7707

• UCREFRP Catalog Number: 7707
• Author: Saul, G. E.
• Title: Effects of repetitive electroshocking on fish populations in experimental raceways and a small headwater stream in southern West Virginia
• USFW Year: 1981
• USFW - Doc Type: 41‎(12)‎
• Copyright Material: YES

AGRICULTURE. A~1MAL PA TItOLOGY

4321-B

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treatments and a single 4 5 eltctroshock. per day eXhibited very low
monality (0.40 to 0.67 mean percent mortality per day), whereas mean
percent mortality for fish shocked two and three times per day was 2.67 and
7.47. respectively. Handling was not found to significantly increase
mortality in fish already subjected to electroshocking.
Known population levels of fathead minnows and dace (Rhinichthys
otrotulus) were electroshocked daily for 10 days in raceways with sand,
gravel. cobble and boulderlbedrock substrates. Actual combined
population levels declined 17.2 percent over the study period. Average
daily depletion estimates closely reflected this change: however, single
. census techniques indicated population increases to 48.3. Small and large
; p~rtion marked sample single census techniques as one group were
significantly diJferent (p < 0.05) from depletion estimates and actual
population levels as two groups,
In general, the depletion estimatesfor both species most closely
followed actual population levels in all raceways as compared to single
census estimators. Substrates had a significant lnfiuence on the estimated
population levels. Virtually all fish were avai1able for capmre over sand and
gravel substrates. whereas. sampling over cobble and boulderlbedrock
substrates yielded an average of 43 and 46 percent, respectively of the
actual population in those raceways. Rock.ysubstrates provided refuge for
fish which resulted in lower percentages entering the catch as compared to
sand and gravel substrates.
. An "expected monaIity" was derived from the average percentage catch
per sampling run in raceways and the monaIity associated with a
comparable number of electroshoc.ks in laboratory tests to predict
electroshock monaIity over sampling periods and substrate types. A
.predicted mortality" derived through the linear regression of depletion
estimates over time yielded results Vel'}' similar to the observed and
expected monaIity for fathead minnows and was more representative of the
change in population size for dace over all substrates than the expected
monallty.
The composite analysis offield data showed a 146.7 percent increase in
one sample single census estimates. a 44.0 percent increase in two sample
single census estimates. and a 55.0 percent decrease in depletion estimates
in the final samples as compared to initial samples. Expected monality
estimates were consistently less than predicted monaIity when adjusted for
the period before intermittent streamflow.
,. This work has demonstrated that repetitive exposure to electroshocking
induces monallty in a predictable manner of fish populations. Depletion
estimates are usually accomplished with a much reduced ex})endimre of
time and effon over mark-recapture methods, however, mona.lity can be
expected due to repetitive electroshocking alone. Researchers are cautioned
to examine the objectives of a particular study before deciding on a
particular estimation technique.

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.~y 11TERBltjM JIIlTRA TEAS A ~UR.KER IN DETER...\.ID.'DiG

.. FORAGE ll\'TAKE A.'li1) nn: EFFECT OF FORAGE 1\'ITROG~

SOURCFS O~ J1I\. AKE OF GR.'ZDiG STEERS Order ~o. 8106971

" .. ... S~. WI1JlA.'f WHJTFIElD, PH.D. University o/Wyoming.1980. 108pp.

i The principle objectives of this research were to evaluate the use of
Ytterbium (Yb) nitrate as a marker in determining forage intake of grazing
cattle and to evaluate forage nitrogen consumed and its effects upon blood
urea nitrogen (B1..11\ ') and forage intake. Ph)'sica1 preparation of esophageal
fistula forage samples used to evaluate forage components was also studied.
Fecal recoveI)' ofYb administered for 5 consecutive davs in a 50 m1
drench was 77.9 ::t: 4.3 and 86.1 ::t: 1.4% for tvoice daily (0600 and 1800 hr)
and 84.2 ::t: 5.4% for once daily (0600 hr) dosing. Forage intake predicted
b)' the use of the Yb ratio technique was not diJferent (P > .05) from the
intake predicted from total fecal collection on experimental days 4 and 5
when Yb was administered tv.ice dailv. and on day 5 when Yb v,'3S
administered once daily. A minimum"of 4 days dOsage was required for the
indicator to reach equilibrium in the animals' ingesta and administering Yb
more than 5 days should provide a sufficient number of collection days.
Soluble nitrogen content of the grazed forage had a correlation of .8034
v,ith inl'itro dr)' matter digestibility (IVDMD), .7928 with total forage
nitrogen and .6317 v,ith BC~. A coefficient of determination of .847 v,'as
associated v,ith the regression ofBL~ on four ..'3riables (total nitrogen.
soluble nitrogen. forage intake, and lignin). These data indicate soluble
nitrogen of forage consumed may have a significant effect upon BID;.
although soluble nitrogen and BLi\ showed no correlation (P > .05) v.ith
fora2e intake.
Protein content of esophageal extnlsa samples hand-squeezed to
remove salh'll was less (P < .01) than that of esophageal extrusa samples not
squeezed. In ,'itro digestibility of esophageal extrusa samples was only

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474

oeeasionally reduced (P < .01) by squeezing. These data indicate that
extrusa collected from esophageal-listulated steers should Dot be hand.
squeezed to remove saliva.

