Ai manual chapter 12


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  • In this chapter, beginning on page 12-1 of your manual, we will be looking at sire selection for a beef herd.
  • Through A.I. you have access to the best bulls in the world; putting the small breeders and large breeders on a even field. Using bulls that have hundreds, even thousands, of recorded offspring reduces risks.
  • The same genetic principles apply to beef cattle that apply to dairy cattle, even though the traits emphasized are a bit different.
  • We can impact selection. We don’t control gestation length, age at puberty, etc.
  • Here are the heritability estimates for some of the traits beef cattle are selected for.
  • This is the only factor that we can impact.
  • We want to measure genetic differences only, not who is better with the feed scoop.
  • If you want to keep 20 replacements and have 60 to pick from you can make faster progress than if you had 20 to pick from. The average natural service sire can cover 30 to 50 cows a year versus an A.I. bull breeding thousands. We don’t need too many to get the job done, so they really have to be good.
  • Without genetic variation we couldn’t make progress.
  • Concentrate on traits that have economic value, and reasonable heritability, allowing selection to work.
  • Still takes 9 months to get a calf, 15 months before we can breed that heifer to calve at 24 months of age.
  • The old bell curve again.
  • These are some of the sources for data used in progeny testing bulls.
  • The resulting EPDs have increased selection options and pressure.
  • These factors are considered in EPDs
  • Traits to consider when breeding heifers, or producing calving ease bulls.
  • If you sell calves this is important, it relates to the product you sell.
  • This factor is important to the feedlot, an extra .1 lb per day adds up.
  • How the bull performs himself is one indicator of his transmitting ability.
  • Simply said.
  • The object is to produce a consistent and predictable end product.
  • More scores relating to the end product.
  • A bull with daughters in production is going to be at least 4-years-old before we know for sure. Because of the years of records, pedigrees can predict it with a moderate degree of accuracy.
  • If you look at 100 calves of a bull which ones will you likely remember, the average or the extremes? Will you be able to take the time to go look for the offspring? GTS does this for us. It gives us a picture of what the average offspring will look like.
  • This program can help you put it all together. Your goals, your criteria for breeding, and mating each cow individually using all the information each time.
  • Let's go to the pages listed and look at the information.
  • You will get many more calves from any given bull in your herd than from any given cow; therefore, the emphasis needs to be on the sires.
  • Many desirable traits in a commercial operation are enhanced by cross-breeding. Heterosis is free.
  • Low heritability traits are impacted more by hybrid vigor than high heritability traits.
  • The more breeds the more hyrid vigor.
  • Maternal and terminal. Identify the kind of cows you need for your environment and select the breeds that meet those needs.
  • This cross will net about 2/3 of the potential hybrid vigor.
  • This system nets nearly 90%. The system is difficult to manage with natural service, but easily managed using A.I. because all the cows can be in one pasture and the different breeds of bulls are in the refrigerator.
  • Used to maximize hybrid vigor. Can be utilized best by using A.I.
  • A system where every calf is sold.
  • A system allowing for replacement development and maximizing growth in the rest.
  • Expensive and labor demanding.
  • A live, small calf is better than a dead, large calf or a ruined heifer.
  • Actual calvings are reported and summarized.
  • Using bulls that are proven to improve the traits selected reduces set backs. Knowing when cows were bred and are due to calve helps increase the chances of saving calves. Today you can use the directory to look at how the bull performed as an individual, and using his EPD’s how he will transmit those things to your herd.
  • Simple but efficient facilities need not be expensive, and allow you to use the most powerful genetic tools available in your herd.
