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Late gestation


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This presentation was prepared for the Blue Ribbon Sheep Forum in Storrs, CT (2/25/12).

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Late gestation

  1. 1. SUSAN SCHOENIAN (Shāy-nē-ŭn)Sheep & Goat SpecialistWestern Maryland Research & Education -
  2. 2.  Seventy (70) percent of fetal growth is occurring.  Important time for udder development and colostrum production.NEEDS   Rumen capacity is decreasing.  Voluntary feed intake of feed is less, especially during last two weeks.INTAKE 
  3. 3.  More feed -- but more importantly, a more nutrient-dense (better quality) diet. We want grain!  To compensate for reduced feed intake.  To meet demands of growing fetuses.  To support udder development and colostrum production.  To prevent pregnancy toxemia and milk fever.  To ensure the birth of strong, healthy lambs of moderate size (weight).
  4. 4.  Energy (TDN) is the nutrient most likely to be deficient, but protein (CP) can also be deficient in the diet, due to a reduced intake of feed. Nutrient requirements vary: ▪ Breed ▪ Size (weight) ▪ Age (lamb vs. mature) ▪ Number of fetuses ▪ Environment
  5. 5.  Concentrates are usually necessary to meet the increased energy needs of pregnant ewes, especially those carrying multiple fetuses. If a low-quality forage is fed, it may also be necessary to provide supplemental calcium (Ca) and/or protein (CP) in the concentrate diet. Corn is only an energy supplement.
  6. 6.  Disease risk  Pregnancy toxemia risk (TDN)  Milk fever risk (Ca)  Poorer immunity (CP) Higher neonatal mortality  Smaller, weaker lambs  Reduced colostrum quality and quantity. Poorer performance  Reduced milk yield  Reduced wool production (in the offspring) due to fewer secondary follicles.
  7. 7.  Pregnancy toxemia risk Milk fever risk (Ca) Ewes more likely to prolapse their vagina. Greater risk of dystocia (difficult birthing).  Too much internal fat  Oversized fetuses  Fat, lazy ewes Feed is expensive - why do you want to overfeed it?
  8. 8.  Low blood sugar (glucose). Caused by an inadequate intake of energy (TDN) during late pregnancy. Leads to a breakdown of fat (energy reserves) into toxic ketone bodies which overwhelm the capacity of the liver (also called “fatty liver disease”). Most commonly affects fat or thin ewes and those carrying multiple fetuses (also called “twin lamb disease”). Stress is another risk factor.
  9. 9. GOOD SOURCES POOR SOURCESFeed stuff % TDN Feed stuff % TDNCorn 88 Poor quality hay < 50Barley 84 Poor quality pasture < 50Oats 76 By-products < 50 [corn cobs, straw]By-products ~75[beet pulp, soy hulls, DDSG]Commercial (sack) feed ~72INTERMEDIATE SOURCESFeed stuff % TDNGood quality hay > 55Good quality pasture (low DM) > 60
  10. 10.  Calcium (Ca) requirements virtually double during late pregnancy . . . but you need to avoid excessive calcium, too. Milk fever is low blood calcium. It is caused by inadequate Ca in the diet or a failure of the ewe to mobilize Ca reserves. It can occur anywhere from six weeks before lambing to 10 weeks after. 1. Pre-partum (non-dairy ewes) 2. Post-partum (dairy ewes)
  11. 11. GOOD SOURCES INTERMEDIATE SOURCESFeed stuff % Ca Feed stuff % CaLimestone 34.0 Grasses 0.30-0.50Dicalcium phosphate 22.0 Soybean meal 0.28-0.38Trace minerals 14-18 Complete (sack) feed 0.55Dry kelp 2.72Balancer pellet 1.60Legume hays 1.3-1.5 POOR SOURCES Feed stuff % Ca Corn 0.02 Oats , wheat 0.05 Barley 0.06
  12. 12. Image source: Informed Farmers (Can) Soils in the Northeast are considered low in Se. During late gestation, selenium crosses the placenta to the fetuses. Low levels of selenium and/or vitamin E can result in . . .  White muscle disease (lambs) 1. Congenital vs. acquired 2. Cardiac vs. skeletal  Poor reproductive performance  Poor performance
  13. 13.  Free choice mineral mixes usually provide adequate selenium . . . but do not guarantee adequate intake. Adding a selenium-fortified mineral mix to a concentrate ration will ensure adequate intake of selenium and other minerals. Selenium and vitamin E can be also supplemented orally via gels or pastes.
  14. 14.  On farms with a diagnosed history of white muscle disease or selenium deficiency, Se/Vitamin E injections may be given per the advice of a small ruminant veterinarian.  Labeled dosage for Bo-Se® [Rx]  1 ml/40 lbs. (1 ml min) for lambs  Not labeled for lambs under 2 weeks of age Se Sedeficiency toxicity  2.5 ml/100 lbs. for ewes  Not labeled for pregnant ewes
