Practical Ration Evaluation: Things to Look for to Determine Whether Your Nutritionist is Doing a Good Job

The following is an excerpt from a paper by Gabriella Varga of Pennsylvania State University presented at the 2003 Western Canadian Dairy Seminar.
Observation of the dairy facility and the cows is a necessary prerequisite prior to ration formulation.  Looking at the cows involves a lot more than just body scoring.  A good nutritionist evaluates the following questions for lactating cows:  How do animals move? Is there evidence of lameness? Do animals have bruises, cuts, abrasions or swollen hocks?  How do the animals interact with people and their herd mates?  How many cows are lying down in the stalls?  How many animals are at the feed bunk?  How do animals approach the waterers?  What time of day is it and do the animals have feed in front of them?
There is other important preliminary information to collect before a ration can be balanced.  The first is to obtain the true body size of the cows.  A representative number of cows would include first lactation, second lactation and adult cows in order to gain insight into the BW of different groups within the herd.
All forages and high moisture feeds need to be sampled to ascertain their nutritional content.  Observation of feed mixing and delivery to the cows is critical. Another important consideration is forage supply and inventory.  Forage supplies should be measured early in the season so realistic amounts of forages can be fed rather than run out in March or April when purchased feed is more expensive and supply limited.
Records and benchmarks have to be determined by the nutritionist as part of the pre-work needed for ration balancing. The five key production indicators to compare to benchmarks are milk per cow per day, days in milk, pregnancy rate, somatic cell count and cull rate.  A benchmark to follow is herds milking twice a day and not using BST should be producing 32 kg or more.  Pregnancy rate is defined as the percent of eligible estrous cycles that resulted in a pregnancy over a given of time.  The US national average is around 14-17%.  To maintain a 13.0-13.5 calving interval, a herd must achieve a pregnancy rate of 22-25%.  The benchmark for somatic cell count is to be under 200,000.  All of the aforementioned indicators can contribute to high cull rates.  The cull rate should be 30% or less. 
Evaluation of the management abilities and human resources available is critical to determining if the nutritionist’s rations will be implemented correctly.  The success of ration programs depends 80% on management and 20% on the computer generated diet.  Management includes the owner/operator, the herd’s person and/or feeder.  The nutritionist has to determine the goals of each far he/she has as a client.  Also, some farms do not have the labor or the skills needed to implement certain rations and feeding strategies. 

Which Ration Balancing Program? There are many selections available in dairy ration balancing software.  Each has their advantages and disadvantages when it comes to user friendliness, price, and nutrition complexity.  Experienced nutritionists will use a model (or a ration balancing program) and learn how to work within its limitations. Why does a “good” ration produce inferior results?  The answer to these questions lies in the gray area between what was formulated and what the cow actually consumed.


Source: Nutrition Update Volume 15 No.1, May 2004