  • Ai manual chapter 12

    1. 1. CHAPTER 12 <ul><li>SELECTING BEEF SIRES </li></ul>
    2. 2. Why Beef A.I.? <ul><li>Maximum Use of Outstanding Bulls </li></ul><ul><ul><li>Choose Bulls for Maximum Herd Improvement </li></ul></ul><ul><ul><ul><li>Superior Progeny-Proven Bulls Available </li></ul></ul></ul><ul><li>Reduced Risk of Harmful Recessive Traits </li></ul><ul><li>More Complete Records </li></ul><ul><ul><li>Improves Replacement Heifer Selection </li></ul></ul><ul><ul><li>Aids Better Production and Feeding Management </li></ul></ul><ul><li>Can Lead to a Shorter Calving Season </li></ul><ul><li>Eliminate Year-Round Bull Expenses </li></ul><ul><li>Increase Offspring Selling Advantage </li></ul>
    3. 3. Underlying Genetic Principles <ul><li>Inheritance is Governed by Units Called Genes </li></ul><ul><ul><li>Each Gene Produces an Exact Duplicate of Itself </li></ul></ul><ul><li>Genes Occur in Pairs </li></ul><ul><li>Random Sampling Occurs Within Each Gene Pair for the Specific Gene, Which is Passed on to the Next Generation </li></ul><ul><ul><li>Three Factors Determine a Calf’s Potential </li></ul></ul><ul><ul><ul><li>Sample Half of its Sire’s Genes </li></ul></ul></ul><ul><ul><ul><li>Sample Half of its Dam’s Genes </li></ul></ul></ul><ul><ul><ul><li>Environment in Which a Calf is Born and Raised (60-90%) </li></ul></ul></ul>
    4. 4. Measuring Genetic Change <ul><li>3 Factors Determine the Rate of Genetic Change </li></ul><ul><li>Change Will be Faster if: </li></ul><ul><ul><li>Heritability is Higher </li></ul></ul><ul><ul><li>Selection Differential is Larger </li></ul></ul><ul><ul><li>Generation Interval is Shorter </li></ul></ul><ul><li>Little Can Change Heritability or Generation Interval </li></ul>Rate of Genetic Change = Heritability x Selection Differential Generation Interval
    5. 5. Heritability <ul><li>Portion of Genetic Variation Among Individuals in a Herd </li></ul><ul><li>Heritability Remains Fairly Constant </li></ul><ul><ul><li>Sets a Limit on the Rate of Genetic Progress </li></ul></ul><ul><ul><li>Higher Heritability = Faster Change </li></ul></ul>* Calculated using data gathered by the Simmental, Angus and Hereford Associations
    6. 6. Selection Differential <ul><li>Superiority of the Animals Selected to be Parents </li></ul><ul><li>Only Factor That Can be Significantly Influenced by the Breeder </li></ul><ul><ul><li>Use Progeny Test Results </li></ul></ul><ul><li>Parents Should be Better Than the Present Genetic Average for Improvement </li></ul>
    7. 7. Accuracy of Selection <ul><li>Determined by Four Factors </li></ul><ul><ul><li>Heritability (% the Trait is Determined by Genes) </li></ul></ul><ul><ul><li>Precision of Measurement </li></ul></ul><ul><ul><li>Extent That Environmental Factors Have Been Equalized Due to a Uniform Environment </li></ul></ul><ul><ul><li>Extent That Uncontrolled Environmental Factors Can be Identified and Removed by Statistical Adjustment </li></ul></ul><ul><li>Genetic Merit Can Not be Measured Directly Due to Environmental Factors </li></ul>
    8. 8. Intensity of Selection <ul><li>More Intense Selection = Larger Selection Differential </li></ul><ul><ul><li>I.E. Top 5% of Animals are Superior to the Top 50% </li></ul></ul><ul><li>Intensity Higher for Bulls in A.I. </li></ul><ul><ul><li>Fewer Bulls Needed </li></ul></ul><ul><ul><li>Most Heifers Needed for Replacements </li></ul></ul>
    9. 9. Genetic Variation of Breed <ul><li>Greater Variation = Larger Selection Differential </li></ul><ul><li>Variation Reduced Through Parent Selection </li></ul><ul><ul><li>Regained in Offspring by Genetic Segregation </li></ul></ul><ul><ul><ul><li>Formation of Sperm and Eggs </li></ul></ul></ul><ul><li>Each Trait has Different Genetic Variation </li></ul><ul><ul><li>Each Breed has Different Variation for Each Trait </li></ul></ul><ul><li>Genetic Differences Provide Only Opportunity for Selection </li></ul><ul><ul><li>Little Can Change Genetic Variation </li></ul></ul>
