Thesis (M. Ag.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 69-71). Also available on the World Wide Web.

Call number: LD2668 .T4 1985 K74 / Master of Science

The objective was to determine how the interaction of implant strategies with the galanin receptor 2 genotype would influence feeding behavior, production efficiencies, carcass characteristics, and meat quality in finishing steers. Angus steers were selected based on GALR2-c.-199T>G genotype (n = 36 TT, 38 TG, and 19 GG). Calves were blocked by body weight and fed a standard feedlot ration, blood and BW were collected every 28 d. Steers were randomly assigned to an implant strategy of Revalor-S (1×) or Revalor-S (2×). Intake and feeding behavior data were individually recorded. There was an effect of genotype on DMI but not feed efficiency. Treatment interactions were observed for several meat quality attributes but not carcass characteristics. Altering implant strategy does not appear to interact with the GALR2-c.-199T>G genotype to alter production or carcass characteristics.

No description available.

Data from 946 Angus and 351 Simmental females were used to quantify relationships between calfhood and early-life traits of females with fertility in the first two breeding seasons, and with calf production in the first, in three and in eleven years of life. These traits were used to develop prediction equations for fertility using logistic regression methodology. For productive performance, three methodologies were compared: least squares, ridge regression and principal components regression. For heifers of both breeds, fertility was associated with birth date, weaning weight ratio and weaning-yearling relative growth rate (RGR). The only calfhood trait that consistently affected fertility in the second breeding season was birth weight of the cow. Fertility of first parity Simmentals was also associated with birth-yearling RGR. First calving season traits explained a higher proportion of variation in second breeding season fertility than calfhood traits of the cow. Among these traits, calving date, calving ease score and sex of the calf were the most important. The combination of birth date and weaning-yearling RGR produced the best models to predict heifer fertility for both breeds. Fertility in the second breeding season was best predicted for Angus cows when calving date, calving ease score and sex of the calf were used as regressors. For Simmental cows, fertility in the second breeding season was best predicted from birth weight of the calf and calving ease score. The regression of weaning weight of the first calf on pre-selected calfhood traits was used to evaluate models produced by least squares, ridge regression and principal components regression. Although biased, the regression coefficient estimates produced by ridge and principal components regression had smaller variances than estimates obtained from least squares. Between the two alternatives to least squares, ridge regression produced better results than principal components regression. Ridge and least squares regression were quite similar in their regression coefficient estimates, in prediction sum of squares (PRESS)-like statistics and, to a lesser extent, in conceptual predictive criteria (C_p)-like statistics. For prediction, the performance of models produced by least squares and by ridge regression were very similar. For analyses of the production traits, least squares regression models for all possible combinations of pre-selected regressor variables were fit. Birth date of the female was negatively associated with the weaning weight of the first calf, and with number of calves weaned, total weaning weight of calves produced and average weaning weight of calves in the first three years of productive life. Age of the dam affected early-life production traits of daughters, as well as the average weaning weight of calves produced per year of productive life and calf survival in eleven years. Heavier females at birth tended to produce smaller number of calves and lower calf weaning weight through their lives than females lighter at birth. Overall female productivity was consistently more positively associated with yearling than with weaning growth traits. Among traits observed in the first calving season, calving date, calving ease score, sex and weaning weight of the calf were associated with subsequent production. Weaning weight of the first calf was always positively associated and it was the most important variable to predict female production, except for survival rate. Prediction equations for production in three years included birth date, birth weight of the female, calving ease in the first parturition, sex of the calf and weaning weight of the first calf. This latter variable was the only one useful to predict production in eleven years. Average calf weaning weights in the first three years of production were best predicted using yearling weight ratio or weaning-yearling ADG and first calf weaning weight. Models including age of the female’s dam best predicted weaning weight of calves per year of productive life in eleven years and calf survival. / Ph. D.

