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0806 PD: Four control points in replacement heifer management

Patrick C. Hoffman Published on 07 August 2006

The goal for management when feeding dairy replacement heifers is to produce high-quality replacement heifers at a low cost. It is difficult to detail all of the business and biological aspects of developing information-based quality control management programs for dairy replacements in this article; therefore, the following key control points will be offered.

Control Point 1: Monitoring systems
Heifer growth should be monitored using modern technology. Basic components of a high-efficiency monitoring system include: an animal handling area, electronic scale and a digital or computerized recording device. In these systems, heifers can be handled, sorted and moved efficiently. Data, such as heifer weights, should be collected during routine management tasks in a form that is easily downloaded for computer software applications.

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To be of value, data collected from monitoring systems needs to be evaluated. While plotting or calculating mean or average growth rates has value, it tends to fall into the affirmation category of information. Heifer weights should be graphed with numerous categorical fields (such as pen, owner, failed passive transfer, pneumonia, heel warts, degree of inbreeding, season, etc.) to determine what factors are causing variance in growth rates.

Control Point 2: Improve neonatal nutrition
Recent research has demonstrated traditional neonatal nutrition programs may be limiting growth potential of calves. The dairy calf is extremely efficient at converting dietary protein intake to body protein deposition – with efficiencies near 60 percent, compared to protein deposition efficiencies in bred heifers of 15 percent. Simply stated, if dairy producers want to improve heifer growth and calve heifers 15 to 30 days earlier, the greatest opportunity to improve the management system lies in the very early phases of growth.

In studies at the University of Illinois, calves were fed milk replacer solids at 10, 14 and 18 percent of bodyweight (BW) for seven weeks. Calf growth rates were improved from a low of 0.60 pounds per day to a high of 2.25 pounds per day. Special formulation of milk replacer is required when additional milk powder is fed because growth is increased by feeding more milk replacer energy, so more protein is required in the milk replacer to meet growth demand.

For example, if milk replacer is fed at 1, 2 or 3 pounds per day, the milk replacer should contain 20, 25 and 30 percent crude protein (CP), respectively, to meet increased growth demand. There have been numerous studies conducted on these practices, and commercial products are now widely available in the United States. Field results have been generally positive.

On-farm milk pasteurization systems are now economically viable for dairy producers and calf growers. Our laboratory recently evaluated the nutrient density of pasteurized waste milk and, on a comparative basis, the mean protein and fat content of pasteurized waste milk would be the equivalent of a 28 percent CP and 31 percent fat milk replacer. Feeding calves 1 gallon of pasteurized waste milk per day supplies 50 and 65 grams more protein and fat per day, respectively, as compared to feeding a calf 1 pound of 20-20 milk replacer powder per day. Research by Godden at the University of Minnesota has demonstrated improvement in calf growth and health when pasteurized waste milk was fed in lieu of 1 to 1.25 pounds of 20-20 milk replacer.

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Critical Point 3: Manage sources of non-nutritional variance
Growth and weights of the heifers should be evaluated once data or information has been collected from the monitoring system. It is common to evaluate the average daily gain of heifers or to plot the weights, heights and lengths of heifers on a graph for comparative purposes. While evaluating the average growth of heifers is useful, evaluating variances of heifer growth probably has greater day-to-day management utility.

Growth of heifers varies for two reasons: genetics or a breach of management. The heifer monitoring and evaluation system should be able to capture any or all heifers that exceed variance tolerances.

The utility of a good heifer monitoring program is to find heifers varying from the system, not to justify appropriate means. Once found, a specific plan of action should be implemented for heifers with excessive variance. Specific heifers that vary from growth objectives should be found and both the animal and records thoroughly examined. Listed in Table 1* are non-nutritional sources of variance that could cause growth variance to occur.

Critical Point 4: Control feed cost
Presented in Table 2* are feed cost data for heifers broken down into specific cost categories. These data represent the average feed cost of a heifer for 62 Wisconsin dairy herds and can be used as a set of dairy calf and heifer feed cost benchmarks.

