Beef Research News
Brought to you by Kansas State University
College of Veterinary Medicine - Agricultural Practices Section
February 2008
Contents:
Biosecurity practices in feedyards
Partitioning of energy in pregnant beef cows
Effect of number of feeding places on performance & behavior
Effect of prebreeding weight or progestin exposure on heifers
Self clearance from BVDV infections in Peru dairies
Improving the Veterinary employment selection process
Biosecurity practices in feedyards
A survey was performed to determine the
biocontainment, biosecurity, and security practices at beef feedyards in
the Central Plains of the United States. Managers of feedyards in
Colorado, Kansas, Nebraska, Oklahoma, and Texas that feed beef cattle
for finish before slaughter were surveyed. The feedyards had to have an
active concentrated animal feeding operation permit with a 1-time
capacity of 1,000 cattle. A voluntary survey of feedyard personnel was
conducted. Identified feedyard personnel were interviewed and responses
regarding facility design, security, employees, disease preparedness,
feedstuffs, hospital or treatment systems, sanitation, cattle sources,
handling of sick cattle, and disposal of carcasses were collected in a
database questionnaire.
The survey was conducted for 106 feedyards with a 1-time capacity that ranged from 1,300 to 125,000 cattle. Feedyards in general did not have high implementation of biocontainment, biosecurity, or security practices. Smaller feedyards were, in general, less likely to use good practices than were larger feedyards. Results of the survey provided standard practices for biocontainment, biosecurity, and security in feedyards located in Central Plains states. Information gained from the survey results can be used by consulting veterinarians and feedyard managers as a basis for discussion and to target training efforts. Feedyards included in this survey may not have implemented more biocontainment, biosecurity, and security practices for several reasons. They may have been unaware of the risks or the appropriate mitigation strategies to decrease risks. Veterinarians should help managers to better understand the routes of transmission for diseases that are most threatening to their operations and to develop optimal plans aimed at preventing disease transmission. In contrast, managers may have understood the risks but perceived that the mitigation strategies were ineffective or uneconomical.
Information about disease risks
and mitigation strategies should be combined with cost-benefit analyses
by veterinarians and managers to establish best management practices for
each feedyard. Action plans developed in consultation with veterinarians
to address disease outbreaks would be valuable to managers for use in
educating feedyard employees about preventive actions and steps for an
effective response. Additional studies will be needed to enable
veterinarians and farm managers to better understand the risks and to
determine those mitigation strategies that provide the most economic
benefits. Veterinarians are pivotal in educating feedyard staff about
the dynamic risk of disease introduction and transmission within the
feedyard, which characterizes the industry, and identifying best
management practices for biocontainment, biosecurity, and security.
Brandt, A., M. Sanderson, B. DeGroot, D. Thomson, L. Hollis.
Biocontainment, Biosecurity, and Security Practices in Beef Feedyards.
JAVMA. January 15, 2008 Vol. 232, No. 2, pp. 262-269.
Partitioning of
energy in pregnant beef cows
The purpose of this study was to determine if the efficiency of energy
retention in pregnant cows was dependent on the time during the
pregnancy that feed was offered. Our hypothesis was that restricting
feed intake during the second trimester of gestation and providing the
saved feed during the third trimester was less energetically efficient
than providing the feed during the second trimester. Twenty cows (4
breed composite: 1/4 Hereford, 1/4 Angus, 1/4 Red Poll, and 1/4
Pinzgauer) that had produced 1 calf before the study were fed a diet
that consisted of (DM basis) 67.3% chopped corn silage, 27.0% alfalfa
hay, 5.5% corn, and 0.2% NaCl. When the cows were 87 ± 0.6 d pregnant,
the first nutrient balance measurement was conducted. Six subsequent
nutrient balance measurements were taken on d 122 ± 0.6, 143 ± 0.6, 171
± 0.6, 206 ± 0.6, 241 ± 0.6, and 262 ± 0.6 of gestation. Each nutrient
balance measurement consisted of a 96-h total collection of feces and
urine and a 24-h indirect calorimetry measurement.
Ten cows were fed for moderate BW
gain during the entire pregnancy, and 10 cows were feed-restricted in
the second trimester and realimented during the third trimester
(low-high, L-H). The BW of the cows at parturition (559 ± 14 kg) did not
differ between treatments (P = 0.20). There was a general trend for the
proportion of ME intake retained to decrease in moderate cows as
pregnancy progressed. The proportion of ME intake retained in L-H cows
decreased during the first 49 d of feed restriction, but the proportion
of ME retained after 77 d of restriction was greater than that retained
at 49 d of restriction. During realimentation, there were no time
effects for efficiency of ME conversion to retained energy, but
efficiency was greater for L-H cows than moderate cows (P < 0.001). The
ability of the cow to adapt its energy metabolism during periods of
moderate feed restriction and realimentation allows development of
management strategies that alter the time interval of the production
cycle during which supplemental feed is offered. Total savings in feed
offered during the production year are minimal, but management
strategies can be developed that shift which feed resources are being
used.
