Key points
- Feeding is critical – you cannot overfeed pregnant hoggets.
- Select the correct sires – genetics, not feeding, is the greatest determinant of lamb birthweight.
- Retaining hogget lambs as replacements speeds up genetic gain.
- Set monthly liveweight targets for mated hoggets.
- Monitor liveweights and compare actuals to targets.
- Ensure appropriate animal health plans are in place.
- Use legume-based forages to optimise post-lambing growth rates in both lambs and hoggets.
- Consider early weaning to give the hogget more time to recover, before mating as a two-tooth.
Flexible policy
Managed correctly, hogget mating has the potential to enhance the productivity and profitability of the future ewe flock – but the inverse is also true.
Speaking at a B+LNZ Farming for Profit field day in Canterbury, Professor Paul Kenyon from Massey University says that not all farmers should breed from their hoggets and, for those that do, it should be a flexible policy depending on feed availability.
“If you don’t do it well, they will fall out of the system later – you will ruin them for future years.”
Correct feeding critical
Feed is the most critical factor in successful hogget mating. This means feeding them consistently well – from when they are weaned as ewe lambs, through until when they are mated as two-tooths.
As a rule of thumb, ewe lambs need to weigh a minimum of 40kg before going to the ram. For a lamb mated in early May, this means an average daily growth rate of 120gms/day from birth.
She then needs to gain 20kg – or 135gms/day – throughout her pregnancy to meet her two-tooth target weights. Given the conceptus weighs 10kg, the hogget should weigh a minimum of 60kg the day before she lambs, and 50kg the day after.
The heavier the ewe lamb is at mating, the less pressure on winter feed resources to reach those post-lambing target weights.
Paul says that to meet the hogget’s energy requirements throughout pregnancy, she needs to be offered pre-grazing pasture covers greater than 1200kgDM/ha with minimum post-grazing covers of 1000kg DM/ha.
To achieve this within a farm system might mean having to reduce numbers of other stock classes – such as mixed-age ewes – or providing an alternative feed source, such as a forage crop.
“Regardless of what option you choose, monitor the hoggets to ensure targets are met,” says Paul.
“There are no magic bullets, but getting the feeding and liveweight correct are the major drivers of success.”
Hogget mating can be an efficient use of feed resources. The extra herbage required to feed seven pregnant hoggets, compared to seven non-pregnant hoggets, is roughly the same total feed demand as one pregnant mature ewe in winter.
Sire determines birthweight
Paul says there is a misconception that overfeeding hoggets in pregnancy can result in large lambs and a high incidence of dystocia.
B+LNZ-funded trials show there is minimal difference (around 300gms) in the birthweight of lambs born to very large hoggets (80kg) and small hoggets (50kg). Rather, you’re likely to see more problems as a result of under-feeding, than over-feeding. Well-grown hoggets have fewer problems giving birth.
“They need to be well-fed throughout pregnancy – and not just in late pregnancy – to ensure they continue to grow structurally.”
Paul says 70-80% of birthweight is determined by genetics, so sire selection has the greatest influence on birthing ease.
Legumes drive growth rates
Going into lambing, hoggets should be set stocked on relatively high pasture covers and those covers need to stay above 1200kgDM/ha.
Legume-based forage mixes generate the fastest growth rates in both lambs and lactating hoggets. Trials comparing hogget lamb growth rates on different forages showed lambs on:
- pasture (stocked at 10/ha) grew an average of 303gms/day
- herb mix (stocked at 14/ha) grew at 351gms/day
- lucerne (stocked at 14/ha) gained 403gms/day.
Early weaning
As hoggets typically lamb later than the mixed-age ewes, they have less time to recover body condition before they are mated as two-tooths.
Paul says early-weaning could benefit hoggets by giving them more time to gain condition, without compromising lamb performance.
Speed up genetic gain
Hogget lambs are often regarded as a bonus, but Paul says they can be so much more. By selecting the correct sires, hoggets’ lambs can be your replacements, effectively speeding up genetic gain.
Coupled with the correct management, mating hoggets with superior sires has the potential to improve on-farm productivity in both the short and long-term.
