Thesis (Ph. D.)--Washington State University, May 2006. / Includes bibliographical references.

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 / 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.

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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

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 evaluate digestibility of cubed hay as a feedstuff for ruminants. Angus (n=6), Hereford (n=3), and Charolais (n=3; total n=12; 226 ± 21.8kg) steers, stratified by breed, were randomly assigned to 3 treatment groups: 1) hay; 2) chopped; 3) cubed. There was no difference (P > 0.05) of DMI or digestibility of DM, OM, NDF, ADF, hemicellulose, and energy among treatments. Steers consuming hay digested more CP than those consuming chopped. Steers consuming cubed digested less CP than those consuming hay or chopped. More fat was digested by steers consuming hay or chopped than by those consuming cubed. Steers consuming cubed retained more nitrogen than those consuming chopped. Those consuming hay were intermediate. Nitrogen metabolized was greater for steers consuming hay than for steers consuming chopped. Those consuming cubed were intermediate. Steers consuming hay and cubed had greater metabolizable protein than those consuming chopped.

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