Freetly, H.C., J. A. Nienaber and T. Brown-Brandl. Partitioning of
energy in pregnant beef cows during nutritionally induced body weight
fluctuation. J. Anim Sci. 2008. 86:370-377.
Effect of number of
feeding places on performance and behavior
Seventy-two Friesian calves (BW = 102.0 ± 1.8 kg) were bought from a
commercial calf farm and distributed to a factorial arrangement of
treatments in a complete block design with 3 treatments and 3 blocks of
similar fasted BW to study the effect of increasing the number of
feeding places per pen on performance, behavior, and welfare indicators
during the 4 wk after arrival. Treatments consisted of 1 (T1), 2 (T2),
or 4 (T4) concentrate feeding places/pen (8 calves/pen). Concentrate and
straw were fed at 0830 in individual feeders, and animals were allowed
to consume on an ad libitum basis. Dry matter intake and ADG were
recorded weekly, and blood samples were taken on d 0 (before transport),
7, 14, 21, and 28. Time spent in maintenance activities, number of
displacements between calves, and the angular dominance value (ADV) were
registered at wk 1 and 3 after arrival. Increasing the number of feeding
places per pen resulted in a quadratic response of concentrate and total
DMI, ADG, and BW during the 28-d period, with T1 showing the lowest
values.
Straw intake and the within-pen SD of ADG tended to decrease linearly (P = 0.10) as the number of feeding places per pen increased. During the 4-wk receiving period, and particularly on d 7 after arrival, serum NEFA responded quadratically, with T1 and T2 calves showing the greatest values. With increasing number of concentrate feeders, the average time spent lying increased (P = 0.001), standing time decreased linearly (P = 0.001), and the diurnal feeding pattern changed (concentrate eating time increased but straw eating time decreased during peak feeding times, P < 0.05). The number of displacements from the concentrate feeders responded quadratically (P < 0.001) with increasing number of feeding places per pen, with T4 calves showing the lowest levels of aggression. In T1 calves, increasing ADV resulted in a linear decrease (P = 0.03) of ADG at wk 1 with a quadratic effect at wk 3 (P < 0.01).
In T2 calves, increasing ADV
resulted in a linear decrease (P = 0.04) of ADG at wk 1 but a linear
increase (P = 0.02) at wk 3. No effect of social rank on ADG was
observed in T4 calves (P > 0.20). Increasing social pressure at the
concentrate feeders beyond the threshold of 4 heifers per feeder had a
negative effect on performance. Within-pen variability in performance
increased linearly as a consequence of greater effects of social
dominance. Physiological indicators of welfare were not consistently
affected by treatments.
González, L.A., A. Ferret, X. Manteca, J. L. Ruíz-de-la-Torre, S.
Calsamiglia, M. Devant and A. Bach. Effect of the number of concentrate
feeding places per pen on performance, behavior, and welfare indicators
of Friesian calves during the first month after arrival at the feedlot.
J. Anim Sci. 2008. 86:419-431.
Effect of
prebreeding weight or progestin exposure on beef heifers
Two experiments evaluated prebreeding target BW or progestin exposure
for heifers developed lighter than traditional recommendations.
Experiment 1 evaluated the effects of the system on heifer performance
through subsequent calving and rebreeding over 3 yr. Heifers (229 kg)
were assigned randomly to be developed to 55% of mature BW (299 kg)
before a 45-d breeding season (intensive, INT; n = 119) or 50% of mature
BW (272 kg) before a 60-d breeding season (relaxed, RLX; n = 142).
Prebreeding and pregnancy diagnosis BW were greater (P 0.006) for INT
than RLX heifers. Overall pregnancy rate did not differ (88.4%; P =
0.51), but RLX heifers had later calving dates (7 d; P < 0.001) and
lighter calf weaning weights (194 ± 4 vs. 199 ± 4 kg; P < 0.07) compared
with INT heifers. Calf birth weight, calving difficulty, second-calf
conception rates, and 2-yr-old retention rate did not differ (P > 0.15)
between systems.
