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Brought to you by Kansas State University
College of Veterinary Medicine - Agricultural Practices Section
December 2007 |
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Contents:
KSU Bull Evaluation and Management
Conference
Fetal protection against BVD
following vaccination
Ovarian follicular dynamics in
cattle
Pre-haul management and transport
duration on beef calf performance
Fall-calving cow-calf pairs
strip-grazing tall fescue
AVMA Offers Online Salary Calculator
KSU Bull Evaluation and Management Conference
You are invited to attend the Kansas State Bull Evaluation and
Management conference on Friday January 11, 2008 in Manhattan, KS. This
conference is exclusively about bulls. This conference will be a
comprehensive continuing education symposium on the selection,
management, health maintenance, biosecurity, and fertility of bulls.
Internationally recognized experts will provide up-to-date information
to optimize bull productivity, utilization, and semen evaluation. For
more information and to register, direct your browser to:
www.vet.ksu.edu/CE/Bull.htm
Fetal protection against
BVD following vaccination
The objective of this research was to evaluate the efficacy of a
commercially available killed bovine viral diarrhea virus (BVDV) vaccine
to protect against fetal infection in pregnant cattle continually
exposed to cattle persistently infected with the BVDV. 60 crossbred beef
heifers and 4 cows persistently infected with BVDV were used for this
study. Beef heifers were allocated to 2 groups. One group was vaccinated
twice (21-day interval between the initial and booster vaccinations)
with a commercially available vaccine against BVDV, and the other group
served as nonvaccinated control cattle. Estrus was induced, and the
heifers were bred. Pregnancy was confirmed by transrectal palpation.
Four cows persistently infected with BVDV were housed with 30 pregnant
heifers (15 each from the vaccinated and nonvaccinated groups) from day
52 to 150 of gestation. Fetuses were then harvested by cesarean section
and tested for evidence of BVDV infection.
1 control heifer aborted after introduction of the persistently infected
cows. Bovine viral diarrhea virus was isolated from 14 of 14 fetuses
obtained via cesarean section from control heifers but from only 4 of 15
fetuses obtained via cesarean section from vaccinated heifers; these
proportions differed significantly. Conclusions and Clinical Relevance—A
commercially available multivalent vaccine containing an inactivated
BVDV fraction significantly reduced the risk of fetal infection with
BVDV in heifers continually exposed to cattle persistently infected with
BVDV. However, not all vaccinated cattle were protected, which
emphasizes the need for biosecurity measures and elimination of cattle
persistently infected with BVDV in addition to vaccination within a
herd.
Grooms, D.L. S.R. Bolin, P.H. Coe, R.J. Borges, C.E. Coutu, Fetal
protection against continual exposure to bovine viral diarrhea virus
following administration of a vaccine containing an inactivated bovine
viral diarrhea virus fraction to cattle. Amer J Vet Res 2007, Vol. 68,
No. 12: 1417-1422.
Ovarian follicular
dynamics in cattle
The study of follicular dynamics began in the mid-20th century, but
progress has been particularly rapid in the last two decades through the
use of tools that have enabled serial, non-invasive examination. A brief
overview of early oogenesis and folliculogenesis is provided as a
backdrop to the evolution of our understanding of follicular dynamics
during the bovine estrous cycle. Studies to date support the concept
that the pair of ovaries acts as a single unit and influences follicular
development primarily via systemic endocrine routes involving ovarian
and uterine products, the gonadotropins, and their receptors. Dominant
and subordinate follicles pass through growing, static and regressing
phases that have distinct morphologic and biochemical characteristics;
these changes are the basis of efforts focused on diagnosing and
manipulating follicular status. An update of research progress
highlights recent findings on the repeatability (predictability) within
individuals of follicle recruitment and wave pattern (two- versus
three-wave cycles), the relationship between oocyte competence and
follicular status, and the dynamics of small follicles. Recent studies
documented that wave emergence and follicular dominance are apparent
earlier than previously reported, and on the basis of periodic
endogenous FSH surges and the presence of FSH receptors, the hypothesis
that follicles become progressively entrained to waves from the earliest
stages of development is introduced. Lastly, recent studies comparing
old cows and their young daughters provide a new understanding of the
effects of aging on gonadotropins and ovarian steroids, follicular
dynamics, ovarian response to synchronization, superstimulation, and
oocyte competence.
G.P. Adams, R. Jaiswal, J. Singh, P. Malhi Progress in understanding
ovarian follicular dynamics in cattle. Theriogenology Volume 69, Issue
1, Pages 72-80 (January 2008)
Effects of pre-haul
management and transport duration on beef calf performance and welfare
Behavioural and physiological indicators of stress as well as growth
performance, and morbidity rates were assessed in 174 steer calves (220
± 37 kg) for 30 days after transport from ranch-to-feedlot. The calves
were conditioned (C) or not (NC), and subjected to short- (2.7 h, S) or
long-hauling duration (15 h, L), yielding treatments CS, CL, NCS and NCL.
