Thesis (Ph.D.) - University of Queensland, 2005. / Includes bibliography.

Made available in DSpace on 2014-06-11T19:26:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-06Bitstream added on 2014-06-13T18:54:03Z : No. of bitstreams: 1 menezes_lm_me_jabo.pdf: 354341 bytes, checksum: fe80f7c1719a7e65ac618ed0d97b9df5 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este estudo teve como objetivo avaliar as relações entre o temperamento e características de escores visuais. Utilizou-se a estatística bayesiana, com análises tricaracterísticas sob modelo animal linear-limiar na obtenção dos parâmetros genéticos e estimação de coeficientes de correlação genética, sendo o seguinte modelo utilizado: y = Xβ + Z1a + Z2m + Z3c + e. Foram avaliadas as características: conformação (CS), precocidade (PS), musculatura (MS), escore de temperamento (ET) e velocidade de saída (VS), avaliadas ao sobreano, além do peso ao desmame (PD), como característica “âncora”. Para as características CS, PS e MS os maiores escores indicaram as melhores expressões das características. Para o ET os maiores escores indicaram animais de pior temperamento e para VS os maiores valores indicaram os animais de melhor temperamento. Foram utilizados dados de animais da raça Nelore, com 125.760 animais na matriz de parentesco, nascidos entre 1984 e 2010, pertencentes à Agropecuária Jacarezinho Ltda. As herdabilidades estimadas para ET, VS, CS, PS e MS foram 0,25 ± 0,01; 0,21 ± 0,01; 0,32 ± 0,03; 0,34 ± 0,04 e 0,31 ± 0,03, respectivamente. As correlações genéticas entre temperamento e escores visuais foram favoráveis, entretanto baixas: ET x CS= -0,13 ± 0,01; ET x PS = -0,10 ± 0,02 e ET x MS = -0,17 ± 0,02; VS x CS = -0,09 ± 0,00; VS x PS = -0,14 ± 0,22 e VS x MS = - 0,14 ± 0,01. Não recomenda-se a seleção indireta para temperamento através da seleção para os escores visuais de CS, PS ou MS. A inclusão de temperamento (ET ou VS) e CS, PS e MS, simultaneamente nos índices de seleção, pode ser realizada, com a expectativa de mudanças a longo prazo / This study aims to evaluate the relationship between temperament and visual scores traits. Bayesian statistics was used, with tri-characteristic analysis under the linear-treshold animal model to obtain the genetic parameters and the estimation of coefficients of genetic correlation, according to the following model: y = Xβ + Z1a + Z2m + Z3c + e. The following characteristics were considered: conformation (CS), precocity (PS), muscularity (MS), temperament score (ET) and flight speed (VS), evaluated at the yearling, besides the weaning weight (PD), as an “anchor” trait. For CS, PS and MS the greatest scores indicate the best expressions of characteristics. For the ET the highest score indicate animals with the worst temperament and for VS the highest values indicate animals with the best temperament. Data from 125.760 Nelore cattle in the kinship matrix, born between 1984 and 2010, belonging to the Agropecuária Jacarezinho Ltda. were used for the analysis. The estimated heritability for ET, VS, CS, PS and MS were 0,25 ± 0,01; 0,21 ± 0,01; 0,32 ± 0,03; 0,34 ± 0,04 e 0,31 ± 0,03, respectively. The genetic correlations between temperament and visual scores were favorables, but low: ET x CS= -0,13 ± 0,01; ET x PS = -0,10 ± 0,02 e ET x MS = -0,17 ± 0,02; VS x CS = -0,09 ± 0,00; VS x PS = -0,14 ± 0,22 e VS x MS = -0,14 ± 0,01. It is not recommended to apply indirect selection for temperament through the selection for the visual scores of CS, PS or MS. The inclusion of temperament (ET or VS) and CS, PS and MS, simultaneously in the selection indices, may be performed, with the expectation of long-term effects

