Selection of Breeding Program An S 426 Fall 2007

1. Selection of Breeding ProgramAn S 426 Fall 2007

2. Selection of Breeding Program Setting of goals is of major importance and includes goals for: 1. Reproduction 2. Calf performance 3. Income 4. Etc. Breeding management will impact each of above in varying degrees: 1. Breeding management practice with greatest impact on reproduction is crossbreeding 2. Selection is best management practice for improving carcass quality

3. Selection of Breeding Program Once goals established, herd assessment is needed – where is herd at 1. Determine breed makeup 2. Determine production level – need accurate records 3. Determine average weight and frame size of cow herd Larger frame cows have higher maintenance costs

4. Table 1. Frame relationship to mature size and carcass weight Yearling Hip Height (in) Expected Weight (lbs) Frame Bulls Heifers Mature Steer Steer Score Cows Harvest Carcass 3 45 43 1025 950 600 4 47 45 1100 1050 660 5 49 47 1175 1150 725 6 51 49 1245 1250 785 7 53 51 1320 1350 850 8 55 53 1395 1450 915 9 57 55 1465 1550 975

5. Figure 1. Comparison of growth curves of small and large framed cattle.

6. Selection of Breeding Program Larger frame feedlot cattle 1. Grow at faster rate 2. Require greater amounts of feed and in feedyard longer, thus greater expenses 3. Heavier finish weights generate more income 4. Real problem if variation in frame sizes in same feedyard, may need to sort for: a. b.

7. Selection of Breeding Program Genetic change 1. Genetic change may not result in improved animals 2. Genetic improvement means superior animals with greater profitability Brought about in two ways: 1. 2.

8. Selection of Breeding Program Selection – factors affecting: 1. Variation – 2. Heritability – 3. Selection differential – 4. Generation interval – Predicting genetic change = Genetic change per year = Progress through selection dependent upon number of traits selected where n = number of traits selected

9. Selection of Breeding Program Single-vs. multiple-trait selection Single-trait selection produces rapid genetic change, but unfortunately likely results in undesirable changes in correlated traits Increasing frame size resulted in increased: 1. 2. 3. 4.

10. Selection of Breeding Program Multiple-trait selection first step towards more effective selection, but challenges remain: 1. Rate of improvement in any one trait decreases 2. Unfavorable genetic correlations remain for economic relative traits (ERT)

11. Selection of Breeding Program Multiple-trait selection first step towards more effective selection, but challenges remain: 3. Methods a. Tandem – emphasis on one trait until desired level attained and then move to next trait b. Independent culling - choosing minimum or maximum levels for each trait - more traits added, more relaxation occurs in order to find animals meeting criteria - once thresholds identified, application of this method is easy and popular

12. Selection of Breeding Program 3. Methods c. Selection indexes – incorporate the cost and income resulting from production 1.) A description of every index should include: a.) Traits included in the index b.) Description of information used in the index, such as EPD or individual phenotypic performance c.) source of economic information and performance levels used to calculate economic weights d.) Relative economic emphasis of each trait to the overall index

13. Selection of Breeding Program c. Selection indexes – incorporate the cost and income resulting from production 2.) Successful application of generalized indexes relies on logical implementation: a.) Identify production and marketing system 1.) When will animals be marketed (at what age) 2.) How will animals be marketed 3.) What is current performance and genetic level of herd

14. Selection of Breeding Program c. Selection indexes – incorporate the cost and income resulting from production 2.) Successful application of generalized indexes relies on logical implementation: b.) Identify the index appropriate to the production system outlined above - questions to be addressed 1.) What traits are included in the index 2.) What are the relative economic values used to weigh the traits 3.) Decide on the appropriate index for evaluation based on the most similarity between above points 1 and 2

15. Selection of Breeding Program c. Selection indexes – incorporate the cost and income resulting from production 3.) Most breed selection indexes are generalized for overall breed improvement and use average costs and income from production rather than accounting for a specific producer’s marketing and production systems a.) Has led to the development of Interactive Decision Support (IDS) systems which allow breeders to input parameters specific to their production systems – two classes:

16. Selection of Breeding Program 1.) Herd – level systems a.) Designed to evaluate overall genetic changes in herd level – not individuals b.) Angus Assoc. Optimal Milk Model – designed for producers to decide the appropriate range of milk EPD given the mature weight of their cows, annual cow costs and variability in feed resources

17. Selection of Breeding Program 2.) Individual animal systems a.) Designed to evaluate individual animal selection decisions and the impact of those decisions on profitability b.) Charolais Assoc. Terminal Sire Profitability Index (TS) – designed to evaluate the selection of sires based on their relative impact on profitability in a terminal sire mating system; allows input of current herd production characteristics and sources of income by the producer

18. Selection of Breeding Program Mating systems 1. Inbreeding – a. Main genetic effect is to increase the number of pairs of homozygous genes b. Usually results in a decline in traits related to physical fitness 1.) 2.)

