Effect of Sex at
Arrival on Health and Performance of High Risk Calves During a 44-Day Receiving
Period
Burciaga-Robles,
L.O., D.L. Step, B.P. Holland, M.P. McCurdy, and C.R. Krehbiel
Story in
Brief
The objective of this
study was to evaluate the effect of sex at arrival of high risk calves on
health and performance during a 44-d receiving period. A total of 111 bulls and 204 steers were
purchased from different auctions and received at the Willard Sparks Beef
Cattle Research Center for the experiment. Animals were processed after a 24-h
period and calves that arrived as bulls were surgically castrated. Health was
assessed by trained personnel every morning and animals that met the pull
criteria were taken to the processing facility and rectal temperature was
recorded. Animals that met the treatment criteria were treated and returned to
their home pens. During the length of the trial, animals that arrived as bulls
had a higher morbidity and mortality rate than those that arrived as steers
(42.3 vs 11.3% and 23.4 vs 3.9%, respectively) and an increased medicine cost
per animal ($12.30 vs $2.65/animal). Although the animals that arrived as bulls
were heavier (249 vs 238 kg; P=0.008), at the end of the trial no difference was
detected in body weight (BW; 307 vs 310 kg). However, average daily gain (ADG) during
the length of the trial was greater for steers compared with animals that
arrived as bulls (1.65 vs 1.35; P<0.0001). Bulls castrated on arrival have
decreased performance and greater health risk compared with cattle that arrive
as steers.
Key words: Bulls, Steers, Health, Performance
Introduction
The interaction
between stress, the immune system, disease, and performance of domestic animals
has been reviewed (Breazile, 1998; Colditz, 2002). For beef cattle, the major stressor
occurs when cattle are weaned, transported to a new environment, commingled,
and exposed to different pathogens, especially respiratory pathogens. In recent years, preconditioning
programs have been developed, and although the specific components of each
preconditioning program vary, they generally include weaning, castration,
dehorning, deworming, and vaccination against common respiratory pathogens
(Peterson et al., 1989). According to
Capucille et al. (2002), the implications of castration of beef cattle are to
prevent aggressive male behavior, control unwanted matings, and remove consumer
prejudices against beef from intact males.
Based on the 1997 U.S National Animal Health Monitoring System, surgical
castration is the preferred method used by US cow/calf producers before
weaning; however, post-weaning techniques were not surveyed. This survey also reported that 25.5% of
the cow/calf operations do not castrate their bull calves before selling their
calf crop. Intact males represent a
challenge for veterinarians and producers involved in backgrounding, stocker,
and finishing operations. The objective of this study was to evaluate, in a
controlled field study, health and performance of weaned calves arriving as
bulls or steers to the
Materials
and Methods
Cattle
and Experimental Design. A total of 315 calves (bulls = 111 and steers = 204) were purchased from
different cattle auctions during the month of November 2005 and delivered in
two groups to the Oklahoma State University Willard Sparks Beef Research
Center, Stillwater, Oklahoma. On
arrival, calves were allowed to rest for 1 hour after the initial waiting
period cattle health was assessed and each calf was individually weighed and
identified with a unique numbered ear tag.
Calves were then placed into holding pens and offered ad libitum access to prairie hay and water. Twenty-four hours after arrival, cattle
were weighed, dewormed (Ivomec Plus 1.0 mL/45.4 kg; Merial Animal Health,
Duluth, GA), vaccinated with a Modified Live Viral (MLV) vaccine (Bovishield Gold 5, Pfizer
Animal Health, New York, NY, USA) and Clostridial
spp bacterin/toxoid (Ultrachoice 7, Pfizer Animal Health, New York, NY,
USA), and the bulls were surgically castrated. All animals in the first group (bulls =
93, steers = 60) received a metaphylactic treatment (Draxxin, 1.1 mg/45 kg, Pfizer
Animal Health,
Statistical
Analysis. Data for BW and ADG, processing costs,
and treatment costs were analyzed as a complete randomized design using the
Proc Mixed procedure of SAS Release 8.02 (SAS Institute Inc.,
Results
Performance. Performance results are summarized in Table
1. Cattle that arrived as bulls
were heavier (249 vs 238 kg, P=0.008) than cattle that arrived as steers. However, steers reached the same BW as
bulls by d 15 of the experiment. No
difference in BW at the end of the trial was a result of increased ADG for
steers compared with bulls. Daily
gain was 27.5% greater for steers compared with bulls during the first 15 days
of the trial. For the second period
of the experiment (d 16 to 30) steers gained 15.3% more than bulls, and for the
last period (d 31 to 44) there was no difference in ADG between treatments. However, for the overall 44-d receiving
trial, steers gained 20% faster than bulls. This difference represented an overall
weight gain of 59.4 vs 71.3 kg for cattle that arrived as bulls vs steers,
respectively, which resulted in steers overcoming the difference in initial BW.
