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Precision feeding and monitoring: Now more than ever

Jeff Reneau

The consequences of this summer's drought and increasing feed cost compounded with stagnant milk prices make for tighter and tighter margins challenging dairy profitability. Weathering tough economic times requires precise scrutiny of input costs while still optimizing productivity and animal health. Precision feeding is defined as providing precise nutrient inputs to consistently assure cow health and productivity. A few years ago we looked at the impact of more precise protein feeding on feed cost and environmental impact. Since the study (2007), corn price has increased 2.3 times and SBM 2.9 times. Needless to say, reducing feed cost by more precise feeding is needed now more than ever. In addition to reducing feed cost, one nice side benefit is reducing unnecessary N excretion to the environment.

An accurate gauge of protein feeding is individual cow and bulk tank milk urea nitrogen (MUN) levels. The average bulk tank MUN level for the 1135 upper Midwest dairies monitored at every bulk tank pickup for two years were 12 milligrams per deciliter with a range of 10 to 13. What would be the economic and environmental impact if you were able to optimize rumen protein-energy digestion that resulted in a MUN level of 10? In a 2011 report in the Journal of Dairy Science (Powell, et al., J. Dairy Sci. 94:4690-4694), USDA forage lab scientists at the University of Wisconsin-Madison indicate that such a goal could be met without sacrificing productivity while significantly decreasing unnecessary ammonia emissions. Having studied the herd records and bulk tank test results of several very well managed high producing herds in Minnesota, I can attest that such precise protein-energy feeding is possible. For Minnesota dairies the potential economic and environmental impact of such an adjustment at current grain prices could be quite significant (see Table 1 below).

Table 1. Environmental and feeding cost impact of reducing CP intake to achieve an average 10 mg/dl MUN in bulk tank milk on 1135 Upper Midwest dairies. MUN data was collected for every pickup over a two-year period (2005-2006). Herd size category was estimated from total milk sold assuming an average of 70 lb/cow.

Change if average MUN was reduced to 10 mg/dl
Herd size category Bulk tank MUN (mg/dl) average by herd size Monthly urinary N excretion
(lb N)
Reduction lb of 58% SBM Estimated monthly
feed cost savings
(assuming 58% SBM replaced with corn 1:1)
less than 25 cows 10.8 -25 -383 $74
between 25 and 50 cows 11.4 -67 -1,044 $154
between 50 and 100 cows 11.8 -139 -2,173 $417
between 100 and 250 cows 12.2 -339 -5,318 $1022
more than 250 cows 12.1 -1128 -17,705 $3442
Urinary N (g/day) = 0.0259 × MUN (mg/dl) × BW (kg), BW = 600 kg (1323 lb).
Daily N intake (g/day) = (UN (g/day) + Milk N (g/day) + 0.97) / 0.83, Milk N = (milk true protein content) / 6.38 + NPN, MUN = 0.5 × Milk NPN. No change in true milk protein content due to changes in diet formulation is assumed.
CP = 6.25 × N.
Corn price: $7.7/bushel.
SBM price: $588/ton.

Successful precision feeding requires consistently managed feed storage, ingredient quality, diet formulation, TMR mixing and feed bunk management as well as routine monitoring of dry matter intakes, milk yields and milk components. Unless you are willing to pay close attention to those details, perhaps you need to continue over-feeding protein as a hedge for less than optimal feeding procedures.

In addition to strict feeding consistency, some other strategies that help facilitate optimizing protein utilization include:

There is an urgent need in the dairy industry to fine-tune and reduce variation in nutritional management at the farm. Inefficient protein feeding increases milk production cost and contributes to environmental pollution. Protein efficiency and N excretion can be controlled by skillful diet manipulation. Another factor worth noting is forage selection. Low MUNs are more easily achieved with higher corn silage than haylage diets. The protein in haylage is rapidly converted to ammonia in the rumen resulting in higher MUN levels. However, without real time monitoring, adjusting diets to minimize excess protein feeding without sacrificing production is difficult. Routine monitoring of milk yield, dry matter intakes and milk components is essential! Frequent bulk tank MUN monitoring (at each pickup) provides an accurate way of guiding protein and carbohydrate feeding to improve protein efficiency and reduce nitrogen excretion. Precision dairy software like MilkLab™ with automated control charting and alert capabilities is very helpful for detecting, with statistical certainty, when unexpected changes occur. It is also useful for nutritionists in detecting response to diet interventions/adjustments. Some Midwest processors are routinely making this service available to producers.

Published in Dairy Star September 22, 2012

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