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Economic feasibility of fall-calving on Oregon high desert cow-calf operationsNordblom, Thomas L. 18 October 1971 (has links)
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
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Effects of strip versus continuous grazing management on diet parameters and performance of yearling steers grazing native flood meadow vegetation in eastern OregonBlount, David Kenneth 23 May 1990 (has links)
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
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Comparison of Canadian and international Angus cattle populations using gene variants and microsatellitesCarruthers, Chelsey Rae 09 November 2009
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.
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Comparison of Canadian and international Angus cattle populations using gene variants and microsatellitesCarruthers, Chelsey Rae 09 November 2009 (has links)
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.
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Application of vaccination protocols to manage beef cattle productivity and mitigate production riskHorne, Willy J. 16 January 2010 (has links)
The U.S. beef industry is very large with many inter-connected facets. Nutrition and health are key components of a system striving to compete economically while striving to produce a high quality product. The decisions made in one part of the system may often determine outcomes in the other parts of the system. Therefore, it is necessary to look at the beef industry in a systems type of framework. Each management decision is likely tied to a result that may alter several other management questions.
At the cow/calf level, producers must decide whether or not to vaccinate their calves. Vaccination leads to reduced disease incidence and severity in the feedyard, thus being beneficial to the feeder. However, if the feedlot does not respond economically in any way, producers may feel that it is not warranted to vaccinated calves. Pre-conditioning programs work in the same manner as they may have beneficial effects for the feeder but not for the harvester. Therefore, pre-conditioning may not be a program that is valued back to the farm level. Answers to these kinds of questions are hard to ascertain. Each segment has its own demands and drivers, which determine how much it can reward to other segments for their efforts. Because the market is continuously changing, the target rewards are changing as well. Therefore targets cannot be theorized, rather exact relationships should be shown. In this dissertation, it is intended to characterize the relationships vaccination protocols and other management strategies can have on various aspects of cattle performance in various industry segments.
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Evaluating the Impacts of Gender, Fatness, Muscling, and Weight on Yield Grade 4 Beef Carcasses.Dillon, James T. 14 January 2010 (has links)
This study was conducted to assess cutout and value differences in Yield Grade 4
beef carcasses by evaluating impacts of gender, fatness, muscling, and weight. USDA
Choice, Yield Grade 4 carcasses (n = 60) were selected according to gender: heifers (n =
20) and steers (n = 40), and weight groups: lightweight heifers (315.5 - 362.9 kg) and
steers (362.9 - 408.2 kg), and heavy weight heifers (362.9 - 408.2 kg) steers (408.2 -
453.6 kg). Within weight classes, carcasses were separated according to ribeye area per
45.36 kg of HCW ratio (REAcm2 :100 kg): heifers (>21.76) and (< or equal to 21.76); steers
(greater than 20.07) and (less than or equal to 20.07) based on analysis from NBQA-2005 (National Beef Quality
Audit - 2005). Data in this study showed that within yield grade 4 carcasses, there are
both conformational and value differences associated with different types of yield grade
4's, particularly when sex-class is considered due to the biological differences associated
with fat and muscle deposition between genders. As expected, carcasses from heifers
had more trimmable fat than steers, and steers had higher yields of certain cuts from the
chuck and in bone differences than did heifers. In this demonstration, applied estimated discounts out-weighted the value differences found in cutout values. There were no
clear associations in carcass traits that could be used to more accurately sort value
differences in Yield Grade 4 carcasses with exception to sex-class. However, the present
data suggests a need to establish a prediction equation that predicts carcass value in
addition to the current Yield Grade equation. In conclusion, further research is needed
incorporating all yield grade carcass types. Standard carcass fabrication styles and fat
trim levels consistent with industry are needed to further assign current subprimal and
minor cut prices. Additional premium and discount prices are needed for a current
industry representation to obtain if premiums and discounts are being applied according
to potential profits or losses incurred because of cutability differences found between the
different yield grades.
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Tenderness, flavor, and yield assessments of dry-aged beefLaster, Megan Ann 15 May 2009 (has links)
Top Choice (n = 48) and Select (n = 48) paired bone-in ribeye rolls, bone-in strip
loins, and boneless top sirloin butts were assigned randomly to one of two aging
treatments (dry or wet) and aged 14, 21, 28 or 35 days. Sensory and Warner-Bratzler
shear (WBS) evaluation was conducted to determine palatability characteristics. WBS
values and consumer ratings showed wet-aged ribeye steaks to be more tender than their
dry-aged counterparts. WBS values for ribeye and top sirloin steaks decreased with
increased aging time. Consumer ratings for tenderness like increased with increased
aging time for beef steaks from all three subprimals. No significant differences were
found for consumer evaluation of top sirloin steaks. Top Choice ribeye and top loin
steaks received higher consumer ratings for overall like and juiciness attributes when
compared to Select steaks. Cutting tests were performed at the end of each aging period
to determine retail yields and processing times. Retail cutting tests showed dry-aged
subprimals had lower total saleable yield percentages and increased processing times
compared to wet-aged subprimals. Cooler shrink and gross cut loss percentages
increased with increased aging time for both Top Choice and Select subprimals.
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Genetic epidemiology and familial risk factors for paratuberculosis seropositivity in beef cattleOsterstock, Jason Barrett 15 May 2009 (has links)
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.
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A comparison of the perceived credibility and usefulness of beef cattle magazine articles with and without photographsSandlin, James Dale 15 May 2009 (has links)
This thesis explored the credibility and usefulness of beef cattle magazine articles
with and without photographs perceived by students at a Southern land-grant institution.
The thesis also explored the use of alternate forms of repeated measure to determine if a
relationship existed in instrumentation when a photograph was presented first or
presented second. The study found that credibility was perceived to be greater when
photographs were present in an article. The study found that usefulness was perceived to
be greater when photographs were not present in an article. The study found a
relationship between credibility and usefulness when presented with and without
photographs. The study found that perceived credibility was greater when an article
presented with a photograph was presented first. The study also found that perceived
usefulness was greater when an article without photograph was presented first. The
findings of this study indicated that magazines should take these factors into account
when a desired outcome is to increase editorial credibility and increase the effectiveness
of the message.
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Sources of biological variation in residual feed intake in beef cattleLancaster, Phillip Allan 15 May 2009 (has links)
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.
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