Selection Criteria Sires Welcome to the Georgia Agriculture 选择准的公牛欢迎来到乔治亚农业.pptVIP

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Selection Criteria Sires Welcome to the Georgia Agriculture 选择准的公牛欢迎来到乔治亚农业.ppt

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Selection Criteria Sires Welcome to the Georgia Agriculture 选择准的公牛欢迎来到乔治亚农业

Bull Selection: Beef Kay Farmer Madison County High School 01432- 3.2 edited by Billy Moss and Rachel Postin July 2001 Why is Bull Selection Important? The bull contributes 1/2 of the genetic makeup of his offspring He’s the most important individual in herd Use a bull to improve the quality and performance of your herd It can be estimated that 87% of the genetics in your cow herd are a result of the last 3 bulls in your cow’s pedigree. Selection Criteria: Sires Varies depending on the use of the calf and the age of the cow being bred Low BW bulls are an advantage for heifers, but not necessary or desirable for larger, mature cows Look for more growth and size when breeding larger framed, mature cows Genetic Tools - Selection Use EPD’s and other estimates of genetic potential to make permanent improvement in the genetic level of the herd Effective when heritability is moderate to high ex: growth- high heritability ex: reproduction- low heritability Why Is Heritibility Important Commercial: sell cattle by weight ^ Weight at various ages is heritable WW is estimated to be: ~ 30% heritable YW is estimated to be: ~ 45% heritable Genetic Tools - Crossbreeding Breeds can be crossed to improve heratability traits that are low Ex: Reproductive Performance - Crossing Angus bulls on Brahman cows (Brahman cattle reach sexual maturity later than other breeds) What is an EPD Expected Progeny Difference The difference between EPD’s of two bulls is the expected difference in progeny averages when bulls are mated to similar cows in a herd # expressed in pounds can only be used as a comparison for animals in the same breed Which Bull Would You Selectto use on mature cows when growth is the most important trait to you? Use of EPD’s Use only to compare two or more bulls EPD’s allow valid comparisons of all bulls of the same breed, but they do not allow you to compare bulls from different breeds EPD Charts Most breed associations provide EPD’s for : 1. Birth Weig