  15. 15.  Make sure all ewes can eat at the same time. Make sure all ewes get their fair share of all feed. Pay particularly close attention to ewes that are old or compromised in some way. Separate pregnant ewe lambs from mature ewes and feed separately. Remove rams after breeding season and feed separately. Do not feed on the ground.
  16. 16.  Stress can predispose This is my pregnant ewes to many special time. Leave me alone. problems. Minimize stress during late pregnancy. Examples:  Missed feedings  Erratic feeding schedule  Shearing, crutching  Moving, handling  Mixing groups  Dogs  Visitors  Weather (be prepared)
  17. 17.  Lack of exercise may increase the chances of pregnancy toxemia and other problems. Daily exercise is recommended through-out pregnancy. Exercise can be encouraged by separating feed, water, and minerals. Fit, active ewes have fewer problems.
  18. 18.  Vaccinate pregnant ewes approximately 1 month (but at least 2 weeks) before they are due to lamb. Lambs will acquire temporary, passive immunity via the colostrum -- provided they consume adequate colostrum What is adequate? ~10% of BW in first 24 hours
  19. 19.  Ewes not previously vaccinated will require two vaccinations, 3-4 weeks apart. If the dam was not vaccinated or the lamb did not consume adequate colostrum, the tetanus antitoxin should be given at the time of docking and/or castrating, especially if rubber rings are used. Lambs from vaccinated dams should be vaccinated twice, 3 to 4 weeks apart, starting at 6 to 10 weeks of age.
  20. 20.  Ewes suffer a temporary loss of immunity to gastro- intestinal worms around the time of parturition.  Fecal egg counts increase If lambing occurs in the spring, the egg rise will coincide with the hypobiotic (dormant) larvae resuming their life cycles. The periparturient egg rise is the primary source of infection for new lambs.
  21. 21.  Traditional approach  Deworm all ewes prior to lambing (2-4 weeks prior). ▪ Use an anthelmintic that is effective against hypobiotic larvae (e.g. ivermectin). New approaches  Increase protein level in late gestation ration. How much?  NRC by 30%  Use the FAMACHA© system and Five Point Check© to determine which ewes require deworming.
  22. 22.  In feed or mineral  Why? [no withdrawal period] 1. FDA approval: to prevent 1. Bovatec® coccidiosis in lambs. 2. Deccox®  Kill or inhibit coccidia 3. Rumensin® [Rx] 2. As an aid to prevent abortions caused by Toxoplasma gondii. 3. Rumen modifier:  propionic acid  by-pass protein  digestive problems  methane gas Coccidiostats, especially Rumensin® can be toxic to equines and dogs.
  23. 23.  Why?  To prevent abortion. 1. If the flock has a history of diagnosed abortions that can be controlled with antibiotics, e.g. Chlamydia, Vibrio. 2. In the event of an abortion storm. How? 1. Feed chlortetracycline (aureomycin) at a rate of 80 mg/head/day during the last 6 weeks of gestation [OTC]. 2. Inject oxytetracycline (LA- 200) at two week intervals during late gestation [Rx].
  24. 24.  Results in cleaner, drier, healthier environment for ewes and especially lambs. Shorn ewes are less likely to lay on their lambs. Shorn ewes are more likely to seek shelter for lambing. Shorn ewes take up less space in the barn and around feeders. Results in cleaner fleeces. But . . . shorn ewes require shelter and more feed. Image by Kelly Cole
  25. 25. FACILITIES Clean, dry, draft-free building  Drop area  Jugs (small pens for bonding) e.g. 5 ft. x 5 ft  Individual feeders and waterers  Grafting stanchion  Mixing pens Clean, well-rested pasture  Shelter  Emergency jugs
  26. 26. SUPPLIES (partial list) Colostrum source Esophageal feeding tube OB sleeves and lubricant Disinfectant for dipping navels Prolapse harness or spoon Needles and syringes Nipples or teats Lamb milk replacer Propylene glycol Calcium Antibiotics Thermometer Record keeping booklet More…
  27. 27. DO’S DON’TS Increase nutrition (gradually)  Overfeed Feed pregnant ewe lambs  Underfeed separately Encourage daily exercise  Stress ewe Minimize stress  Introduce new animals Vaccinate for CD-T  Change groupings Manage periparturient  Leave rams in egg rise  Worry Feed a coccidiostat Shear or crutch ewes Prepare facilities Gather/inventory supplies
  28. 28. Lambing should be fun! Thank you for your attention. Any questions?Susan