    10. 10. # of Traits Under Selection <ul><li>Fewer Traits = Faster Progress </li></ul><ul><li>Greater Response if Traits Are Positively Correlated, Smaller if Negatively </li></ul>
    11. 11. Generation Interval <ul><li>Average Age of Parents at Birth of Progeny </li></ul><ul><ul><li>Usually Five Years </li></ul></ul><ul><li>Can Only be Changed Significantly Through Embryo Transfer and Other New Technologies. </li></ul>
    12. 12. Understanding Genetic Expression <ul><li>Range of Production Follows Normal Distribution Curve </li></ul><ul><ul><li>Half of Cows Produce Above Breed Average </li></ul></ul><ul><ul><li>Half of Cows Produce Below Breed Average </li></ul></ul><ul><li>Important to Remember </li></ul><ul><ul><li>Poorest Bull Will Have Some Good Daughters </li></ul></ul><ul><ul><li>Best Bull Will Have Some Poor Daughters </li></ul></ul>
    13. 13. Performance Records <ul><li>Beef Improvement Federation (BIF) Helped Standardize Testing </li></ul><ul><li>Set Up Central Bull Testing Stations </li></ul><ul><ul><li>Used to Eliminate Environmental Differences </li></ul></ul><ul><li>In Late 1970s Several Breed Associations and Organizations Started Structured Sire Evaluation Programs </li></ul><ul><ul><li>Results Expressed as EBVs (Estimated Breeding Values) </li></ul></ul>
    14. 14. Expected Progeny Differences <ul><li>EPDs Are Today’s Results </li></ul><ul><ul><li>Breed Association Sponsored National and International Cattle Evaluation Programs </li></ul></ul><ul><li>Predict Expected Differences in Progeny Performance </li></ul><ul><li>Expressed in Appropriate Unit of Measure </li></ul><ul><ul><li>I.E. Birth, Weaning and Yearling Weight in Pounds </li></ul></ul>
    15. 15. EPD Calculations <ul><li>Calculations Include: </li></ul><ul><ul><li>Pedigree Information </li></ul></ul><ul><ul><li>Individual Performance </li></ul></ul><ul><ul><li>Progeny Performance </li></ul></ul><ul><li>Accurate Selection of Animals Across Herds </li></ul><ul><ul><li>Up to Nine Times More Accurate Than Performance Ratios </li></ul></ul><ul><li>Accuracy Values = Measure of Reliability </li></ul><ul><ul><li>Amount and Distribution of Included Information </li></ul></ul><ul><ul><li>Range From 0 to 1.0 </li></ul></ul>
    16. 16. Calving Traits <ul><li>Birth Weight </li></ul><ul><ul><li>Accurate Indicator of Calving Ease, Future Growth and Mature Weight </li></ul></ul><ul><ul><li>I.E. Herd Average Birth Weight = 70 lbs. </li></ul></ul><ul><ul><ul><li>A 90 lb. Calf Should Grow Faster Than a 50 lb. Calf </li></ul></ul></ul><ul><ul><li>Low Birth Weight = Reduced Calving Difficulty </li></ul></ul><ul><li>Calving Ease Score </li></ul><ul><ul><li>Provides Information About Expected Relative Ease of Calving of Future Calves by the Sire </li></ul></ul>
    17. 17. Weaning Weight <ul><li>Important Factor Affecting Income of Cow-Calf Operation </li></ul><ul><li>Can be Increased by Selecting Bulls With Superior Growing Progeny </li></ul><ul><li>Adjust to 205-Day Mature Cow Basis </li></ul><ul><li>Expressed in Average Daily Gain From Birth to Weaning </li></ul><ul><li>Must Adjust for Age of the Cow </li></ul><ul><ul><li>Correction Factors Vary by Breed </li></ul></ul>
    18. 18. Feedlot Growth <ul><li>Gaining Ability Most Strongly Emphasized in Production Record </li></ul><ul><ul><li>Easy to Measure </li></ul></ul><ul><ul><li>Highly Heritable (50%) </li></ul></ul><ul><ul><li>Has Great Economic Impact </li></ul></ul><ul><li>3 lbs. / Day Expresses Inherent Gaining Ability </li></ul><ul><li>Expressed as a Percentage Figure or Ratio </li></ul>
