The goal of a replacement heifer rearing program is to provide the opportunity for the heifer to fully develop her lactation potential at the desired age with minimal expense. The first and most important step in this process is proper development of the young calf. Although calves are usually weaned at 8 weeks or older, many producers use early weaning programs to lower the costs of feed and labor. Calves tend to scour less when consuming solid feeds compared with liquid feeds. As a result, health costs may decrease.
The following table illustrates the difference in the cost of feed and labor for weaning a calf at 5 or 8 weeks of age. This example represents estimated prices for a good quality milk replacer and calf starter. Under these circumstances, weaning a calf at 5 weeks instead of 8 weeks saves $26.89 per calf. The savings in total feed cost were $16.50 ($21.00-$4.50=$16.50). Although calves weaned at 5 weeks consumed more calf starter over the eight-week period, feed cost is reduced by substituting calf starter for more expensive milk replacer. The $10.39 savings in labor cost resulted from reduced time required to feed calf starter compared with milk replacer. Using the estimated times in the footnote of Table 1, it required 4.8 hours of labor to wean at 5 weeks of age and continue dry feed until 8 weeks compared with 6.5 hours to feed milk replacer until 8 weeks of age.
Calves can be successfully weaned when adequate rumen development has occurred. The rumen and reticulum are not fully developed at birth. In fact, liquid feeds are shunted past the reticlorumen by the esophageal groove. At this time the abomasum is the primary compartment of the stomach. By the time of weaning, the rumen must have developed enough to take part in the digestive process.
Nutritional management of the calf can affect rumen development. The calf should be fed milk or milk replacer at a rate of 10% of birth weight. This amount can be held constant until weaning. Small amounts of high quality calf starter should be offered beginning at 4 days of age. Offering small amounts regularly will keep the starter fresh and encourage intake. Starter consumption is critical for adequate rumen development. Calves can be successfully weaned when they consume 1.5 to 2 pounds of starter per day for three or more consecutive days. Clean water should be offered beginning at day 4. Water consumption encourages starter intake and is needed to support the developing bacterial population in the rumen.
In most cases, calves can be weaned at 4 to 5 weeks if starter consumption is adequate. Calves that had scours and were off feed, or fed poor quality starter, or did not have water available may not be ready to wean at 4 weeks. Weaning should be delayed in these calves for an additional week or two to allow for adequate rumen development. Through careful management, early weaning can be successful and help reduce the cost of rearing replacements.
Table. Costs of selected items for early vs late weaned calves.
|Item||5 Weeks||8 Weeks||Difference|
|Milk Replacer a||$35||$56||$21|
|Calf Starter b||$19.50||$15.00||-$4.50|
a 1.25 lbs/d @$.80/lbs
c $6/hr 7 min/day for milk fed calves and 2min/day for weaned calves