Master of Science / Department of Animal Sciences and Industry / Robert L. Weaber / Feet and leg soundness is an important trait for beef producers as it has an impact on cow longevity and animal well-being. The objective of this study was to investigate genetic parameter estimates for feet and leg traits, understand the relationship between feet and leg traits and Stayability EPD, and develop a scoring method for feet and leg traits in Red Angus cattle. Cattle were scored on 14 subjective traits: Body Condition Score (BCS), Front Hoof Angle (FA), Front Heel Depth (FHD), Front Hoof Claw Shape (FC), Rear Hoof Angle (RA), Rear Heel Depth (RHD), Rear Hoof Claw Shape (RC), Foot Size (FS), Hoof Orientation (HO), Knee Orientation (KO), Front Side View (FSV), Rear Leg Side View (RS), Rear Leg Hind View (RH), Composite Score (CS). Red Angus cattle (n=1885) were scored for all 14 traits by trained evaluators. All traits except CS were scored with the assumed optimum level being in the middle with undesirable scores being located on the extremes. Scores were observed on a scale of 1-100 and analyzed, then scores were simplified to 1-9 where scores were collapsed by 10’s into bins, starting at 10 since there were no scores observed below that point and the rubric used did not have an associated phenotype below that point. A three-generation pedigree file was obtained from the Red Angus Association of America (RAAA) that contained 13,306 animals, as well as a performance file on all animals observed in the study. Data were modeled using multiple linear bivariate animal models with additive and residual random effects, and age and contemporary group (herd-year) as fixed effects. Genetic parameters were estimated with ASREML4.0. Heritability estimates on the 1-9 scale for BCS, FA, FHD, FC, RA, RHD, RC, FS, HO, KO, FSV, RS, RH, and CS were 0.13, 0.18, 0.12, 0.08, 0.17, 0.24, 0.15, 0.29, 0.15, 0.15, 0.11, 0.29, 0.11, and 0.09 respectively. In general, feet and leg traits were lowly to moderately heritable, and are similar when compared to estimates for the same traits scored on a 1-100 scale. This informs a less granular and more simplified scale of measurement can be an appropriate method of feet and leg trait classification. Front hoof angle, FHD, RA, and RHD were all highly genetically correlated (r = 0.83 - 0.97), suggesting that angle and heel depth are controlled by many of the same genes. Front claw shape and RC were highly genetically correlated (r = 0.80) with each other but were not as significantly correlated with FA, FHD, RA, RHD (r = -0.43 to 0.38). This suggests that hoof angle/depth should be measured separately from claw shape. Rear leg side view, and RH had a strong correlation (r = 0.69). Strong correlations between FSV, HO, and KO also existed, yet there was noticeable variation among point estimates and standard error. Six traits on the 1-9 scale were selected to generate estimated breeding values (EBV’s) based on their heritability and correlation with other traits; BCS RHD, RC, FS, RSV, RH. A linear model was used to determine breeding values for BCS, RHD, RC, FS, FSV and RH. Those breeding values were regressed on Stayability EPD. When fixed effects of herd, age and year born were accounted for, RC (P < 0.0001), RSV (P = 0.0517), and FS (P = 0.086) had relationships as predictor variables for Stayability EPD. The use of feet and leg traits as predictor variables for improved Stayability EPD can be achieved with a simplified scoring system (1-9 vs. 1-100) in Red Angus cattle. By narrowing the number of traits needed to measure with a more simplified scoring method should allow for more rapid adoption among current beef cattle producers. A greater number of observations could be useful to validate these results and provide more accurate point estimates for feet and leg trait heritabilities and correlations.

Master of Science / Department of Animal Sciences and Industry / Jennifer M. Bormann / Robert L. Weaber / The objective of this study was to investigate the parameter estimates for feet and leg traits, relationships within feet and leg traits, and between feet and leg traits and production traits in Red Angus cattle. Subjective scores for 14 traits including: Body Condition Score (BCS), Front Hoof Angle (FHA), Front Heel Depth (FHD), Front Claw Shape (FCS), Rear Hoof Angle (RHA), Rear Heel Depth (RHD), Rear Claw Shape (RCS), Size of Hoof (Size), Front Side View (FSV), Knee Orientation (KNEE), Front Hoof Orientation (FHO), Rear Side View (RSV), Rear View (RV), and a Composite Score (COMP) were collected by trained evaluators on 1885 Red Angus cattle at different ranches across the United States. A three-generation pedigree file was obtained from the Red Angus Association of America (RAAA) that contained 13,306 animals, and EPDs on all animals with feet and leg scores were obtained. All traits except COMP were scored as intermediate optimum traits. Data were modeled using a linear bivariate animal model with random additive genetic and residual effects, and fixed effects of age and contemporary group (herd-year). Variances were estimated with ASREML 3.0 and 4.0. Heritability estimates of BCS, FHA, FHD, FCS, RHA, RHD, RCS, Size, FSV, Knee, FHO, RSV, RV, and COMP were 0.11, 0.20, 0.17, 0.09, 0.19, 0.25, 0.17, 0.36, 0.16, 0.17, 0.17, 0.30, 0.14, and 0.12, respectively. These results showed feet and leg traits were lowly to moderately heritable. Strong, positive genetic correlations were found between FHA and FHD (0.89), FHA and RHA (0.88), FHD and RHA (0.85), FHA and RHD (0.85), FHD and RHD (0.94), and FHO and Knee (0.95), indicating these traits may be highly related to one another. Strong negative correlations were found between Knee and FSV (-0.59) and FHO and FSV (-0.75). The strongest correlation was between front limb traits (FHA, FHD, FSV, FHO, Knee, and Comp) and the Stayability EPD (STAY) was FSV (r =0.16; r_s =0.20) and for rear limb traits (RHA, RHD, RCS, RSV, RV, and Comp) and STAY was RCS (r = -0.12; r_s=-0.14). This indicates that cattle with more slope to the angle of the shoulder stay in the herd longer and cattle with less curl to the inside of the claw tend to stay in the herd longer. Further studies with more data could help validate the relationship between feet and leg traits and production traits.

Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / Daniel U. Thomson / Cattle health and welfare are of utmost concern to producers, packers, processors, and consumers of beef. In addition, poor animal welfare can lead to decreases in economic return, in the form of production losses, product losses, or even live animal losses. Two major contributors to such losses include carcass bruising and cattle fatigue, or Fatigued Cattle Syndrome. Bruising in fed beef cattle costs the industry millions of dollars annually, and cattle fatigue leads to production losses and animal death during and after transport. Much research in cattle welfare is focused upon the more vulnerable classes of cattle in the industry, such as small calves, cull beef cows, and cull dairy cows. Limited research exists on the animal welfare concerns in fed beef cattle, likely because these animals are considered healthier and better fit for transport compared to other classes. The overall goal of this research was to assess the health and welfare of fed cattle after transport to commercial slaughter facilities by addressing two large concerns in the industry: 1) bruising in fed cattle and 2) Fatigued Cattle Syndrome and its prevalence and physiologic characteristics. The first objective of this research focused upon bruising, and was to determine whether a relationship exists between trauma incurred during unloading and prevalence of carcass bruising in finished beef cattle at commercial slaughter facilities. In addition, other risk factors which may contribute to carcass bruising in finished beef cattle are addressed. The second and third objectives focused upon Fatigued Cattle Syndrome in the fed cattle population. The second objective of this research was to determine the prevalence of abnormal mobility scores and the clinical signs associated with to abnormal mobility in finished cattle in six commercial slaughter facilities across the United States. The third objective was to determine if mobility score and clinical signs reflect concurrent changes in physiologic parameters such as blood concentrations of specific biochemical markers and biomechanical integrity of hooves. This information is both valuable and novel in the fed beef cattle industry. Along with the implementation of practices that will promote better health and welfare of fed cattle presented to slaughter facilities, gathering such information will help improve animal welfare, increase economic returns, and strengthen consumer confidence in the industry.

The purpose of the study was to develop a realistic method of determining the optimum replacement time of steers in a feedlot in which there are sequential feeding cycles. There are two models for steers developed and discussed in this paper. The first model optimizes the length of stay in the feedlot assuming that feedlot capacity is the limiting constraint. The second model optimizes the length of stay in the feedlot when working capital is the limiting constraint. A third model is developed to determine the optimum length of feeding time for market hogs in a feeding barn. An evaluation of each model is made. It is concluded that the cattle models have a limited use because of the high variability in performance. The hog replacement model is quite valid and can be used in a modern hog feeding enterprise. / Land and Food Systems, Faculty of / Graduate

The objective of this study was to determine if increasing the forage level and feeding grain whole as opposed to dry-rolled is a feasible alternative to high energy rations with a similar age at time of slaughter. Steers were fed either twenty or forty percent forage, with whole or dry-rolled corn. There were no differences in fat thickness, longissimus area, KPH, marbling, USDA quality grade, Warner-Bratzler shear force, or cook loss. Cattle fed high forage and whole corn tended to have lower hot carcass weights. Additionally, the forty percent forage treatment tended to have lower USDA yield grades, and had darker colored steak. Also, steaks from the dry-rolled corn treatment had steaks that were redder, and more yellow. Results from this study suggest that increasing forage level, and corn processing might not result in significant differences in carcass characteristics or meat tenderness, but could negatively impact meat color.