STIJDlES OF TIIE PRODUcnON CHARACIERISTICS OF

SEVERAL SHEEP BREED TYPES AND CROSSFS

WOOu.sTON. ROBERT R., PH.D. University o/New South Wales (A.ustralia).
1975.

Sheep breed comparisons were undertaken near Hay in New South
Wales. The production characteristics of three crossbred ewe types and two
Merino strains were compared, as were three sire breeds.
Considerable differences emerged in the abilities of the ewe breed types
to perform under conditions of increased joining frequencies. Australia's
most widely used prime lamb ewe t)'Pe. the Border Leicester-Merino cross
was unsuitable for use in intensive breeding schemes because ofits relative
inability to breed successfully at out-of-season joinings. The two Merino
strains and the two Dorset- Merino types performed moderately under these
conditions, but the Merinos tended to have a lower average litter size.
Dormer-Merino cross ewe successfully combined the attributes ofa high
average litter size with a superior ability to conceive in out-of-season
joinings. The likely performance of each breed type. in several breeding
systems is discussed.
Fleece characteristics diJfered between the five ewe types. The finer
Merino fleeces had a similar monetary value to the heavier. comer Border
Leicester x Merino fleeces. Dorset-based t)'Pes had fleeces with
intermediate mean fibre diameters. but their fleece weights were lower than
those of other types and were consequently valued lower. The effects of an
increase in the frequency of pregnancy and lactation on fleece
characteristics were not clear and possible reasons are discussed.
Although milk samples taken from ewes of the five breed types did not
diJfer significantly in composition. single bearing crossbred ewes had higher
milk seaetion rates than equivalent Merino ewes.
Lambs with crossbred mothers had higher pre-weaning growth rates
than those with Merino mothers but these diJferences tended to diminish
after weaning and the mean ages at 35kg and 45kg did not differ
significantly. When compared at equal carcass weights. composition of the
progeny as estimated by sample joints was not largely affected by dam
breed type, although lambs '9oith Border Leicester x Merino dams tended to
produce fatter carcasses.
Differences emerged in lamb growth rates due to sire breed. Lincoln-
sired lambs grew significantly slower than Dorset-sired lambs. After
weaning, Suffolk-sired lambs grew significantly faster than Dorset-sired
lambs and reached slaughter weight at a significantly lower age. Contr.uy to
several overseas reports. diJferences in carcass composition due to sire
breed were small, even in hea,'Y weight carcasses.

AGRICULTIJRE. A~1MAL PATHOLOGY

CA..'\Th"E TRA.~SMlSSmLE VEJ\"EREAL SARCOm:
IDTh"TIFICATION A.l\'D FL~cnONAL CHARACIlJUZATION OF
LYMPHOCYTES FRO:\1 PERIP~ BLOOD, DRAINING
LnIPH NODES, A.''D TUMORS AT DIFFERE.'\"T ST_'GES OF .
GROWTH Order ~o. 8111904
CftA."'DLER. JOSEPH PETER. PH.D. The University o/Connecticut, 1981
135pp.
The premise of this thesis is that proper isolation, identification, and
controlled functional analysis oflymphOC)tes can be used to monitor the
host-mmor relationship of dogs bearing the canine transmissible venereal
sarcoma (CTVS). lymphocytes from peripheral blood, draining lymph
nodes. and tumors were monitored during the course of tumor grov.th and
spontaneous rejection by immunofluorescence surface marker analysis.
spontaneous incorporation of (3H)-thymidine. ph~tohemagglutinin (PHA)
and protein A mitogenesis. and responsiveness to tumor-associated
antigens, (T AA). CTVS cells in milled l)mphocyte tumor OJlture (~LTq
and allogeneic lymphOC)'tes in mixed lymphOC)te reaction (MLR).
All tumor-bearing dogs had reduced peripheral blood l)mphOC)1e
counts affecting evenly both T and B lymphocytes. The number of
peripheral blood null cells fluctuated but showed no discernible pattern
with respect to the status of the tumor. However. reduced levels ofB
lymphocytes were e,ident in lymph nodes draining progressive tumors,
while null cells ""ere decreased in I~mph nodes draining regressive bJmors.

Dissertation A.bstracts 11lIerru1tio1ll1l VoL 41 No. /1 June 1981