Typescript. / Digitized by Kansas Correctional Industries

The basic objective of this thesis was to estimate the economic effects of yield grade standards for carcass beef on the various market sectors of the Canadian beef industry. The adoption of the standards was expected to enhance consumer demand, improve efficiency within the processing and marketing services sectors, and improve resource allocation and revenues of livestock producers. A conceptual model showing the interrelationships among market sectors was developed and formulated into a system of equations for econometric estimation. The model contained variables relating to the supply and demand of market participants affected by the change in grading standards. Measurement of these variables was based on published quarterly data, including four years of yield grading, over the 1961-76 period. The statistical results showed a significant economic variables relating to the supply and demand of market participants affected by the change in grading standards. Measurement of these variables was based on published quarterly data, including four years of yield grading, over the 1961-76 period. Binary variables were incorporated in the model to identify any structural change in the relationships coincident with the grade change. Problems in estimation arose due to the simultaneous nature of the model, and intercorrelation problems involving predicted prices for adjacent market levels in certain structural equations. Two alternative specifications of the processing and marketing services relationships were formulated to address this problem. First, variables relating to demand at the adjacent market level were substituted for the corresponding price. The second method involved the ratio of adjacent market level prices. Both specifications resolved the problem,, but in the substitution case intercorrelation was transferred to other variables. Estimates of the parameters of the various equations were obtained by using the two stage least squares regression procedure. The statistical results showed a significant economic impact of yield grades, as measured by the slope and intercept binary variables, in the estimated retailer demand and producer supply equations. But, these results cannot be considered conclusive. A lack of information concerning impact of yield grades, as measured by slope and intercept binary variables, in the estimated retailer demand and producer supply equations. But, these results cannot be considered conclusive. A lack of information concerning historical costs in the processing and marketing sectors necessitated the use of proxy variables which may not have accurately captured the full impact of the grade change. A further problem was that potential yield grade adjustments in carcass weights were dominated by the effects of rapidly rising feed grain prices throughout the grade change period. / Graduation date: 1982

The traditional practice on beef cow-calf ranches in the high desert region of Eastern Oregon has been to breed the cows to calve in the Spring months. Interest has been growing recently in the practice of Fall-calving; that is, breeding cows to calve in the months of October and November. The Squaw Butte Experiment Station at Burns, Oregon, began a Fall-calving program with part of their range beef herd several years ago. They found that climatic conditions are generally more favorable for calving in the Fall, resulting in higher weaned-calf percentages. Calves from both Spring and Fall-calving herds were weaned in late Summer, with Fall calves averaging around 500 pounds compared with 330 pounds for the Spring calves. There was little doubt about the biological feasibility of the Fall-calving practice in that area, but its economic feasibility was somewhat in question. The purpose of this research was to analyze the economic aspects of Fall-calving and determine what are the most important factors in deciding its economic feasibility. A linear programming model was developed for comparing Fall and Spring-calving systems under different conditions. The model was designed to maximize net returns to labor, management and fixed resources in the beef enterprise. This model took account of range forage utilization patterns. Solutions from the model indicated that Spring-calving systems may have slightly higher net returns than Fall-calving because of two main differences: (1) the lighter Spring-born calves bring a higher average price per cwt. , and (2) the Fall-calving herd requires about 1500 pounds more Winter hay than cows in the Spring-calving herd. An algebraic relationship was found between calf price differentials and the price of meadow hay, which would equate the net return values for Spring and Fall-calving systems. With an expected differential of $2. 95, between the average prices of calves sold from the Spring and Fall-calving herds, it was found that a price as low as $14.12 per ton of meadow hay would be needed to equate the net returns of a Fall-calving system with those of a Spring-calving system (with calf sales on September 1). Labor costs were not included in the model, but the ranch operator's labor situation may well be the most important element in his decision to go with Fall rather than Spring calving. The main difference is in the times of the year that labor is needed. The Fall-calving system needs more labor in the Fall, and the Spring-calving system needs even more in the Spring. / Graduation date: 1972

