By Dr. James C. Coomer, Ph.D., P.A.S.
Feed bunk management represents a very important aspect of the productivity and profitability of all dairy operations. Proper feed bunk management is important for maximizing dry matter intake (DMI) and optimizing production. For each one pound increase in DMI, a cow can produce 1 to 2 lb. more milk. Even in the current challenging economic times, one pound of DMI generally cost about ten cents and a pound of milk is selling for more than ten cents (mailbox price). So even at the low end of the range listed before, additional DMI usually results in an increase in income over feed cost. This assumes that any changes to increase DMI do not drastically reduce the cow’s efficiency of nutrient utilization from the feed. Several aspects of feed bunk management need to be considered:
• Feeding environment
• Selection of feed ingredients
• Presentation of feed ingredients
Provide 18-30 inches of bunk space per cow, with the feedbunk floor having a smooth surface placed at ground level or raised four to six inches. This will allow each cow sufficient space to eat and enables them to eat in a natural “head down” position. A smooth surface in the bunk or on the feeding floor will prevent excessive abrasion to the cow’s tongue. Neck rails or cables at the feed bunk need to be positioned ahead of the cow so they do not restrict access to the feed. If you notice the hair rubbed off the top of the cows neck area, the bar or cable may need to be adjusted to give the cows better access to the feed bunk. Observation of the cows while eating will help to determine if they have good, unrestricted access to the feed.
The feeding area should be covered or shaded and have a cooling system (soaker hose and fans) for use during hot weather (temperatures above 65 with high humidity, can result in heat stress for the cow). During heat stress, DMI can drop 10% or more if cows are not provided shade and supplemental cooling. This drop in DMI can result in a 10-15 lb. reduction in daily milk production. A drop in DMI can also occur when environmental temperature is very low and feed bunks are not protected from wind.
Water intake is one of the most important factors affecting DMI. It is important to provide an adequate water supply and space to enable all cows to consume 10-15 gallons of water immediately after being milked. Providing water in the exit alley is one way to help with this goal. Additionally, you should have at least two water supply stations for every group of cows and supply at least four inches of linear water space per cow in the group. Check and clean water supply stations daily and check for stray voltage annually (even if the stations are plastic, water is a good conductor of electricity).
Selection of Feed Ingredients
Selection of feed ingredients is important for two main reasons:
• Palatability of the ration
• Proper rumen function and digestion
It is important to offer dairy cows the most appealing ration while still providing proper nutrition for optimal production. Sometimes it is necessary to incorporate a feedstuff known to be less desirable (i.e. fish meal, blood meal, anionic salts, etc.) into a ration for nutritional reasons. When this situation occurs, producers should take precautions to reduce or eliminate opportunities for feed refusal or decreased DMI. One way to accomplish this is to mix the unique feedstuff with feedstuffs of known desirability prior to feeding. Always avoid feeding these unique feedstuffs separately (top dressed) which allows the cow to choose not to eat it and, thus consume an unbalanced ration.
In terms of selecting feed ingredients for proper rumen function, several aspects are important.
• Do not feed moldy feedstuffs to dairy cows if it can possibly be avoided. Mold counts over 10,000 colony forming units (CFU) per gram of feed dry matter may cause digestive upsets. Some molds produce compounds known as mycotoxins that can negatively affect the rumen environment as well as the cow’s health and wellbeing. Several compounds may help alleviate the negative effects associated with certain mycotoxins in feed. A mycotoxin’s ability to be absorbed by the animal may be hindered when certain ingredients are included in the ration. The addition of extra vitamins and some minerals when mycotoxin contaminated feeds are being fed, may help animals deal with the negative effects of the mycotoxins.
