Effects of Bedding Type on Animal Performance, Manure
Nitrogen Retention and Composting Efficiency
Bridget Johnson, Vern Anderson, and Doug
Landblom
Research Summary
Year one results have not demonstrated a significant
improvement in the performance of developing heifers when bedding is added to
feedlot pens during winter feeding in southwest North Dakota. In addition, no significant differences were
found in nutrient content of fresh manure, although potassium levels tended to
be higher in bedded treatments. Analysis
of composted manure and bedding revealed corn stover and oat straw as the
superior bedding sources for nutrient retention.
Introduction
This project was designed to evaluate the effect of five
different bedding sources on animal performance and to measure each bedding
source’s subsequent effect on nutrient binding capacity and composting
efficiency. Previous research has shown
that bedding improves cattle comfort and performance (Anderson et al., 2001),
but there is little information on the use of bedding to capture nutrients from
livestock manure. Therefore, it was
hypothesized that bedding could serve a dual purpose by providing cattle
comfort during inclement weather and absorbing and capturing nutrients that
would otherwise be lost to runoff or volatilization. In addition to providing an absorptive
material in the pen, organic bedding materials provide the carbon necessary for
composting livestock manure. Composting
has several benefits including killing weed seeds, concentrating nutrients,
reducing volume and when applied to soil, improving drainage, structure, and
nutrient holding capacity of all types of soils (Card 2002). Most research to date has studied the
quantity of bedding that should be used, when wintering cattle, whereas this
project will focus on the impact bedding source has on animal performance,
nutrient absorption capacity and the effect differing carbon sources have on
efficiency of the composting process.
Material and Methods
One hundred heifers were weighed, blocked by weight, and
assigned to the following five treatments: 1) control – no bedding, 2) barley
straw, 3) oat straw, 4) corn stover and 5) wheat straw, and wintered for 111
days. Each experimental treatment was
replicated four times. Nutrient
composition of a common heifer development diet that was fed across treatments
is shown in Table 1. Daily feed delivered and ending residual feed weights were
recorded and used in feed efficiency computations. Bedding was added to each treatment pen on a
weekly basis and heifer body weights were taken at 28-day intervals, and at the
conclusion of the study. To evaluate the
effect of carbon source on composting, all treatment heifers were removed from
the pens and, as soon as weather permitted, bedding packs and pen manure were
scraped and piled to begin the composting process. Samples for nutrient analysis were collected
immediately and measurements were taken to estimate pile volume. Piles were monitored weekly for changes in
temperature and were turned with a front-end loader when the average
temperature fell below 120 º F (48.5 º C).
Composting was considered completed when pile temperatures continually
declined regardless of turning. Once
composted, piles were sampled for nutrient analysis and measured to determine
final volume.
Results and Discussion
No significant difference was found for start weight (P =
.9994), end weight (P = .9932), average daily gain (P = .8528) or feed
efficiency (P = .8026) among wintered heifers with or without bedding, as shown
in Table 2. The timing of the trial,
coupled with mild weather and protection from the wind, may have lessened the
impact of weather events and the overall effect of the bedding sources on
animal performance. Ambient temperature
ranges were monitored during the feeding trial and are illustrated in Figure 1.
Figure 1.
Temperature Variations During Feeding Trial
There were no significant differences in feed intake among
treatments. However, heifers in the
unbedded control treatment tended to eat more during the second feed period (P
= .2041). If bedding was consumed by
heifers it was not enough to reduce feed intake. Feed intake values were
monitored for each 28-day period and are summarized in Table 3.
Heifers were bedded each week with approximately 84 pounds
of bedding. The goal was to provide
approximately 266 pounds of bedding per head over the feeding period based on findings
by Birkelo
and Lounsbery (1992). Four weeks after
initiation of the project, it was determined that additional bedding was
required to create an adequate bedding pack.
Sufficient bedding was added to each pen to create a pack and future
bedding weights were adjusted to create similar weights among treatments. Heifers received approximately 320 pounds of
bedding per head over the feeding period.
However, heifers receiving wheat straw had a significantly higher
bedding weight than heifers in other treatments. After scraping and piling, manure pile
volumes were calculated using three pile measurements taken immediately after
piling was completed. A significant
difference in pile volume was measured between the unbedded control pens and
pens that received bedding. Total
bedding weights and volumes are shown in Table 4. Final volume and change in volume were
calculated after composting. All bedded
treatments decreased in volume where as the unbedded control increased in volume. It is likely that excess soil was added to
the piles during the process of turning. In the case of the unbedded control,
there was not enough decrease in volume by composting to account for added
soil, resulting in increased volume.
Manure samples collected immediately after piling were sent
to the NDSU Soils Lab and analyzed for dry matter (DM), ammonia-nitrogen (NH4),
nitrogen (N), phosphorus (P), potassium (K) and organic matter (
Once initial sampling and measuring of manure piles was
completed, piles were moved to a location where they could be monitored and
turned until the composting process was completed. Two temperatures were taken from each pile on
a weekly basis. Temperature differences
became significant three weeks after piling and remained significantly
different for four weeks. During the
seventh through ninth weeks, temperatures among treatments were similar.
Temperature differences became significant during weeks ten and eleven and
returned to similar until week seventeen. Throughout the composting period,
temperatures of the bedded treatments exceeded those of the control. No one
treatment was consistently higher in temperature throughout the entire 17-week
monitoring period; however, oat straw had the highest temperature nine out of
17-weeks. Figure 2 shows the compost
temperature fluctuations among treatments.
Precipitation received during the 165-day composting period totaled 7.55
inches. The largest single-day event occurred on June 12, 2004, when 0.70 inch
was recorded. The lack of adequate moisture, high air temperatures, and high
dry matter portion of the manure and bedding material explains why the
composting process took 165 days. Air temperatures during the composting period
can be found in Figure 3.
Figure 2.
Figure 3.
Compost samples were collected from each of the replicated
bedding source piles and were analyzed for dry matter (DM), ammonia-nitrogen
(NH4), nitrogen (N), phosphorus (P), and potassium (K) at the NDSU Soils Lab.
Compost nutrient levels are summarized in Table 7. Compost dry matter values did not differ (P =
.3333) among treatments. The corn stover
and oat straw treatments contained significantly more nitrogen than either the
barley or wheat straw (P < .05) bedding sources. In addition, corn stover
and oat straw had significantly higher potassium than barley straw, control,
and wheat straw (P< .05). Phosphorus also tended to be highest in corn
stover (P= .0960). When a comparison was made between manure and compost
nutrient composition, potassium levels became strikingly obvious. This can be
attributed to the concentration of nutrients that occurs in the composting
process.
Implications
Although significant differences were not detected in animal
performance or nutrient composition of fresh manure and bedding pack, composted
manure nutrient analysis suggests corn stover and oat straw may be the superior
bedding sources for retaining nutrients.
Further research will have to be conducted to determine the implication of
these findings and the practicality of using bedding as a tool to retain
nutrients from feedlots.
Literature Cited
Birkelo,
C.P. and J. Lounsbery. 1992. Effect of straw and newspaper bedding on cold
season feedlot performance in two housing systems.
Card,
A.B. and