Beef Research News
Brought to you by Kansas State University
College of Veterinary Medicine - Farm Animal Section
August 2007
Contents:
Behavior, temperament and beef cattle performance
2007 Texas Tech survey of feedlot consulting nutritionists
Protection against experimental BVD with modified-live vaccine
BRD: phenotypic, environmental,
and genetic correlations with performance
Behavior,
temperament and beef cattle performance
A study was conducted to evaluate variation in feeding behavior and
temperament of beef cattle sired by Angus, Charolais, or Hybrid bulls
and their associations with performance, efficiency, and carcass merit.
The behavior traits were daily feeding duration (FD), feeding head down
(HD) time, feeding frequency (FF), and flight speed (FS, as a measure of
temperament). A pedigree file of 813 animals forming 28 paternal
half-sib families with about 20 progeny per sire was used. Performance,
feeding behavior and efficiency records were available on 464 animals of
which 381 and 302 had records on carcass merit and flight speed,
respectively. Large standard errors reflect the number of animals used.
Direct heritability estimates were 0.28 ± 0.12 for FD, 0.33 ± 0.12 for
HD, 0.38 ± 0.13 for FF, and 0.49 ± 0.18 for FS. Feeding duration had a
weak positive genetic (rg) correlation with HD (rg = 0.25 ± 0.32) and FS
(rg = 0.42 ± 0.26), but a moderate negative genetic correlation with FF
(rg = -0.40 ± 0.30). Feeding duration had positive phenotypic (rp) and
genetic correlations with DMI (rp = 0.27; rg = 0.56 ± 0.20) and residual
feed intake (RFI; rp = 0.49; rg = 0.57 ± 0.28), but was unrelated
phenotypically with feed conversion ratio (FCR). Feeding duration was
negatively correlated with FCR (rg = -0.25 ± 0.29). Feeding frequency
had a moderate to high negative genetic correlation with DMI (rg = -0.74
± 0.15), FCR (rg = -0.52 ± 0.21), and RFI (rg = -0.77 ± 0.21). Flight
speed was negatively correlated phenotypically with DMI (rp = -0.35) but
was unrelated phenotypically with FCR or RFI. On the other hand, FS had
a weak negative genetic correlation with DMI (rg = -0.11 ± 0.26), a
moderate genetic correlation with FCR (rg = 0.40 ± 0.26), and a negative
genetic correlation with RFI (rg = -0.59 ± 0.45). The results indicate
that behavior traits may contribute to the variation in efficiency of
beef cattle and there are potential correlated responses to selection to
improve efficiency. Feeding behavior and temperament may need to be
included in the definition of beef cattle breeding goals, and approaches
such as the culling of unmanageable cattle and the introduction of
correct handling facilities or early life provision of appropriate
experiences to improve handling will be useful.
Nkrumah, JD, DH Crews Jr, JA Basarab, MA Price, EK Okine, Z Wang, C Li,
SS Moore. Genetic and phenotypic
relationships of feeding behavior and temperament with performance, feed
efficiency, ultrasound, and carcass merit of beef cattle.
J. Anim Sci. published online first on June 25, 2007. doi:
10.2527/jas.2006-657
2007 Texas Tech survey
of feedlot consulting nutritionists
Forty-two consulting feedlot nutritionists were asked to participate in
a survey regarding nutritional recommendations for feedlot cattle.
Eleven nutritionists either chose not to participate or did not reply to
our request. Thirty-one nutritionists agreed to participate, and 29
completed the survey. Their practices are located in the following
states: TX, KS, and OK (46.43%); IA, NE, CO, and SD (31.25%); WA and ID
(8.93%); AZ and CA (6.25%); and other states (7.14%). The survey was
conducted using a web-based system and included 74 questions divided
into sections that covered: general information about the nutritionist's
practice (n = 8 questions); commodity information (n = 13); use of grain
coproducts (n = 5); information regarding roughage sources and levels (n
= 4); methods used to adapt cattle to finishing diets (n = 3);
information about supplements and micro-nutrients (n = 7); types of feed
mixers (n = 2) and feed mills (n = 1) used by clients; feeding (n = 1)
and cattle management (n = 5); liquid feeds (n = 7); recommendations for
nutrient formulation (n = 15); information resources used as the basis
for nutritional recommendations (n = 2); and perceived needs for
additional information on items or nutrients not addressed in the
survey. With respect to nutrient formulation practices, results
indicated that recommended concentrations of major nutrients and trace
minerals typically fell within a range of 1 to 2 times the NRC (2000)
recommendations for beef cattle; however, some important aspects of the
NRC models (e.g., formulation for degradable intake protein) were not
applied by the majority of respondents. Data from this survey provide a
snapshot of practices used by feedlot nutritionists and should aid in
development of future National Research Council models and
recommendations.
