Author: Neil B. McCleeryPublisher:
ISBN:
Category : Hereford cattle
Languages : en
Pages : 58
Book Description
The Effects of Mild Inbreeding on Weaning Weight and Grade of Hereford Cattle
Author: Neil B. McCleeryPublisher:
ISBN:
Category : Hereford cattle
Languages : en
Pages : 58
Book Description
Evaluation of Response to Selection and Inbreeding in a Closed Line of Hereford Cattle
Author: J. S. BrinksPublisher:
ISBN:
Category : Agriculture
Languages : en
Pages : 40
Book Description
The Effect of Inbreeding and Environmental Factors on the Weaning Weight and Post-weaning Growth of Range Hereford Cattle
Author: Geoffrey Oswald HarwinPublisher:
ISBN:
Category : Cattle
Languages : en
Pages : 158
Book Description
The present study was initiated to determine the effects of inbreeding and certain environmental and genetic factors on the weaning weight of range Hereford calves. The study was also extended to include an investigation of the effect of these variables on post-weaning traits of range Hereford females including yearling gain and weight at 18 months, 2 1/2 years and 3 1/2 years of age. The data used in the study were obtained from a long term cattle breeding project initiated by Colorado State University in 1946 at the San Juan Basin Experiment Station and included onservations from 16 inbred lines of Hereford cattle, crosses between yhese lines and a control herd. The preliminary phase of the study was concerned with the development of appropriate mathematical models enabling minimum variance unbiased estimates of the various genetic and ebvironmental factors under investigation. The interactions between the various main effects as they affect weaning weight were investigated simultaneously by means of a least squares analysis. The interactions of sex x mating system, sex x age of dam and year x age of dam were significant. Investigation of the within year regression of weaning weight on age of calf also indicated a significant interaction between age of calf and year. Preleminary investigation indicated a marked curvilinear decline in weaning weight with inbreeding and differential response to inbreeding of both lines and sexes. The results of the preliminary studies were used in developing the final models...
History and Performance of Inbred Lines of Hereford Cattle Developed at the United States Range Livestock Experiment Station
Author: The Level of Inbreeding and Its Effect on Weight Traits in Simmental Cattle
Author: Barbara J. WardTechnical Bulletin
Author: Technical Bulletin - Colorado Agricultural Experiment Station, Colorado Agricultural and Mechanical College
Author: Colorado Agricultural Experiment StationPublisher:
ISBN:
Category : Agriculture
Languages : en
Pages : 344
Book Description
Direct and Correlated Responses to Selection for Weaning Weight and Postweaning Gain in Hereford Cattle
Author: Renato IrgangPublisher:
ISBN:
Category :
Languages : en
Pages : 330
Book Description
Single trait selection was practiced in three lines of Hereford cattle derived from a common base population. Bulls were selected within sire families for increased weaning weight (WW) in line WWL, increased postweaning gain (PG) in line PGL and ramdomly selected in the control line (CTL). The data consist of 2,467 progeny produced from 1967 to 1981 by 125 sires and 922 dams. After 3 years of stablishing the foundation population, 12 years of continuous selection resulted in slightly less than two generations of selection of selection and in low inbreeding coefficients. Direct selection applied to either WW or PG improved both traits. However, selection for PG increased both PG and WW faster than selection for WW. Selection for WW and for PG increased milk production, preweaning daily gain, yearling weight and feed intake. Correlated responses in these traits were larger in PGL than in WWL. Selection for either WW or PG also increased the amount of fatness in bulls in feedlot. However, it did not result in any significant change in feed efficiency. Increased birth weight was observed from PG selection but not from WW selection. Realized heritabilities and regression coefficients of correlated responses on cumulative selection differentials, estimated from "quasi-replicates" generated by grouping individual descendents from sires utilized in different years of the foundation population, indicated that genetic drift affected responses to selection and suggest that replication of selection experiments is necessary ...
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