Cost per pregnant 2-yr-old cow was
less for the RLX than the INT heifer development system. Of heifers that
failed to become pregnant, a greater proportion (P = 0.07) of heifers in
the RLX than in the INT system were prepubertal when the breeding season
began. Therefore, a second 2-yr experiment evaluated melengestrol
acetate (MGA, 0.5 mg/d) as a means of hastening puberty in heifers
developed to 50% of mature BW. Heifers were assigned randomly to the
control (n = 103) or MGA (n = 81) treatment for 14 d and were placed
with bulls 13 d later for 45 d. Prebreeding and pregnancy diagnosis BW
were similar (280 and 380 kg, respectively; P > 0.10) for heifers in the
control and MGA treatments. The proportion of heifers pubertal before
breeding (74%), pregnancy rate (90%), calving date, calf weaning weight,
and second breeding season pregnancy rate (92%) were similar (P > 0.10)
between treatments. Developing heifers to 50 or 55% of mature BW
resulted in similar overall pregnancy rates, and supplementing the diets
of heifers developed to 50% of mature BW with MGA before breeding did
not improve reproductive performance.
Martin, J.L., K. W. Creighton, J. A. Musgrave, T. J. Klopfenstein, R. T.
Clark, D. C. Adams and R. N. Funston. Effect of prebreeding body weight
or progestin exposure before breeding on beef heifer performance through
the second breeding season. J. Anim Sci. 2008. 86:451-459.
Self
clearance from BVDV infections in Peru dairies
In this cross-sectional study, a stratified
two-stage random sampling procedure was employed to select 221 dairy
herds for bulk tank milk (BTM) sampling, and a subset of 55 dairy herds
for individual blood sampling of a number of young animals (spot test),
to predict presence or absence of current BVDV infection, and for data
collection. The prediction was based on the high probability of
seropositivity in groups of animals where PI animals are present because
of the efficient spread of virus from PI animals to the surrounding
group. BTM samples were collected in August 2003 (n = 192) and February
2004 (n = 195), and the 55 herds selected for spot testing and data
collection were visited in December 2003. All samples were tested for
presence of BVDV specific antibodies using a commercial indirect ELISA (SVANOVA
Biotech AB, Uppsala, Sweden). The results demonstrated a very high level
of exposure to BVDV in the region, and the proportion of herds with high
antibody levels in the BTM was above 95% on both occasions. Despite
this, almost two thirds of the herds had spot test results indicating
absence of current infection, suggesting a high probability of
self-clearance.
A logistic regression model with
the results from the spot tests as dependent variable was used to
investigate possible herd and management factors associated with
self-clearance, and suggested that this may occur regardless of herd
size. Even though it is well established that the process of
identification and elimination of PI animals is required within a
systematic BVDV eradication programme, the present study strongly
suggests that many herds may be cleared without intervention even in
regions with high cattle density and high BVDV prevalence. Consequently,
in any BVDV infected population (regardless of the herd-level BVDV
seroprevalence), and at any given point of time, a large proportion of
the herds will be free from infection due to self-clearance.
Self-clearance is therefore a process that works in favour of any effort
to control BVDV, which should be taken into account when planning and
assessing the cost-effectiveness of a systematic control programme.
Ståhla, K., A. Lindbergb, H. Riverac, C. Ortizd and J. Moreno-Lópeza.
Self-clearance from BVDV infections—A frequent finding in dairy herds in
an endemically infected region in Peru. Prev Vet Med. Vol 83, Issues
3-4, 2008. P 285-296.
Improving the Veterinary employment selection process
The rural mixed-animal veterinarian is a critical control point for safe, wholesome, affordable food production and security. The population of students entering food-animal practice is decreasing, and future shortages are likely. Veterinary practice owners will continue to struggle to find associates to fill open positions. Identifying and hiring the correct veterinarian for an open position is a challenging proposition for the rural practitioner. Kansas State University hosted a forum to facilitate the hiring process and provide education regarding the mechanism of an effective selection interview.
A unique experiential technique
known as "speed interviews" was used to facilitate communication between
conference participants and to practice newly acquired skills. A survey
of participants revealed similar viewpoints toward most job attributes.
Veterinary students and prospective employers expressed realistic
expectations of job requirements, salaries, and debt load. Students
expressed willingness to work and desire to practice in the types of
practices defined by the veterinarians. The symposium provided valuable
insight for practitioners and students regarding the recruitment
process. Appropriate and accurate representation at the time of
job/associate selection is critical for long-term success and employee
retention. The goal of the event was to provide a service to both
prospective employers and students by offering education regarding the
employment selection interview process and placing attendees in an
environment rich with people who have complimentary goals.
White, B.J., K.P. Gwinner, D.M. Andrus, J.B. Prince. Unique Educational
Methods to improve the veterinary employment selection process for rural
mixed-animal practices. Jour Vet Med Educ. 2007 Vol 34, Issue 4,
517-523.
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Beef Production Medicine
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bwhite@vet.ksu.edu