United States Department of Agriculture
Agricultural Research Service
Northwest Irrigation & Soils Research Laboratory
Revised March 1999
Diurnal Cycling in Forage Quality
by
H.F.
(Hank) Mayland and Glenn E. Shewmaker*
Sundown (PM) Versus Sunup (AM) Cutting
of Forages
On 5 August 1996, Mayland was interpreting soluble-carbohydrate data
measured in the 'Grazing Preference Study' noted above and reconciling them
with published values. A check of literature available at the lab and a call to
J.C. Burns, Raliegh, NC showed a general increase in sugars during the daylight
hours and a suggested diurnal cycling of sugars in the plant. No information
was found then about effects of diurnal cycling of sugars on grazing behavior
or animal choices of variously cut hays. An experimental protocol was developed
to evaluate animal response to sundown- (PM) versus sunup- (AM) harvested hay.
Vegetatively growing HiMag tall fescue was harvested on a PM/AM schedule 20-22
Aug. and 20-21 Sept. 1996 at Kimberly, Idaho. Hay was field cured, baled, and
trucked to Raleigh, NC where it was fed in a preference trial. Results from
that first study, summarized below, were very exciting and led to other studies
evaluating the potential application of this technology. As information becomes
available it will be presented in technical meetings and publications, as news
releases and by word of mouth. It is very important that the
PM-harvest occur the night before the AM-harvest so that both have the same
conditions for sugar accumulation.
PM/AM- Cut Tall Fescue Grass
Fisher, D.S., H.F. Mayland, and J.C. Burns. 1999. Variation
in Ruminants' Preference for Tall Fescue Hays Cut Either at Sundown or at
Sunup. J. Anim. Sci. 77:762-768. Cattle, Sheep, and Goats all showed a
strong preference for the PM-cut hay, sometimes eating 50% more of the PM hay.
This preference, indicated by dry matter intake, was associated with greater
total nonstructural carbohydrate (TNC) concentrations. The TNC's accumulated
during the day, diluting acid detergent fiber (ADF), and neutral detergent
fiber (NDF).
Table 1. Effect of sundown versus sunup harvests of HiMag tall fescue (endophyte-free) hay on forage quality and dry matter intake during one meal per day by steers. Data are from D.S. Fisher, J.C. Burns, and H.F. Mayland, USDA-ARS, Raleigh, NC and Kimberly, ID.
|
Treatment |
Time cut |
Crude Protein |
In vitro true dry matter disappearance |
Total nonstructural carbohydrates |
Neutral detergent fiber |
Acid detergent fiber |
Relative feed value |
Dry matter intake |
|
|
|
(%) |
(%) |
(%) |
(%) |
(%) |
|
(g/meal) |
|
20 Aug |
PM |
22.2 |
84.7 |
8.15 |
49.6 |
26.0 |
246 |
987 |
|
21 Aug |
AM |
21.7 |
82.4 |
6.21 |
52.0 |
27.1 |
233 |
544 |
|
21 Aug |
PM |
21.7 |
83.1 |
7.73 |
51.5 |
26.8 |
236 |
788 |
|
22 Aug |
AM |
19.9 |
82.1 |
6.71 |
53.5 |
28.2 |
221 |
427 |
|
20 Sep |
PM |
20.6 |
88.8 |
11.82 |
43.5 |
22.4 |
297 |
1460 |
|
21 Sep |
AM |
19.9 |
87.5 |
9.3 |
47.0 |
24.3 |
268 |
1310 |
|
|
|
|
|
|
|
|
|
|
|
CV (%) |
|
3.2 |
0.7 |
8.8 |
2.4 |
2.1 |
-- |
16 |
|
MSD |
|
0.8 |
0.6 |
0.78 |
1.3 |
0.6 |
-- |
154 |
|
Contrast P |
|
<0.1 |
<0.01 |
<0.01 |
<0.01 |
<0.01 |
-- |
<0.01 |
PM/AM- Cut Alfalfa
Fisher, D.S., H.F. Mayland, and J.C. Burns. 1998. Variation in ruminant preference for alfalfa hay cut either at sundown or sunup. J. Anim. Sci. 1998, 76 (Suppl. 1, Abstract # 753). Technical manuscript being prepared. A 2nd technical manuscript is being prepared on long term dry matter intake and in vivo digestibility by steers.