    19. 19. Examples <ul><li>Bull’s Performance Test Average 3.5 lbs.; ABS Selected Bull Gained 4.5 lbs. </li></ul><ul><ul><li>ABS Bull Gain Superiority +29% (1:29 Ratio) </li></ul></ul><ul><ul><ul><li>4.5 / 3.5 = .29 </li></ul></ul></ul><ul><li>Same ABS Bull Later Sires Group Gaining 2.75 lbs.; All Others Gaining 2.5 lbs. </li></ul><ul><ul><li>ABS Bull Gain Superiority +10% (1:10 Ratio) </li></ul></ul><ul><ul><ul><li>2.75 / 2.5 = .10 </li></ul></ul></ul>
    20. 20. Feed Efficiency <ul><li>Difficult to Obtain </li></ul><ul><li>Usually Not Available </li></ul><ul><li>Rule of Thumb </li></ul><ul><ul><li>Fast-Gaining Cattle are Generally More Efficient </li></ul></ul>
    21. 21. Numerical Grades or Scores <ul><li>Carcass Cutability - Yield Grade: </li></ul><ul><ul><li>BIF Recommended Appraisal of Carcass Yield </li></ul></ul><ul><ul><ul><li>“ Cutability” Recommended Formula Includes: </li></ul></ul></ul><ul><ul><ul><ul><li>Ribeye Area </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Fat Thickness Over the Rib </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Kidney Fat </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Carcass Weight </li></ul></ul></ul></ul><ul><ul><ul><li>Higher Cutability = More Lean Meat on Carcass </li></ul></ul></ul><ul><ul><li>Yield Grades Assigned by USDA Graders </li></ul></ul><ul><ul><ul><li>Grades 1 and 2 = Trim Cattle </li></ul></ul></ul><ul><ul><ul><li>Grade 3 = Average Cattle </li></ul></ul></ul><ul><ul><ul><li>Grades 4 and 5 = Over-Fat Cattle </li></ul></ul></ul>
    22. 22. Numerical Grades or Scores <ul><li>Quality Grade </li></ul><ul><ul><li>Appraisal of Carcass Quality </li></ul></ul><ul><ul><ul><li>Measured by Amount of Marbling and Age at Slaughter </li></ul></ul></ul><ul><ul><li>Most Cattle are Fed to Choice or High Select </li></ul></ul><ul><ul><li>Reflects Potential Eating Preferences of Consumers </li></ul></ul><ul><li>Frame Score </li></ul><ul><ul><li>Objective Measure Indicates Lean-to-Fat Ratio </li></ul></ul><ul><ul><li>Used to Predict Mature Size </li></ul></ul><ul><ul><li>Measured at the Hip, Directly Over the Hooks </li></ul></ul><ul><ul><li>Can Indicate Final Slaughter Weight </li></ul></ul>
    23. 23. Maternal Ability <ul><li>Includes: </li></ul><ul><ul><li>Fertility </li></ul></ul><ul><ul><li>Ease of Calving </li></ul></ul><ul><ul><li>Milk Production </li></ul></ul><ul><ul><li>Other Traits That Produce Large Healthy Calves </li></ul></ul><ul><li>Important Trait for Efficient Beef Production </li></ul><ul><ul><li>Difficult to Measure at Young Ages </li></ul></ul><ul><li>Can be Predicted for Young Bulls With an Accuracy of Almost 50% </li></ul>
    24. 24. Pedigree
    25. 25. Genetic Type Summary Program <ul><li>GTS Accurately and Objectively Describes Type Trait Transmitting Differences </li></ul><ul><li>Large Number of Progeny are Visually Scored </li></ul><ul><ul><li>Use Linear Evaluation System </li></ul></ul><ul><li>Make Herdmate Comparison </li></ul><ul><ul><li>Standardized Transmitting Abilities (STAs) </li></ul></ul><ul><ul><ul><li>Calculated for Each Sire on Various Type Traits </li></ul></ul></ul><ul><li>Use STAs to Produce Cattle Best Fitted for Environment and Management Conditions </li></ul>
    26. 26. Genetic Manager <ul><li>Computerized Mating Program </li></ul><ul><ul><li>Make Comprehensive Mating Decisions Using All Available Information and Breeding Objectives </li></ul></ul><ul><ul><ul><li>Uses Sire and Dam EPDs, GTS Data and Pedigree Information </li></ul></ul></ul><ul><ul><li>Control Mating Process and Tailor Genetic Manager </li></ul></ul><ul><ul><ul><li>Mating Targets: Allows Producer to Establish Targets </li></ul></ul></ul><ul><ul><ul><li>Bull Selection: Allows Producer to Determine Sires Available for Selection </li></ul></ul></ul><ul><ul><ul><li>Cow Selection: Identify Specific Mating Criteria and Targets for Each Cow </li></ul></ul></ul><ul><ul><li>Prints Specific Indexed Mating Recommendations </li></ul></ul>