Methane (CH₄) production from enteric fermentation in ruminant animals is a contributor to global greenhouse gas emissions. Because CH₄ has an impact on increasing global temperatures, there is a push for government regulations to reduce CH₄ from livestock animals. At 1.9% of U.S. CH₄ emissions beef cattle are a large contributor to agricultural CH₄ emissions or (EPA, 2020). Enteric CH₄ emissions are also a loss of energy for the animal, accounting for 2-12% of energy loss from the ruminant animal (Johnson & Johnson, 1995). This energy loss from the diet is contingent upon forage content, where increasing forages in the diet increases CH₄ yield (g/kg of gross energy intake; van Gastelen et al., 2019). Mootral is a feed supplement that contains garlic (<i>Allium sativum</i>) and bitter orange (<i>Citrus aurantium</i>) extracts. The organosulfur compounds in garlic the flavonoids found in bitter orange extracts are known to decrease CH₄ production, (Busquet et al., 2005a; Balcells et al., 2012; Seradj et al., 2014). However, it is unclear how the forage content and Mootral inclusion will interact to effect CH₄production and animal performance. Because feedlot cattle are fed a range of forage:concentrate ratios while in the feedlot, it is important to know how effective mitigation strategies are in different forage:concentrate diets. Therefore, the objective of the current study was to quantify CH₄ production and determine growth, intake, and carcass characteristics of feedlot steers fed Mootral in diets with a low, medium, and high forage content. Knowing the effect of garlic and flavonoids on methanogenesis, we hypothesized that Mootral would decrease CH₄ emissions without impacting growth, intake, and carcass characteristics of feedlot steers. We expect that the CH₄ mitigating ability of Mootral will be greatest in the diet with the most forage. For the experiment, 144 Angus x Simmental steers were allotted by body weight (BW; 363 kg, breed composition, and farm origin to a 3 x 2 factorial arrangement of 6 treatments (4 pens per treatment) to determine the effect of Mootral (garlic + citrus extract; 0.25% of the diet DM vs. 0.0%) on methane emissions, growth and carcass characteristics of feedlot cattle. During the first 84 days, cattle were fed three different forage concentrations in the diet (15, 41.5, or 68% corn silage) with or without Mootral. From day 85 to slaughter, corn silage was included at 15% of the diet DM with or without Mootral. Methane emissions were measured on day 42-46 and day 203-207. Data were analyzed using the GLIMMIX procedure of SAS. There was an interaction (<i>P </i>= 0.03) between forage content and Mootral for DMI from d 0 to 84, where Mootral decreased DMI of steers fed 15% corn silage but did not affect DMI of steers fed 41.5 or 68% corn silage. There were no effects (<i>P </i>≥ 0.22) of forage content or Mootral on BW or average daily gain at any time, or on DMI from d 84 to slaughter and overall. Intake from d 0-84 was lower and gain:feed from d 0-84 and overall was greater (<i>P </i>= 0.04) for steers fed 68% compared to 15 or 41.5% corn silage. On d 42-46, steers fed 41.5 and 68% corn silage had increased (<i>P </i>≤ 0.02) methane emissions compared to steers fed 15% corn silage. Mootral did not affect methane emissions on day 42-46 (<i>P</i> ≥ 0.47), but there was a forage effect, where steers fed the 41.5 and 68% corn silage diets emitted more methane on a g/d (<i>P</i> = 0.05) and a g/kg of DMI (<i>P</i> = 0.007) basis and tended (<i>P</i> = 0.07) to produce more methane on g/kg BW basis compared to steers fed the 15% corn silage diet. Steers fed Mootral emitted less (<i>P </i>≤ 0.03) methane on a g/d, g/kg DMI, and g/kg BW basis on d 203-207 compared to steers not fed Mootral. Mootral tended to decrease (<i>P </i>≤ 0.09) fat thickness and yield grade. In conclusion, increasing forage content increased methane emissions and Mootral decreased methane production in 15% corn silage diets and improved carcass leanness.

The objective of this study was to determine the effects of feeding endophyte-infected tall fescue seed to Angus steers during the stocker phase on beef shelf life. Endophyte-infected tall fescue seed had no effect on pH, TBARS, activity of superoxide dismutase and metmyoglobin reductases, and sensory attributes of strip loin steaks or patties (P >= 0.082). However, E+ patties had 0.5% more DMb (P = 0.017) and 27% greater redness (a*) on d 5 of display (P < 0.001). Retail display of steaks decreased lightness (L*), redness, oxymyoglobin percentage (OMb), and MRA from 45.01, 32.60, 67.61%, and 9.54 µM/min/g on d 0 to 40.11, 21.83, 48.95%, and 2.30 µM/min/g, respectively on d 7 (P <= 0.001). Retail display of patties decreased L*, OMb, and, MRA from 52.30, 64.04%, and 5.56 µM/min/g on d 0 to 48.88, 58.5%, and 2.16 µM/min/g, respectively on d 5 (P <= 0.001).

Due to the production costs associated with beef cattle production, it is important to equip beef cattle producers with sound, research-driven information to aid in the decision making process regarding their operation. Extension personnel as well as other organizations involved with beef cattle producers should be knowledgeable of the audience that they are disseminating information to and how this audience prefers to receive information. Knowing the demographics and educational and informational needs of the audience helps shape programming endeavors to meet the needs of the audience. The beef cattle producers surveyed indicated that they preferred to receive information from farm and feed supply dealers, other cattle producers, farm demonstrations, and cattle and farm magazines. The average producer was 53.6 years of age, had been involved in beef cattle production for 28.4 years, was a college graduate, and received less than 25% of their total income from their beef cattle operation.