Formulating modern dairy cow diets has become much more complex in recent years. In order that high-producing milk cow rations can meet a host of nutritional requirements, computerized ration modeling programs have become a necessity.
Along with making sure that nutritional needs are met from a varying assortment of feedstuffs, computer models also have the ability to “least-cost” a diet, arriving at the most economical price for a desired level of milk production.
Our understanding of ruminant biology and digestive physiology has progressed to a point where we know that microbial protein is the best source of metabolizable protein (MP) in cows and the correct balance of rumen-degradable protein (RDP), rumen-undegradable protein (RUP) and carbohydrates are essential for proper MP to be absorbed in the small intestine.
Every feedstuff, supplement or additive we feed to our cows has variable fractions of RDP, RUP and carbohydrates, as well as vitamins and minerals.
An ingredient such as corn is high in starch, a carbohydrate, with a minimal level of protein, so RDP and RUP aren’t much of a factor.
Soybean meal, on the other hand, is loaded with protein, a higher proportion of it being RDP. However, heat-treated soybeans have more RUP. And the list goes on.
As we look for the correct balance of RDP and carbohydrates that will optimize rumen fermentation and microbial protein, we must also be aware of the amino acid profiles of RUP.
Attempting to balance all of these variables is a daunting task when trying to get it all balanced correctly on a sheet of paper on the kitchen table – not to mention trying to arrive at a ration that is the most economical.
Neither is dairy ration balancing software just an advanced version of the latest linear or non-linear optimizer. Hundreds of equations are incorporated into various modules that predict rumen microbial growth based upon the types of feedstuffs being offered in a ration.
If, for instance, a diet is being balanced to support 100 pounds of milk production in a Holstein cow weighing 1,500 pounds, and there’s not an adequate source of bypass methionine available, the program will let you know with a message of some sort that the desired milk production cannot be attained with the ingredients available.
The best programs today allow for the operator input of a host of nutritional components made available through feed testing laboratories.
The developers of the rations’ models have been working closely with the testing laboratories to develop the different assays that quantify various values of nutritional fractions such as starch and sugar or neutral-detergent fiber (NDF) digestibility, which are then entered into the program.
Internal equations then predict what level of MP can be expected from microbial protein or RUP.
Prediction equations are the engines that run modeling software. Virtually every aspect of a cow’s digestive process can be described mathematically.
Many years of scientific research has established the nutritional requirements for dairy cows. We have very accurate measurements of what feed intakes for any cow producing any amount of milk will be.
We know how heat and humidity will affect feed intakes and how overall comfort will affect her production. All of this can be modeled mathematically.
Forages are the foundation of dairy cow diets. The higher the quality of forages – protein levels and fiber digestibility – the greater the MP from RUP will be. If a dairy farmer has access to a certain quality of forage, samples can be taken and a very accurate prediction of milk production can be attained.
Apart from monitoring costs of a ration with modeling software, one of the most powerful attributes of computer ration balancers is the ability to predict what a change in forages may do to milk production before it actually happens – and costs you money.
A dairy farmer had been feeding a good-quality grass haylage that tested about 14 percent crude protein (CP) and 54 percent NDF. He was soon to be running out of it and the only replacement option available at the moment was a grass haylage that tested 11 percent CP and 64 percent NDF.
Inputting the forage analysis information for the lower-quality forage into a ration balancer predicted that the cows would drop about 7 pounds of milk. However, the dairy farmer wasn’t going to wait and see if that was really going to happen.
Believing the information was accurate, he gave his approval to make the necessary adjustments to the grain mix. Protein and energy levels were adjusted so that MP from both microbial bacteria and bacteria from RUP was very nearly the same as it had been with the good-quality forage.
Yes, to compensate for the decreased protein and energy lost in the poorer-quality forage, the cost of the grain mix increased about $20 per ton – a penny per pound.
But this was a much better choice than losing 7 pounds of milk, which would have cost him over a dollar per cow in milk production. Milk production stayed the same with the changes.
The tools and technology we have available for feeding our cows today are readily available and accessible. One little mistake, one little oversight in ration formulation, can cost a dairy farm many hundreds of dollars per day and is easily avoided.
In the hands of competent nutritionists, computer modeling significantly reduces the risk associated with feed changes and price volatility. With so much at stake and so much to lose in the dairy business today, taking a proactive approach to ration formulations with computerized ration balancing is a no-brainer. PD
John Hibma
Nutritionist
Central Connecticut Co-operative Farms Association