    27. 27. Using The Sire Directory <ul><li>Most Breed Associations Actively Test Sires </li></ul><ul><ul><li>Many Publish Annual or Bi-annual Sire Summaries </li></ul></ul><ul><li>ABS Has Adopted Various Data Charts </li></ul><ul><ul><li>Used in Beef Sire Directories </li></ul></ul><ul><ul><li>Present Most Current and Reliable Data </li></ul></ul><ul><li>Beef Producers Use Information to Compare and Choose Sires </li></ul><ul><li>See Pages 12-8 to 12-10 for Explanations of All Types of Information Available </li></ul>
    28. 28. Genetic Improvement Source <ul><li>Most Opportunity for Selection are Herd Sires </li></ul><ul><li>Stringent Selection of Required Seedstock is Needed to Increase Productivity </li></ul><ul><li>Heritability Determines Attention a Trait Receives in the Selection Program </li></ul><ul><ul><li>Low Heritability = Less Change </li></ul></ul><ul><li>Proven Sires Readily Available With A.I. </li></ul><ul><li>Provides a More Objective Breeding Program </li></ul><ul><li>Jump Generations </li></ul><ul><ul><li>Mate Top Bulls to Top Cows </li></ul></ul>
    29. 29. Cross-breeding <ul><li>Provides Opportunity to Improve Maternal Ability and a Calf’s Inherited Growth Ability </li></ul><ul><li>Desirable Characteristics in Two or More Breeds Can be Combined </li></ul><ul><ul><li>Achieves a Better Combination Than One Breed </li></ul></ul><ul><li>Progress is Accelerated by Cross-breeding </li></ul><ul><li>Provides Benefits of Heterosis (Hybrid Vigor) </li></ul>
    30. 30. Hybrid Vigor <ul><li>Expression of Offspring of Parents of Two Different Breeds </li></ul><ul><li>Increase in Growth, Fertility and Production Over the Parent Averages </li></ul><ul><li>Greater Genetic Difference in Parents = Greater Expression of Hybrid Vigor in Offspring </li></ul><ul><ul><li>I.E. Brahman x Hereford Has More Hybrid Vigor than Angus x Hereford </li></ul></ul><ul><li>Hybrid Vigor Varies Among Traits </li></ul>
    31. 31. Hybrid Vigor <ul><li>Main Advantage </li></ul><ul><ul><li>Improved Fertility </li></ul></ul><ul><ul><li>Improved Calf Survival </li></ul></ul><ul><ul><li>Improved Growth Rate </li></ul></ul><ul><li>Reported Calf Production per Cow is 20 to 30% Higher for Crossbred Cows Bred to a Bull of a Third Breed </li></ul>
    32. 32. Selecting Breeds <ul><li>To Develop High Producing Herds Select Breeds Based on: </li></ul><ul><ul><li>Fertility – Disposition </li></ul></ul><ul><ul><li>Milk Production – Feedlot Growth </li></ul></ul><ul><ul><li>Udder Quality – Mature Size </li></ul></ul><ul><li>To Produce Animals for Slaughter Select Breeds Based on: </li></ul><ul><ul><li>Growth Rate – Carcass Quality </li></ul></ul><ul><li>No Single Cross Will Suit All Areas or All Management </li></ul>
    33. 33. Two-Breed Rotation <ul><li>Simple, Widely-Practiced Crisscross System </li></ul><ul><li>Daughters of Bulls of Breed A are Bred to Breed B </li></ul><ul><ul><li>I.E. Hereford x Angus; Brahman x Simmental, etc. </li></ul></ul><ul><li>Doesn’t Provide Full Advantage of Cross-breeding </li></ul><ul><ul><li>Limits Use of Breeds for a Specific Purpose </li></ul></ul><ul><ul><ul><li>Breeds Must be Middle-of-the-Road for Most Traits </li></ul></ul></ul><ul><li>Hybrid Vigor Reduced to 67% of Maximum Level </li></ul>