A trial was conducted May 1 to September 4, 1989 at the Eastern Oregon Agricultural Research Center (EOARC) Burns, OR to examine the effects of strip or continuous grazing management on the diet and performance of steers grazing native flood meadows. The objective was to determine if strip grazing would be a more efficient means of grazing management than continuous grazing. The experiment was designed to test diet quality, botanical composition of the diet, daily dry matter (DM) intake and performance of yearling steers. Eighty yearling steers weighing 253±17 kg were selected from cattle at the Squaw Butte Experiment Station. The experimental design was a randomized complete block, with blocking based on past forage production. Treatments were continuous or strip grazing. A representative meadow of approximately 22.4 ha was divided into four equal pastures. Continuous grazing steers had access to 5.6 ha pastures for the duration of the study. Animals on strip grazing were confined to an area that was estimated to provide 5-7 days of forage using New Zealand portable electric fencing. Strip sizes were predetermined based on standing forage crop. Steers were not allowed to graze more than 7 days in any one strip. Diet quality was estimated from bi-weekly esophageal samples. Extrusa was collected from 4 esophageal fistulated steers per treatment on two consecutive days. Collections were timed to coincide with the mid point of the strip being currently grazed. Samples were pooled by collection dates and analyzed for CP and IVOMD. Dietary OM intake was estimated from biweekly, 24 hr total fecal collections starting the day following esophageal collections. Total DM fecal output from 6 fecal collection steers per treatment was corrected with the %IVOMD to predict actual DM intake. Diet botanical composition was estimated by microhistological examination of fecal sub-samples. Animal weight gains were recorded bi-weekly. Experimental animals grazed together at all times during the trial. Initial stocking densities were 2.0 AU/ha in each treatment pasture. Steers were counted as .56 AU with 20 steers grazing 5.6 ha pastures. The average strip size over the trial was .46 ha; and depending upon standing crop of forage, ranged from .23-1.15 ha. Record moisture from snowmelt and rainfall resulted in greater than expected standing crop of forage. This growth resulted in under stocking of both treatment pastures. A 1.08 ha block was removed as hay from the higher forage producing strip treatment block to adjust for over abundant forage. This resulted in a total mean strip grazed area of 4.37 ha or 22% less than continuous grazing. Actual grazing density means over the summer were 2.6 AU/ha for continuous and 3.15 AU/ha for the strip treatment. Available forage was determined from clipped plots on a DM basis and expressed as herbage allowance at a given point in time. Herbage allowance for steers in continuous grazed pastures ranged from 405-1153 kg/AU when measured at bi-weekly intervals and 68-186 kg/AU for strip grazed steers when estimated at the beginning of each strip. Grazing pressure was higher for strip grazed steers (.10 AU/kg) compared to continuous (.02 AU/kg). Diet quality declined significantly over the summer (P<.01). Analysis for CP in steer diets provided values of 13.9 vs 10.9% for continuous and strip treatments, respectively. However, this difference was not significant (P=.14). Digestibility analysis suggested that forage in continuous diets tended (P=.07) to have higher IVOMD than strip diets (64.6 vs 60.7%), respectively. Daily herbage intake was similar (P=.42) for both treatments when expressed as a percentage of body weight. Diet botanical composition was positively affected by the type of management system. The amount of the major grass species, meadow foxtail (Alopecurus pratensjs), was increased (P=.05) 39% in the diet of strip grazing steers. Differences were noted in the amounts of other, less frequently occurring grass species. The total amount of grass tended (P=.06) to be higher in strip diets (49% vs 35% for continuous). Rushes (Juncus spp.) and sedges (Carex spp.) contributed a similar percentage to the diets of both treatments. Forbs comprised less than .5% of the overall diet of both strip and continuous steers. Individual animal performance tended (P=.09) to be higher under continuous grazing management. The ADG was 1.16 and .77 kg for steers in continuous and strip grazing, respectively. However, total animal production per hectare grazed area (26.14 vs 22.13 kg/hd) was not considered different (P=.17). / Graduation date: 1991

