Lamb Production and Husbandry

Lamb Production and Husbandry

• Breeding Management
  We are trying to produce as many fast growing good conformation lambs as possible.
  We aim for 200 lambs sold for every 100 ewes mated.
  We use prolific crossbred ewes which also have good mothering ability. Diet also plays a part in the amount of lambs produced.
  Rams are meat breeds such as Texel and Suffolk.


• Birth, Growth Rates and Puberty
  Lambs weigh 3 – 5kg at birth.
  They are slaughtered at 30 – 40kg depending on breed and age.
  Ewe lambs reach puberty at about 40kg


• Reproduction
  Sheep are seasonally polyoestrous. This means they only come into heat during a certain period of the year, September to February.
  The oestrous cycle is 17 days and oestrous lasts for 36 hours.
  The gestation period is 149 days.


• Synchronised Breeding
  Traditionally rams go in with ewes in early September and stay there for 6 – 8 weeks. This leads to a very drawn out lambing season.
  Oestrous can be synchronised artificially leading to shorter breeding season and therefore compact lambing which eases flock management.
  Progesterone impregnated sponges are placed in the ewes’ vagina and left for 12 – 16 days. This prolongs the life of the corpus luteum.
  When the sponges are removed all at the same time the sheep come into oestrous all at the same time within a few days.


• Breeding out of Season
  This is breeding sheep in July/August to ensure lambs are born early enough to have them ready for slaughter for the Easter market when prices are highest.
  Place sponges in vagina the same as for synchronised breeding but when they are removed give the sheep an injection of another hormone called Pregnant Mare Serum Gonadotrophin (PMSG).
  If synchronised ram ratio to sheep is 1:10 but if not synchronised it is 1:40.


• Breeding Systems in Ireland
  •Two breeding systems are employed: early lamb and mid-season lamb.


• Flushing
  The farmer achieves this by stocking ewes heavily (25-30/ha) on bare pasture sometime between weaning and mating.
  Then 3-4 weeks before the mating season they are stocked lightly ( 15-18/ha) on better pasture.
  Flushing leads to:
  –More eggs released at ovulation i.e. more twins and triplets
  –More regular heat periods
  –Higher conception rates i.e. less barren ewes
  –Better attachment of the embryo to the uterine wall


• Ram Effect
  Some ewe breeds can be encouraged to ovulate six weeks earlier than normal by the sudden introduction of the ram.
  Rams produce pheromones which can stimulate the oestrus cycle in the ewes.
  Only successful with some breeds and if the ram and ewes are kept 2 km apart for six weeks before mating.
  Ram effect can help synchronise breeding without sponging.


• Preparation for Mating/Flushing
  Ewes should be in BCS of 3.5-4.0 at the beginning of the mating season.
  This will result in high conception rates.
  Flushing ewes involves having them improving condition during the mating season. In other words bring the ewes from a low to a high plane of nutrition.


• Mating
  Ram should be in good condition, feet should be pared and excess wool around eyes and sexual organs should be clipped.
  The normal ratio of ram:sheep is 1:40 but this should be reduced to 1:10 if sheep are synchronised.
  Keep accurate breeding records so we know what lambing dates will be.
  We do this by putting a marker dye on the ram’s chest so he marks each ewe as he mounts her. This is called a raddling harness and the dye is changed every 17 days to pick up repeat services.
  Ewes that come into oestrus repeatedly should be culled.


• Mating to Lambing
  Continue grazing sheep on good quality grass for 3 – 4 weeks after mating is finished to ensure proper embryo development and attachment to the uterine wall.
  In mid pregnancy (weeks5 – 15) ewes can be fed on a moderate plane of nutrition as they only need to maintain their weight. Keep on grass and when it runs out feed silage or hay.
  75% of foetal growth occurs in the last 2 months of pregnancy and so hay or silage should be supplemented with concentrates (15% CP).
  Steaming up involves feeding twin bearing sheep 0.1kg of concentrates per day 7 weeks from lambing and building this up to 0.7kg per day at lambing. This helps to prevent twin lamb disease (pregnancy toxaemia).


• Housing
  Ewes should be housed before lambing for a number of reasons:
  –Land is rested
  –Easy inspection of ewes
  –Less chance of dog attacks
  –Easier to feed concentrates
  –Easier to vaccinate
  –Warmer for lambs


• Lambing
  Keep accurate breeding records so you know when sheep are going to lamb.
  Have sheep scanned earlier so you know which have twins or triplets.
  Inspect regularly during lambing and get veterinary assistance if there is any serious problem.
  Small or weak lambs must be carefully minded. Feeding colostrum and maintaining body temperature are vital. Chilled lambs are heated up using an infrared lamp or a hot box. In severe cases a glucose injection may be needed.
  A fostering crate can be used to put a triplet on a ewe that had just one lamb.


