BullSelectionL8

• What factors determine how a bull looks on the day of a bull sale?

  Bull's genotype and environment
• How can you make a bull bigger and can it's size be passed on to his progeny?

  By feeding him preferentially but it can't be passed on
• What should a buyer be looking for in a bull?

  A bull that will pass superior genes on to his progeny, not a bull that looks superior on the day
• What are EBVs used for in bull selection?

  Separate genetics from environment and determine the genetic potential of a bull, which is the part that will show up in his calves
• How are most registered cattle in NZ evaluated?

  Breed plan Estimated Breeding Values (EBV's)
• In what units are EBV's measured?

  Measured in units for that traits (e.g. kg)
• How are EBV's measured?

  "Deviation from the breed base performance" so can be positive or negative.
• What should be considered while choosing a bull based on EBV's?

  Depending on the trait, one may want higher or lower values
• What's a Breed Plan?

  A modern genetic evaluation program for beef cattle
• What does a breed plan produce?

  EBVs for range of traits: CE, growth, fertility, carcass
• What's an EBV?

  A prediction of the GENETIC VALUE of an animal for a trait
• What's an EBV based on?

  Animal's own performancePerformance of all known relativesRelationship between performance of different traits
• What are selection criteria?

  Easily measurable traits, measurable before selection decisions are made, and heritable. They are used to maximize the response in economically important traits
• What can selection criteria include?

  Breed, bull stud, coat color, horns, conformation, LW/gain, U/S measurements, pedigree/show performance, GGT (facial eczema)
• What are Calving Ease Traits?


  Measurements that help predict how easily a cow will give birth based on calving difficulty scores, birthweights, and gestation length information
• What are Calving Ease EBVs (%) based on?

  Calving difficulty scores, birth weights and gestation length information, more positive EBVs are favorable and indicate easier calving
• What is Direct Calving Ease (CE % Dir)?

  Indicates the influence of the sire on calving ease in purebred females calving at two years of age
• What is CE % Daughters?

  Indicates how easily that sire's daughters will calve at two years of age
• What is Gestation Length EBV?

  An estimate of the time from conception to the birth of the calf
• What's Gestation Length EBV based on?

  Artificial Insemination and hand mating records, lower (negative) GL EBVs indicate shorter gestation length and therefore easier calving
• What is Birth Weight EBV?

  Based on the measured birth weight of progeny, adjusted for dam age
• What does a low Birth Weight EBV indicate?

  Lighter calf at birth and lower likelihood of a difficult birth, important when selecting sires for use over heifers
• What is the 200-Day Growth EBV?


  Best single estimate of an animal's genetic merit for growth to early ages
• How is the 200-Day Growth EBV calculated?

  The weight of progeny taken between 80 and 300 days of age and values are adjusted to 200 days and for age of dam
• What is the 400-Day Weight EBV?

  Best single estimate of an animal's genetic merit for yearling weight
• How is the 400-Day Growth EBV calculated?


  It is calculated from the weight of progeny taken between 301 and 500 days of age, adjusted to 400 days and for age of dam
• What is the 600-Day Weight EBV?

  Best single estimate of an animal's genetic merit for growth beyond yearling age
• How is the 600-Day Growth EBV calculated?

  The weight of progeny taken between 501 and 900 days of age, adjusted to 600 days, and for age of dam
• What does Mature Cow Weight EBV estimate?

  Genetic difference in cow weight at 5 years of age
• How is Mature Cow Weight EBV calculated?

  The cow weight when the calf is weighed for weaning and adjusted to 5 years of age
• What does Mature Cow Weight EBV indicate?

  Indicator of growth at later ages and potential feed maintenance requirements of the females in the breeding herd
• What does Milk EBV stand for?

  An estimate of an animal's milking ability
• What does the Milk EBV indicate for sires?


  For sires, indicates the effect of the daughter's milking ability, inherited from the sire, on the 200-day weights of her calves
• What does the Milk EBV indicate for dams?

  For dams, indicates their milking ability.
• What does Scrotal Size EBV estimate?

  An animal's genetic merit for scrotal size
• How is the Scrotal Size EBV calculated?

  From the circumference of the scrotum taken between 300 and 700 days of age and adjusted to 400 days of age
• What is the correlation between scrotal size and age of puberty in female progeny?

  A small negative correlation
• What is the impact of selecting for increased scrotal size on female progeny?

  Reduced age at calving
• What does the Days to Calving EBV indicate?

  Indicates the fertility of the daughters of the sire
• How is Days to Calving calculated?

  It is the time interval between the day when the female is first exposed to a bull in a paddock mating to the day when she subsequently calves