(a) Role of animals and birds in the propagation of zoonotic diseases in humans (10 marks) (b) Preparation and nutritive value…

(a) Role of animals and birds in the propagation of zoonotic diseases in humans (10 marks)

Animals and birds act as:

• Reservoir hosts, which maintain and shed the agent: dogs (rabies), cattle and buffaloes (brucellosis, bovine tuberculosis, anthrax), rodents (plague, leptospirosis), poultry and wild birds (avian influenza, salmonellosis), bats (Nipah virus) and cats (toxoplasmosis).
• Amplifying hosts, in which the agent multiplies before reaching humans, such as pigs and wading birds in Japanese encephalitis.
• Hosts for vectors that bite humans, such as monkeys and ticks in Kyasanur Forest disease.

Routes of spread to humans:

• Direct contact: bites, scratches, and handling of infected animals, aborted material and carcasses, an occupational risk for farmers, veterinarians and butchers.
• Food: raw milk, and undercooked meat and eggs.
• Inhalation of aerosols and dust from contaminated litter (Q fever, psittacosis).
• Vectors, and water or environment contaminated by urine and faeces.

Crowding, close contact with wildlife, live-animal markets and loss of habitat raise the risk. Control needs One Health cooperation: animal vaccination, pasteurisation, meat inspection and education.

(b) Preparation and nutritive value of Shrikhand (10 marks)

Shrikhand is a traditional Indian sweet made from strained curd (chakka), sugar and flavours.

Preparation:

1. Heat skim or standardised milk to about 85 °C and cool to 30 to 32 °C.
2. Inoculate with 1 to 2% lactic culture and hold for 12 to 16 hours to make dahi.
3. Drain the whey in a muslin bag or with a separator to get chakka.
4. Knead the chakka with powdered sugar (about 1 part chakka to 0.8 part sugar) to a smooth mass.
5. Add flavours and colour (cardamom, saffron, nutmeg, nuts, or mango pulp for amrakhand), then pack and store at 4 to 5 °C.

FSSAI standards give minimum fat and protein and a maximum sugar level. Shelf life is about a week under refrigeration.

Nutritive value: rich in energy (sugar and fat), milk protein of high biological value, calcium, phosphorus and B vitamins, and lactose is partly reduced by fermentation; live culture may give probiotic benefit. It is high in sugar, so should be eaten in moderation.

(c) Classification and processing of animal casings (10 marks)

Casings are the tubular envelopes that hold sausages.

Classification:

• Natural casings, from the intestines of hog, sheep, goat and cattle (small intestine, large intestine and caecum or "bung") and from stomach and bladder. They are edible and permeable. Sheep casings are narrow (about 16 to 24 mm) and hog casings wider (about 28 to 40 mm).
• Artificial casings: collagen (edible or non-edible), cellulose, fibrous, plastic and alginate, made in uniform sizes.

Processing of natural casings:

1. Collect fresh intestines at slaughter; strip the contents, fat and mesentery.
2. Wash, and scrape off the mucosa and outer layers (sliming), leaving the strong submucosa.
3. Soak, rinse, grade by diameter, length and quality, and test for leaks with air or water.
4. Preserve with dry salt or brine, tied in bundles, and store cool.
5. Before use, soak in warm water and flush out the salt.

(d) Preparation of meat emulsion and precautions during the process (10 marks)

A meat emulsion is a fine mixture of lean meat, fat and water in which fat globules are coated and held by salt-soluble muscle proteins (myosin, actin), used for sausages, frankfurters and nuggets.

Method:

1. Use fresh, chilled meat (0 to 4 °C), trim and grind it.
2. Chop the lean meat in a bowl cutter with salt (about 2%), curing salt or nitrite, phosphate and some ice, to extract proteins.
3. Add fat, then the remaining ice or cold water, spices and binders (starch, soy).
4. Chop to a fine, sticky, uniform paste.
5. Stuff into casings or moulds without air pockets.
6. Cook until the centre reaches about 70 to 72 °C, then chill.

Precautions:

• Keep the temperature below about 12 to 15 °C during chopping with ice, since heat denatures protein and melts fat, and the emulsion breaks.
• Follow the order of ingredients and correct fat and water levels, and avoid over- or under-chopping.
• Keep equipment clean, and nitrite within the legal limit.
• Cook to a safe core temperature, cool quickly and store cold.

(e) Disposal and utilisation of rabbit fur (10 marks)

Rabbit skin and fur are valuable by-products that should not be wasted.

• Removal: after slaughter and bleeding, the skin is removed as a cylinder (case skinning) starting from the hind legs, and flesh and fat are scraped off.
• Drying: the pelt is turned fur-side in, put on a wire or wooden stretcher and dried in a cool, shaded, ventilated place, not in the sun or near heat; it may be salted.
• Tanning and dressing: soaking, pickling and tanning (chrome or alum), then dressing and dyeing.
• Uses: garments, caps, gloves, collars, trimmings, toys and rugs; short hair for felt in hats; and glue from scraps.
• Angora rabbits give wool, which is sheared or plucked three to four times a year, and spun into yarn.
• Waste skin and trimmings can go for glue, gelatin or manure, and are never left to rot.