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Recent Questions Asked about Litter

July 25, 2012

Authors: Shane Gadberry and Paul Beck

University of Arkansas, Division of Agriculture, Department of Animal Science

County agents are being asked questions pertaining to litter based rations.  Here are several points to consider –

Minerals

  • Broiler litter is very high in major mineral and trace mineral content.  Only provide free choice access to salt for cattle on a broiler litter based diet.
  • Mineral content
    • Calcium = 2 to 3.2%* (required level 0.27%)
    • Phosphorus  = 1.6 to 1.9 % (required level 0.23%)
    • Ca:P  ratio= 1.3 to 1.7
    • Potassium  = 3.1 to 4.2% *  (required level 0.6-0.7%)
    • Sulfur  = 0.7 to 1.2% * (required level 0.15%)
    • Copper = 216 ppm*               (required level 10 ppm)
    • Iron = 386 ppm
    • Manganese  = 495 ppm (required level 20-40 ppm)
    • Zinc = 350 ppm (required level 30 ppm)

*Denotes minerals that are in excess of the maximum tolerable levels.

  • Calcium deficiency is often mistakenly blamed for causing milk fever in cattle fed a high litter diet.  Litter is very high in calcium content and the best method to reduce chances of milk fever is to reduce litter to no more than 50% of the diet beginning 30 days prior to calving.
  • Symptoms similar to grass tetany are sometimes encountered. Grass tetany is due to a shortage of blood magnesium. The high potassium levels in poultry litter can bind the dietary magnesium. Additional magnesium (supplied as magnesium oxide) may be necessary for late gestation and early lactation cows.

Vitamins

  • It is recommended to feed vitamin A to cattle on litter based diets.  Dry cows need 1,270 IU/lb dry feed and lactating cows need 1,770 IU/lb.  Producers will need to determine the quantity of vitamin A in available premixes to determine how much to add to the diet.  For example, if mixing 2,000 lbs of a litter based diet that is 82% dry matter; 2,902,800 IU of vitamin A is needed in the total mix.  Two pounds of a premix containing 1,500,000 IU/lb vitamin A would roughly meet the needs for lactating cows.
  • Mixing capabilities can be a challenge to adding vitamins.  If purchasing supplemental energy feeds to mix with litter through a local cooperative mill, check if vitamins can be added at this point.
  • Using injectable vitamins is a good alternative.  Injections can be repeated every 60 days.  Due to the intramuscular dose of vitamin A, there is a 60 day withdrawal period before marketing.  Check manufacturer label for dosage, repeat dose interval, and withdrawal before slaughter.  When marketing mature cattle through local auctions, it is best to assume these cattle will go directly to slaughter.

Protein

  • Litter is a good source of crude protein, but not all of the protein is true protein and some of the protein may become bound to fiber during heating, reducing protein availability.
  • Historical recommendations of only adding energy based feeds such as corn, soybean hulls, or hominy have worked well for mature beef cows.  The energy should help capture any non-protein nitrogen as microbial protein which in return makes protein available for absorption from the gastrointestinal tract.
  • Distillers grains and corn gluten feed are moderately high to high in crude protein and are economical sources of energy.  While these feeds may add energy and true protein to the diet, they may also add high levels of sulfur.  Broiler litter samples in Arkansas average 0.8% sulfur with a normal range of 0.5 to 1.0%.  The consequences of adding high protein and(or) high sulfur feedstuffs is not documented to the best of our knowledge.  Many of the minerals are already exceeding maximum tolerable level in litter based diets.

Roughage

  • Effective fiber is important at keeping the rumen healthy.  Effective fiber can be provided by adding cottonseed hulls or grinding in hay with the litter.  Limit feeding litter and providing access to hay or pasture can also help provide effective fiber.  Pelleted fiber sources such as peanut hulls or cottonseed hulls do not have the stimulus as the non-pelleted form.  Dr. Darrell Rankin in the Department of Animal Science, Auburn, AL has observed that cattle don’t seem to have problems with pelleted roughage like peanut hulls on diets that are low in starch such as a litter and soybean hulls based ration.

Nutrient Analysis

  • A nutrient analysis is very beneficial.  Poultry house manure management varies.  With demand for poultry litter as feed, growers may turn-over their bedding material more rapidly affecting the amount of fiber verses other nutrients in the litter.

Energy (TDN) Supplementation

  • Some cattle producers want to feed litter without adding supplemental energy.  It is commonly mentioned that they remember a family member feeding litter years ago without adding anything to the litter.  A couple of things to consider.  One, litter alone may work for non-lactating, mid-gestating cows; however, adding additional energy to the litter at this point can help improve body condition gain, however, beyond this point, NRC predicted requirements exceed the average TDN estimate for litter.  Two, the cattle these producers are referencing may be quite different than cattle today.  For example, the genetic trend for the milk EPD of Black Angus is +37 [calves are weighing 37 lbs heavier at weaning due to improved milking ability of their dams] compared to the early 1970’s.

Mixing

  • Cattle producers using litter to stretch or replace forage during drought will likely not have a grinder/mixer.  Many will be mixing with tractor bucket loaders.  Three things should be considered when mixing 1) size (volume) of the scoop, 2) moisture (dry matter) of the feed, and 3) bulk density of the feed.  The following table provides average as-is weight and dry matter content of different feedstuffs being added to litter.  These are loose form weights, pelleted feeds will differ in density.  A 5 gallon bucket will be approximately 1.06 ft3, so weighing an empty bucket and a ‘to the rim’ feed filled bucket with bathroom scales can be used to approximate the density (lb/ft3).   Also, knowing the ratio of weight for one ingredient to the next can be useful.
Ingredient

Density

(Lb/ft3)

Dry Matter

(%)

Broiler litter

27

78

Corn

45

88

Soybean hulls

14

91

Hominy

28

88

Rice bran

20

92

Cottonseed hulls

13

93

Hay (in the bale: 4’x5’)

12

88

Example – On a dry matter basis the goal is to obtain an 80% litter and 20% soybean hull mix.

First, convert the dry matter proportions to as-fed proportions:

Ingredient

DM

(% mix)

Conversion

Factor (Dry matter)

As-fed

(% mix)

Litter

80

÷

0.78

=

103

÷

125

x

100

=

82.4

Soybean hulls

20

÷

0.91

=

22

÷

125

x

100

=

17.6

Total

100

125

100

Note: 100% can also be interpreted as 100 lbs.

Second, convert percentages to areas of volume

Ingredient

As-fed

(% mix)

Conversion

Factor (Density)

Space occupied

(Ft3)

Litter

82.4

÷

27

=

3.05

Soybean hulls

17.6

÷

14

=

1.26

Total

100

Note: 100% can also be interpreted as 100 lbs.

Third, calculate the ratio of space occupied by one ingredient compared to the other ingredient

Ingredient

Space occupied

(Ft3)

Litter

3.05

÷

1.26

=

2.4

Soybean hulls

1.26

Total

Fourth, interpret the results.  For every 2.4 scoops of litter, add 1 equal size scoop of soybean hulls. Given the variability in feed moisture and density, consider being more conservative on roughage substitutes and less conservative with the amount of energy based feeds.  This will help ensure adequate energy is being added to meet requirements

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