Last update: September 30, 2013 09:22:55 AM E-mail Print

 

FLOCK HEALTH DURING DROUGHTS


Modern small stock breeds have been bred for high levels of production.  This has changed the priorities of the metabolic processes.  As the nutrient resources become more limiting, the available energy, protein and other nutrients are reserved for the survival functions of the body.  This varies between breeds.

Merino sheep will reduce the supply of resources to the wool growth and muscles whilst maintaining a pregnancy.  Dorper sheep will more readily abort the fetus but maintain muscle mass.

The immune system is very often neglected in high producing animals that suffer from malnutrition.

One of the most common problems during droughts is the failure of transmission of colostrum to the lamb or kid.  This results in lambs with very poor immunity especially against clostridial diseases.  The feed intake is also abnormal, less palatable feeds are consumed, even toxic or irritating plants that will not normally be part of the diet are consumed.  Supplementation will also lead to the intake of higher than normal levels of, for example grains and urea.

The results in an abnormal and often unstable rumen and gut flora and Enterotoxaemia will occur at a much earlier stage than what is usually found. Lambs start dying from Pulpy Kidney disease at 3 to 4 weeks of age.  It is therefore recommended, in a drought situation to do the following:

  1.  Vaccinate lambs from the age of 4 weeks with single antigen Pulpy Kidney vaccine, alum based (Enterotoxaemia Alum Precipitated OBP G1350 or Pulpyvax MSD G2192).
  2. Repeat the vaccination every six weeks up to the normal weaning age.
  3. Boost the lamb’s immunity with vitamin A and trace elements 10 days after the first vaccination (Embamin TE + Embavit, Lionel’s Vet).
  4. Do not drench with anthelmintics until at least 10 days after the first Enterotoxaemia vaccination.
  5. Early weaning of lambs will be of benefit for both the ewe and the lamb.  Early onset of creep feeding will make it possible to wean lambs at 50 days (please enquire about managing early weaning).  

We have had numerous cases of lambs dying from enterotoxaemia (Bloednier) at 3 to 6 weeks old over the past weeks.  Lamb dysentery (Bloedpens) usually occurs in lambs under 3 weeks old.

Adult sheep will also need additional care:

  1.  Severe nutritional stress, especially resulting low levels of protein may lead to reduced immunity.  Recovering animals should receive a booster against the common diseases especially enterotoxaemia.
  2. Animals with reduced immunity are more prone to bankrupt worm species and kraal problems such as Trichuris (Whipworm) and Strongyloides (White Bankrupt Worm)  Immunity can be boosted with vitamins and trace elements.
  3. Treatment for helminth parasites may be required even though the normal response is that it is not required during a drought.  Monitoring fecal egg counts is very important when non blood sucking parasites are a problem.  Wireworm is seldom present during droughts, however animals are more susceptible.
  4. Peer group management should be applied during drought feeding.  Flocks should be divided into groups according to age, sex, size, condition score, pregnancy status and breeds as required to reduce competition during feeding.
  5. Feeding every second day is less stressful than daily feeding if there is no natural grazing available.
  6. Feed close to the water, close to home and near shade to reduce energy wastage and to increase levels of observation.
  7. The use of urea should be carefully monitored.  If, for example 1% urea is included in a full feed, 1 kg of feed will include 10g of urea which can be fatal.  Dominant animals may eat more than this even if the average intake is for example 900g (the recommended DM intake of a 50 kg sheep for maintenance).  Also bear in mind that the rumen flora may not be very active resulting in reduced conversion of urea into protein.
  8. Grain overload and rumen acidosis is a common problem even with alkali treated maize if the intake of grain is more than 300 g to 500 g per day.   

After adequate rain the natural pastures have very low nutritional levels initially.  Malnutrition may still be very serious.  We advise that supplementation should only be decreased once the alternative feeds are mature enough to supply animal’s needs.

We also stress the fact that animals that have suffered severely during a drought may need to be vaccinated as soon as they pick up condition to restore their immunity.

Please feel free to contact me for more information.

Dr. Johan A van Rooyen M.Med.Vet.,M.B.A., M. in Sust. Agric. PDTE 

State Veterinarian:  Research and Training

Staatsveearts:  Navorsing en Opleiding

Grootfontein Agricultural Development Institute

Grootfontein Landbou-navorsingsinstituut

Cel: 082 463 3087  Tel 049 842 1113 Ext. 6632

Facs: +27 49 842 4352 Facs-email 0866338928

E-mail: JohanVR@nda.agric.za

CC:  flocprotec@telkomsa.net