Rations don't always require a TMR
Component feeding is an art form. For success, balance your rapidly degradable nutrients with feeds that break down slowly.
by Michael F. Hutjens
The author is a professor of animal science emeritus at the University of Illinois, Champaign-Urbana.
A recent market survey of Hoard's Dairyman readers summarized that 37.1 percent of dairies do NOT feed total mixed rations (TMR). This article will address strategies for feeding component-based herds. Component feeding includes herds that feed forages and grain/concentrates separately, including those with robotic feeding systems. Herd sizes tend to be smaller with more emphasis on meeting individual cow nutrient requirements than group averages.
The amount of grain or concentrate per feeding should be limited to 6 to 7 pounds as-fed (90 percent dry matter basis) per feeding to avoid drastic changes in rumen pH and environment. Shelled corn and barley-based grain mixtures could have greater rumen impacts than grain mixtures with oats and ear corn with by-product feeds (such as beet pulp, soy hulls and/or corn gluten feed).
Farms with computer feeders or robotic milking systems can feed concentrate three to eight times per day, which is an advantage. If you are milking twice a day, adding some grain with the forages can be another way to spread out grain levels and add another feeding period.
Balance for rate of breakdown
Meal complementation refers to a balance of rapidly degraded protein sources (such as pasture-based systems) with rapid carbohydrates such as sugar or ground cereal grain sources (such as 800 micron shelled corn or a liquid supplement). These rapidly degraded sources are balanced with slower protein and carbohydrate feed ingredients in the ration.
Your grain mixture could balance forage protein and carbohydrate sources. For example, protein from pasture sources could benefit from quicker sources of energy such as available starch or sugar sources. Additional protein sources in the grain mix could include rumen undegraded protein such as treated soybean meal or corn distillers grains.
The grain mixture could also be balanced with fast carbohydrate sources (barley or shelled corn) along with slower soluble carbohydrate sources such as citrus pulp, beet pulp, wheat midds or corn gluten feed. The focus is to avoid rumen pH values under 6.0 while capturing rumen ammonia nitrogen produced by the rumen microbes.
Forage complementation focuses on mixing legume/grass haylage or pasture (high in degraded and soluble protein with limited effective fiber) with corn silage. Corn silage is lower in protein, a source of rumen fermentable carbohydrate as starch and functional fiber if chopped/processed correctly.
If corn silage is limited or not fed as a forage source, adding 3 to 5 pounds of 800 to 1,000 micron shelled corn or rolled barley to the haylage-based forage program would be a plus, providing fermentable carbohydrates for the rumen microbes.
Grain palatability a must
Palatability becomes an important factor to ensure cows consume the grain mixture because it may be fed separately from forages. Cows reduce their feed intake when offered dusty grain mixtures with fine particles.
High-moisture corn (over 25 percent moisture) is a palatable grain source. Target over 2,000 average micron particle size (dry corn is 800 to 1,000 average micron size). Additionally, adding 1 to 3 percent animal fat or oil can reduce dustiness. Spraying on 3 to 7 percent liquid molasses or blends, too, can reduce fines, lower dustiness and improve palatability.
Robotic grain mixtures usually are pelleted to avoid dustiness and encourage cows to consume their allotment. Ground grain intake is typically 0.4 to 0.6 pound per minute, while pelleted grain mixture may reach 0.7 to 1.0 pound per minute. Be aware that pelleted feeds are finely ground before pelleting, which can challenge the rumen environment and pH.
Steam-flaked shelled corn provides a wafer-like particle size which is palatable while being available in the rumen due to the gelatinization of the starch. Also, avoid unpalatable feed ingredients that can impart undesirable odors such as blood meal, pork meat and bone meal and fish meal. Odor can be a "turn off" for finicky cows.
A palatable protein topdress can be important if protein is fed individually to cows based on their level of milk production and needs. This topdress protein supplement should contain rumen undegraded protein sources, including lysine and methinione.
Targeted feed additive use
Another advantage to component feeding is providing recommended feed additives only to cows that will respond. Close-up dry cows could be topdressed with an anionic product/salt, yeast product, additional vitamin E and organic selenium. Heavy close-up dry cows could be supplemented with niacin and rumen-protected choline.
Fresh cows could be supplemented with yeast products, buffers, additional rumen undegradable protein sources, rumen-protected amino acids and rumen-protected choline as warranted. Undegradable protein sources can be topdressed to higher producing cows without committing to excessive levels of high-energy grain sources (barley, wheat, and/or shelled corn).
A tailor-made regimen
Component feeding allows herds to "tailor feed" cows on an individual basis. The following guidelines may be helpful:
1. Conduct individual cow MUN (milk urea nitrogen) tests. MUN values reflect the degree of rumen ammonia capture. You should target 10 to 14 mg/dl with levels as low as 8 in fine-tuned cows.
2. Feed 1 to 2 pounds of forage dry matter 30 minutes to 1-1/2 hours before feeding 6 to 7 pounds of grain mixture. This can help form the rumen mat and stimulate sodium bicarbonate production from the cow's saliva.
3. Monitor individual milkfat and milk protein percentages to determine if rumen acidosis (also called SARA) is occurring. Each dairy breed has different ratios of fat to protein. Watch for signs of SARA or rumen acidosis as cows may consume grain and concentrates and reduce forage intake, unbalancing the ration. Observe manure scores, milk components, free-choice sodium bicarbonate consumption and metabolic disorders.
4. Gradually elevate the amount of protein concentrate and grain after calving to avoid rumen stress. One guideline is raise this 1 to 1-1/2 pounds per cow per day.
5. Raise the protein topdress faster to meet the cows' requirements as high-producing cows will mobilize body fat as an energy resource. Topdressing protein will meet the amino acid needs of the fresh and early-lactation cows. Topdressed protein levels may be raised at a faster rate than the grain energy fractions.
6. Ask your nutritionist to balance several rations at different levels of milk production and lactation number (heifers will have a growth requirement). These rations will provide topdressing and feeding guidelines.