Potential reasons for breeding Whats really involved in hoggets - - PDF document

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Associate Professor Paul Kenyon

What’s really involved in successful hogget mating? Potential reasons for breeding hoggets

• the production of a lamb within the first year of life
• more lambs produced on farm within a given year
• more efficient use of herbage in spring
• an increase in lifetime performance
• an early selection/screening tool
• more progeny born on farm therefore potentially more

selection pressure

• potential reduction in the generation interval if progeny born

to hoggets are selected as replacements

Potential limitations of breeding ewe hoggets

• low and variable reproductive performance
• increased feed requirements during their first year of life
• the need for adequately sized hoggets at 8 months of age
• potential for reduced 2-year-old live weight and

reproductive performance and decreased lifetime reproductive performance

• progeny born to hoggets are often smaller at weaning and
• f lower value
• hogget breeding is often associated with extra costs
• increased workload.

Performance levels in NZ

140 120 100 80 60 40 20 70 60 50 40 30 20 10

Lambing percentage Frequency

Account for approx. 4% of NZ lambs per year

2 Management plan to maximise performance from hogget breeding

Pre-breeding management

• Vaccination against abortive organisms
• Shearing
• Do not shear close to breeding

Pre-breeding management

• Breeds

– Yes there are breed differences – but not every farmer can change or is willing to change – Finn/East Fr. and their composites highest performers – Coopworth the highest performer of the traditional breeds

Pre-breeding management

• Live weight at breeding – from a reproductive perspective

– Ideally should be a minimum of 38 – 40 kg – Each extra 1 kg above 36 kg is worth an extra 2% of lambs

• although recent data suggests no further reproductive

benefit above 45 kg

• Target condition score 2.5

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Pre-breeding management

• Use teasers

– Expose hoggets to teasers for 17 days prior to planned start of breeding

• Ideal ratio 1:75

– Recent data suggests teasing can be used in late March/early April to allow for breeding of ewe hoggets in April

Management during breeding

• Ewe lambs are shy breeders – so ram to ewe hogget ratio

is important during the breeding period – 1:50 to 1:75

• Avoid the use of ram lambs during the breeding period

– Unless ratios are low

• Mature rams can be re-used in the same season

Management during breeding

• Limit the length of the breeding period to avoid late lambing

hoggets

• If using teasers breed for 26 days (9 +17)

Management in pregnancy

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The below figure indicates that in late pregnancy fetal growth is the major driver of weight change which explains why a change in weight of the hogget needs to occur in early pregnancy

Management in pregnancy

– To maximise the weight of the ewe lamb and her

• ffspring at weaning she needs to be gaining 150 g/d in

total live weight throughout pregnancy

• this live weight gain needs to start during the

breeding period – gains in early pregnancy have the biggest impact

• this either requires a reduction in other classes of

stock or an increase in alternative feed sources

Modelling of weight response per kg

Time point

• W. Wgt hogget B.Wgt lamb

W.Wgt lamb Mating 1.3 kg 16g 71g Day 50 of preg. 1.1 kg 9g 37g Day 100 of preg. 0.7 kg 5g 23g Day 147 of preg. 0.5 kg 4g 16g

Management in pregnancy

• Mid pregnancy shearing can be used with hoggets

– Although a survival response in the lambs is dependant

• n the weather at lambing.
• Trial data does not suggest an increase in dystocia

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Management in pregnancy

• Management during/prior to lambing

– paddocks should ideally provide shelter – herbage intake minimum covers of 1200 kgDM/ha – advantages from separating multiple- and single-bearing ewe lambs

Management in lactation

Management in lactation

• Ensure pasture covers do not get below 1200 kg DM/ha
• Consider weaning early to allow young mother more time to

recover – this can benefit the young dam and if done correctly will not impact on weaned lamb growth

Potential lifetime effects

6 Summary points about lifetime effects

• Our data matches the work undertaken in the past both in

New Zealand and overseas

• What this shows is….

– yes there can be a check as a two-tooth – but it is not permanent and it does not negatively affect their lifetime performance (in fact it has a positive effect)

Summary points about lifetime effects

• Reproductive performance (two-tooth to five years) did not

differ overall

• But given that they lambed as a hogget their lifetime

reproductive performance was higher (just over 1 extra fetus)

• Ewe wastage did not differ between those bred as a hogget
• r not over the 5 year period

Does being born to a hogget impact on the progenies performance?

• In single born progeny it appears there is no real effect

– a slight suggestion that they may carry more internal fat

• In twins the data we have to date suggests that those born

to hoggets may be stunted in terms of growth (to at least 18 months of age)

Conclusion

• Hogget breeding has the potential to improve on farm

productivity

• Breeding a hogget does not negatively affect her lifetime

performance – in fact it has a positive effect

• The are no magic bullets for getting hogget breeding

correct – but getting the feeding and live weights correct are the major drivers of success