• Sufficient long fiber in the ration helps prevent digestive upset and lactic acidosis. Adequate long fiber is needed to stimulate cud chewing, which enhances saliva production. Saliva is the primary source of bicarbonate to the rumen and helps buffer the rumen pH and maintain rumen pH in an optimum range of 6.2-6.8. Long fiber is predominately supplied in the form of forages. If hay is the main source of long fiber, provide it at least twice daily if fed separate from other feeds. If hay is fed free choice, then adequate bunk space should be provided to ensure all cows can eat hay at the same time. Ideally the long fiber would be included into a TMR such that all cows have to consume long fiber with every mouthful of diet eaten. Long fiber particles need to be at least two inches long and do not need to be more than four inches long to be effective. Particles longer than four inches can be sorted by the cow.
• When using haylage, a 3/8 to 1/2 inch theoretical length of cut (TLC) is preferred with 20-25% of the particles over 1.5 inches in length. Corn silage should have a 3/8 inch to 3/4 inch TLC (depending on amount of processing, length can be longer with better processing). A kernel processor on the silage harvester is recommended in order to break up the kernels and cobs in the silage. Unbroken kernels often end up as undigested manure particles and become fertilizer. Large cob fractions can be easily sorted by the cow.
• Also of concern to rumen function is avoidance of too many high-moisture ingredients in the diet. Using several wet fermented feeds (such as distiller’s grains, gluten feed, wet brewer’s grains and silages) can result in a very wet ration with a low pH. This can lead to reduced DMI and digestion in the rumen. Other wet feed ingredients, such as whey or whey permeate may bring in excessive amounts of salt and result in lower DMI. Strive to keep diet moisture content near 50%.
Presentation of Feed Ingredients
Cows should be fed a well-balanced ration and first lactation cows fed separately, if at all possible. Use the following lead factors for balancing rations for groups of cows:
• One group feeding – use a 25-30% lead factor above the herd production average.
• Two group feeding – use a 20% lead factor above the average production of the group.
• Three or more feeding groups – use a 10% lead factor above the average production of the group.
For example, if all the cows in the herd are fed as one group, the ration should be balanced for 30% more milk production than the average production of the herd. If the herd is averaging 70 lb. of milk the lead factor would be (70 X 30%) 21 lb. milk. Add the 21 lb. of milk to the 70 lb. average and find the target milk production level for ration balancing. In this example the ration should be balanced for 91 lb. of milk. These guidelines allow the high producing cows in the group to produce to their potential.
The diet should be uniform, cool, and fresh (not moldy). The use of Silo King® forage treatment will help produce high quality forages with good bunk stability at feed out. Feed or “push-up” the ration a minimum of two to three times per day. Additional feedings or push-ups generally result in increased DMI. Recent research has indicated that the most beneficial time to push up feed is 30-60 minutes after feeding or cows returning from milking. During hot weather, feed 60% to 75% of the daily ration at night. Feed should be consumed uniformly along the length of the bunk without evidence of sorting. Do not allow feed bunks to remain empty for more than two hours per day (presence of unpalatable feed is the same as an empty bunk). Use of a trail cam to video or take pictures of the bunk at night may be required to determine if bunks are empty for more than two hours per day.
Sufficient feed should be offered to allow for 3% to 5% feed refusals. Feed refusals should look similar to the original diet and need to be removed daily. If cows need more or less feed on a daily basis, the easiest way to adjust feed amounts is to mix feed for more or less cows so the ration will remain balanced. If cows consistently consume more or less than the projected amount of feed, then reformulate the diet to account for the different DMI. A small amount of DMI fluctuation is to be expected on a daily basis due to weather changes and animal management issues (i.e. vaccinations, moving cows to new groups, breeding, etc). Daily changes to feed offered should be limited to 3% or less to avoid large changes in DMI or feed refusals.
Feed bunk management includes the feeding environment of the cow, the ingredients fed to the cow, and the manner in which ingredients are presented to the cow. Each of these areas affects dry matter intake. On most dairy operations, dry matter intake is likely the largest single factor affecting milk production. Level of milk production has been shown to be positively correlated to profitability on most dairy operations. It becomes obvious that feed bunk management is one of the most critical aspects of managing a profitable and prosperous dairy enterprise. AK