One simple way to improve feed efficiency in heifers is to employ good bunk management. Feeding heifers to exact levels of intake and using the heifers' inherent nature to sort feed as a guide to manage bunks has been demonstrated to improve feed efficiency. Paying proper attention to eating behavior and managing the feed bunk accordingly can increase feed efficiency and decrease feed cost.
Feed is meant to be consumed by animals. A properly designed feed bunk for heifers should first and foremost minimize feed losses behind the feed bunk. Research data from Michigan State University demonstrated that up to 20 percent of feed can be lost to the aft (behind) side of the feed bunk.
In general, feed losses will be less when heifers are required to place their heads through and reach down for feed, as opposed to reaching horizontally for feed. Feed wagons where the feed is located at the same horizontal plane as the animal’s muzzle have been demonstrated to increase feed losses.
Fence line feed bunks should be properly fitted for each size group of heifers. Post and rails, throat guards, and/or self-locks should be checked and adjusted to proper dimensions. Listed in Table 1 are minimum bunk space requirements and suggested dimensions for post-and-rail feeding fences and waters. Producers wishing to limit feed dairy heifers should follow the bunk space requirements for "All Animals Eat at Once" in Table 1.
|3-4 Mo.||5-8 Mo.||9-12 Mo.||13-15 Mo.||16-24 Mo.|
|Feed Always Available|
|Hay or Silage||4 in./head||4 in./head||5 in./head||6 in./head||6 in./head|
|Mixed Ration or Grain||12 in./head||12 in./head||12 in./head||18 in./head||18 in./head|
|All Animals Eat at Once|
|Hay, Silage, or Ration||12 in./head||18 in./head||22 in./head||26 in./head||26 in./head|
|Throat (height, in.)||14||16||17||19|
|Neck Rail (height, in.)||28||30||34||41|
|Maximum Water (height, in.)||29||31||33||34|
Research at the University of Wisconsin has demonstrated that heifers will sort feed similarly to lactating dairy cows. Heifers, as with lactating dairy cows, will choose to consume the shortest particles first and refuse long feed particles. Because long forage particles and/or corncobs generally contain more NDF or less energy than small feed particles such as grain, heifers may consume diets higher in energy than formulated. Likewise, if heifers are allowed to refuse long feed particles, they will not reach fill limitations as soon and, subsequently, dry matter intake will increase. Data in Figure 1 demonstrate the effects of reducing feed offerings to heifers, forcing the heifers to consume all or most long feed particles. The result is a slight decrease in feed intake, which results in saved feed and improved feed efficiency.
Research data from South Dakota State University suggest heifers (or steers) should not be overfed on a daily basis. Precisely monitoring and controlling feed intakes and feeding the heifers to exact intakes (very minimal feed waste) will reduce feed wastage and increase feed efficiency. The combination of proper bunk design and feeding heifers to exact intakes has been shown to result in 10 to 15 percent improvements in feed efficiency. To feed heifers to exact intakes, a bunk scoring vocabulary should be utilized. A simplified bunk scoring vocabulary is:
|0||No feed remaining|
|1||A few small scatter particles of feed remaining|
|2||Many feed particles remaining, concrete still visible|
|3||Large amounts of feed remaining, no bunk concrete visible|
The objective of a controlled bunk management feeding system is to feed heifers to a bunk score of 1 every day. If bunks are empty (Score 0) or excessive feed is remaining (Scores 2 and 3), then feed intakes are moved up or down in small increments (2 percent) to facilitate feeding heifers to a bunk score of 1. This type of feeding system also helps assure heifers consume all large feed particles and feeds such as corncobs. Full consumption of diet also assures the formulated diet is actually being totally consumed.
Bunk design and management are often overlooked in heifer management programs. Proper bunk management has been demonstrated to increase feed efficiency 10 to 15 percent, which directly results in a 10 to 15 percent reduction in feed cost or in an annual feed cost savings of $30 to $40 per heifer.
Patrick C. Hoffman
University of Wisconsin-Madison