WHAT IS THE RECOMMENDED AMOUNT OF FEED REFUSAL OR PUSH OUT FEED FOR EACH GROUP OF COWS?

Dairymen have very different opinions on how much feed should be left over (not eaten) by cows each day. Should there be zero percent feed left at the end of 24 hours or is it best to have 5 or 6% left over? This feed is often called push outs. It may be mixed with fresh feed and given to heifers, steers, or far off dry cows. Nutrition consultants often recommend that dairymen should feed cows enough feed so that 3 to 5% is left over each day. They do not recommend feeding left over feed to far off dry cows. It may be fed to steers and sometimes to heifers.

I visited the top producing herd in Minnesota last year on an official dairy tour. The owner said they have nearly zero push outs. The herd average was 32,000 pounds of milk for 250 cows. What is this dairymen doing that makes his feeding program so successful?

The owner told our group that he places highest priority on high quality roughage, particularly alfalfa haylage. The owner raised his own alfalfa so he had complete control of the crop. He tried to do everything right including soil tests, weed control, dates of harvest, and working closely with his alfalfa consultant. His dairy cows were fed the best alfalfa that was harvested under good weather conditions. Alfalfa that was damaged by rain during harvest was fed to non-lactating animals and steers.

Dr. Dan Little is a veterinary nutrition consultant in Minnesota. Dr. Little states that the correct amount of leftover-push out feed varies from farm to farm. Some farms can have near zero push outs while other farms should have 6% push outs for maximum milk production. The reasons for these differences are related to improper mixing of the TMR and below average quality of roughage. For best results the last bite of feed has to be exactly like the first bite of feed. Farms that have high quality forage and good mixing technique will probably have very low levels of push out feed. Farms that have average quality forage and irregular mixing technique will have higher levels of push out feed. If moisture levels of the TMR are low, then cows will sort the feed and push out feed will increase.

Dr. Little worked with three farms that had near zero push out feed after 24 hours. They decided to feed more TMR so that push outs would increase to 5 or 6%. They did this and found that the cows dry matter intake (DMI) did not change. However, milk production increased on all 3 farms by 4 or more pounds per day. This was difficult for me to understand how this could happen. I called Dr. Little and asked him if he could explain the increase in milk production with no increase in DMI. The answer of Dr. Little was very enlightening. He said the reason was that the push out feed was different from the feed that the cows actually consumed. The push out feed had to be lower in energy and higher in fiber. The feed the cows actually consumed had to be higher in energy.

Dr. Little stated that all three herds made a profit by increasing the amount of TMR fed to cows so that 6% was pushed out after 24 hours. One herd actually increased milk production by 12 pounds per cow per day. Even if push out feed was thrown away these dairymen still made more profit by increasing milk production. Key factors to consider are DME and income over feed costs.

These results prompted Dr. Little to examine the efficiency of dry matter as it relates to milk production. The term for this is called dry matter efficiency (DME). It measures how cows convert feed to milk. DME is calculated by dividing milk production in pounds by pounds of dry matter consumed. Good herds will range from 1.4 to 1.6. DME should be calculated for all groups. Fresh heifer groups usually have the lowest DME. The high groups for both heifers and cows normally have the highest DME ranking. You should expect to read more research on DME in the future. It is another benchmark to monitor nutrition and milk production.

(Parts of this article were published in Dairy Today, April 2001, pages 32-34)