Like with the tall fescue, alfalfa was grown in 1997 near Kimberly, Idaho swathed on PM/AM schedule, baled, and shipped to Raleigh, NC where is was fed in 'preference' study to cattle, sheep, and goats. Hays were offered alone as meals to each animal during an adaptation phase prior to the experimental phase. In the experimental phase, each possible pair of hays (15 pairs) was presented to sheep and goats for approximately 2.5 h and to cattle for approximately 0.5 h Presentation of the pairs was randomized. In all three harvests in the three experiments, preference for PM hays was greater than for AM hays (p<.01). Shifting the mowing of alfalfa hay from morning to late afternoon was effective in increasing forage preference in these three ruminant species.
Table 2. Effect of sundown versus sunup harvests of Germain WL 322HQ hay on forage quality and dry matter intake during one meal per day by steers. Data are from D.S. Fisher, J.C. Burns, and H.F. Mayland, USDA-ARS, Raleigh, NC and Kimberly, ID.
|
Treatment |
Cutting |
Time cut |
|
|
Total nonstructural carbohydrates |
Neutral detergent fiber |
Acid detergent fiber |
Relative feed value |
Dry matter intake |
|
|
|
|
|
|
(%) |
(%) |
(%) |
|
(g/meal) |
|
8 Jul |
2 |
PM |
|
|
4.29 |
40.7 |
31.1 |
148 |
1022 |
|
9 Jul |
2 |
AM |
|
|
3.49 |
42.7 |
32.8 |
138 |
842 |
|
14 Aug |
3 |
PM |
|
|
5.16 |
41.9 |
32.0 |
142 |
619 |
|
15 Aug |
3 |
AM |
|
|
3.97 |
42.0 |
32.5 |
140 |
324 |
|
22 Sep |
4 |
PM |
|
|
6.55 |
36.6 |
27.9 |
171 |
1320 |
|
23 Sep |
4 |
AM |
|
|
5.46 |
37.2 |
28.5 |
167 |
1107 |
|
|
|
|
|
|
|
|
|
|
|
|
CV (%) |
|
|
|
|
6 |
6.1 |
6.8 |
-- |
25 |
|
MSD |
|
|
|
|
0.31 |
2.8 |
2.5 |
-- |
240 |
|
|
|
|
|
|
|
|
|
|
|
|
Contrast P: PM vs AM |
|
|
<0.01 |
<0.3 |
<0.2 |
-- |
<0.01 |
||
PM/AM- Cut C-4 Switchgrass (Panicum virgatum L.)
Fisher, D.S., J.C. Burns, and H.F. Mayland. 1999. Diurnal Harvest Timing
and Ruminant Preference for Switchgrass Hay. For presentation Am. Soc. Agron.,
annual meeting Oct - 5 Nov. 1999, Salt Lake City. Sheep preferred but goat
varied in preference for PM vs AM-harvested switchgrass hays. This response was
attributed to greater variability among the harvest treatments. This may be a
climatic or genetic response.
Production Response Keyed to Diurnal Cyling of Forage Quality
Dairy Cows will eat about 8% more of a total mixed ration (TMR) containing 40% afternoon-cut alfalfa hay than one containing morning-cut alfalfa hay and will produce about 8% more milk. Adjusting schedules to cut hay in afternoon and early evening can increase feed value of hay by 15%. Kim D. 1995. Effect of plant maturity, cutting, growth stage, and harvesting time on forage quality. Ph.D. Diss. USU, Logan, UT.
Green-chopped alfalfa cut in the afternoon will have more feed value and is relished more by cows than if cut in the morning (Mayland, observation).
When making silage from alfalfa or clover hay, one can enhance the fermentation process by cutting the hay in the afternoon compared to cutting in the morning.
Owens, V.N., et al. 1999. Protein degradation and fermenation characteristics of red clover and alfalfa silage harvested with varying levels of total nonstructural carbohydrates. Crop Sci. 39:1873-1880.
Dairy cows foraging pastures under 24-h strip grazing management produced 8% more milk when fence was moved after the afternoon milking (4pm) vs after early morning milking (6am). Orr, R.J., et al. 1998. Matching grass supply to grazing patterns for dairy cows under strip-grazing management. Report of Instit. Grassld. Leviron. Res., North Wyke, Okehampton, Devon, EX20 2SB, UK. Personal communication.
Increased sugars in afternoon forage may explain increased bite counts in
afternoon vs. morning grazing.
Documenting Diurnal Cycling in Forage Quality
Daily cycling of forage quality, especially as it affects animal eating
behavior and economic value, has not been researched prior to 1995. Plant
physiological data on sugar accumulations rarely included entire above ground
plant material grown in full canopy in the field. Unequivocal evidence of
animal preference for sundown- versus sunup-harvested forage has led us to
investigate and document gains and losses of soluble sugars at periodic intervals
on 12 or 24-h basis.
