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David Davis
21262 Genoa Road
Linneus, MO 64653
Phone: 660 895-5121
FAX: 660 895=5122
Email:
DavisDK@missouri.edu
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July-September 2005
Forage Systems Update
Vol 14, No. 3
Impact of Herbage Allowance on Lactating Beef Cows Grazing Stockpiled Tall Fescue
L.E. Meinhardt and R.L. Kallenbach
Efficient forage utilization by beef cattle is essential for optimum
economic production and performance in a cow-calf operation. The
most efficient way to utilize forage is by grazing; however, forage
growth is dormant between late autumn and early spring. During this
period, producers commonly rely on stored feed even though it is
expensive. Use of stored feed accounts for 70 percent of the annual
beef cow maintenance cost. Research at the University of Missouri
found extending the grazing season into winter reduces dependence on
stored feed and decreases winter-feeding costs by one-third to
one-half (Bishop-Hurley and Kallenbach, 2001). One way to extend
the grazing season is to utilize stockpiled tall fescue (Festuca
arundiacea Schreb).
Tall fescue, the predominant forage in the transition zone, lends
itself well to stockpiling. It produces more autumn growth,
maintains yield and quality throughout the winter, and responds to
nitrogen fertilization better than other cool-season grasses. A
great deal of research has been conducted on stockpiled tall fescue,
although much of this research has been done on yield, quality,
fertilization, defoliation, and accumulation (Berry and Hoveland,
1969; Collins and Balasko, 1981a, b; Fribourg and Bell, 1984;
Kallenbach et at., 2003). There have also been several successful
stockpile-grazing studies with gestating, spring calving beef cows
and stocker calves (Allen et al., 1992a, b; Hitz and Russell, 1998;
Tucker et al., 1989; Waller et al., 1988). In recent years,
producers are switching to fall calving operations and as a result
more cows are lactating over winter. Only a few studies have
documented using stockpiled tall fescue with lactating fall calving
cows. Animals in these studies were typically allocated feed equal
to three percent of their body weight each day with 70 percent
utilization. Remarkably, the scientific basis for this allowance is
largely unknown, yet the literature indicates that it is widely
accepted.
As fall calving gains popularity, the need for identifying an
appropriate stockpile herbage allocation level increases. Lactating
cows have much higher nutrient requirements than gestating cows
(NRC, 2000) and may require higher herbage allowances. On the other
hand, it may be economical for cows to loose body condition in the
winter, when forage supplies are limited, and regain weight when
lush spring growth occurs. However, research is needed to evaluate
the most economical herbage allowance of stockpiled tall fescue for
lactating fall calving beef cows.
It is less expensive to maintain a lactating cow on lower herbage
allocation levels than higher allocations; however, this does not
mean that the lower allocations are the most economical. Forcing
high utilization rates with low allocation levels may limit cow
intake causing excessive weight loss, decrease reproductive
performance, and decreased milk production resulting in reduced calf
gain. Spring regrowth may also be adversely affected by low
allocation levels. Some studies show that spring growth is not
affected by grazing stockpiled during the winter (Allen et al.
1992a; Riesterer et al., 2000) while other studies report decreases
in spring yield (Hall et al., 1998). Research is limited on why
these contradictions occur.
Animal performance when consuming tall fescue herbage is often
hindered due to a fungal endophyte, Neotyphodium coenophialum
[(Morgan-Jones and Gams) Glenn, Bacon and Hanlin]. The endophyte
infection results in an accumulation of toxic alkaloids know to
cause a series of animal health disorders, costing the United States
livestock industry an estimated $609 million annually (Hoveland,
1993). Resent research indicates endophyte toxicity should be less
severe in stockpiled tall fescue. However, there is insufficient
evidence on the effects of grazing infected stockpiled tall fescue
on fall calving cow-calf performance.
The objectives of this trial are: 1) establish optimum daily herbage
allowance for lactating beef cows and their calves wintered on
stockpiled tall fescue, 2) estimate dry matter utilization rate of
stockpiled tall fescue at different herbage allocation levels, 3)
observe the impact of grazing endophyte infected tall fescue
over-winter on animal performance, and 4) determine the effect of
herbage allocation level on spring regrowth. Conventional winter
hay-feeding practices will also be evaluated for an economical
comparison with stockpiling tall fescue. Answering these objectives
is necessary in order to maintain a profitable fall calving herd
throughout winter.
Materials and Methods
The experiment was conducted at FSRC in a randomized complete block
design with three replications and four stockpiled tall fescue
herbage allowance treatments; 2.25, 3.00, 3.75, and 4.50 percent of
cow and calf body weight per head per day
(BW hd-1 d-1).
Sixty, cow-calf pairs were stratified into twelve groups and then assigned
to treatments at random. The first year of the experiment began on
2 December 2004 and ended 24 February 2005. Stockpiled tall fescue
was strip-grazed with forage allocated every 3.5 days. Pre-grazing
herbage mass was determined at the beginning of the experiment and
every 21 days thereafter, by clipping ten, 32 inches x 15 feet
strips from each pasture. Strips were cut to as near as ground
level as possible. Cows and calves were weighed and body condition
scored at the beginning of the experiment and every 21 days
thereafter. All cows were maintained on hay from 24 February until
weaning on 20 April 2005. The experiment will be repeated again
this winter.
Year One Project Summary
The first year of allocation data collection has been completed.
Cows allocated herbage at 2.25% of BW
hd-1 d-1
lost the most weight
(avg. daily loss of 2.3 lb
hd-1 d-1),
while the other three
allocation levels did not differ (avg. daily loss of 1.9 lb
hd-1 d-1).
