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<br />~ EXCELLENCE z
<br />College of Agriculture
<br />The University u( 1Vcoming
<br />lt~i!(iam A. Lavcock, Head
<br />August 16, 1988
<br />Terrell Johnson
<br />Cyprus Yampa Valley Coal Corp.
<br />29588 Routt Co. Rd, y27
<br />Oak Creek, CO 80467
<br />Dear Terrell:
<br />Department of Range Management
<br />PO Box 3354
<br />Laramie, WY 82071
<br />(307) 766-5263
<br />Following my sending you information on cattle bloat deaths,
<br />utilization levels, and ~ alfalfa in our experimental pastures on your
<br />mine, you asked for my opinion on the increased death probabilities
<br />if ercentage composition of alfalfa was increased from 60-65~ to
<br />80-~5~. I have talked with Dr. Ron Delaney of the Plant Science
<br />Department (an alfalfa expert) and he confirmed m,Y thoughts, i.e., as
<br />the percentage of alfalfa increased from 65p on up, the threat of ~
<br />bloat would increase only slightly if at all. The reason is that ~khyM'
<br />cattle selectively consume alfalfa when it is present--even in small ~r"`It-.?
<br />;'quantities so the ~ in their diet p of change much ~~~+7
<br />even from quantities of 20$ alfalfa in a nasture on up. The in
<br />~,'tth~iet would chance as all of the available alfalfa was eaten but
<br />,' ',the intial diet would be very high in alfalfa at all levels.
<br />,..
<br />' ~ l In our studies on Mine 2, the number of cattle lost over the
<br />^.~I,S years was the same (4 animals) for both the continuous light pasture
<br />~'~ (?5=36$ alfalfa) as in the continuous heavy pasture (64-68$ alfalfa). F1F~~
<br />''li./~rAlthough•we haventt computed it, the ~ death loss based on number of ,~~„~''~
<br />.t;~,animals would be twice as high in the pasture with the least alfalfa{~'i`
<br />r:''i;because the stocking rate in the light continuous pasture was half '~
<br />:;,that of the heavy continuous pasture. This would indicate that the (~/
<br />~!,%~~I'death loss decreases with intensity of grazing. This makes sense because
<br />a+,;:the cows in the light pasture Karl-ample alfalfa to eat all summer while
<br />`~1;;;'~ those.in the heavy pasture had the alfalfa eaten down by mid summer and
<br />`~~~; -'then had re-growth to eat along with the grasses the rest of the summer.
<br />1\!,/
<br />„~;,~ Total•''losses in the short duration (rotation) grazing were 5 head over
<br />~;` ,the ,5 years.
<br />;.,\
<br />(' •'i7,'~' - In regard to the effect of grazing system on bloat losses, our
<br />1 ~,j•i`.7~,,studies dontt provide any definitive answers. However I have talked
<br />;;,,r;i,~to,a number of knowledgable people including Dr. Delaney and 2 livestock
<br />" ~•extension specialists about this. They all indicated that the potential
<br />;',;'~,~,'r~bloat losses probably are higher for any rotation system like our
<br />~~',~~Ishort duration system. The reason is that cattle are moved every 3-4
<br />~C~';!'days onto fresh pastures where there is substantial regrowth of
<br />,,~k~alfalfa (21-28 days of growth). Because of their selectivity for C-
<br />\'~~al'falfa, the potential for loss is greatest for the first day or 2
<br />- `each time they are moved--in our study there were 24 moves during each
<br />,~ %s ummer„(8 pastures, each grazed 3 times in a rotation).
<br />,.!~''~~'~; - ~ Please let me know if you need any additipnal information.
<br />Sincerely yours,,/,~/1y,,/,/~~
<br />Bill Laycock ~ "
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