Limit feeding diets high in concentrate, or by-product feeds, can be an effective strategy to reduce the amount of hay inventory needed without sacrificing cow productivity. A typical dietary intake (on a dry matter basis, DM) is around 2.0 to 2.5% of body weight (BW). For a 1250 lb cow offered hay free choice that equates to around 30 to 35 lbs. of hay on an as fed basis (assuming 88% dry matter). Although ruminants require roughage to maintain proper rumen function the minimum amount needed is a 0.5 lb of forage/100 lb of BW (0.5% of BW). For a 1250 lb cow that is a little more than 6.0 lbs of forage on a DM basis (~7.0 lbs as fed). Grain and by-product feeds are more nutrient dense and, with proper management, can be used to replace nutrients lost due to reduced hay intake. Limit fed diets can reduce the overall DM intake to around 1.5% of BW, while still meeting nutrient requirements. Limit feeding is a sound nutritional management practice; however, there are several things that need to be considered before embarking down this road
Many concentrate feeds contain high levels of starch which presents some risk of digestive upset and metabolic disorders when fed at high levels. With proper management and careful ingredient selection these associated risks can be significantly minimized. The rate of rumen fermentation is greater for some grains than others. Feeding an ionophore can assist with preventing digestive disturbances and improve feed efficiency. Also, selecting feedstuffs high in digestible fiber like soy-hulls, wheat middlings, or dry distillers grains with solubles (DDGS) can significantly reduce or eliminate starch from the diet without affecting energy density.
It is important when utilizing a limit feeding system to analyze the nutrient composition of the hay source and any byproduct feeds to ensure the diet is adequately balanced. Additionally, the mineral composition of the diet should be carefully evaluated. It is likely the traditional mineral program will not be appropriate.
In addition to evaluating the actual diet costs, the added costs associated with increased labor and feed storage and handling facilities need to be factored into a decision to use this type of feeding system. Some feedstuffs store well in bins and others, like DDGS, do not. All should be kept dry to prevent spoilage. Many producers are not set up to handle or feed bulk commodities. If this is the case, commercial feeds manufactured as pellets/cubes may be an option. However, processing will increase costs. Additionally, access to a scale to weigh feed is necessary to prevent over and under feeding problems.
Limit fed diets also require a higher level of management. When starting a limit feeding program animals should be gradually adapted to the diet. This can be done by replacing the forage portion with concentrate over a 10 to 20 day period. Feed delivery can be a challenge as the cows will be ready to eat. Feed should be delivered at a similar time each day and bunk space should allow all cattle to eat at the same time. Preventing access to the feed bunks until the feed is laid out would be best, particularly if you do not have equipment that allows for mixing the hay and concentrate together. If this is not possible then deliver the hay first and then the concentrate. This will allow the cows to consume the hay first and assist with preventing digestive upset from consuming too much concentrate. Fences should be in good repair. Hungry, bored cattle will crowd and reach through fences. A low quality forage such as straw or stover can be provided in round bale feeders as a “filler” to alleviate this, but it will increase the costs of the system. Also, make sure that cattle have access to plenty of water - normally about 15 to 20 gallons per cow per day.
Since limit fed diets are restricted intake diets, the cows may appear hungry and will not show as much fill as with typical forage diets. They will be at the fence at feeding time and emotionally it is hard for livestock caretakers to see cattle that appear hungry. If the diets are balanced properly, the cow’s nutritional requirements will be met. Livestock managers must resist the urge to feed the cows more. The goal is to have cows in adequate condition (5 at calving) while reducing feed costs. Feeding more than is needed will implode the goal. Body condition should be closely monitored during the feeding period and diets should be adjusted to maintain desired condition and to match requirements for the cow’s stage of production. It is possible to get animals over conditioned on limit fed diets.
All feed and equipment cost parameters should be included in the decision making process.