Beef Research News
Brought to you by Kansas State University
College of Veterinary Medicine - Farm Animal Section
January 2008
Contents:
Nebraska initiates Tritrichomonas Import Regulations
Heat Stress effect on follicular growth
Prevalence of Tritrichomonas in AL Beef Bulls
MLV vaccine timing effect on newly-received calves
Distillers byproducts in beef feeding industry
Nebraskas initiates Tritrichomonas Import
Regulations
In January 2008, the state of Nebraska enacted
requirements that all bulls (non-virgin or over 24 months of age) are
required to be test negative for Tritrichomonas prior to entering the
state. The bulls must have three consecutive negative trichomoniasis
culture tests at least one week apart or one negative PCR test within 30
days prior to importation and samples must be collected by an accredited
veterinarian and conducted by a laboratory accredited by the AAVLD and
the bull must not be used for breeding purposes between the tests and
the time the bull(s) is imported into Nebraska. The certificate of
veterinary inspection must contain information regarding the
Trichomoniasis status of the bull(s). For more specific regulations and
exceptions to the testing requirements please review the full order at
http://www.agr.ne.gov/division/bai/trich_order_4.pdf
Heat Stress effect on
follicular growth
The objective was to determine whether exposure of Gir (Bos indicus)
cows to heat-stress (HS) causes immediate and delayed deleterious effect
on follicular dynamics, hormonal profile and oocyte competence. The cows
were kept in tie-stalls for an adaptive thermoneutral period of 28 days
(Phase I, Days −28 to −1). In Phase II (Days 0–28) cows were randomly
allocated into control (CG, n=5) and HS (HS, n=5) treatments. The HS
cows were placed in an environmental chamber at 38°C and 80% relative
humidity (RH) during the day and 30°C, 80% RH during the night for 28
days. The CG group was maintained in shaded tie-stalls (ambient
temperature) for 28 days. During Phase III (Days 28–147) animals were
placed in tie-stalls (Days 28–42) followed by pasture (Days 42–147)
under thermoneutrality. In each phase, weekly ovum pick up (OPU)
sessions were to evaluate follicular development, morphology of cumulus–oocyte
complexes (COCs), and developmental competence after in vitro
maturation, fertilization, and culture. Serum concentrations of
progesterone (P4) and cortisol were evaluated by radioimmunoassay.
Exposure of Gir cows to HS had no immediate effect on reproductive
function, but exerted a delayed deleterious effect on ovarian follicular
growth, hormone concentrations, and oocyte competence. Heat-stress
increased the diameter of the first and second largest follicles from
Days 28 to 49. Indeed, HS increased the number of >9mm follicles
(characterized as follicular codominance) during this phase. Cows
exposed to HS had longer periods of non-cyclic activity (P4<1ng/mL), as
well as shorter estrous cycles. However, HS did not affect cortisol
concentration as compared to CG. Although HS had no significant effect
on cleavage rate, it reduced blastocyst development during Phase III. In
conclusion, long-term exposure of B. indicus cattle to HS had a delayed
deleterious effect on ovarian follicular dynamics and oocyte competence.
de S. Torres-Júnior, J. R., M. de F.A. Pires, W.F. de Sá, A. de M.
Ferreira, J.H.M. Viana, L.S.A. Camargo, A.A. Ramos, I.M. Folhadella, J.
Polisseni, C. de Freitas, C.A.A. Clemente, M.F. de Sá Filho, F.F.
Paula-Lopes, P.S. Baruselli. Effect of maternal heat-stress on
follicular growth and oocyte competence in Bos indicus cattle
Theriogenology Volume 69, Issue 2, Pages 155-166 (15 January 2008)
Prevalence of
Tritrichomonas in AL Beef Bulls
The objective of this study was to estimate the prevalence of
Tritrichomonas foetus infections in Alabama (USA) beef bulls through
prospective and retrospective surveys. The prospective survey included
240 Alabama beef bulls that were sampled between January 2005 and March
2006. Preputial smegma was collected from the 240 bulls with a dry
pipette and cultured in an InPouch™ TF T. foetus culture pouch (BioMed
Diagnostics; White City, OR, USA). The samples were evaluated
microscopically once a day for 6 days for growth resembling T. foetus.
To avoid false-positives due to fecal trichomonads, all suspect cultures
were sent to both the Alabama Department of Agriculture Veterinary
Diagnostic Laboratory in Auburn, AL, USA and the Auburn University
College of Veterinary Medicine Parasitology Laboratory (Auburn, AL, USA)
for polymerase chain reaction (PCR) confirmatory assays. Of the 240
bulls cultured in the prospective survey, 3 (1.25%) cultures were
considered suspect on microscopic evaluation. However, PCR-based assays
were negative for T. foetus, suggesting that the samples most likely
contained fecal trichomonads. The retrospective analysis included 374 T.
foetus cultures performed at the Alabama Department of Agriculture
Veterinary Diagnostic Laboratory between October 2002 and March 2005. Of
the 374 bulls included in the retrospective analysis, only 1 (0.27%) was
confirmed positive by a PCR-based assay.
