Selection practices and evaluation of growth and composition in three lines of synthetic beef cattle

Data in the present study came from two separate beef cattle breeding projects at Iowa State University. Data set-I included growth and carcass information of progeny in the small, medium, and large lines of synthetic cattle. Progeny were born during the years 1978 through 1990 at Rhodes and McNay research farms. Data were used to evaluate selection practices in the three synthetic lines, to evaluate effects of some crossbreeding parameters on carcass traits, and to estimate genetic parameters and genetic trends for carcass traits. Data set-II included carcass and serially measured live-animal traits collected over a 6-year period (1991--1996). Most of the data came from progeny of purebred Angus and Simmental sires with known expected progeny difference and synthetic females from a previous project. Data set-II was used to study effects of sex and breed on growth and composition of feedlot cattle and to determine the best strategy to adjust serially measured traits to a constant age end point. The overall mean generation interval was 4.11 years. When averaged by line, 1.82, 1.47, and 1.28 generations of selection was made in the small, medium, and large lines, respectively. Mean actual sire index differentials per generation were, 1.28, -.47, and .84sigma for the small, medium, and large lines, respectively. There was a significant (P \u3c .05) difference in direct additive effect between Jersey, Angus, and the Simmental breeds for most of the carcass traits considered. However, differences in breed maternal, average individual heterosis, and average maternal heterosis were not different from zero (P \u3e .10). Heritability of hot carcass weight, dressing percentage, longissimus muscle area, fat thickness, and percentage of kidney, pelvic, and heart fat in the small line were, .30, .09, .21, .34, and. 15, respectively. The respective values in the medium line were, .52, .35, .33, .29, and .07. Heritability values in the large line were in the order of .31, .18, .17, .31, and .18, respectively. Sire selection based on weaning indices showed a significant (P \u3c .05) genetic change for some of the carcass traits. It was concluded that index equations designed to improve beef carcasses need to incorporate carcass information in an index. Analysis of serially measured fat thickness, longissimus muscle area, body weight, hip height, and ultrasound percentage intramuscular fat showed a limitation in the use of growth models based on pooled data. Therefore, it was concluded that regression parameters from a within-animal regression of a serially measured trait on age, averaged by sex and breed, are the best choice in describing growth and adjusting data to a constant age end point

Immunogenetic Factors Affecting Infectious Bovine Keratoconjuntivitis (IBK)

The analysis of field data, revealed an estimate of .18 for heritability of resistance to pinkeye and an average decrease in weaning weight of 9.5 kg for infected animals. Tear samples were collected for the 2004 pinkeye season for the analysis of two factors (IgA and Lactoferrin) involved in ocular defense. Significant differences were found between infected and non- infected animals, in the levels of tear fluid IgA

Risky driving behaviors for road traffic accident among drivers in Mekele city, Northern Ethiopia

<p>Abstract</p> <p>Background</p> <p>Due to its perception as a disease of development, road traffic accident and related injuries tend to be under recognized as a major health problem in developing countries. However, majority of the world's fatalities on the roads occur in low income and middle income countries. Since the main cause of road traffic accident is attributed to human risky behaviors, it is important to identify significant factors for risky behaviors of drivers.</p> <p>Methods</p> <p>A quantitative cross-sectional study with a sample size of 350 drivers was conducted in April 2011. The study was conducted among Taxi, Bajaj (three tire vehicles) and private owned car drivers. After proportion to size allocation for Taxi (75), Baja (103) and private owned car (172) drivers, we used systematic random sampling method to identify illegible study subjects. Data was collected with face to face interview using a pretested questioner. Univariate, bivariate and multivariate analysis was done using SPSS version 16.</p> <p>Results</p> <p>The mean age of the respondents was 28.7 (SD 9.9). Majority were 339 (96.9%) males. Significant number of the study subjects 233 (66.6%) had risky driving behaviors. More than a quarter 100 (28.6%) had less knowledge about basic traffic signs. Majority of drivers 181 (51.7%) had negative attitude towards risky driving behaviors. Significant percent of them 148 (42.3%) had a habit of using mobile phone while driving vehicle and 28 (9.7%) had experience of driving after drinking alcohol. All the Bajaj, 97(62.6%) house car and 58(37.4%) taxi unfasten their seat belt while driving. Majority 303 (86.6%) followed the recommended speed limit of driving. About 66 (18.9%) of them had experience of punishment or warning by traffic polices in the previous 1 year and 77 (22%) ever had car accident while driving.</p> <p>Conclusions</p> <p>Drivers of secondary education and with high average monthly income were more likely to have risky driving behavior. Having supportive attitude towards risky driving behaviors and not getting advice about risky driving from significant others increases the likelihood of developing risky driving behavior. Interventions targeted at developing negative attitude towards risky driving behaviors on drivers and significant others should be implemented to bring positive behavior change. The interventions need to be segmented with educational status and income.</p

