BreedingManagementL6

• Breeding Period


  Time frame for mating ewes and rams to maximize pregnancy rates
• Why do we want the female to become pregnant as early as possible?

  Can improve productivity in terms of kg offspring weaned
• Why do we want high conception rates?

  More ewes bred in the first cycle will be pregnant to the first 17 days of breeding = lambs born earlier will be older and heavier at weaning
• What decides the length of the mating period (ram to ewe ratio and breeding length)?

  Target barren ewe percentages, use of terminal sire for the later bred ewes, breeding period is generally 34 to 51 days
• What effects the ewe to ram ratio?

  Flock size, topography, dam/sire age, stage of season, sire availability
• What does breeding rams teams do?

  Reduces the risk of a ʻpoorʻ ram having a negative effect
• Why would you use young rams (7 - 9 months of age, hoggets)?

  Reduce generation interval increasing genetic gain and cheaper costs
• Since rams are less experienced, it's best to use them in teams for 17 days only. This minimizes any negative affects on ram hogget liveweight and ewe breeding performance. Ram teams aren't not ideal for use with young ewes even with lower ratios
• Conception Rate Calculation


  Formula: (Number of ewes conceiving / Total ewes at breeding) x 100
• What does ram harnesses allow farmers to identify?

  Ewes not bred (can be culled pre-winter), late lambing ewes, ewes bred to terminal sire
• Mating Ratio Calculation


  Formula: Number of rams / Number of ewes in a breeding group
• Early pregnancy


  Period with potential reproductive losses, distinguishing partial vs. total loss
• Fetal Abortion Rates


  Low nationally, can spike with 'abortion storms' due to various pathogens
• Main causes of fetal abortions:

  Toxoplasma gonadii, Campylobacter, Salmonella, etc
• Toxoplasmosis

  Causes abortion, transmitted by cats; managed with Toxo-vac injection and remove stray cats
• Campylobacteriosis


  Causes late pregnancy (6wks) abortion, controlled by vaccination and traditional methods like exposing young ewes and reducing stock density
• Pregnancy Scanning


  Determines pregnancy status, crucial for managing ewe nutrition and lamb survival
• Pregnancy Detection Options

  Includes crayon harness marks, weight changes, and udder checks
• Scanning Percentages Impact

  Higher scanning % leads to more multiples, affecting management decisions
• By knowing litter size and implementing management plans to lift lamb survival (by 10%)


  Farmers can increase profitability significantly
• Optimum Scanning Time

  45 days post-ram removal, offering fetal age and litter size info
• 3 pregnancy detection options:


  Wet/dry; dry, single/multiple bearing; dry, single/twin/triplet plus bearing
• Benefits of Pregnancy Scanning

  Improves cash flow, lamb survival, ewe health, and flock reproductive performance, target feeding of multiple-bearing ewes