Farm Animal Metabolism and Nutrition

effects include haemolytic anaemia, lesions
in the liver, kidney and central nervous
system and alterations in immune and
endocrine function. The net result is a
depression in food intake, growth and
reproductive performance, but other effects
such as diarrhoea and photosensitization
may also occur with certain toxicants. The
secondary metabolism of fungi results in
the elaboration of deleterious substances
known as mycotoxins. Compounds of
significance include aflatoxins, ochratoxins,
Fusarium mycotoxins, endophyte alkaloids,

phomopsins and sporidesmins. Many of

these mycotoxins also adversely affect

digestive morphology and rumen function

and act on other organs to cause hepato-

genous photosensitization, nephropathy,

neurotoxicity and reproductive dysfunc-

tion. There is increasing awareness that a

number of plant and fungal toxicants may

occur together to precipitate additive or

even synergistic effects in farm animals.

Consequently, major difficulties may be

anticipated in future attempts to establish

tolerance limits and regulatory guidelines

Anti-nutritional Factors and Mycotoxins 401

Table 18.7.Examples of worldwide guidelines and regulations for plant and fungal secondary compounds.

Secondary Maximum
Countries compounds Commodities levels Status

Worldwide Condensed tannins Pasture and browse plants 40 Advisory
(g kg^1 DM)
EU Total glucosinolates Rapeseed 20–35 Statutory (for
(μmol g^1 ) payment of
subsidy)
UK Free gossypol Straight and complete 20 Statutory
(mg kg^1 ) feedstuffs except:
cottonseed cake or meal 1200
complete feedstuffs for
cattle, sheep and goats 500
complete feedstuffs for
poultry and calves 100
UK HCN Straight and complete 50 Statutory
(mg kg^1 ) feedstuffs except:
linseed 250
linseed cake or meal,
cassava products 350
complete feedstuffs for chicks 10
EU Aflatoxin B 1 (μg kg^1 ) Straight feedstuffs except: 50 Statutory
groundnut, copra, palm kernel,
cottonseed, babassu, maize
and products derived from the
processing thereof 20
Complete feedstuffs for cattle,
sheep and goats (with the
exception of complete
feedstuffs for calves, lambs
and kids) 50
Complete feedstuffs for pigs
and poultry (except those for
young animals) 20
Other complete feedstuffs 10
Aflatoxin M 1 (mg kg^1 ) Milk/milk products 0.5 Statutory
Ochratoxin A (μg kg^1 ) Cereals and cereal products 4 Advisory
USA/ Deoxynivalenol Animal feed 5–10 Advisory
Canada (mg kg^1 )