The amount of water in the litter is its moisture content. Dry matter content is the percent weight of the litter when all water has been driven off. There is no meter for measuring litter moisture. The ones used for forage, soil or wood will not work reliably with litter. Moisture and dry matter content of poultry litter can be determined through litter moisture analysis. Once you find one, the other will be easy to calculate. The analysis can be done as follows:
1. Collect Litter Sample: The objective of litter sampling is to obtain a small sample of litter that represents the whole litter in the house. You’ll have to collect a huge sample of litter from different locations in the poultry house, mix them thoroughly and then take a small sample from the huge sample for test. The 2 methods that can be used in litter sampling are the point and trench methods.
Point Method: You’ll need a 5 gallon (20 litres) bucket, a narrow, square-ended spade and a 1 quart plastic bag. To begin, visually divide the house into 3 zones as shown in fig 1 below. Walk the length of the building along one zone in a zigzag manner and take samples from 8-10 points. Ensure you take samples under/around feeders and waterers that are proportional to the space they occupy. If the feeders occupy 10% of the house, 10% of the sample should be taken under/around the feeder.
Here is how to collect the samples. At each sampling point, dig a small trench the width of the shovel. The depth should reach the top of the floor. After digging the small trench, take a slice of about 1 inch, making sure that you take equal amount from all depths (see fig 2). As you take the 1 inch slices, put them in a bucket. Repeat this process in the other 2 zones, putting the samples in the bucket.
After collecting all the samples, mix them thoroughly in the bucket or in a wheel barrow etc, making sure to break caked litters into small pieces. From this huge sample collected, collect a subsample for analysis. Fill the freezer bag with the subsample and seal until you’re ready to analyse it.
Trench Method: You’ll need a 5 gallon (20 litres) bucket, a narrow, square-ended spade, a wheel barrow and a 1 quart plastic bag. This method involves digging a trench that starts from the centreline of the house to the sidewall (fig 3). The width of the trench should be the width of the shovel and its depth should be the entire depth of the litter. The trench should run perpendicular to the feed and water lines so as to collect a representative sample. As you dig the trench, place all the litter from it into a wheel barrow and whenever the barrow is 2/3 full, thoroughly mix the litter and transfer 1 or 2 shovel-full into the 5 gallon bucket. The rest is thrown away. Repeat this until the trench is complete. Then thoroughly mix the litter in the bucket and put a subsample into the freezer bag.
2. Analysis (Dry Samples in an Oven): For best result, the samples should be processed that day. If it’s not possible, seal them in a plastic bag and refrigerate. Use the following steps to obtain the dry weight of the sample:
a. Place a metal pan on a weighing scale and record the weight (e.g. pan weight = 300g). Note: An accurate scale that reads in grams is important for accurate calculation.
b. With the pan still on the weighing scale, add the litter sample until the scale read 100g additional weight (i.e. total scale reading is 400g). This 100g is the wet weight of the litter sample.
c. Place the pan and its content in an oven and dry at 120oF (48.9oC) for 24 hours. After the 24 hours have elapse, bring out the pan and its content.
d. Weigh the pan and its content immediately after drying (let’s assume 376g). This weight minus the pan weight will give the dry weight of the litter (i.e. Dry weight = 376g-300g=76g).
d. Calculate the litter moisture content with the following formula:
litter moisture content (%) = [(Wet litter weight- Dry Litter Weight)/Wet Litter Weight] X 100
[(100g-76g)/100g]x100 = 24%
3. Result: In our example, the litter contains 24% water. Once you know the moisture content you can calculate the dry matter content, which is the weight of the sample without water. Simply subtract the percent moisture content from 100 and you’ll get the dry matter content. In our example it is 100-24 = 76%.
In poultry litter management, the goal is to maintain litter moisture at 20-25% to prevent problems of ammonia pollution and increase in bacteria population. Knowing the moisture content of your litter is important when you want to feed them to ruminants. While analysing the fertilizing value of litter in a laboratory, the moisture content is also calculated.