Role of micronutrients in Animal health
Authors: Deepa Joshi, Arpita Sharma, Taramani Yadav and Pooja Gupta Soni

Introduction

Micronutrients or trace elements usually implies to the elements occurring relatively at low concentration (usually <100 mg kg-1) in the dry matter of living organism. Micronutrients are not only important for better crop productivity, but also essential for sustaining animal and human health. In animals they are required in diet for their overall improved health and also essential for production of egg, meat and milk. The importance of micronutrients can be very well realized by the fact that their deficiencies in animal diet can lead to restricted growth and reduction in animal productivity.

An animal which is deficient in a particular element is likely to show the physical signs of its deficiency which may be either 'clinical' or sub-clinical". Clinical signs are the signs which are externally visible on animal body and therefore their diagnosis is relatively simple and easy such as browning of hair in case of copper deficiency.

Subclinical deficiency symptoms are difficult to diagnose compare to clinical signs as the animal show no visible signs of deficiency in his body but overall production of animal gets restricted, such as loss of fertility through selenium deficiency and loss of immunity to infection through cobalt deficiency. Non-visibility of these symptoms is more problematic in the context that they can be more widespread thereby causing more harm leading to more loss of production.

Essential micronutrients and their major role in animals

Fe, Zn, Cu, Mn, Mo, Se, I and Co are the essential elements which play a pivotal role in animal health and each element play at least a major role in physiological functioning of animal.

Deficiency symptoms and the major role by micronutrients in ruminant livestock
Element Role Deficiency symptom / Diseases
Fe Protein and enzyme function. Blood haemoglobin. Anemia
Cu Haemoglobin formation, enzyme function, and pigments Anaemia, poor growth, bone disorders, infertility, brain and spinal cord lesions. Decolouration of hair.
Co Vitamin B12 function and energy assimilation. Poor growth, anaemia, loss of coat, low immunity to disease, infertility
Se Vitamin E function Poor growth, white muscle disease, infertility
I Thyroid gland function Goitre and reproductive failure
Mn Enzyme activation Enzyme activation
Zn Enzyme function Stiff and swollen joints, parakeratosis.
B Enzyme function Weak bones, poor immune function

Fischer (2008)

Requirement of micronutrients by animals (mg kg-1 of DM)

Element Young calf Growing bullock Cows Lambs Sheep
Fe 40 35 30 30 40
Cu 1.2 15 15 5 7
Co 0.11 0.11 0.10 0.1-0.2 0.1-0.2
Se 0.1 0.1 0.1 0.1 0.1
I in Winter 0.5 0.5 0.5 0.5 0.5
I in Summer 0.15 0.15 0.15 0.15 0.15
Mn 25 25 40 25 40
Zn 50 40 40 40 40
B 5 5 5 5 5


Different approaches to correct nutrient deficiency

It is important to take a balanced and holistic approach to treating micronutrient deficiencies in practical farm situations. It may be that providing multiple routes to solving a problem is appropriate such as (Fischer ,2008)

Treating the soil with fertilizers and nutrients particularly in which the soil and animal is likely to be deficient.

• Treating the fodder or herbage with micronutrients through foliar spray.
• Treating the animals by feeding him feeding blocks and licks.
• Supplementation of micronutrients through feed.
• Directly injecting the animals with nutrients

References:
Fischer, G. E. J. Micronutrients and Animal Nutrition and the Link between the Application of Micronutrients to Crops and Animal Health. 2008. Turk. J. Agric. For. 32: 221-233.

About Author / Additional Info:
I am currently pursuing Ph.d. in Agronomy from National Dairy Research Institute.