Limit feeding heifers. Sounds like a plan when feed ingredient prices are soaring out of sight. Less feed, less cost, right? Maybe, maybe not.
What is limit feeding? When I first heard that phrase, with the implication that heifers aren’t being fed as much as “normal,” my first thought was, “Hope their heifer barn isn’t close to the house because hungry heifers are not quiet heifers.”
First, let’s look at what “limit fed” means as we talk about heifers. Growing heifers have to consume the right amount of nutrients to keep normal body functions going (maintenance) and additional nutrients to allow them to grow at the desired rate per day (growth).
Unlike lactating cows, we don’t have to feed them even more nutrients to support milk production. So, where we play the “increase dry matter intake to get more milk game” with lactating cows, we usually don’t have trouble getting enough nutrients in heifers to support maintenance and growth.
In fact, diets can be formulated that deliver all the necessary nutrients, but don’t take up the whole amount of dry matter that the heifer could eat if she was allowed to eat all she wanted. That is the concept behind limit feeding.
Deliver the right nutrition in a smaller package. What it isn’t, is letting heifers run out of feed and declaring them “limit fed!” This would be the logic of the teenager who doesn’t want to go put out another bale of hay.
Pat Hoffman, from the University of Wisconsin, shed some light on this topic at the Tri-State Dairy Nutrition Conference held in Fort Wayne, Ind., last month.
Last year, Hoffman designed a study with the intent of evaluating limit feeding. Bred heifers were fed one of three diets (delivered as a TMR) for 111 days. Each diet was formulated to provide the same level of nutrients required by the heifers.
The control group’s diet delivered all the nutrients and all of the dry matter the heifer would normally consume. The other two diets delivered the same nutrients, but were more concentrated, delivering nutrients at either 80 percent or 90 percent of the level of dry matter they could consume.
This trial found significant differences in feed efficiency and manure excretion. Logically, if less feed is being pushed through a rumen, rate of passage slows and feed can be more thoroughly digested.
That, combined with the lower amount of feed fed resulted in less manure production.
There are some interesting possibilities for limit feeding, but I caution anyone considering it to do so carefully.
Some things to consider: facilities, feeding methods, feeds, ration management and economics.
• Facilities: There has to be plenty of space at the feed bunk for each and every heifer in the group. They can’t be fighting for eating space when limited feed is available.
Space per heifer will vary by age.
• Feeding method: TMR is the logical delivery method unless heifers are fed individually in headlocks. The lower the level of dry matter carrying the nutrients, the more concentrate in the diet. Sort city.
• Feeds: What feeds are most available to include in your ration? If you grow most of your forages, there are usually some feeds of lesser quality that go to heifers (older hay, rained-on hay, etc.)
Can these be used for other animals, or will they need to be sold and better-quality feeds purchased?
• Ration management: Rations should be changed regularly. If we are feeding for 2 pounds of gain per day, in 14 days we are feeding a 1,028-pound animal, not a 1,000-pound animal.
In 30 days, we have 1,600-pound animals, not 1,000-pound animals.
If we are limit feeding, how often do we have to increase feed fed? There is no extra feed to fill up growing heifers and provide at least part of the increased nutrient demand until the ration is changed.
The bunk will be licked clean, so we can’t rely on that sign to increase feed fed. Who will make sure this gets done?
• Finally, we need to look more closely at the economics.
What is the cost per pound of gain? How much of an increase in feed efficiency can we reasonably expect in real-world situations? Does the increased feed efficiency off-set the cost of a more concentrated diet? How much should we credit that cost for the decreased level of manure production?
There is a lot we don’t yet know about limit feeding. More research time is being devoted to helping answer these questions. It is an option that might, if well managed, have a place for some animals on some farms.
Don’t underestimate the level of management it will take to do it well.
Pat Hoffman’s article is available in pdf format at http://tristatedairy.osu.edu/Proceedings percent202008/Hoffman.pdf.