Upon arrival at the feedlot, calves were randomly assigned to 16 pens
(four pens per treatment, one of which was equipped with a radio
frequency identification system for continual monitoring of individual
bunk attendance (15 calves)). As part of the NC treatment calves were
also exposed to a short (2 h) transport 24 h after their initial arrival
to the feedlot. All calves were fed a barley silage/barley grain-based
starter ration and weighed every 7 days. Cortisol concentrations were
higher in NC compared to C calves regardless of transport distance (P <
0.05). NC calves also had higher pre- and off-loading cortisol
concentrations than C calves. In transit, CS steers had the lowest heart
rate (HR, 67.8 bpm ±0.61; P < 0.0001). HR was highest (P < 0.05) during
the first 15 min of the journey for all calves and gradually declined
until 121–161 min into the trip. NC calves spent more time at the feed
bunk (222.9 min day−1 versus 128.6 min day−1) in the first 2 days in the
feedlot. CL calves were observed more frequently at the water than NCL
calves (P < 0.05). An interaction was observed for shrinkage (P < 0.001)
and ADG (P < 0.01). Shrinkage was greater in CL than in NCL steers (23.6
kg versus 14.6 kg), and in NCL than in either CS (7.8 kg) or NCS (9.2
kg) steers. The lowest (P < 0.005) ADG was recorded for CL and NCS
calves (0.8 and 0.9 kg, respectively), although their DM intake (6.0 and
6.8 kg day−1) was similar (P > 0.05) to calves in the other treatment
groups. Morbidity rate was 5.17% with no treatment effect. Conditioning
calves prior to transport allowed calves to better tolerate the
stressors of transport and handling.
Schwartzkopf-Gensweina, K.S. , M.E. Booth-McLeana, M.A. Shaha, T. Entza,
S.J. Bachb, G.J. Mearsa, A.L. Schaeferc, et al. Effects of pre-haul
management and transport duration on beef calf performance and welfare.
Applied Animal Behaviour Science. Volume 108, Issues 1-2, 10 December
2007, Pages 12-30
Fall-calving cow-calf
pairs strip-grazing tall fescue
In a 2-yr study, we evaluated the impact of different forage allocations
on the performance of lactating beef cows and their calves grazing
stockpiled tall fescue. Allocations of stockpiled tall fescue at 2.25,
3.00, 3.75, and 4.50% of cow-calf pair BW/d were set as experimental
treatments. Conventional hay-feeding was also evaluated as a comparison
to grazing stockpiled tall fescue. The experiment had a randomized
complete block design with 3 replications and was divided into 3 phases
each year. From early December to late February (Phase 1) of each year,
cows and calves grazed stockpiled tall fescue or were fed hay in the
treatments described above. Immediately following Phase 1, cows and
calves were commingled and managed as a single group until weaning in
April (Phase 2) so residual effects could be documented. Residual
effects on cows were measured after calves were weaned in April until
mid-July (Phase 3). During Phase 1 of both years, apparent DMI of
cow-calf pairs allocated stockpiled tall fescue at 4.50% of BW/d was 31%
greater (P < 0.01) than those allocated 2.25% of BW/d. As allocation of
stockpiled tall fescue increased from 2.25% to 4.50% of cow-calf BW/d,
pasture utilization fell (P < 0.01) from 84 ± 7% to 59 ± 7%. During
Phase 1 of both years, cow BW losses increased linearly (P < 0.02) as
forage allocations decreased, although the losses in yr 1 were almost
double (P < 0.01) those in yr 2. During Phases 2 and 3, few differences
were noted across treatment groups, such that by the end of Phase 3, cow
BW in all treatments did not differ either year (P > 0.40). Calf ADG in
Phase 1 increased linearly (P < 0.01) with forage allocation (y = 0.063x
+ 0.513; R2 = 0.91). However, calf gain/ha decreased linearly (P < 0.01)
as stockpiled tall fescue allocations increased (y = -26.5x + 212; R2 =
0.97) such that gain/ha for cow-calf pairs allocated stockpiled tall
fescue at 4.50% BW/d was nearly 40% less (P < 0.01) than for those
allocated 2.25% of BW/d. Allocating cow-calf pairs stockpiled tall
fescue at 2.25% of BW/d likely optimizes use, because cow body condition
is easily regained in the subsequent spring and summer months, less
forage is used during winter and calf gain/ha is maximized.
Curtis, L.E., R. L. Kallenbach, C. A. Roberts. Allocating forage to
fall-calving cow-calf pairs strip-grazing stockpiled tall fescue.
Published online first on December 11, 2007. J. Anim Sci. 1990.
0:jas.2007-0525v1. doi:10.2527/jas.2007-0525
AVMA Offers Online Salary
Calculator
The American Veterinary Medical Association offers a free veterinary
salary calculator designed to help veterinarians benchmark their annual
incomes against similarly employed colleagues. To access: go to the
Member Resources section of the AVMA web site (www.avma.org) and click
on the Jobs bar. Once logged on, veterinarians can enter a variety of
search criteria, including employment type, the species that they work
with, whether they are owners or associates, and how many years of
experience they have. Along with median salaries, the calculator lists
salaries for most categories at the 25th, 75th, and 90th percentile. All
information contained in the calculator is drawn from the AVMA Report on
Veterinary Compensation. Currently, the calculator lists salary figures
from 2005. Once the AVMA completes the survey in 2008 to cover the 2007
salary figures, the data will be updated. All salaries are based on
full-time employment.
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Beef Research News is produced by the Agricultural Practices section at
Kansas State University. To modify your subscription to this service
please email Brad White
For more information please contact:
Brad White
Beef Production Medicine
Q211 Mosier Hall
Manhattan, KS 66506
bwhite@vet.ksu.edu
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