These results are comparable to results reported by Renfro et al., (2004), in
which intact males upon arrival had lower ADG compared with animals arriving as
steers.
|
Table 1.
Performance of bulls and steers during a 44-d receiving period |
||||
|
Weight (kg) |
Bulls |
Steers |
Std. error |
P-value |
|
d 0 |
249.0 |
238.0 |
4.34 |
.008 |
|
d 15 |
266.8 |
261.9 |
3.97 |
.21 |
|
d 30 |
293.4 |
291.0 |
4.07 |
.57 |
|
d 44 |
307.1 |
310.0 |
4.15 |
.49 |
|
ADG (kg) |
|
|
|
|
|
d 0-15 |
1.12 |
1.54 |
.14 |
.003 |
|
d 16-30 |
1.76 |
2.03 |
.08 |
.002 |
|
d 31-44 |
1.10 |
1.24 |
.10 |
.17 |
|
d 0-44 |
1.35 |
1.62 |
.06 |
<.0001 |
Health. Health results are summarized in Table 2. In this study, sex at arrival
influenced the health status of the animals on trial. Total morbidity, considered as animals requiring
at least one treatment for BRD, was increased by 31% for bulls compared with
steers. Total mortality was also
affected by sex; bulls had a 23.4% mortality rate compared with 3.9% for
steers. This number is similar to data reported by Renfro et al., (2004), which
showed an increased mortality associated with sex on arrival at the
feedlot. Another variable measured
was the number of treatments required by each experimental group. For this calculation the total number of
animals treated and not the whole population was used. The percentage of bulls requiring only
one treatment for BRD was lower compared with steers, whereas the number of
animals requiring two or more treatments for BRD was greater for bulls. This
was reflected in an increased medicine cost for bulls compared to steers.
|
Table 2. Health
of bulls and steers during a 44 d receiving period |
|||
|
|
Bulls |
Steers |
P-value |
|
Morbidity, % |
42.3 |
11.3 |
<.0001 |
|
Mortality, % |
23.4 |
3.9 |
.0005 |
|
Only one
treatment, % |
55.3 |
91.3 |
<.0001 |
|
Two or more
treatmentsa, % |
44.7 |
8.7 |
<.0001 |
|
Medicine cost ($) |
12.30+1.63 |
2.65+1.63 |
<.0001 |
|
aThe total number of animals treated (not all cattle on trial) was used for this calculation. |
|||
Implications
It is important for
producers to identify and address associated risk factors involved with
receiving calves. Recognizing
high-risk cattle based on health and management history is important for
profitability. Implementing
strategic procedures to decrease costs and increase performance will help
ensure sustainability of beef cattle production. Bulls castrated on arrival have been
associated with decreased performance and increased health risk compared with
cattle that arrive as steers.
Because many cow/calf producers do not castrate their calves before
sale, more research is needed to address different management procedures that
might have a positive impact on the health and performance of calves arriving
as bulls. This is especially
important because of the documented (Renfro et al., 2004) negative impact that cattle arriving as bulls has on feedlot
performance and carcass characteristics, resulting in decreased hot carcass
weight, yield grade, and quality grade.
Literature
cited
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Vet. Clin. North Am: Food Anim. Pract. 4:441-480.
Capucille, D.J. et al. 2002. Compendium
on Continuing Education for the Practicing Veterinarian. 24:66-73.
Colditz, I.G. 2002.
Livest. Prod. Sci. 75, 257-268.
Fisher, A.D. et al.
1997. J. Anim. Sci. 75:1899-1908.
Gregory K.E. and
J.J. Ford. 1983. J. Anim. Sci. 56:771-777.
Muratta, H. 1997.
Vet, J. 153:229-231.
Peterson, E.B. et al. 1989. J.
Anim. Sci. 67:1678-1686.
Renfro, D.C. et al. 2004. In:
2004 Plains Nutrition Council Spring Conference. P. 109.
Copyright 2006
Oklahoma Agricultural Experiment Station
Authors List
Burciaga-Robles Luis
- Graduate Student.
Step,
McCurdy, Math -
Graduate Student.