Calculating Feed Protein Percentages
Photo taken at the end of March one year when a friend's health problems forced them to reach out for help with their goats.
Same buck pictured about 90 days after he arrived. He recovered completely and went on to live a long, healthy and productive life.
Spring is the time of year when animals are shedding out and if they are underweight, it's suddenly easily visible. Dairy animals tend to lose weight during the first 90 days after they give birth while their milk production is steadily increasing until their production plateaus. Even meat animals will drop in weight between giving birth and weaning their offspring, so farmers and producers start asking how to keep weight on their livestock or put weight back on their working animals.
The first step is to assess body condition scores. Get acquainted with the species you're working with and watch BCS carefully to monitor how well inputs are meetings your stock's needs. Then look into parasite load to make sure you're not feeding more creatures than the animal you want to feed. Finally, take a good hard look at diet.
This brings us to the question of how to evaluate the quality of a given diet. While there are many aspects of nutrition that need attention, calcium to phosphorus ratios and the percentage of dietary protein are some of the ones we've had to look at most closely over the years. So where to start?
To evaluate protein levels, first, find out or test to get the protein levels on everything they eat (forage test hay, read labels, etc).
Then figure out how much they eat of each part of their diet in a given time frame.
Then multiply the quantity of a given feed by the percentage of protein. Add all those products together and divide by the total quantity.
For example, let's say you feed 4 pounds of 16% protein alfalfa and 1 pound of 12% protein oats every day.
16% protein x 4 pounds = 64
12% protein x 1 pound = 12
4 + 1 = 5 pounds total per day
64 + 12 = 76
76 ÷ 5 pounds total per day = 15.2% protein
Animals on this diet are consuming a total of 15.2% protein.
In order to calculate the total for everything they eat, obviously, you'd need to plug in your numbers for each thing they eat. You may have to estimate forage quantity and/or calculate everything else separately, test forage and guess at the impact of forage.
There are many good ways to feed livestock and the season, local climate and cost factors due to location will greatly impact feed and forage options. We prefer to offer animals options of their natural foods that include a variety of foods because we have the bias that there's no one perfect food for livestock and a monoculture diet creates health challenges over time. Hopefully, this will help sort out what might help better meet the needs of your livestock as you see the need to make adjustments over time.
