamide. In addition to the heifer grower ration, early cut forages are preferred for the recently weaned younger heifers, as they are higher in energy and protein and lower in fiber. High-fiber products should be avoided in young calves as the rumen–reticulum is still under development, and unable to fully digest fiber-rich diets.¹ The major goal when it comes to feeding is to sustain uniform weight gain and growth, which will allow the heifer calf to attain puberty and thus breeding at the recommended age. The National Research Council³ suggests an average daily gain of 0.7–0.8 kg, assuming that a healthy calf is being raised in a thermoneutral environment. In addition, Drackley⁴ clearly states that a growth rate of 0.9 kg/day is achievable and does not affect mammary development, but needs to be adjusted to improve animal health and farm productivity. Therefore dry matter intake (DMI) must be managed properly based on environmental conditions. DMI should be increased when temperatures are below 15 °C; failure to provide extra energy can result in decreases of up to 0.2 kg/day of average daily gain.³ If forage availability is not an issue, heifers raised on pasture should not have problems reaching the goal suggested by the National Research Council, despite the extreme variability in quantity and quality. Special attention should be paid to the trace and major minerals, as supplementation may be warranted depending on the region and season.