The objectives of this study were: (1) to estimate the effects of certain non-genetic sources of variation in weight, gnde, and condition of beef cows; (2) to estimate the heritability of weight, grade. and condition of beef cows; and (3) to estimate the genetic, phenot;rpic, and environmental correlations between weight, grade, and condition of beef cows. Weights, grades., and condition scores taken on 1371 Angus cows were used to evaluate the genetic and environmental nature of these traits. This sample of cows represented 365 sire groups. Four models were used in this study: 1. Model A - Cow weight and grade were considered dependent variables; herds and sires within herds were considered random independent variables; and season, age, condition, nursing status, and their interactions were considered fixed independent variables. Least-squares procedures involving Henderson's (1953) Method II were used to adjust tor fixed effects and to obtain variance and covax-iance components. Heritability estimate and correlation coefficients were obtained by paternal half-sib analysis. 2. Model B differed from Model A in that condition 3 score was considered a dependent variable instead of an independent variable. 3. Model C was the same as Model A except that the coefficients (kₒ and k₂) for the within sire (σw²) component of variance included in the among sire and herd adjusted expected mean squares (EMS) were considered unity whereas as in Model A they were calculated according to Method II of Henderson. 4. Model D - Heritability estimates were computed by doubling the estimate of intra-sire regression of offspring on dam from 198 dam-daughter pairs representing 63 sire groups. The dam-daughter pairs were part of the group or 1371 cows. The results of this study indicated that season, age, condition score, nursing status, and age by nursing status remain significant when condition score was not considered as a fixed environmental effect (Model B). However, a comparison of the magnitude of the mean squares for these effects in Models A and B indicated that season, age, and nursing status are highly confounded with condition score. Season and flesh condition were found to have a significant effect on grade of beef cows when they were included in the same model (Model A). When condition score was not included (Model B) age had a significant effect on grade. Age, season, and nursing status were found to have a significant effect on flesh condition (Model B). Paternal half-sib heritability estimates for cow weight using Models A, B, and C were 0.38 ± 0.11, 0.29 ± 0.11, and 0.56.± 0.11, respectively. Estimates for grade from the same models were 0.49 ± 0.11, 0.43 ± 0.11, and 0.67 ±0.12, in that order. Estimates from Model A should be the most reliable. The differences in the estimates from Models A, B, and C, illustrate that variation in heritability estimates is not entirely due to genetic differences. Considerable variation can occur depending on how much adjustment has been made to fixed effects, and the methods used in estimating the variance and covariance components. The heritability estimates of cow weight and grade obtained by intra-sire regression of offspring on dam were 0.22 ± 0.14 and 0.10 ± 0.06, respectively. The paternal half-sib heritability estimate for condition score was 0.31 ± 0.11, which implies that adjusting cow weights and grades for condition may actually involve adjusting for genetic differences as well as differences due to environmental influences. The correlation between weight and grade or beef oowe was found to be largely genetic whereas the correlation between condition and cow weight or grade was primarily environmental. / Ph. D.

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 50-52). Also available on the World Wide Web.

Call number: LD2668 .T4 1985 S336 / Master of Science

Thesis (Ph. D.)--University of Alberta, 2009. / Title from pdf file main screen (viewed on Aug. 14, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Animal Science, Department of Agricultural, Food and Nutritional Science, University of Alberta." Includes bibliographical references.

The effects of month on body weight, body condition scores, internal parasite prevalence and on nutritionally related blood metabolites were studied in Angus, Bonsmara and Nguni steers raised on sweet veld. Pre-slaughter stress was also determined using catecholamines, cortisol, dopamine, packed cell volume and serum creatinine levels. The blood chemical constituents evaluated included glucose, cholesterol, total protein, creatinine, urea, globulin, albumin, calcium, phosphorus, magnesium, aspartate amino transferase (AST), alkaline phosphatase (ALP) and creatinine kinase (CK). The Nguni steers maintained their body condition throughout the study period whereas Angus steers had the least body condition scores. Parasite levels were high during the rainy season and low during the dry season. The predominant internal parasites were Haemonchus (39.3 percent), Trichostrongylus (37.8 percent), Cooperia pectinita (25.5 percent), Fasciola gigantica (16.3 percent) and Ostertagia ostertagi (11.2 percent). The Nguni had the least parasite infestation levels and had high PCV levels. Nguni had higher levels of cholesterol and glucose (2.86 and 4mmol/l, respectively) than the other two breeds. Nguni and Bonsmara steers had higher (P<0.05) mineral levels. There were significant breed and month differences for glucose, cholesterol, creatinine, calcium, albumin, phosphorus, albumin-globulin ratio and ALP levels. Bonsmara was more susceptible to transport and pre-slaughter stress as it had the highest (P<0.05) levels of adrenalin (10.8nmol/mol), noradrenalin (9.7nmol/mol) and dopamine (14.8nmol/mol) levels, whereas the Nguni had the least levels of adrenalin (6.5nmol/mol), noradrenalin (4.6nmol/mol) and dopamine (4nmol/mol) levels. In conclusion, Nguni steers were better adapted to the local environmental conditions