(a) Mention the general functions of minerals in animals. Justify the importance of Vitamin D in optimum calcium and phosphorus…

(a) General functions of minerals; importance of vitamin D in calcium and phosphorus nutrition

Functions of minerals. Minerals are needed for: (1) skeletal and dental structure (calcium, phosphorus, magnesium) and keratin and connective tissue; (2) osmotic pressure and water balance (sodium, potassium, chloride); (3) acid-base balance (phosphate, bicarbonate, electrolytes); (4) nerve impulse and muscle contraction (Na⁺, K⁺, Ca²⁺, Mg²⁺); (5) enzyme activation and cofactors (zinc in carbonic anhydrase, copper in cytochrome oxidase, manganese, selenium in glutathione peroxidase); (6) oxygen transport and energy metabolism (iron in haemoglobin and myoglobin, phosphorus in ATP); (7) hormone formation (iodine in thyroxine, cobalt in vitamin B₁₂); and (8) blood clotting (calcium) and immunity and reproduction (zinc, selenium).

Vitamin D. Cholecalciferol (D₃) is made in the skin from 7-dehydrocholesterol by sunlight and is also obtained from sun-cured hay and feed; ergocalciferol (D₂) comes from plants. It is hydroxylated to 25-hydroxy vitamin D in the liver and to 1,25-dihydroxy vitamin D (calcitriol) in the kidney, stimulated by parathyroid hormone (PTH) and low phosphate. Calcitriol increases calcium-binding protein (calbindin) and intestinal absorption of calcium and phosphorus, promotes their renal reabsorption, and with PTH mobilises bone mineral when blood calcium falls, while supporting bone mineralisation. Deficiency causes rickets in young animals, osteomalacia in adults and poor Ca:P utilisation even when their dietary levels are adequate, and milk fever and poor production in high-yielding cows. A Ca:P ratio of about 1–2:1, adequate sun exposure or supplementation, and avoidance of excess (toxic calcification) give optimum nutrition.

(b) Physiological functions of plasma proteins

Plasma proteins (about 6–8 g/dl) are mainly made in the liver, except immunoglobulins, which come from plasma cells. They are albumin, globulins (α, β, γ) and fibrinogen. Their functions are:

• Colloid osmotic (oncotic) pressure, mainly by albumin, which retains fluid in the vessels; low albumin causes oedema, as in liver disease, nephropathy and heavy parasitism.
• Transport: albumin carries fatty acids, bilirubin, calcium, drugs and hormones; transferrin carries iron; ceruloplasmin carries copper; lipoproteins carry lipids; and thyroxine- and cortisol-binding globulins carry hormones.
• Immunity: γ-globulins (IgG, IgM, IgA, IgE) neutralise pathogens, and complement proteins and acute-phase proteins (haptoglobin, C-reactive protein) help defence.
• Blood coagulation: fibrinogen, prothrombin and other clotting factors.
• Buffering: proteins contribute to acid-base balance and maintain blood viscosity.
• Protein reserve: they supply amino acids in starvation, and enzyme inhibitors such as α₁-antitrypsin protect tissues.

(c) Feeding and management of animals in flood-affected conditions

Before and during the flood. Move animals early to high ground or raised platforms, secure identification, keep feed, fodder and mineral mixture stored above water level, and keep silage, hay or dry fodder bales ready.

Feeding. Give clean dry roughage (hay, dry straw, urea-treated straw), with a little concentrate or energy feed in small, frequent portions; avoid mouldy, wet or flood-damaged fodder because of mycotoxins; introduce green fodder gradually. Provide clean, disinfected water (potassium permanganate or chlorination), a mineral mixture and salt, vitamin A and E supplements, and urea-molasses mineral blocks if fodder is scarce. Lactating and pregnant animals need priority.

Management and health. Give clean, dry bedding and keep animals off waterlogged ground. Control footrot, dermatitis and mastitis with footbaths (copper sulphate) and hygiene. Vaccinate against haemorrhagic septicaemia, black quarter, anthrax, FMD and enterotoxaemia, deworm and control flies and ticks, and treat snakebite and pneumonia. Dispose of carcasses safely by deep burial with lime, and rehabilitate with fodder depots and veterinary camps through State animal husbandry departments.