Rams

• Breeding period


  Maximise pregnancy rates and utilising breeding and pregnancy management tools
• Why do we want the female to become pregnant as early as possible?

  The earlier the ewe is pregnant the earlier her offspring will be born and if weaning date is based on a calendar date lambs will be older and in theory heavier on average
• Can improve productivity in terms of kg offspring weaned
• Scenario: 2000 ewes bred achieving either 70 or 80% conception rate over a two cycle breeding period, 100% lambing percentage, lambs weaned 100 days after lambing starting with an average birth weight of 5 kg growing at 300 g/d to weaning, all lambs born on same day within each cycle, 1 kg of lamb is worth $4 at weaning if sold store
• Why do we want high conception rates?

  A high conception rate means more of the ewes bred in the first cycle will be pregnant to the first 17 days of breeding, thus at a given weaning date lambs born earlier will be older and heavier at weaning
• What decides the length of the mating period?

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

  Flock size, topography, size of paddock, dam/sire age, stage of season, availability of sires
• Average ewe to ram ratio in NZ is likely 100:1
• Why would you use young rams (7 – 9 months of age, hoggets)?

  Decrease the generation interval and thus increase genetic gain, cheaper source of rams
• Management of hogget rams pre-breeding

  Undergo all the same tests as a mature ram pre breeding, need to be in good body condition (target minimum 3.5), ideally should be 60 kg plus
• Management of ram lambs (hoggets) during breeding

  Best used in teams, not in mixed aged ram teams with older rams, used for 17 days only, use smaller, flatter paddocks, lower ewe : ram hoggets ratios (i.e., 30 – 50:1), not ideal for use with young ewes unless even lower ratios
• Monitoring breeding - why?

  The use of ram harnesses allows farmers to identify ewes not bred, late lambing ewes, and ewes bred to terminal sire
• How to use crayon harness

  Colours should be changed every 17 days to identify which cycle ewes are bred in, if high conception rates in first cycle or intensive interactions (interventions) used over the lambing period, crayon colours can be changed at shorter intervals
• Importance of early pregnancy

  Early pregnancy is a period where some reproductive losses can occur, partial loss vs total loss
• Avoid major stressors and very low levels of feeding in this period
• Fetal abortion rates


  Nationally rates are low, however 'abortion storms' can occur on individual farms having a dramatic impact, main causes are toxoplasma gonadii and campylobacter
• Toxoplasmosis


  Abortion can occur throughout pregnancy, involves the cat as a vector, traditional management and what farmers do now
• Campylobacteriosis (vibriosis)


  Abortion mainly in last 6 weeks of pregnancy but can cause early loss, traditional control and now we use vaccination
• Pregnancy detection options


  Traditional techniques, based on an average Australian farm with 5944 ewes, as scanning % increases there are more multiples so the benefit of managing them separately increases, by knowing litter size and implementing management plans to lift lamb survival farmers can increase profitability significantly
• Pregnancy detection options


  The optimum time to scan is 45 days after the ram leaves the ewe flock, options include wet/dry, dry, single bearing, multiple bearing, can give age of fetus also
• Benefits from pregnancy scanning sheep

  • Sale of diagnosed non-pregnant stock, improved lamb survival rates, reduced ewe losses, reduced lamb losses, improved lactational performance, improved subsequent flock reproductive performance, determination of lamb loss rates, targeted feeding of ewes in poor body condition