Nutrients: Signs of Excess

In general, there is very little room for providing excess amounts of those nutrients that make up at least 0.1% of the diet.6 In some cases, as little as a 50% overage can result in toxicity.6 Trace minerals are the next most likely candidates for toxicity, as feeding 50-100 times the requirement may lead to health complications.6 The fat-soluble vitamins, particularly vitamins D and A, are the next most toxic to overdose, followed by the water-soluble vitamins.6 Nutrients which are unlikely to be toxic include: thiamine, riboflavin, pantothenic acid, folic acid, potassium, cyanocobalamin (vitamin B12), and vitamin C.5 The table5,7 below explains some of the signs and health problems that result from overdosing various nutrients.

Signs of Excess
  • Weight loss/poor weight gain
  • Gout
  • Behavioral changes (feather picking, rejection of food, regurgitation)
  • Death
  • Obesity
  • Fatty liver infiltration
  • Diarrhea
  • Oily feathers
  • Antherosclerosis
Vitamin D3
4-10 × requirement
  • Gout
  • Increased calcium absorption & bone resorption
  • Hypercalcaemia
  • Mineralization of soft tissue
  • Polyuria
  • Nephrocalcinosis
  • Hypercalcification
Vitamin A
20-100 × requirement
  • Weight loss
  • Decreased food intake
  • Swollen/crusted eyelids
  • Inflammation of mouth and/or nares
  • Decreased bone strength
  • Dermatitis
  • Yellow pigmentation on the sole of the feet
  • Hepatopathy
  • Hemorrhaging
Vitamin E
100 × requirement
  • Decreased growth
  • Anemia
  • Decreased bone mineralization
  • Decreased liver storage of vitamin A
Vitamin K
1000 × requirement
  • High mortality
  • Anemia
  • Hyperbilirubinemia
10 × requirement
  • Pruritus
  • Gastroenteritis
  • Vasodilation
Pyridoxine (B6)
50 × requirement
  • Decreased egg production
  • Infertility
2 × requirement
  • Increased mortality
  • Decreased use of vitamin B6
2.5% of diet
  • Nephrosis
  • Visceral gout
  • Renal gout
  • Hypercalcemia
  • Hypophosphotemia
  • Decreased food intake
20 × requirement
  • Decreased growth
  • Decreased egg production
  • Decreased egg quality
20-50 × requirement
  • Iron deficiencies
50 × requirement
  • Decreased weight gain
  • Weight loss
100 × requirement
  • Decreased egg weight
  • Decreased hatchability
  • Dermatitis
50 × requirement
  • Decreased growth
  • Hepatopathy
  • Death
10-20 × requirement
  • Gastroenteritis
  • Decreased food intake
  • Anemia
  • Decreased bone mineralization
  • Depression
2 × requirement, or if present in greater than the 2:1 calcium: phosphorus ratio
  • Decreased performance
  • Decreased calcium absorption
  • Nutritional secondary hyperparathyroidism
5-10 × requirement
  • Decrease in growth
  • Loss of appetite
  • Poor feathering
  • Polydipsia
  • Excessive thirst
  • Polyuria
  • Edema
  • Dehydration
  • Mortality
  • Reduced performance
  • Eventual development of hemosiderosis
  • Possibly hemochromatosis (change in skin pigment)
1000 × requirement
  • Antithyroidal or goitrogenic effects
  • Growth affected
  • Egg production affected
  • Hatchability affected
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