    34. 34. Three-Breed Rotation <ul><li>Superior to Two-Breed Rotation </li></ul><ul><ul><li>Adds Third Breed to Better Adapt Herd to Production Demands </li></ul></ul><ul><li>87.5% of Maximum Hybrid Vigor Expressed </li></ul><ul><li>Breed Each Cow to Bull of Breed Least Represented in Her Genetic Make-up </li></ul><ul><ul><li>I.E. </li></ul></ul>Brahman Gelbvieh Angus
    35. 35. Four-Breed Rotation <ul><li>Provides Additional Genetics </li></ul><ul><li>Enables Producer to Control Type of Cattle She/He Wishes to Produce </li></ul><ul><li>Hybrid Vigor Will be Near Maximum Level </li></ul><ul><ul><li>I.E. </li></ul></ul>Brahman Angus Gelbvieh Simmental
    36. 36. Terminal Crosses <ul><li>Specialized Meat Sires are Bred to F1 (First Generation) Crossbred Cows </li></ul><ul><li>All Offspring are Intended for Slaughter </li></ul><ul><ul><li>No Replacement Heifers Kept </li></ul></ul><ul><li>Allows for Specialized Use of Maternal and Growth Traits to Maximize Calf Weights </li></ul><ul><li>Hybrid Vigor is at Maximum (100%) </li></ul><ul><li>Replacement Heifers Must be Bought or Produced Elsewhere </li></ul><ul><ul><li>Difficult to Locate Good F1 Replacements </li></ul></ul>
    37. 37. Rotation-Terminal Combination <ul><li>Obtain Maximum Advantage From Cross-breeding </li></ul><ul><li>Option 1: </li></ul><ul><ul><li>Breed All Young and Desirable Cows on a Rotation System </li></ul></ul><ul><ul><ul><li>Produces Replacement Heifers for Herd </li></ul></ul></ul><ul><ul><li>Older and Less Desirable Cows Bred to Terminal Sires </li></ul></ul><ul><ul><ul><li>All Offspring Slaughtered </li></ul></ul></ul><ul><li>Option 2: </li></ul><ul><ul><li>Breed Entire Herd on Three-Breed Rotation </li></ul></ul><ul><ul><li>Bring in Terminal Sires for Non-A.I. Settled Cattle </li></ul></ul>
    38. 38. Dystocia <ul><li>Difficult or Prolonged Birth </li></ul><ul><ul><li>Primary Cause of Calf Losses at Birth </li></ul></ul><ul><li>Causes </li></ul><ul><ul><li>Calf is Too Large to Move Easily Through Birth Canal </li></ul></ul><ul><ul><ul><li>Consider Both Pelvic Area and Birth Weight of Calf </li></ul></ul></ul><ul><ul><li>Calf Enters Birth Canal Abnormally </li></ul></ul><ul><ul><ul><li>Relatively Low Frequency of Presentation (1 to 5%) </li></ul></ul></ul>
    39. 39. Selecting Sires for Calving Ease <ul><li>Birth Weight of Calves is Good Indicator </li></ul><ul><li>Cull Cows Experiencing Difficult Calving </li></ul><ul><ul><li>Can Breed to Sires With Low Birth Weights </li></ul></ul><ul><li>2-Year-Old Heifers Have Higher Incidence of Calving Problems </li></ul><ul><ul><li>Breed to Calving Ease Sires </li></ul></ul><ul><li>Use Proven Low Birth Weight Bulls to Lower Occurrence of Difficult Births </li></ul><ul><li>Calving Ease Information Available From Breed Associations </li></ul>
    40. 40. Calving Ease Information <ul><li>American Angus and Hereford Association’s </li></ul><ul><ul><li>Make Available Average Calving Ease Scores </li></ul></ul><ul><ul><ul><li>Scores Reported on Herd Improvement Records </li></ul></ul></ul><ul><ul><li>Summarized in Performance Pedigrees </li></ul></ul><ul><li>Calving Ease Index </li></ul><ul><ul><li>Rating Combines Calving Ease Scores for Heifers, Second Calf and Older Cows Plus Birth Weights </li></ul></ul><ul><ul><ul><li>Scores Reported to Breed Associations </li></ul></ul></ul><ul><li>Subjective Estimate of How Progeny Will Perform </li></ul><ul><ul><li>Star Ratings are Assigned Based on Objective Data </li></ul></ul>
    41. 41. Summary <ul><li>A.I. Allows Progeny-Proven and Young Bulls to be Used </li></ul><ul><li>Aids Management With Better Record Systems and Planned Calving Seasons </li></ul><ul><li>A Bull’s Performance Can be Evaluated Using: </li></ul><ul><ul><li>Calving Traits – Weaning Weight </li></ul></ul><ul><ul><li>Average Daily Gain – Feed Efficiency </li></ul></ul><ul><ul><li>Maternal Ability – EPDs </li></ul></ul><ul><li>Performance Data Can be Found in the ABS Beef Sire Directory </li></ul>
