RRL-Blog

The Dependable Feed Efficiency Tool You Could be Overlooking

Posted on
November 12, 2019
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By: Mark Kirk, Business Development and Customer Relations Manager

Measuring the amount of starch in cattle manure is essential to keeping track of efficiency and capturing opportunity cost in any operation. Most of the time, efficiency is measured by the feed to gain ratio, but seldom is the amount feed that passes through cattle to the manure, measured. Fecal starch is just that - the amount of starch undigested and unutilized. Any starch in manure is literally money wasted. It’s like putting fuel in your truck and pouring out what is left in the tank at the end of the day only to refill it the next day.

Measuring fecal starch is an inexpensive and easy process, but not the most glamorous task of the day. Most forage labs provide specific, easy-to-follow protocols and specific containers for submitting fecal starch samples for measurement. To begin, take 10 to 20 half-cup subsamples per pen, depending on pen size. Gather subsamples from a good distribution of the freshest piles, and be careful not to scrape the ground when sampling.

Put all of the pen’s subsamples into a bucket and mix well, then fill the pre-labeled manure container to the ‘fill to’ line. Use lab-supplied sample submission containers. Do not use forage sample bags or Ziplock bags to submit manure samples. In these bags, the manure sample just becomes a manure bomb.

Some people even put duct tape around the lid as an extra precaution. Mail or deliver the clearly labeled containers and submission forms to Rock River Laboratory as soon as possible. Avoid placing samples in the direct sunlight or a hot vehicle for any extended period of time as again these can become very messy.

The beef fecal starch analysis results provide Dry Matter (DM) percentage, Crude Protein percentage, and starch as a percentage of the dry matter. At Rock River Laboratory, the report then calculates an apparent Total Tract Starch Digestion (TTSD) based on a research-backed equation (Zinn et al., 2007.).

Based on four years of data, Rock River Laboratory has realized the goal, median, and minimum recommendations for fecal starch percentage of DM and percentage of TTSD. The recommended goal is based on the top 85th percentile and the minimum is the bottom 15th percentile. Those recommendations include: 

Goal: 2.9% fecal starch / 97.7% TTSD

Median: 7.5% fecal starch / 95.2% TTSD

 Min: 18.4% fecal starch / 87.0% TTSD

For an animal with a 20-pound dry matter intake of a ration made up of 45 percent starch, every three-unit change in fecal starch corresponds to about 1.5 units different TTSD. This boils down to about a half-pound of undigested corn grain per head, per day for every three-unit difference in TTSD. A decrease in TTSD from 95 percent to just 92 percent in 1,000 head of cattle is equivalent to 500 pounds corn wasted each day. This represents an opportunity cost of over $13,000 per year.

There are several ways to improve TTSD. For those feeding corn grain, make sure you have adequate grind particle size. The finer the grind, the higher the ruminal digestibility and therefore the greater TTSD. Considering other starch sources is another way more complete digestion can be realized. Steam flaked corn, wheat, and barley each have less density than dry ground corn and hang in the rumen longer - allowing for greater utilization by the animal. Another option is to feed fermented starch sources like high moisture corn or corn silage.

Keeping track of fecal starch is good way make sure you are capturing all the potential out of your beef rations. It is often overlooked as an easy way to measure the efficiency of the diet and a great investment with potential big returns. Work with your nutritionist or laboratory of choice to learn more about measuring fecal starch for improved efficiency in your feeding program.

Posted in:
Animal Nutrition