|
2002 Annual Report Beef Section |
Dickinson
Research Extension Center
1089 State Avenue Dickinson, ND 58601 |
Dietary supplementation on stockpiled native range 1
W. Poland, J. Nelson, L. Tisor and G. Ottmar
Dickinson
Research Extension Center
North Dakota State
University
Preliminary data suggests
that dry beef cows can be maintained with dietary supplementation on stockpiled
native range in the Northern Great Plains during late fall and early winter.
Economics of these wintering systems will be largely dependent upon appropriate
stocking rates and level and composition of required daily supplementation.
Introduction
Cost associated with winter feeding the cow herd is a major expense (approximately 38% of the total production costs) associated with cow/calf operations in North Dakota. Procurement and feeding of harvested forages account for a large portion of this total expense. Reducing the use of harvested forages while maintaining cow performance could substantially lower overall operating costs of beef production and increase profitability of cow/calf enterprises. Lengthening the grazing period and/or reducing a reliance on harvested forage has been suggested as one method for reducing winter feeding costs.
Western North Dakota has
a variety of forages that could be utilized by grazing cows in late fall and
early winter when daily nutrient demands are relatively low. Two of the more
noticeable of these are stockpiled perennial forage (ungrazed forage that is
allowed to accumulate for support of grazing at a later date; Forage and Grazing
Terminology Committee, 1992) and annually-seeded forages. However, a deficit
of one or more dietary nutrients may limit the effective utilization of these
forages by dry, pregnant cows. Providing small quantities of an appropriately
formulated dietary supplement to animals consuming lower quality forages has
been shown to be an effective mechanism for improving animal performance by
enhancing forage utilization (digestibility and/or intake).
As grain producers contemplate
the benefits of crop rotations, cow/calf operators can provide a viable, local
market for alternative crops and co-products. This interaction, in many cases,
would establish a floor price on a potential feedstuff that otherwise may have
little marketable value. Besides being able to use fibrous residues, cows also
offer the potential for using alternative grains and grain co-products as base
ingredients in supplement formulations. Historically, a marriage between crop
and beef producers has been mutually beneficial.
Data from other Great Plains
states suggest that extending the grazing season, with appropriate supplementation
regimes, is an effective mechanism for reducing the winter feeding costs and
increasing profit potential of beef cow operations. Appropriately formulated
supplements, utilizing locally available feedstuffs, seem key to the success
of these endeavors. Data from the Northern Great Plains regarding the composition
and availability of forage and grazing animal performance during the late fall
and early winter period is limited. Data specific to North Dakota is severely
limited. The generation and distribution of this type of information are essential
if the cow/calf producers of North Dakota are to continue to operate in the
increasingly competitive environment present in the beef industry today.
Objectives
i. Determine whether late
fall/early winter grazing and supplementation is a feasible mechanism for reducing
winter feeding costs and increasing the net value of the cow/calf enterprise.
ii. Determine whether either
energy or protein is the first-limiting nutrient for beef cows grazing stockpiled
perennial forage in late fall and early winter grazing.
Procedures
In each of two year (2000
and 2001), summer-calving cows will graze stockpiled winter range in western
North Dakota. Grazing will begin in late October and continue until late January.
Cows will be randomly allotted into one of 4 supplemental treatment groups.
Each group will consist of 6 dry, pregnant cows. Treatments will include an
unsupplemented control and 3 supplemented groups. Supplemental treatments will
be formulated to supply additional energy and gradient levels of rumen-degradable
protein. Supplemental formulations will be based upon combinations of barley,
field pea and sunflower meal. Supplements will be available daily to individual
animals, with supplemental intake limited to 2.5 - 3.0 lb/d by using a computer-controlled
automatic feeder wagon (Cyber feeder, Sheyenne Advanced Feeding Systems, Cooperstown,
ND; Nelson and Ringwall, 1996).
At the end of grazing,
all animals within a treatment group will be moved to drylot at the DREC ranch
headquarters. Cows will remain in this facility until grazing commences the
following spring. Ration formulation and feed delivery to each treatment group
while in drylot will be based upon a targeted body condition using standardized
nutrient requirements (NRC, 1996).
On each system, the cows will be weighed and condition scored on 14-day intervals throughout the course of the winter. Other animal data to be recorded will include days to first postpartum heat, response to synchronization and artificial insemination, and subsequent breeding performance. Herbage available for grazing will be sampled at 28-d intervals to detect changes in dry matter yield and composition (botanical and chemical). In addition, annual exclosures will be established in each pasture to allow sampling of ungrazed herbage. Chemical composition of herbage (available for grazing and ungrazed) will be determined by an independent laboratory.
All feed deliveries and
refusals for respective treatment groups within year and experiment will be
recorded. Feed recording will begin at weaning in each year and end as cattle
move to spring calving pastures. After moving to pasture, all cows will be managed
similarly until weaning the next fall.
Animal and herbage data
will be analyzed utilizing a split-plot in time arrangement in sample collection.
Within experiment, whole plots will be arranged using a completely random design,
blocked across years. Treatment will represent a fixed effect within the whole
plot. Animal within year and treatment combinations will serve as the experimental
unit in the analysis of the whole plot. Sampling date will be treated as a fixed
effect and be used as the split-plot factor.
In 2000, cattle that were
to graze native range were weighed and body condition score in mid October and
allotted to treatments on November 2. Serious complications were encountered
with the automated feeding wagon that was to be used in delivering supplements
in this study. Specific experiment was terminated this year due to a lack in
ability to consistently delivery of supplemental treatments on November 29.
Cows were maintained on winter pastures and group fed an equal mixture of three
supplements at a rate of 3 pounds of total supplement per head per day three
times weekly (7 pounds of total supplement per head per feeding). Rate was increased
to 4 pounds per head per day on January 3, 2001, to counteract abnormally cold
weather experienced in the preceding November and December. Despite weather
conditions (below normal temperatures and excessive snow cover), body condition
scores did not reach the level necessary to require early removal of cattle
from pastures. Cattle will remain on pastures until January 31, 2001. An individual
feeding facility will need to be constructed in the summer of 2001 to accommodate
the continuation of this study. Experiment will need to be replicated in winters
of 2001-2002 and 2002- 2003 to achieve desired replication.
Results
Given the difficulties
in implementing this experiment and the especially severe early winter conditions
in November and December, results should be received as preliminary. Effects
of grazing date on body weight and condition score of mature beef cows receiving
protein supplementation grazing stockpiled native range are shown in figure
1. Both body weight and condition score declined through early to mid January.
With increased supplementation levels after the first of the year, both criteria
began to improve by the end of January and steadily improve through 56 days
of drylot feeding. Forage dry matter available for grazing (lb/ac) is depicted
in figure 2. Grass and forb dry matter declined dramatically
between the initiation of grazing in late October and early December. Most of
this decline appeared to relate to extensive snow and ice cover reducing the
amount of forage available for grazing. Subsequent declines in forage dry matter
were minimal through the end of January. The nutritional composition of available
forage is shown in table 1. The nutritional composition of
available forage was relative stable across the grazing season.
Discussion
Preliminary data suggests
that dry beef cows can be maintained with dietary supplementation on stockpiled
native range in the Northern Great Plains during late fall and early winter.
Economics of these wintering systems will be largely dependent upon appropriate
stocking rates and level and composition of required daily supplementation.
Literature cited
None
Figure 1. Effect of date on body weight and body condition score of mature beef cows grazing stockpiled native range and receiving protein supplement.
Figure 2. Effect of date on grass and forb dry matter (lb/ac) from stockpiled native range grazed by mature beef cows receiving protein supplement.
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