L6

• Bull Breeding soundness is an issue in farming beef cattle
• Serving capability test


  A test to assess a bull's fertility and ability to serve cows
• Appropriate male to female ratio when mating heifers and cows

  Typically 1 bull to 30-40 cows, lower ratio for heifers
• Bull Breeding Soundness Examination (BSE)


  • Critical to obtaining optimum reproduction in the beef cow herd
  • Predicts the potential fertility of a bull
• What a BSE involves

  1. History and health status of herd

  2. Physical examination

  3. Semen collection and examination

  4. Libido or serving assessment
• 10% of yearling bulls are either sterile or sub-fertile, 4% of proven sires develop serious fertility problems between breeding seasons
• A BSE is a screening process to assess probable fertility
• Field study of infertility


  • Molesworth Station - 70% Angus and 50% Hereford bulls culled after 3 years
• Research study by Greg Tattersfield found 81% stud and 65% commercial bulls were sound, 14% stud and 22% commercial were unsound, 5% stud and 15% commercial were sub-fertile
• Physical evaluation of a bull

  1. Palpation of scrotum and testes

  2. Examination of extended penis and prepuce
• Scrotal circumference (SC)


  Directly related to sperm production, higher SC indicates higher fertility
• Scrotal circumference varies by breed and age, with most growth from 6 to 36 months and peaking at 4-6 years
• Minimum SC for bulls is 32-34 cm, larger bulls can be mated to 60 cows
• Scrotal circumference


  Highly heritable and positively correlated to age of puberty in bull's daughters
• Libido or sexual activity


  Apparently has no relationship to semen production in bulls
• Serving capacity (Blockey test)


  The number of services a bull achieves during the first 3 weeks of natural mating
• Serving capacity tests are no longer used in NZ, replaced by simpler serving capability tests
• Reasons bulls may fail BSE include immaturity, poor condition, lameness, health issues, penile damage, inadequate testicular size
• Guarantee clauses when buying bulls often include requirements for structural soundness, fertility, vet certificates, and serving capability tests
• Kowai Bull Quality Assurance Certificate

  • Pasture reared
  • Accurate identification and recording
  • Performance assessed through Breedplan
  • No unnecessary supplementation
  • Selected for temperament
  • TB Accredited Free Herd
  • Brucellosis and mannosidosis free herd
  • Tested clear and Vaccinated for BVD
  • Guaranteed for fertility and soundness
• Management of a new bull

  • Give vaccinations
  • Give a mate once he gets home
  • Avoid placing him in mob with older bulls
  • Provide access to good quality feed and hay
• Bull to cow ratios

  Typically 1 bull to 30-40 cows, lower ratio for heifers, can increase ratio to 1:60 in a 60 day mating period
• Management during mating


  • Check bulls at least twice a week
  • Have a spare bull available
  • Replace any suspect bulls immediately
  • Avoid placing young sires with old experienced sires
  • Mate sires to similar aged heifers/cows
  • Use a fresh bull for second cycle if single sire mating
  • After mating, drench and place in paddock with plenty of feed
• Consult a vet and have an annual policy for treating and inspecting bulls, schedule BSE 1-2 months before mating