Missouri Dairy Business Update

Volume 13, Number 5
May 2013

MU Southwest Center Grazing Dairy - May Update

SW Center Parlor
By Dr. Stacey Hamilton, University of Missouri Extension

The Southwest Center Dairy finished the spring data collection to determine pasture intake of individual lactating dairy cows. Cows were fed an exact amount of an inert marker twice daily in the grain mix. After milking manure samples were collected from each cow as well. By measuring the amount of this marker in the manure, we will be able to predict how much total manure the cow defecated for that period of time.  Pasture samples were hand plucked to mimic what the cows would have consumed for the grazing period. Analysis of the pasture forage will determine the amount of a certain alkane (lipid-fat) in the forage. By measuring the manure sample for the same alkane we will be able to determine the digestibility of the pasture.   Dividing the predicted manure output by the digestibility will give us the estimate of daily pasture intake for each cow.

We will continue to collect this data four times each year (May, June, August, October) from select cows that have previously been enrolled in the GROWSAFE feedout system where their feed efficiency in relationship to their gain was measured as yearling heifers. Our goal is to determine if these heifers which have a known feed efficiency (RFI) will continue to have a similar RFI as a lactating dairy cow. As we continue to collect the data we will begin to look for genetic markers that may reveal which animals are more efficient in their feed to milk ratio. If such markers are found, producers may then begin to select animals in their breeding program that require less feed for the same amount of meat or milk.

Additional information will be gained from this study as well. It is not well known or documented what the actual pasture intake is for cows fed forage pasture in a well managed system. By determining what actual intakes may be for lactating dairy cows, producers may realize they are over/under  stocked and adjust their stocking rate accordingly. As we gain more information on pasture intake we are simultaneously evaluating pre and post grazing pasture measurements to give producers a quick tool to determine the pasture intake of their herd of cows.

The analysis of the manure samples for the alkane and marker takes several months due to the requirement the samples are completely freeze dried. This means although a weeks worth of samples were taken in early May, it may be not be until this winter we start to get results from our collections.  Stayed tuned for more information.

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