Vasconcelos, JT, ML Galyean.
Nutritional recommendations of feedlot consulting nutritionists: The
2007 Texas Tech University survey. J. Anim Sci.
published online first on June 25, 2007. doi:10.2527/jas.2007-0261
Protection
against experimental BVD type 2 with modified-live vaccine
A study was conducted to evaluate protection resulting from use of a
modified-live noncytopathic bovine viral diarrhea virus (BVDV) type 1
vaccine against systemic infection and clinical disease in calves
challenged with type 2 BVDV. Calves were allocated (n = 5/group) to be
nonvaccinated or vaccinated SC on day 0 with BVDV 1 (WRL strain). Calves
in both groups were challenged intranasally with BVDV type 2 isolate 890
on day 21. Rectal temperatures and clinical signs of disease were
recorded daily, and total and differential WBC and platelet counts were
performed. Histologic examinations and immunohistochemical analyses to
detect lesions and distribution of viral antigens, respectively, were
performed. After challenge exposure to BVDV type 2, nonvaccinated calves
developed high rectal temperatures, increased respiratory rates, viremia,
leukopenia, lymphopenia, and infection of the thymus. Vaccinated calves
did not develop high rectal temperatures or clinical signs of
respiratory tract disease. Vaccinated calves appeared to be protected
against systemic replication of virus in that they did not develop
leukopenia, lymphopenia, viremia, or infection of target organs, and
infectious virus was not detected in peripheral blood mononuclear cells
or the thymus. The modified-live BVDV type 1 vaccine protected against
systemic infection and disease after experimental challenge exposure
with BVDV type 2. The vaccine protected calves against infection and
viremia and prevented infection of target lymphoid cells.
Kelling, C.L., B.D. Hunsaker, D.J. Steffen, C.L. Topliff, K.M. Eskridge.
Characterization of protection against
systemic infection and disease from experimental bovine viral diarrhea
virus type 2 infection by use of a modified-live noncytopathic type 1
vaccine in calves. Am J Vet Res. 2007 68(7):
788-796.
BRD: phenotypic,
environmental, and genetic correlations with performance
Bovine respiratory disease (BRD) is the most costly feedlot disease in
the United States. Selection for disease resistance is one of several
possible interventions to prevent or reduce the economic loss associated
with animal disease and to improve animal welfare. Undesirable genetic
relationships, however, may exist between production and disease
resistance traits. The objectives of this study were to estimate the
phenotypic, environmental, and genetic correlations of BRD with growth,
carcass, and LM palatability traits. Health records on 18,112 feedlot
cattle over a 15-yr period and slaughter data on 1,627 steers over a
4-yr period were analyzed with bivariate animal models. Traits included
ADG, adjusted carcass fat thickness at the 12th rib, marbling score, LM
area, weight of retail cuts, weight of fat trim, bone weight, Warner-Bratzler
shear force, tenderness score, and juiciness score. The estimated
heritability of BRD incidence was 0.08 ± 0.01. Phenotypic,
environmental, and genetic correlations of the observed traits with BRD
ranged from –0.35 to 0.40, –0.36 to 0.55, and –0.42 to 0.20,
respectively. Most correlations were low or negligible. The percentage
of carcass bone had moderate genetic, phenotypic, and environmental
correlations with BRD (–0.42, –0.35, and –0.36, respectively). Hot
carcass weight and weight of retail cuts had moderate, undesirable
phenotypic correlations with BRD (0.37 and 0.40, respectively).
Correlations of BRD with LM palatability and ADG were not detected. Low
or near zero estimates of genetic correlations infer that selection to
reduce BRD in feedlot cattle would have negligible correlated responses
on growth, carcass, and meat palatability traits or that selection for
those traits will have little effect on BRD susceptibility or
resistance.
Snowder, GD, LD Van Vleck, LV Cundiff, GL Bennett, M Koohmaraie, and ME
Dikeman. Bovine respiratory disease in
feedlot cattle: Phenotypic, environmental, and genetic correlations with
growth, carcass, and longissimus muscle palatability traits.
J Anim Sci 2007. 85: 1882-1885.
Key Words: beef cattle • carcass trait • health • performance •
selection • shipping fever
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