19. Selection of Breeding Program Mating systems 2. Outbreeding – a. Main genetic effect is to increase the number of pairs of heterozygous genes b. By increasing heterozygosity there is a tendency to cover up detrimental recessive genes and improve traits related to physical fitness 1.) 2.)

20. Selection of Breeding Program Mating systems Crossbreeding – two reasons for its use: For certain traits may result in heterosis Breed complementarity

21. Selection of Breeding Program Table 1. Summary of heritability and level of heterosis by trait type. A Trait Heritability Level of Heterosis Carcass / end product High Low Skeletal measurements (0 to 5 %) Mature weight Growth rate Medium Medium Birth weight (5 to 10 %) Weaning weight Yearling weight Milk production Maternal ability Low High Reproduction (10 to 30 %) Health Cow longevity Overall cow productivity a Adapted from Kress and MacNeil. 1999

22. Selection of Breeding Program For certain traits may result in heterosis average of average of a. % heterosis = crossbred - purebreds x 100 average of purebreds 1.) b. Traits not expressing heterosis will equal the average of the parent breeds for that trait in the crossbred offspring

23. Selection of Breeding Program For certain traits may result in heterosis c. Why important in beef cattle business 1.) Largest benefit to commercial production is crossbred cows – improves: a.) b.) c.) d.) d. Keys for successful crossbreeding program: 1.) 2.) e. Crossbreeding systems

24. Selection of Breeding Program Breed complementarity – implies using breeds in a crossbreeding program where their strengths and weaknesses complement one another a. Example 1.)

25. Selection of Breeding Program Composite breeds – 1. Maintain heterosis 2. Utilize breed complementarity 3. Once formed, can be managed like a purebred herd Formed Retained % Improved produc. from maximum heterosis of cow herd(%) 2-breed 50 12 3-breed 67 15 4-breed 75 17

26. Table 1. Breed performance levels for seven traits in beef cattle. a,b.

27. Table 2. 2004 Adjustment factors to add to EPD of 15 different breeds to estimate across-breed EPD. a,b. Breed Birth Weight Weaning Weight Yearling Weight Milk . Angus 0.0 0.0 0.0 0.0 Beefmaster 9.7 39.0 37.9 --- Brahman 13.0 34.8 -4.4 24.6 Brangus 5.7 20.0 20.4 --- Braunvieh 6.5 30.0 13.9 22.2 Charolais 10.5 38.4 53.4 2.6 Gelbvieh 5.4 7.1 -21.1 1.7 Hereford 3.4 -2.0 -13.7 -17.8 Limousin 4.5 1.8 -19.9 -15.9 Maine Anjou 6.7 17.6 5.5 7.6 Pinzgauer 7.7 28.3 25.5 6.1 Red Angus 3.6 -1.4 0.7 -7.8 South Devon 6.7 21.7 40.8 3.5 Salers 4.9 30.7 46.1 9.0 Shorthorn 7.8 31.4 44.5 12.1 Simmental 6.4 22.4 21.9 10.0 Tarentaise 3.6 30.1 13.4 17.8 a Van Vleck and Cundiff, 2004 b Updates to across-breed EPD adjustments can be found at www.beefimpovement.org

28. Table 3. Average across-breed EPD for nonparent animals born in 2002-2003 by breed. a. Breed Birth Weight Weaning Weight Yearling Weight Milk . Angus 2.6 35 65 17 Beefmaster 10.1 45 49 --- Brahman 15.1 51 22 32 Brangus 7.7 41 54 --- Braunvieh 7.6 37 21 22 Charolais 12.0 57 85 8 Gelbvieh 6.4 44 48 19 Hereford 7.2 33 46 -5 Limousin 6.9 36 44 2 Maine Anjou 9.2 34 37 11 Pinzgauer 7.6 29 26 5 Red Angus 4.1 27 49 6 Salers 7.8 34 60 12 Shorthorn 6.7 44 66 11 Simmental 9.7 65 102 18 South Devon 6.4 40 45 16 . a Adjustment using the 2004 across-breed EPD adjustments listed in Table 2.

29. Selection of Breeding Program Successful breeding program depends on: 1. 2. a. b.