Calves in the 2.25% BW hd-1 d-1 treatment had an ADG of 1.2
lb hd-1 d-1
while those in the 4.5% BW
hd-1 d-1
had an ADG of 1.6 lb
hd-1 d-1
(Table 1). Since the acres required to winter a cow-calf
pair would double between the lowest and highest allocations,
economic analyses suggest stockpiled tall fescue should be allocated
levels at 3.0% BW
hd-1 d-1
(Table 1). In addition, cow and calf
performance data taken later in the spring at weaning time showed no
significant differences between stockpile allocation treatments
imposed during the winter (Table 2).
Table 1. Average daily gain (or loss) and body condition score (BCS) of
fall-calving cows and average daily gain of their calves provided four different
allocations of stockpiled tall fescue. Data collected from 12/2/2004 to
2/24/2005.
|
Forage Allocation* |
Average Daily Gain |
Ending Cow BCS** |
Acres Required for 84 days of feeding |
|
Cow |
Calf |
|
% |
------------lb/d------------ |
score |
acres/cow-calf pair |
| 2.25 |
-2.3 |
1.2 |
4.1 |
0.78 |
| 3.00 |
-2.0 |
1.4 |
4.6 |
1.04 |
| 3.75 |
-1.8 |
1.5 |
4.7 |
1.30 |
| 4.50 |
-2.0 |
1.6 |
4.5 |
1.56 |
| LSD |
0.2 |
0.1 |
0.3 |
- |
* % of body weight per head per day including calf weight.
** All cows started at an average body condition score of 5.8 on a 9 point scale.
Table 2. Average daily gain (or loss) and body condition score (BCS) of
fall-calving cows and average daily gain of their calves provided four different
allocations of stockpiled tall fescue. Data collected 4/20/2005.
|
Forage Allocation* |
Average Daily Gain** |
Cow BCS At Weaning |
Calf Weaning Weight |
|
Cow |
Calf |
|
% |
------------lb/d------------ |
score |
lb |
| 2.25 |
-0.6 |
1.0 |
4.9 |
401 |
| 3.00 |
-0.8 |
0.9 |
4.9 |
423 |
| 3.75 |
-0.9 |
0.9 |
5.0 |
437 |
| 4.50 |
-0.9 |
0.9 |
5.0 |
428 |
| LSD |
NS |
NS |
NS |
NS |
* % of body weight per head per day including calf weight.
**Calculated between project end (2/24/2005) and weaning (4/20/2005)
References Cited
Allen, V.G., J.P. Fontenot, D.R. Notter and R.C. Hammes, Jr. 1992a. Forage system for beef production from conception to slaughter I. Cow-calf production. J. Anim. Sci. 70:576-587.
Allen, V.G., J.P. Fontenot, and D.R. Notter. 1992b. Forage systems for beef production from conception to slaughter II. Stocker systems. J. Anim. Sci. 70:588-596.
Berry, R.F., and C.S. Hoveland. 1969. Summer defoliation and autumn-winter production of Phalaris species and tall fescue varieties. Agron. J. 61: 493-494.
Bishop-Hurley, G.J. and R.L. Kallenbach. 2001. The economics of grazing beef cows during winter. p. 274. In Proc. American Forage and Grassland Council. 22-25 April, 2001. Springdale, AR. AFGC, Georgetown, TX.
Collins, M., and J.A. Balasko. 1981a. Effects of N fertilization and cutting schedules on stockpiled tall fescue I. Forage yield. Agron. J. 73:803-807.
Collins, M., and J.A. Balasko. 1981b. Effects of N fertilization and cutting schedules on stockpiled tall fescue II. Forage quality. Agron. J. 73:821-826.
Fribourg, H.A. and K.W. Bell. 1984. Yield and composition of tall fescue stockpiled for different periods. Agron. J. 76:929-934.
Hitz, A.C. and J.R. Russell. 1998. Potential of stockpiled perennial forages in winter grazing systems for pregnant beef cows. J. Anim. Sci. 76:404-415.
Hoveland, C.S. 1993. Importance and economic significance of the Acremonium endophytes to performance of animals and grass plant. Agric. Ecosyst. Environ. 44:3-12.
Kallenbach, R.L., G.J. Bishop-Hurley, M.D. Massie, G.E. Rottinghaus, and C.P. West. 2003. Herbage mass, nutritive value, and ergovaline concentration of stockpiled tall fescue. Crop Sci. 43:1001-1005.
National Research Council. 2000. Nutrient Requirements of Beef Cattle. 7th ed. National Academy Press, Washington, DC.
Riesterer, J.L., and D.J. Undersander, M.D. Casler, and D.K. Combs. 2000. Forage yield of stockpiled perennial grasses in the upper Midwest USA. Agron. J. 92: 740-747.
Riesterer, J.L., M.D. Casler, D.J. Undersander, and D.K. Combs. 2000. Seasonal yield distribution of cool-season grasses following winter defoliation. Agron. J. 92:974-980.
Tucker, C.A., R.E. Morrow, J.R. Gerrish, C.J. Nelson, G.B. Garner, V.E. Jacobs, W.G. Hires, J.J. Shinkle, and J.R. Forwood. 1989. Forage systems for beef cattle: effect of winter supplementation and forage systems on reproductive performance of cows. J. Prod. Agric. 2:217-221.
Waller, J.C., J.C. Forcherio, H.A. Fribourg, M.C. Smith, and R.J. Carlisle. 1988. Performance of fall-calving cows and their calves grazing fescue-based forage systems. J Prod. Agric. 1:338-342.
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