Feed bunk stocking density can impact dairy cow productivity
When the feed bunk is overstocked it can have negative impacts on profits.
Overstocking at feed bunks can impact the time budget and behavior of a dairy cow. This occurs if a cow spends longer than 2.5-3.5 hours a day away from the barn. This time budget includes 5 hours for eating, 12-14 hours for lying and resting and 2-3 hours for walking. Disruption of this time budget can occur if a cow has to wait at the feed bunk to eat. The cow will lose time in one of the other areas of her time budget impacting productivity.
The recommended amount of bunk space per cow is 24 inches. Less than 24 inches of bunk space per cow is considered to be overstocking of the feed bunk. When a feed bunk is overstocked, cows will have to wait to eat. While waiting, she is losing time to rest which in turn will decrease milk production. Overstocking at the feed bunk will also make it more likely that a cow will be displaced by another cow due to increased competition.
It is important to understand that cows do not make up for lost feed time. They do not come back to the feed bunk when there are less cows. Cows will instead eat 25 percent faster and eat larger meals. This will lead to ruminal acidosis, which happens when the pH of the rumen drops drastically for an extended period of time. Acidosis in dairy cows can result in lower milk yields, lower milk fat yield, and sole ulcers.
The design of a dairy free stall barn has an impact on bunk space. In a 4-row free stall barn, bunk space per stall is 24 inches. However, in a 6-row free stall barn, there are 18 inches of bunk space per stall. This means that if a 6-row free stall barn has more than one cow per stall the negative impacts of feed bunk overstocking will be seen sooner than in a 4 row free stall barn.
Inadequate feed bunk space in the transition cow pen will negatively impact a dairy herd. Michigan State University Extension recommends that each transition cow has 30 inches of bunk space and the stalls are only 80 percent stocked. Close-up dry and fresh cows are already predisposed to decreased dry matter intake and a sensitivity to acidosis. In order to have a smooth transition period, it is important to plan ahead and make sure your transition animals have the space they need.
If the feed bunk is overstocked there are ways to decrease some of the negative impacts. Some of these are:
- Develop a long term strategic culling plan to keep the ideal number of animals in each pen. Add cows to the "Do not breed" list earlier.
- This will allow cows to complete the lactation without spending money on breeding for an inferior cow.
- Look at your replacement heifer inventory.
- Many farms have more heifers than they need. They can be sold young or as fresh 2-year-olds.
- The decision as to which heifers to sell can be done by looking at health events and genetic potential.
- Feed more times per day and/or add more feed push-ups to the daily routine.
- This will attract a cow who has not had enough feed intake for the day to get up and eat.
- Add head locks to the feed bunk.
- Headlocks will limit the number of cows that can eat at one time, but they make it harder for one cow to push another one away from feed.
- Create a first lactation group
- Older cows will not be able to push the smaller ones away from the feed bunk.
- The ration can be tailored to help continued growth for those younger cows.
For more information or questions about this topic, contact MSU Extension dairy educator Marianne Buza at firstname.lastname@example.org.