Seven single nucleotide polymorphisms in six genes (LEP, IGF2, MC1R, PMCH, CAPN1, and CAST) which had been shown to affect traits of economic importance were used to compare the allele frequencies and diversity of a Canadian population of Angus cattle and an International population. Genetic diversity was also measured using 22 microsatellite markers that were assumed not to be affected by selection.<p> The Canadian population consisted of 107 cows and 57 bulls, while the Canadian Angus Associations International Embryo Program population consisted of 26 calves. Black and red animals were represented in each population. Although the bulls of the Canadian population represent Angus from 16-17 years ago, and the cows of the Canadian population represent Angus from 2006-2007, no difference was observed in either the set of microsatellite genotypes nor the SNP genotypes.<p> A significant difference was found between the Canadian and International populations at CAST, with the Canadian population exhibiting a higher frequency of the favorable A allele than the International population. This allele is positively correlated with tenderness. No significant differences were found for the other genes. Both populations were in Hardy Weinburg equilibrium for all genes except MC1R, which affects coat color.<p> Using microsatellites, the total genetic variability of the two Angus populations was measured, showing that 93% of total variability was attributed to differences within, and not between, populations. Randomly chosen cattle could also be assigned to the correct population 97% of the time, based on microsatellite genotypes, and 75% of the time based on SNP genotypes.<p> Mean heterozygosity was 0.578 based on microsatellites and 0.332 based on SNPs. The proportion of genetic variability between the two populations was 3% based on microsatellites and 7% based on SNPs. It is possible this reflects the results of indirect selection differences in various countries.<p> Finally, Neis genetic distance was measured between the Canadian and International populations. The Canadian and International populations had a pairwise genetic distance of 0.097. In comparison, the genetic distance of Canadian Angus was 0.135 to Blonde dAquitaine, 0.251 to Simmental, 0.258 to Gelbvieh, 0.281 to Limousin, 0.305 to Holstein, 0.334 to Belgian Blue, and 0.452 to Hereford based on microsatellite markers.<p> The results of this study show that the Angus breed contains as much or more genetic diversity than other cattle breeds. Greatest genetic differences exist between individual animals, not between populations of cattle in Canada and other countries.

Seven single nucleotide polymorphisms in six genes (LEP, IGF2, MC1R, PMCH, CAPN1, and CAST) which had been shown to affect traits of economic importance were used to compare the allele frequencies and diversity of a Canadian population of Angus cattle and an International population. Genetic diversity was also measured using 22 microsatellite markers that were assumed not to be affected by selection.<p> The Canadian population consisted of 107 cows and 57 bulls, while the Canadian Angus Associations International Embryo Program population consisted of 26 calves. Black and red animals were represented in each population. Although the bulls of the Canadian population represent Angus from 16-17 years ago, and the cows of the Canadian population represent Angus from 2006-2007, no difference was observed in either the set of microsatellite genotypes nor the SNP genotypes.<p> A significant difference was found between the Canadian and International populations at CAST, with the Canadian population exhibiting a higher frequency of the favorable A allele than the International population. This allele is positively correlated with tenderness. No significant differences were found for the other genes. Both populations were in Hardy Weinburg equilibrium for all genes except MC1R, which affects coat color.<p> Using microsatellites, the total genetic variability of the two Angus populations was measured, showing that 93% of total variability was attributed to differences within, and not between, populations. Randomly chosen cattle could also be assigned to the correct population 97% of the time, based on microsatellite genotypes, and 75% of the time based on SNP genotypes.<p> Mean heterozygosity was 0.578 based on microsatellites and 0.332 based on SNPs. The proportion of genetic variability between the two populations was 3% based on microsatellites and 7% based on SNPs. It is possible this reflects the results of indirect selection differences in various countries.<p> Finally, Neis genetic distance was measured between the Canadian and International populations. The Canadian and International populations had a pairwise genetic distance of 0.097. In comparison, the genetic distance of Canadian Angus was 0.135 to Blonde dAquitaine, 0.251 to Simmental, 0.258 to Gelbvieh, 0.281 to Limousin, 0.305 to Holstein, 0.334 to Belgian Blue, and 0.452 to Hereford based on microsatellite markers.<p> The results of this study show that the Angus breed contains as much or more genetic diversity than other cattle breeds. Greatest genetic differences exist between individual animals, not between populations of cattle in Canada and other countries.

Paratuberculosis is an intestinal infection of ruminants caused by Mycobacterium avium subsp. paratuberculosis (MAP). Genetic associations with paratuberculosis have been described in Holstein cattle. The objectives were to describe the association between paratuberculosis status of the dam and her offspring in beef cattle, develop methods to assess familial aggregation of paratuberculosis in cattle of unknown pedigree, and model the paratuberculosis status of beef cattle given familial and herdlevel covariates. Texas beef cattle were tested for paratuberculosis using serum antibody and microbiologic culture of feces. Available pedigree data were used to confirm familial relationships. The association between the paratuberculosis ELISA status of the dam and her offspring was assessed using mixed-effects models. Increased odds of being classified as a “suspect” or greater based on ELISA results were observed if the dam was classified as a “suspect” or greater. A positive linear association was observed between the ELISA value of the dam and her offspring. Analysis of pedigree data using conditional logistic regression identified ancestors associated with significantly increased odds of being classified as “low positive” or greater. Microsatellite markers were used to classify cattle into genetically similar groups using allele frequency data. Nine clusters of genetically similar cattle were identified among paratuberculosis test positive cattle, herd matched controls, and pedigreed cattle. Clusters were validated using animals of known pedigree. Increased odds of paratuberculosis seropositivity were observed for some clusters compared to the cluster with the lowest seroprevalence. A predictive model was developed using a Bayesian framework to assess the association between antibody status of the dam and her offspring adjusted for herd-level risk factors. Predictors associated with highly probable increased odds of seropositivity included herd seroprevalence and herd fecal prevalence of MAP. The association between dam and offspring ELISA status was small (OR 1.35) and not highly probable. The results of this work support familial aggregation of paratuberculosis ELISA status, but herd-level risk factors appear to be more important in predicting ELISA status. A large proportion of observed serological reactions were not supported by fecal culture results; therefore, observed associations might be limited to humoral responses to Mycobacterium spp.

