Using EPDs in Selection Lecture

Using EPDs in Selection Objectives • • • • • Define Expected Progeny Difference. Interpret EPD categories. Analyze EPD variations within breeds. Recognize the importance of EPD use in selection. Apply EPD concepts. Selection of livestock • Two Ways • • Phenotype – The appearance of an animal. Genotype – What genes are present and how they are combined. 3 Breeding Values (EPD) Expected Progeny Difference – 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. 4 Common EPD’s Common EPDs: Performance-based, Carcass-based, and Ultrasound. • Performance-based EPDs – 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. • Ultrasound EPDs – Done from an ultrasound of the actual bull. Examples of ultrasound EP’s are Rib-eye Area, Fat (Outer), and % Retail Product. 5 How to Compare EPDs BW WW Milk YW Marb REA FAT %IM F RE FAT %RP Bull A -0.5 +61 +15 +111 +.20 +.19 +.01 7 +.50 +.22 +.00 4 +.28 Bull B +0.1 +50 +21 +51 +.20 +.44 +.01 7 +.26 +.66 -.046 +.28 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 6 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. 7 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. 8 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. Birth Weight 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. Weaning Weight 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