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Gilt management

Gilt management. Prof. Paul Hughes & Assoc. Prof. Roy Kirkwood. What are we trying to do when managing gilts ?. What are we trying to do when managing gilts ?. Ensure she has adequate body reserves to have a long, productive breeding life. What are we trying to do when managing gilts ?.

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Gilt management

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  1. Gilt management Prof. Paul Hughes & Assoc. Prof. Roy Kirkwood

  2. What are we trying to do when managing gilts ?

  3. What are we trying to do when managing gilts ? • Ensure she has adequate body reserves to have a long, productive breeding life

  4. What are we trying to do when managing gilts ? • Ensure she has adequate body reserves to have a long, productive breeding life • Then breed her as early as possible as long as this breeding time ensures a good first litter size

  5. What are we trying to do when managing gilts ? • Ensure she has adequate body reserves to have a long, productive breeding life • Then breed her as early as possible as long as this breeding time ensures a good first litter size

  6. What are “adequate body reserves” for a gilt ? • How much fat does she need ? • How heavy should she be ?

  7. What are “adequate body reserves” for a gilt ? • How much fat does she need ? • How heavy should she be ?

  8. What about targets for gilt fat levels ? • While it would be nice to target 18mm P2 backfat at 1st farrowing this is unachievable in many modern genotypes • Anyway, except for extremes of leanness, there appears to be little or no relationship between gilt backfat level & lifetime performance • This may reflect the fact that the vast majority of tissue mobilisation in young lactating females is protein not fat Adapted from Foxcroft & Patterson (2010)

  9. What are “adequate body reserves” for a gilt ? • How much fat does she need ? • How heavy should she be ?

  10. Why breed gilts at 135-150kg ? • <135kg>150kg • Low wt at 1st farrowing - High wt at 1st farrowing • Low body reserves at 1st farrowing - High gilt cost to 1st farrowing • High anoestrus rate after 1st weaning - High nutrient requirements • High risk of early culling - High risk of early culling • Low production over 1st 3 parities Adapted from Foxcroft & Patterson (2010)

  11. What are we trying to do when managing gilts ? • Ensure she has adequate body reserves to have a long, productive breeding life 2. Then breed her as early as possible as long as this breeding time ensures a good first litter size

  12. Conventionally this consists of 2 steps Birth 1. Stimulate puberty Puberty 2. Mate at a suitable time after puberty(2nd oestrus ?) Mating

  13. Stimulating puberty

  14. Methods Available to Stimulate Early Puberty • Boar contact - usually referred to as The Boar Effect • Stress • transport • management stressors (mixing & relocation) • Exogenous hormones • PG600 • Folligon & chorulon • GnRH

  15. Using boars to get gilts cycling • Start when gilts are 25-28 weeks old • Ensure gilts have at least 1.5m2 (preferably 2m2 ) of space • Use boar 10 months old + • Use regularly mating boar • Give full physical contact (same pen) • Give boar contact for 15-20 min daily – if it’s not working well: • Try a different boar • Split the boar contact into 10 minutes each in morning & afternoon • Expose gilts in groups of 12 or less

  16. Consider using a vasectomised boar

  17. Advantages of using vasectomised boars • Boars get regular matings • No need to supervise boar exposure periods • Get a further benefit in FR & LS

  18. Value of using a vasectomised boar Control gilts – not mated at 1st heat 84% 9.5 9.0 Mated with vasectomised boar at 1st heat 90% 10.7 10.1 Farrowing rate* 1st Litter Size* 1st Litter Size* * All data for 2nd heat matings with stock boar Sources: Bischof & Hughes, unpublished data, Riley & Foote (1999)

  19. Which selected gilts should be culled without being bred ?

  20. What is the value of those gilts that are slow to reach puberty when given boar contact ? Bred % Lifetime piglets born alive Retention at 3rd parity Fast responders* (<40d) 95 23.6 58 Slow responders 73 21.4 47 * Represents ~85-90% of selected gilts in most herds Adapted from Foxcroft & Patterson (2010)

  21. When to mate a gilt ?

  22. Before deciding when to mate the gilt be aware that she needs to be kept cycling if you’re not going to mate her at the pubertal heat.

  23. Boar contact and continued cyclicity in giltsPG600-induced puberty Boar contact YES NO Showing 2nd oestrus (%) 85 46 Having a 2nd ovulation (%) 82 59 Source: Paterson and Lindsay (1980)

  24. Boar contact and continued cyclicity in giltsBoar-induced puberty Boar contact YES NO Cycles/ 100 days 4.9 3.0 Short (<18d) cycles (%) 0 4 Long (<25d) cycles (%) 3 31 Source: Siswadi and Hughes (unpublished)

  25. Traditionally, gilts are mated at 2nd oestrus as it:- raises ovulation rate- possibly improves embryo survival ratethus facilitating production of a large first litter size

  26. At which heat should a gilt be bred ? Farrowing rate (%) Litter size (total) 1st. 72 10.1 2nd. 87 11.3 3rd. 88 11.4 4th. 91 11.4 Adapted from Kummer (2005)

  27. Feeding the gilt For the 2-3 weeks before mating she needs to be on full feeding Prior to that she can be restrictively fed if her weight is getting too high

  28. Gilt Nutrition & Egg Quality Feeding x Week of oestrous cycle Week 1 High Low High Week 2 High High Low Week 3 High High High Embryo survival rate 84% 82% 68% Almeida et al (2000)

  29. If using Regumate to have gilts ready for breeding at the best time to fit into mating batches etc. what are the rules ?

  30. Rules for heat synchronisation using Regumate • Not effective unless the gilt is cycling • Train gilts using oral dosing of canola oil for 4 days before using Regumate

  31. Effective Use of Regumate • Randomly cycling gilts • feed for > 14 days to ensure all gilts have completed their luteal phase. Gilts return ~5-6 days after the last dose • Known dates of oestrus • Feed from 12-14 days after the start of the previous oestrus until 6 days before planned breeding

  32. Oestrus timing after Regumate Percent of gilts Day after last Regumate feeding

  33. Suggested Gilt Management Framework

  34. Suggested Gilt Management Framework Select gilts at 22-23 weeks & 100kg+

  35. Suggested Gilt Management Framework Select gilts at 22-23 weeks & 100kg+ Start daily boar contact at 25-28 weeks

  36. Suggested Gilt Management Framework Select gilts at 22-23 weeks & 100kg+ Start daily boar contact at 25-28 weeks Mate gilts at 30-34 weeks Cull unmated gilts at 34 weeks

  37. Thank you

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