Beef Research News
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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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