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The goal of most dairy replacement management programs is to rear heifers at a low economic and environmental cost while maximizing future lactation performance. The National Research Council (NRC) Nutrient Requirements of Dairy Cattle provides well-defined nutrient guidelines for dairy heifers. We have several options for feed ingredients to meet these requirements.
We often hear the phrase heifer feed to describe a lower-quality forage or feedstuff. While these feeds may not yield the best feed efficiency, they can serve to satisfy the nutrient requirement of these animals. Some feeds need to be offered in moderation because they are high in certain minerals such as sulfur or phosphorus. Fat content and overall energy levels also need to be monitored in several of these feeds. Minimizing energy can be a challenge when lactating total mixed ration (TMR) refusals are offered in varying amounts to certain groups of heifers. Often times, lower energy, bulky feeds are used to dilute this energy content. Limit-feeding can be an option to reduce energy intake if adequate bunk space is available.
Several variables can impact heifer nutrient requirements beyond the specific animal factors of breed, body size and gestation status. Seasonal variation and housing can have a significant impact on maintenance costs. The thermoneutral zone for mature dairy cows is 40 to 75 degrees Fahrenheit. Growing heifers will be about five degrees above this. When temperatures exceed the upper level of the thermoneutral zone, feed intake is reduced to minimize heat production in the body. For heifers, this results in reduced daily weight gain. Heifers are able to dissipate heat more effectively than cows, but efforts should be made to implement heat abatement strategies in these animals, as well.
Providing shade is valuable to heifers in open lots. Heifers in confinement require adequate air exchange. Heifers typically consume one to 1.5 gallons of water per 100 pounds of bodyweight per day. Water consumption may increase by 20 percent or more during hot weather. Access to a continuous supply of clean, fresh water is essential to help cool and maintain performance in growing age heifers. Keeping heifers within their thermoneutral zone during hot weather can keep them comfortable, help maintain daily weight gain and improve conception rates at breeding age.
Any environment or housing system that includes well-bedded and managed freestalls or bedded packs will improve feed efficiency because of lower maintenance costs. However, any housing that allows heifers to be dirty and wet or allows animals to be heat- or cold-stressed will decrease feed efficiency due to increased maintenance energy requirements to maintain a normal body temperature.
Although their energy demands are not as great, older heifers still require careful consideration of their nutritional needs and those needs vary greatly between farms and facilities as well as with the seasons. Work closely with your nutritionist to evaluate your facilities and available feedstuffs to design the best program to meet the nutritional needs of the next generation of your dairy herd.
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