    42. 42. Summary <ul><li>A.I. Facilitates Cross-breeding Programs and Better Sire Selection </li></ul><ul><li>Cross-breeding Systems </li></ul><ul><ul><li>Two-, Three-, Four-Breed Rotation </li></ul></ul><ul><ul><li>Terminal Cross System </li></ul></ul><ul><ul><li>Rotation-Terminal Combination </li></ul></ul><ul><li>Use Sires With Low Birth Weights to Help Reduce Calving Problems </li></ul>
    43. 43. Question 1 <ul><li>Describe the advantages of using A.I. in a beef herd? </li></ul>A.I. allows the producer to maximize their use of outstanding bulls. They are also able to reduce the risk of introducing harmful recessive traits, and A.I. helps tighten management of the herd. Further benefits include having better records and a shortened calving season. There is also a reduction in bull keeping expenses. Breeding stock can also be sold at a higher price.
    44. 44. Question 2 <ul><li>What is heritability? </li></ul><ul><li>Which trait is more highly heritable, weaning weight or average daily gain? </li></ul>Heritability represents the portion of the variation among individuals in the same herd that is genetic. Average Daily Gain
    45. 45. Question 3 <ul><li>What is meant by Expected Progeny Difference? </li></ul>EPD is the expected difference in performance of a sire’s or dam’s progeny when compared to the progeny performance of all sires and dams evaluated in the same breed.
    46. 46. Question 4 <ul><li>Define the following terms that are found in the ABS Beef Sire Directory: </li></ul><ul><li>205-day adjusted weight </li></ul><ul><li>Calving ease index </li></ul><ul><li>Feedlot ADG </li></ul>The bull’s own weaning weight adjusted to 205 days. Star ratings are a subjective estimate of a bull’s calving ease. Average weight gained daily while at a feedlot.
    47. 47. Question 5 <ul><li>What is hybrid vigor? </li></ul><ul><li>How is it related to heritability? </li></ul>Hybrid vigor is the increase in growth, fertility and other production traits of the hybrid individual over the average of both parents. They are inversely related to each other, meaning that a trait with high heritability has low hybrid vigor and a trait with low heritability has high hybrid vigor.
    48. 48. Question 6 <ul><li>Which trait expresses the greatest response to hybrid vigor, reproduction or carcass quality? </li></ul>Reproduction
    49. 49. Question 7 <ul><li>Name some breeds that are known for improving maternal traits. </li></ul><ul><li>What breeds are better known for improving growth and carcass quality? </li></ul>Angus, Red Angus, Hereford, Simmental, Gelbvieh and Brahman Charolais, Limousin, Piedmontese and Maine-Anjou
    50. 50. Question 8 <ul><li>There are several systems of cross-breeding. Discuss how each works. </li></ul>Two-breed rotation = you mate animals of two different breeds. Three-breed rotation = you mate the cow to one of the three breeds least present in her genetic make-up. Four-breed rotation = you mate four breeds on a rotation.
    51. 51. Question 8, cont. Terminal crosses = you mate all F1 generation heifers to meat sires; keep no replacements. Rotation-terminal combination = you mate young and desirable cows to produce replacements and breed all others to produce calves for slaughter.
    52. 52. Question 9 <ul><li>Because two-year-old heifers have grown to about 85% of their mature size but produce calves 90% as large as those of older cows, they are most likely to have trouble calving. </li></ul><ul><li>What types of calving information are available to help make sire selection easier? </li></ul>Birth weight differences, average calving ease scores, calving ease index, Star Ratings