Objectives of this study were to characterize residual feed intake (RFI) in growing calves and to examine relationships with growth, carcass composition, physiological indicators, energy metabolism and reproduction. To accomplish these objectives, multiple experiments were conducted. In all experiments, RFI was calculated as the difference between actual DMI and expected DMI from linear regression of DMI on mid-test metabolic BW and ADG. To examine the relationships between RFI and rate and composition of growth, and reproduction an experiment was conducted with postweaning Brangus heifers (N = 348). Measures of carcass composition (longissimus muscle area, LMA; and 12th rib fat thickness, BF) were obtained by ultrasound at the start and end of each experiment. To determine if serum IGF-I concentration is associated with RFI, two experiments were conducted with Angus bulls and heifers (N = 95) divergently selected for serum IGF-I concentration. To evaluate relationships with energy metabolism, calves with low and high RFI were selected for determination of heart rate as an indicator trait for energy expenditure (4 experiments) and liver mitochondrial function (3 experiments). Residual feed intake was not correlated with ADG, but was positively correlated with gain in BF such that the more efficient calves were leaner. Calves from the low IGF-I selection line had lower RFI suggesting that RFI and IGF-I are related and that IGF-I could be used as an indicator trait to aid in selection for improved RFI in Angus cattle. Calves with low RFI had lower energy expenditure and greater mitochondrial acceptor control ratios than calves with high RFI suggesting improved regulation of energy metabolism. A similar percentage of heifers with low RFI attained puberty as those with high RFI by the end of the experiment. Results from this study indicate that producers can utilize RFI to select for improved feed efficiency with minimal impact on growth, carcass composition and reproduction.

Objectives of this research were to characterize residual feed intake (RFI) in growing and finishing steers and examine phenotypic correlations between performance, feed efficiency, carcass, digestib ility, and physiological indicator traits. The research included two growing studies and one finishing study. Braunvieh-sired crossbred steers (n = 169) and Santa Gertrudis steers (n = 120) were individually fed a roughage-based diet for 77 d during the growing phase. Santa Gertrudis steers (n = 120) were individually fed a grain-based diet for 80 d during the finishing phase. Individual body weight (BW) and feed intake data were recorded. Residual feed intake was calculated as the difference between actual dry matter intake (DMI) and DMI predicted from linear regression of DMI on mid-test metabolic BW. During the growing phase, initial ultrasound measures of 12th rib fat thickness (FT) and final ultrasound measures of Longissimus muscle area (LMA), FT, and intramuscular fat (IMF) were obtained. During the finishing phase, initial and final LMA, FT, and IMF ultrasound measurements were obtained. Finishing steers were slaughtered at 1.0 cm of FT and carcass cooler traits measured. Blood samples were collected at the start and end of each feeding period and analyzed for physiological indicators. Temperament traits were also measured at the start and end of each feeding period. Growing and finishing steers with low RFI consumed 19-22% less feed than growing and finishing steers with high RFI, but did not differ in average daily gain (ADG). Consequently, steers with low RFI were also more efficient as measured by feed conversion ratio and partial efficiency of growth. Steers with low RFI had less FT compared to steers with high RFI. Initial serum IGF-I was correlated with RFI in growing steers indicating that IGF-I could be a potential indicator trait for RFI in growing cattle. Additionally, RFI was correlated with digestibility to indicate more efficient cattle had higher dry matter digestibility. Results indicate that RFI has potential to allow producers to select more efficient animals without increasing growth rate. Moreover, serum IGF-I may facilitate early detection and more accurate selection of animals that are superior for growing RFI.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 67-78). Also available on the Internet.