Rodninga,S.P., D.F. Wolfe, R.L. Carson, J.C. Wright, H.D. Stockdale, M.E.
Pacoli, H.C. Busby, S.E. Rowe. Prevalence of Tritrichomonas foetus in
several subpopulations of Alabama beef bulls. Theriogenology. 2008 Vol
69, Issue 2: 212-217.
MLV vaccine timing
effect on newly-received calves
Stress commonly associated with weaning, marketing, and shipment of
feeder cattle can temporarily compromise immune function; thereby,
reducing the effective response to vaccination intended to control
bovine respiratory disease (BRD). Two vaccination timing treatments were
used to evaluate the effect of timing of a multivalent modified live
virus (MLV) BRD vaccine on health, performance, and infectious bovine
rhinotracheitis (IBR) antibody titers of newly-received stocker cattle.
Crossbred bull and steer calves (n = 528) were weighed (197 ± 2.4 kg)
and randomly assigned to MLV vaccination treatment: 1) MLV vaccination
upon arrival (AMLV), or 2) delayed (14 d) MLV vaccination (DMLV). All
cattle were processed similarly according to routine procedures with the
exception of initial MLV vaccination timing. Subsequently, BW were
recorded on d 14, 28, and 42. Blood samples were collected on d 0, 14,
28, and 42 to determine serum IBR titers, comparisons were made between
treatments on a receiving-day basis and an equivalent post-vaccination
day basis. Daily BW gains were greater (P 0.05) for DMLV calves from d 0
to 14 (0.88 vs. 1.16 ± 0.22 kg/d) and from d 0 to 42 (0.65 vs. 0.75 ±
0.09 kg/d). Days to first treatment, total treatment cost, percentage
death loss, and pasture ADG after the 42-d receiving period did not
differ (P 0.15). Morbidity rates for BRD were high for both AMLV and
DMLV (71.5 and 63.5%, respectively) and did not differ (P = 0.12).
Positive IBR titer seroconversion were greater (P 0.03) for DMLV calves
on d 42 of the study, and 28 d and 42 d equivalent post-vaccination
basis. Delaying vaccination 14 d may increase ADG during the receiving
period compared to vaccinating upon arrival; and seroconversion to IBR
was greater in DMLV calves, indicating a possible improvement in
acquired immune response when MLV vaccination is delayed.
Richeson, J. T. , P. A. Beck, M. S. Gadberry, S. A. Gunter, T. W. Hess,
D. S. Hubbell III, C. Jones Effects of on-arrival versus delayed
modified-live virus vaccination on health, performance, and serum
infectious bovine rhinotracheitis titers of newly-received beef calves
J. Anim Sci., doi: 10.2527/jas.2007-0593 Published online first on
January 11, 2008
Distillers
byproducts in beef feeding industry
The ethanol industry is expanding rapidly. This expansion in production
of renewable energy also increases production of byproducts. These
byproducts, primarily distillers grains plus solubles (DGS), are
utilized very efficiently by ruminants. When the starch in corn is
fermented to produce ethanol, the remaining nutrients (protein, fat,
fiber) are concentrated about 3 fold. While DGS is an excellent protein
source for ruminants, the large supply and the price relative to corn
make DGS an attractive energy source as well. This is especially
important with reduced availability and higher price of corn because of
demand by the ethanol industry. A meta-analysis of 9 experiments, where
various levels of wet DGS were fed to feedlot cattle, shows that wet DGS
produced higher ADG and G:F compared to cattle fed corn-based diets
without DGS. A similar analysis with dry DGS showed similar type of
responses but with less apparent feeding value for dry DGS compared to
wet DGS. Metabolism studies suggest the fat in DGS may be partially
protected from ruminal degradation leading to greater proportion of
unsaturated fatty acids at the duodenum and greater total tract fat
digestibility. Both the fat and the undegradable protein in DGS appear
to explain some but not all of the greater feeding value of DGS compared
to corn. Lower quality roughages may be used in feedlot diets containing
wet DGS because of the protein, moisture, and physical characteristics
the DGS contains. The feeding value of DGS is greater than dry rolled
corn or high moisture corn; however, the feeding value of DGS appears to
be less when fed in finishing diets based on steam-flaked corn than in
those based on dry-rolled or high-moisture corn.
Klopfenstein, T.J., G. E. Erickson, V. R. Bremer. BOARD-INVITED REVIEW:
Use of distillers byproducts in the beef cattle feeding industry J. Anim
Sci., doi: 10.2527/jas.2007-0550 Published online first on December 21,
2007
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