• Rearing Lambs
  Growth rate of lambs depends greatly on milk production of ewe.
  The high feeding level from before lambing should be continued after lambing.
  Feed silage and concentrates (15% CP) until spring grass is available.
  After a time milk is less important and grass and concentrates are more important in the diet of the lambs.
  Lambs being produced for the Easter market must be creep fed better grass and concentrates.


• Weaning and Post-Weaning
  Lambs and ewes are separated for a period of 7 days, during which time the ewes go dry.
  During this time the ewes should be examined for mastitis and if they have it cull them.
  Lambs are put on good quality grazing to keep them growing well while ewes are put on bare pastures until it is time to flush them again.


• Diseases of Sheep
  Pregnancy Toxaemia (twin lamb disease)
  –Caused by inadequate nutrition in late pregnancy.
  –Only in ewes with twins or triplets
  –Ewes try to mobilise body fat reserves which causes liver malfunction
  –To prevent it sheep should be steamed up.
  –Concentrates must be fed at this time because the rumen is too small (due to foetal growth) to take in enough bulky feeds to meet her requirements.


• Diseases of Sheep
  Chill/Starvation of Lambs
  –Most common cause of death in young lambs
  –Caused by insufficient intake of colostrum and/or exposure to severe weather conditions
  –Common in mountain production as lambing usually takes place outdoors
  –To prevent:
  •Feed ewe well in late pregnancy to ensure healthy active lamb and good milk supply
  •Supervise lambing
  •Ensure intake of colostrum within one hour of birth
  •Lamb indoors


• –To Treat:
  •Starved lambs should be fed colostrum immediately, use a stomach tube if necessary
  •Chilled lambs should be dried, warmed and fed
  •Place in a hot box or under an infrared lamp
  •Severely chilled lambs (<37OC) should be given a sterile injection of glucose into the body cavity


• Diseases of Sheep
  Clostridial Diseases:
  –Soil borne bacteria that cause a variety of diseases such as lamb dysentery, pulpy kidney, tetanus, braxy, blackleg, black disease.
  –To prevent vaccinate ewes two weeks before lambing.
  –Lambs born to vaccinated ewes acquire some disease resistance from colostrum


• Diseases of Sheep
  Foot Rot
  –Highly contagious disease caused by Fusiformis bacteria
  –First sign is scald between toes which spreads to sole of foot and up under horn causing horn to separate from tissue
  –Severe lameness
  –Commonly occurs in lowland sheep production on wet soils and in unhygienic winter housing.
  –To prevent:
  •Pare hooves to expose infected tissue and footbath to kill the bacteria. Use a 10% solution of formalin or copper sulphate.


• –To Treat
  •Animal should be isolated.
  •Carefully pare foot and treat with an antibiotic aerosol spray.
  •Keep separate from the rest of the flock until cured.
  •If there is a known problem all sheep should be moved to clean pasture and the infected pasture should be rested for at least 14 days which is the lifespan of the Fusiformis bacteria.


• Diseases of Sheep
  
  
  
  1. Orf
  
  
  
  –A viral disease which is highly infectious
  –A zoonose
  –Wear gloves and protective clothing when handling infected sheep
  –Causes scabby mouth and can be fatal
  –To prevent vaccinate ewes before lambing and lambs when they are four weeks old.


• Diseases of Sheep
  
  
  
  1. Fly strike (Maggots)
  
  
  
  –External parasitic disease caused by maggots (larvae) of green bottle and blue bottle flies which are active from May to September.
  –They are attracted to dirty fleece where they lay eggs that hatch in a few days.
  –The maggots feed on skin and flesh for a few days before falling onto ground to complete life cycle.
  –Infected animals fail to graze or thrive properly.
  –Animals may die from blood poisoning
  –To prevent (a) have good stomach worm control (b) clip (dag) dirty fleece (c) dip sheep with a summer dip


• Diseases of Sheep
  Sheep Scab
  –Highly infectious external parasitic disease caused by mange mite, Psoroptes ovis. Notifiable disease.
  –Symptoms are nervousness, nibbling and biting at affected area, scabs, wool loss, death.
  –Mange mites are active from October to March, they bite and pierce the skin forming swellings that burst and form scabs.
  –To prevent dip sheep between September 15 and January 31 with a DAFF approved dip.


• Diseases of Sheep
  Some other diseases of sheep are:
  –Cobalt pine caused by a lack of cobalt.
  –Swayback caused by a lack of copper.
  –Stomach and Intestinal worms as with cattle
  –Liver fluke
  –Naval ill/joint ill