Figure 1. Conceptual model of total nonstructural carbohydrates (TNC)
as a function of time before harvest and after harvest. Curve A
represents TNC level if PM-cut forage was immediately frozen, curve B
represents gradual drying of PM-cut forage that would decrease the cut forage's
respiration rate, curve C represents AM-cut forage immediately frozen, and
curve D represents gradual drying AM-cut forage.
Shewmaker, G.E., H.F. Mayland, C.A. Roberts, P.A. Harrison, and E.A.
Sleper. 1999. Carbohydrate Accumulation Rates in Tall Fescue. In
preparation. Samples were taken at 2-h intervals, from sunup to sundown, from
eight tall fescue cultivars, and four times during the season. Over the time
period of 2-h post-sunup until 2-h pre-sundown, total nonstructural
carbohydrates (TNC) increased linearly from 222, 212, 127, and 98 g TNC/kg DM
in May, July, Aug, and Sept. respectively at rates of 3.2, 2.4, 3.0, and 4.4 g
TNC/kg DM / hr. Tall fescue forage samples taken for TNC determination should
be taken within a 1-h period for values to be within 5% of mean, otherwise
sampling times should be blocked. The linear portion of TNC values were plotted
by cultivar against time. The TNC slopes were not different amoung cultivars.
Intercepts were different for cultivars and were proportional to animal
preference. Kenhy had the highest TNC intercept and highest cattle preference
while Mozark had the lowest intercept and preference.
Shewmaker, G.E., H.F. Mayland, J.C. Burns, and D.S. Fisher. 1999.
Alfalfa quality and Implications for Testing. Proc. Western Crop Sci. Soc.
Annual meeting Powell, WY, 28 - 30 June 1999. Forage samples were taken at
3-h intervals, around the clock for 3 to 5 days prior to swathing of each of 4
cuts of alfalfa. Diurnal variation of carbohydrates (TNC) was detected. In May
the TNC increased linearly from about 9am to 9pm at 2.9 g TNC/kg DM/h (coef
determination = 0.90). Fresh alfalfa forage samples taken for TNC determination
should be taken within an 1-h period for values to be within 5% of mean or
sampling times should be blocked.
Scientists Working on Various Phases of Carbohydrate Cycling & Forage Quality:
Mayland, H.F. (Hank) USDA-ARS, Kimberly, ID mayland@kimberly.ars.pn.usbr.gov
Burns, Joe C., USDA-ARS, Raliegh, NC jburns@cropserv1.cropsci.ncsu.edu
Burritt, Beth, USU, Logan, UT bethb@cc.usu.edu
Chatterton, N. Jerry, USDA-ARS, Logan, UT njchatt@cc.usu.edu
Crawford, Richard, U.MO, MountVernon,MO crawford@ext.missouri.edu
Dove, Hugh, CSIRO, Canbera, ACT 2101, Australiahugh.dove@pi.csiro.au
Fisher, Dwight.S. USDA-ARS, Watkinsville, GA Dwight_Fisher@scientist.com
Flath, Robert USDA-ARS, Albany, CA, retired raflath@ix.netcom.com
Harrison, Phil USDA-ARS, Logan, UT
Henry, David, CSIRO, Wembly, WA, Australia d.henry@ccmar.csiro.au
Hussein, H. U., UNV, Reno, NV hhussein@agnt1.ag.unr.edu
Kim, Dayoon, Systemic Formulas, Ogden, UT dkim@systemicformulas.com
Lee, Julien, CRI, Grasslands, Palmerston N., NZ leej@agresearch.cri.nz
MacAdam, Jennifer, USU, Logan, UT jenmac@cc.usu.edu
Martin, Scott Univ. GA, Athens, GA scottm@arches.uga.edu
McCaughey, W. Paul Brandon, Mannitoba pmccaughey@em.agr.ca
Owens , Vance, SDSU, Brookings, SD owensv@www.ces.sdstate.edu
Provenza, Fred, USU, Logan, UT stan@cc.usu.edu
Roberts, Craig, Univ. Mo, Columbia, MO roberts@psu.missouri.edu
Roitman, Jim, USDA-ARS, Albany, CA jnr@pw.usda.gov
Rook, Andrew, Inst. Grassland & Environmental Res. Okehampton, Devon, UK EX20 2SD aj.rook@bbsrc.ac.uk
Shewmaker, Glenn, Univ. ID, Twin Falls, ID gshew@uidaho.edu
Sleper, Dave, Univ. MO, Columbia, MO sleperd@missouri.edu
Villalba, Juan, USU, Logan, UT villalba@cc.usu.edu
.