In a perfect world, there would be absolutely no difference between the total mixed ration (TMR) developed by a dairy producer and his/her consulting nutritionist and the actual ration fed to the milking herd.
In the real world, though, the gap between the ideal ration and what's actually fed can be fairly wide, says University of Wisconsin dairy researcher Pat Hoffman.
He's involved in an ongoing pilot study of feeding practices on more than 700 Wisconsin dairy farms.
“We've found that many farms are doing a very good job,” says Hoffman. “The rations are well-formulated and fed and the numbers are right where they are supposed to be. But we've also found quite a few farms where there's plenty of room for improvement.”
He lists several steps producers can take to bring intended rations and actual delivered rations into line:
Test moisture routinely. “If your nutritionist assumes that the moisture content of the haylage going into the ration is 60%, but it turns out that it's really just 40%, ration density is going to get out of whack in a hurry,” says Hoffman.
He recommends testing moisture contents of all ration forages with a Koster tester or microwave oven at least once a week.
Monitor NDF digestibility. Hoffman and fellow researchers have been surprised at high variations of neutral detergent fiber (NDF) digestibility in rations.
“It can vary as much as 30 units and that can have a big effect on dry matter intake and ration density,” he says.
Keeping close tabs on NDF digestibility will allow your nutritionist to change ration formulating strategies.
“For example, if you find a diet is low in NDF digestibility, the nutritionist might consider adding beet pulp or soy hulls to bring digestibility levels up,” he says.
Analyze TMRs. Nutritionists often rely on book values for individual ration ingredients to formulate rations. This is especially true for byproduct and commodity feeds, which are infrequently sent to a lab for analysis. The nutrient content of these feeds, however, can vary substantially.
If book values are incorrect, the nutrient density of the TMR will be incorrect.
“A TMR analysis looks at all the feeds in the diet at one time and fully accounts for real nutrient contents of byproduct and commodity feeds,” says Hoffman. “Also, every time there's a ration change or a significant drop in milk production, the TMR analysis gives nutritionists a way of checking their work and making sure there are no errors in the formula.”
Adhere to good mixing and feeding practices.
“We can't be imprecise with loaders and scales and still expect that the nutrient densities we'd like will be delivered to the cows,” says Hoffman.
He recommends checking scales on the mixer for accuracy several times per year and setting up a regular maintenance schedule for all equipment.
Other potentially helpful steps include establishing written protocols for mixing (including ingredient mixing sequence), continuously stressing to feeders the importance of accuracy when weighing and mixing, and making sure that there's a direct communication path between feeders and nutritionist.