Ultrasound Prediction Model for % Intramuscular Fat in Beef Cattle

Real-time ultrasound technology offers producers an opportunity to measure compositional traits in beef cattle. A recent research project focused on the development of a prediction model for the Classic Scanner 200. The accuracy of this model has been previously reported and can be found in the Journal of Animal Science 2000, Volume 78, pages 11-18

Estimating Heritability of Percentage of Intramuscular Fat and Ribeye Area Measures By Scan Session in Angus Bulls and Heifers

The present study included 3,066 ultrasound-predicted percentage of intramuscular fat (UPFAT) and 4,502 ultrasound ribeye area (UREA) measures of bulls and heifers from the Iowa State University beef cattle breeding project. Data were collected over a four-year period between 1998 and 2001. The objective of the current study was to estimate variance components and heritability of UPFAT and UREA. Data were analyzed based on single- and multiple-trait animal models. Heritability of UPFAT increased from a minimum of 0.36 at a mean age of 37 weeks to a maximum of 0.54 at a mean age of 54 weeks. Heritability of UREA ranged from 0.30 at a mean age of 35 weeks to a maximum of 0.48 at a mean age of 50 weeks. Heritability of yearling UPFAT and UREA were 0.50 and 0.45, respectively. For the range of ages included in the present study the results suggest optimum heritability of UPFAT and UREA starting at about one year of age

Estimation of Heritability and Repeatability of Ultrasound Ribeye Area Measures Using Random Regression Models

The present study included 4,653 observations from 882 Angus bulls and heifers born during the spring of 1998 to 2001. Each year cattle were scanned four to eight times for ribeye area (UREA) and other ultrasound traits, starting at a minimum age of 27 weeks. The objective of the current study was to estimate variance components, heritability, and repeatability of UREA. Direct additive genetic variance increased from 7.11 to 19.4 cm4 as measurement age increased from 27 to 62 weeks. For the same time period direct permanent environmental variance increased from 14.7 to 26.6 cm4. When averaged by four weeks intervals, heritability of UREA ranged from 0.29 to 0.39. Mean repeatability values ranged from 0.80 to 0.86. Yearling heritability and repeatability were estimated at 0.39 and 0.80, respectively. For the range of ages considered, the present results showed an optimum heritability and repeatability of UREA measures around 52 weeks through at least 62 weeks of age

Beef Cattle Breeding Project Progress Report: Body Composition EPD Determined from Ultrasound Measures

The Iowa State University beef cattle breeding project was initiated in 1996 and is being conducted at the Rhodes and McNay research and demonstration farms. The project uses the field data of the American Angus Association (AAA) along with the research resource cattle of the farms to study questions that will enhance the genetic investigations using the field data

Trends in Genetic Parameter Estimates for Ultrasound Back Fat and Rump Fat Thickness Measures in Angus Bulls and Heifers

The objective of the current study was to evaluate heritability and repeatability of serially measured ultrasound 12–13th rib fat thickness (UBF) and rump fat thickness (URF) measures in purebred Angus bulls and heifers.Data included 5000 observations from 912 bulls and heifers.Results from multiple trait analysis showed h2 of 0.29 and 0.40 for yearling UBF and URF, respectively.However, the difference in h2 estimates between yearling measures based on random regression models was smaller.At one year of age, h2 of URF was 0.37 as compared to 0.33 for UBF.Heritability and repeatability values were at their optimum at one year of age. Therefore, yearling bull and 13 to 14 months old heifer ultrasound subcutaneous fat thickness measures from good quality images can be used to evaluate genetic potential of next generation parents in Angus cattle.Information from URF measures may not have an apparent advantage in terms of improving rate of genetic change in percentage retail product in yearling Angus cattle than what could be achieved through selecting against 12th and 13th rib fat thickness