Using EPDs in Selection Edited by: Jessica Hawley & Brandon Freel Originally compiled by Colorado Agriscience Curriculum
Define Expected Progeny Difference. • Interpret EPD categories. • Analyze EPD variations within breeds. • Recognize the importance of EPD use in selection. • Apply EPD concepts. EPD Video Objectives
Selection of livestock Two Ways Phenotype – The appearance of an animal. Genotype – What genes are present and how they are combined.
Breeding Values (EPD) ExpectedProgenyDifference – A measurement of genetic potential based on the performance of relatives. (ACC) Accuracy is an important term used in understanding EPDs. It is a measure of expected change in the EPD as additional young are born to the sire. A high accuracy value is better as the chances of the EPD being correct rise.
Common EPD’s Common EPDs: Performance-based, Carcass-based, and Ultrasound. Performance-basedEPDs – Are based on a measurement of how well the bull’s offspring perform. Examples of performance-based EPDs are birth weight, weaning weight, milk and yearling weight. Carcass-based – Are based on how well the bull’s offspring have performed on the rail. Examples of carcass-based EPDs are Rib-eye Area, Fat (Outer), Retail Product, and % Intramuscular Fat. UltrasoundEPDs – Done from an ultrasound of the actual bull. Examples of ultrasound EP’s are Rib-eye Area, Fat (Outer), and % Retail Product.
How to Compare EPDs • How much more will Bull B weigh at birth than Bull A? • Answer: .6 pounds. • How much more will bull A weigh at weaning than Bull B? • Answer: 11 pounds • Which bull would be a better bull for heifers? • Answer: Both would be fine. But smaller calves would come from A. • Which bull has a bigger Rib-eye Area? • Answer: Bull B
Selection of Cattle Should include both visual and genetic appraisal Valuable genetic traits Depends on producers goal Culling – Cows should be culled from the herd based on the productivity of their calves. Evaluation – Cows should be culled based on evaluation of the udders, eyes, skeleton and teeth.
Selection of Heifers Try to select heifers that will conceive early in the breeding season, calve easily, produce a good supply of milk, wean a heavy calf, make a desirable genetic contribution to your cow herd, and have calves with desirable carcass traits.
Accuracy and Herd EPD’s Accuracy - The reliability that can be placed on the EPD. Accuracy of close to 1.0 indicates higher reliability. Herd- Indicate the number of herds from which daughters are reported.
BirthWeight Predictor of a sire’s ability to transmit birth weight to his progeny, compared to the progeny of an average bull for a specific breed; expressed in pounds.
WeaningWeight Predictor of a sire's ability to transmit weaning growth to his progeny, compared to the progeny of an average bull for a specific breed; expressed in pounds.
Yearling Weight Predictor of a sire's ability to transmit yearling weight, compared to the progeny of an average sire for a specific breed; expressed in pounds.
Maternal Milk Predictor of a sire's genetic merit for that part of weaning weight attributed to milk and mothering ability. It is compared to daughters of an average bull for a specific breed.
Scrotal Circumference Predictor of the difference in transmitting ability for scrotal size, compared to the progeny of an average bull for a specific breed; expressed in centimeters.
You are a rancher looking to improve your herd overall. This requires you to look at all traits and choose the bull you think will offer the most multi-trait excellence. Please right a paragraph discussing why you chose a specific bull.
Define Expected Progeny Difference. • Interpret EPD categories. • Analyze EPD variations within breeds. • Recognize the importance of EPD use in selection. • Apply EPD concepts Objectives