CAL: Trace elements Flashcards
Describe Se levels in UK soil
Generally deficient (soil originated from granite and volcanic rocks)
Why are most cases of Cu deficiency secondary diseases?
In the rumen, molybdenum, sulphur or iron can bind with copper making it unavailable to the animal.
Why is Cu important to animals? 4
involved in enzymes associated with myelin formation, erythropoiesis, collagen synthesis and pigmentation
Clinical signs - Cu deficiency
Swayback and hindlimb dysfunction (poor myelination of terminal spinal cord nerves)
Anaemia and lethargy (interrupted RBC formation)
Bone and CT abnormalities and spontaneous fractures (severe)
Unusual skin pigmentation, lightening of hair coat in dark coloured cattle
Poor thrift (young growing cattle)
Diarrhoea
Decreased milk yield in dairy (scant evidence)
Reduced fertility (cattle)
How do you administer cobalt/vitamin B12 to sheep? 2
Oral drench - cobalt
SC or IM injection - vitamin B12
Intra-ruminal bolus - cobalt
Clinical signs - Selenium/vitamin E deficiency - 4
White Muscle Diseases (WMD, classic sign, due to muscle cell necrosis, striated muscle cells are particularly susceptible to damage)
Neurological signs
Locomotor abnormalities (stiffness-recumbency)
Alimentary signs (indirect, inability to feed)
Poor growth rates (sheep and cattle, autumn)
Poor reproductive performance (sheep, possibly cattle, due to early embryonic loss)
Increased disease susceptibility and SCC levels (due to role in immune function, inconsistencies in evidence)
What does Se/vit E normally do in an animal?
Antioxidant function - protect cells against free radicals and lipid peroxidases
Which species/breeds are susceptible to copper deficiency?
Cattle and deer most commonly
Sheep rarely but breed variation (Scottish Blackface > Texel)
Which species/breeds are susceptible to Se/Vit E deficiency?
All species are equally susceptible
Which species/breeds are susceptible to cobalt deficiency?
Sheep most susceptible
Rare in cattle
Which TE is most associated with poor thrift?
Cobalt deficiency. That said, poor thrift associated with TE deficiency is often multi-factorial and poor nutrition and/or parasitism are also important contributors
Signs - cobalt deficiency
Poor thrift
2 types of swayback = ?
Congenital - newborn lambs, recumbent, tremors, poor coordination
Delayed/ enzootic ataxia - 2-4 month old lambs, certain sheep breeds, well-defined geographic areas, presents as progressive weakness of hindlimbs
When can WMD affect lambs?
Congenital - affected lambs are often stillborn or die soon after birth, typically it affects lambs at 2-6 weeks of age. Affected lambs have a sudden onset of stiffness progressing to recumbency
Which TE(s) have been associated with lameness/gait abnormalities?
Copper (swayback)
Se/Vit E (WMD)
Which TE(s) have been associated with possible reduced fertility?
Cu - weak evidence
Co - may not be a direct effect, rather poor ewe BCS
Se/VitE - early embryonic loss, evidence inconsistencies
Which TE(s) have been associated with possible increased disease susceptibility?
Se/Vit E
Which TE(s) have been associated with poor thrift?
Cu
Co - lambs, not adult cattle
Se/Vit E
Which TE(s) have been associated with recumbency?
Cu - swayback
Se/Vit E - WMD
How can the dietary status of sheep be assessed?
Compare the composition of forage/ration with somewhat arbitrary figure:
single figure ‘requirements’ (Co, Fe and Mn)
Expansive theoretical requirements (Cu, Se and Zn)
Why do TE demands rise in small, out-wintered lambs by up to 30%
when ewes mobilise body fat to meet energy deficits, there is meagre TE release from adipose tissue
Why don’t you test plants for TE levels and animals instead?
TE level vary markedly depending on: plant type part of plant where in field it is growing season level of soil contamination
animal absorption of TE will vary
Requirements vary with age and physiological status
How do you assess Se levels?
Small number (3) of blood samples
Blood or serum Se or glutathione peroxidase can be analysed
No body store
Little variation in animals grazing same pasture/forage
How do you assess Cu levels?
Stored in liver Much variation (especially if deficient) Take as many liver samples as possible (can be difficult so testing blood samples may be valuable to confirm clinical deficiency. For economic reasons, usually limited to 5-7 samples.) Adequate level (cattle) is >95 micromol/kg)
How do you assess Vitamin B12/Co levels?
No real store so test blood
Moderate degree of variation so take 10 samples, can get expensive so people tend to test 6-7 to reduce cost.
How do you interpret TE levels?
Not alone - in the light of history and clinical findings (especially poor thrift)
Also, even if an animal TE level falls into the marginal or low categories, it doesn’t mean there will be an economic response to supplementation.
Especially in cases of poor thrift, treatment/control trials are excellent in determining whether the TE levels are limiting impact on weight gain and response to supplementation Biologically sensible period of at least 8 weeks to allow any differences in weight gain to become apparent.
Which TEs can cause death if given in an overdose?
Cu - toxicity more common than deficiency in sheep. Overdose causes RBC lysis and acute/sub-acute/chronic death.
Co/Vit B12 - no reported toxicity but not desirable to be overdosed
Se - very toxic with overdose and leads to rapid death.
