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Dairy Corner: How to optimize dry matter intake

Assess what’s happening at the feed bunk, supply proper ration

There is only one way I know to supply the essential nutrients to high-producing cows to yield large volumes of milk, milk-fat, milk-protein and solids — assure dairy cows optimize dry matter intake of good feed is at its best.

As a dairy nutritionist, I am so convinced each bite of lactation diet counts that each time I walk into a dairy barn, I conduct a five-minute routine. First, I walk along the bunk and look at the cows, which are eating as well as look over to the cows lying in their stalls. I also pick up a handful of lactation diet and pick through it.

Here is a “short” checklist of the many things that I look for as signals for optimum or problematic dry matter intake:

  • Number of cows up to the feed bunk.
  • Deposition of cowherd.
  • Number of mature and first-calf heifers.
  • Number of cows sorting the diet.
  • Body condition of the herd.
  • Manure consistency of the cows.
  • Number of lame cows.
  • Percentage of resting cows chewing their cud.
  • Handful of diet: Moisture, mixture consistency, smell, amount of long stem-fibre and any visible mould.

In these short five minutes, these observations give me a ballpark idea as to how much lactating diet is being eaten on “as fed” and “dry matter intake” basis. When the dairy producer walks with me, I often fine-tune these observations by asking specific questions about the cows or their diet. By getting a handle on the dry matter intake of the lactation barn, I am really getting an idea of the amount of dietary energy intake, which is almost a perfect correlation.

Dietary energy when compared to other essential nutrients such as protein, minerals and vitamins is the single largest nutrient required by lactating dairy cows and drives good milk yield and its components. Among dairy nutritionists like myself, the general rule of dairy energy dynamics states: for every extra kilo of DMI or containing about 1.6 Mcal/kg NEL (re: net energy of lactation) that a cow consumes at peak DMI in its lactation cycle, yields 2.0–2.5 kilos more milk for each day afterward until the end of lactation.

Watch for limiting factors

There are many factors in a dairy barn that limits DMI/energy intake and milk performance. That’s because the actual amount of “as fed” diet a cow can eat is first dictated by its own rumen capacity, as well as fermentation by the rumen bugs and rate of feed passage through the entire digestive system. A good illustration demonstrates: a high fiber diet with low digestibility restricts DMI intake, two-fold. First, the fiber fills up the rumen, quickly. Second, low quality feed stays in the rumen longer to be digested, which become a physical barrier upon more incoming feed.

On the other hand, a lactating diet containing high-quality forages promotes high dry matter intake by dairy cows, simply because; it takes more of this diet to fill the rumen, its fiber is likely more digestible by the rumen microbes, which speeds up its rate of passage. In this case, DMI becomes more regulated by hormone signals to the cow’s brain, which literarily shuts off consumption. Furthermore, there are many chemical restraints in the rumen such as its buffering capacity against buildup of acids in order to maintain a healthy pH of 5.5–6.0, which helps facilitates good rumen function.

Here are a few suggestions that can help achieve optimum and consistent feed intake:

  1. A separate nutrition program three weeks before calving. Close-up dry cows that consume about 12 kg of dry feed, daily have been shown to have greater DMI as early-lactating cows and less post-partum metabolic problems. These diets don’t have to be complex.
  2. Promote good rumen fermentation – Typical rations for lactating dairy cows should be formulated to contain 19 to 21 per cent ADF, 28 to 32 per cent NDF (with 75 per cent coming from effective forage fibre) and limitations placed of 35 to 42 per cent placed on non-structural carbohydrates.
  3. Know DMI and ‘As Fed’ Intake — Keep a record of weekly DMI and ‘As fed’ intake of the lactation herd as well as the moisture content of the diet.
  4. Formulate a “friendly diet” – Feed a portion of the grain that has slower rates of starch digestion such as grain corn to prevent acidosis. Avoid feeding too much unsaturated fats and/or bypass fats. Make sure to limit feed unpalatable feed ingredients. Last, check your forages and grains for visible mould and other contaminants.
  5. Use a Direct Fed Microbial (DFM) — I often formulate a DFM in rations that contains bacteria, grain and forage enzymes and yeasts, shown to improve feed digestibility and prevent sub-acidosis rumen acidosis. Fed at 10 g per head per day it costs about 25 cents per head per day.

Along with these suggestions, it also takes common sense to help promote dry matter intake in lactating dairy cows. The other day while I was conducting a barn-walk and pulled out several pieces of orange baler twine from the freshly laid TMR ration. Balling up in a cow’s gut would probably be not a good thing.

About the author

Columnist

Peter Vitti is an independent livestock nutritionist and consultant based in Winnipeg. To reach him call 204-254-7497 or by email at [email protected]

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