Good heifer nutrition starts with an understanding of the heifer’s base nutrient requirements. The nutritional requirements and philosophies of feeding a growing animal are significantly different from feeding lactating cows, and should be recognized as such. Dietary energy, protein, mineral and vitamin feeding guidelines for large-breed dairy heifers gaining 1.8 pounds per day are available in the 2001 National Research Council recommendations and appear to be reasonable under most management situations.

Because heifers are frequently reared in conditions outside of thermal neutrality (such as heat stress or cold stress), heifer nutrition programs need to be adjusted to the heifers’ environment. Specifically, heifers will require more energy in the diet when the following conditions or combination of conditions exist:

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•temperatures below 50°F
•wet conditions
•dirty haircoats
•cold, wet, noninsulative resting areas
•wind chill
•the absence of solar radiation

These conditions require more maintenance energy to be used by the animal. Therefore, more energy is needed in the diet for growth to occur.

The effects of environmental conditions on dietary energy needs are more profound on 300-pound heifers when compared to those heifers weighing more than 1,000 pounds. As heifers gain body mass and rumen capacity, they are much more adept at handling cold, wet environmental conditions. In most situations with young heifers, producers should opt to improve the environment and provide optimal resting areas rather than trying to feed more energy in the diet to overcome poor conditions.

A simple tool to monitor heifer environments is a monthly checklist of environmental conditions by pen. The checklist should include BW, temperature, coat conditions, crowding, lot conditions, etc. This information should be collected objectively and shared with the nutritionist and herd veterinarian to facilitate nutrition and management adjustments.

While it is often necessary to vary dietary energy to maintain optimal heifer growth, feeding excessive dietary energy is the principal cause of overconditioning heifers. At calving, overconditioned heifers will be more prone to calving difficulties and metabolic diseases. Dietary protein does play a minor role in heifer body condition, but overfeeding energy remains the biggest culprit. When heifers become overconditioned, dietary energy should be reduced by including low-energy forage such as straw into the diet or limiting the amount of feed offered.

Maintaining an inventory of low-quality forages is critical to control situations when feed inventories provide excessive energy. As with energy, protein requirements of heifers are dynamic. The younger a heifer is and the faster a heifer grows, the more protein is required in the ration to meet growth demands; however, feeding excessive protein to heifers does not prevent overconditioning or enhance stature growth. When excess protein is fed, heifers simply excrete it as nitrogen in the urine.

Excessive protein (nitrogen) is not economically prudent and can create environmental concerns. To prevent overconditioning, heifer rations should be balanced using appropriate growth rates with energy densities appropriate for the heifers’ environmental conditions.

Field studies have demonstrated heifer raisers commonly oversupplement minerals and vitamins to dairy heifers in an effort to assure dietary adequacy. Oversupplementing minerals and vitamins increases heifer-rearing cost. To ensure proper levels of minerals and vitamins are fed, test forages and feeds for their mineral content using precision wet chemistry procedures and then provide supplements to reach requirements, with modest overages allowed. If possible, free-choice mineral and vitamin supplementation should be avoided.

Specifically, heifer raisers should be sure to feed precise levels of dietary phosphorus because oversupplementation results in excessive levels of the mineral in manure, which is an environmental concern.

Feeding heifers is expensive and great care should be taken not to waste feed. Feedbunks should be designed and managed to control feed waste. Properly adjusting neck rails, throat heights or installing slant bars in the feed alley can often dramatically reduce feed wastage. Hay racks, portable bunkers or other make-do feeders should not be used, as too much feed is lost on the ground. Do not feed heifers forages or grains placed on the ground. In addition, do not provide heifers unlimited feed. Precisely monitoring feed intakes and feeding heifers as needed should reduce feed wastage and increase feed efficiency. PD

References omitted due to space but are available upon request.

—From 2005 4-State Dairy Management Seminar Proceedings

Table omitted but is available upon request to .

Patrick C. Hoffman, Department of Dairy Science, University of Wisconsin-Madison

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