(a) Describe the physical, chemical and microbiological examination of blood stains required for veterolegal purposes. (20…

(a) Examination of Blood Stains for Veterolegal Purposes Veterolegal cases, such as illegal slaughter of cattle under state cow-protection laws, poaching under the Wildlife (Protection) Act, 1972, cruelty cases and livestock theft, often turn on whether a stain is blood, whether it is animal or human, and from which species. Evidence must meet the standards of the Bharatiya Sakshya Adhiniyam, 2023.

Collection and preservation: photograph the stain in place, then take the stained article, or scrape or swab the stain (with a control sample from an unstained area), air-dry it, pack it in paper envelopes (not plastic, which causes putrefaction), seal and label it, and record the chain of custody from the scene to the laboratory.

1. Physical examination

• Colour and age: fresh blood is bright red, turning reddish-brown and then brown-black over days as haemoglobin changes to methaemoglobin and haematin. The stain's shape, size and distribution (drops, spurts, smears, drag marks) help reconstruct events.
• Microscopy: in fresh or moist stains, intact red cells can be seen. Non-nucleated, round cells indicate mammals (oval in camels); nucleated, oval cells indicate birds, reptiles and fish. Hair, feathers, scales or tissue fragments in the stain help identify the species.
• Ultraviolet light: blood stains absorb UV and appear dark, which helps locate faint stains.

2. Chemical examination

• Presumptive (screening) tests depend on the peroxidase-like activity of haem. The benzidine test gives a blue colour but is now replaced by tetramethylbenzidine (TMB) because benzidine is carcinogenic. The phenolphthalein (Kastle–Meyer) test gives a pink colour, leucomalachite green gives a green colour, and luminol gives blue chemiluminescence in darkness for invisible or washed stains. These are sensitive but not specific, since plant peroxidases and some metals also react.
• Confirmatory tests prove the presence of haemoglobin. The Teichmann (haemin crystal) test heats the stain with glacial acetic acid and sodium chloride to form brown rhombic haemin crystals. The Takayama (haemochromogen) test uses pyridine and glucose in alkali to form pink, feathery haemochromogen crystals, and works even on old stains. Spectroscopy shows the characteristic absorption bands of haemoglobin derivatives.

3. Species identification (serological and molecular)

• Precipitin test (Uhlenhuth): an extract of the stain is layered with species-specific antiserum (anti-human, anti-bovine, anti-caprine and others); a precipitate ring shows the species. Variants include gel diffusion (Ouchterlony) and crossed-over immunoelectrophoresis.
• ELISA with species-specific antibodies.
• DNA methods: PCR of mitochondrial genes (cytochrome b, 12S rRNA) identifies the species from very small or old stains, for example to establish cow or buffalo origin of meat and blood, or to identify wildlife species. DNA profiling can link a stain to an individual animal.

4. Microbiological examination

• Pathogen detection: culture and microscopy of stains, soil or hides from a suspected anthrax death show Bacillus anthracis (capsulated, square-ended bacilli; McFadyean's reaction with polychrome methylene blue). The Ascoli thermoprecipitation test detects anthrax antigen even in putrefied tissues or dried hides.
• Other uses: bacterial or fungal growth and putrefaction also affect how far a stain can still be analysed, and are considered in interpreting its age, although microbial growth is not a precise clock.

Interpretation and report: the expert reports whether the material is blood, its species (and, where possible, the individual), and the limitations of each test, and keeps the remaining sample for the defence.

(b) Reconstituted and Recombined Milks Definitions (International Dairy Federation): reconstituted milk is made by adding water to milk powder (whole milk powder or skim milk powder); reconstituted skim milk results when only skim milk powder is used. Recombined milk is made by combining milk-fat (anhydrous milk fat or butter oil) and milk solids-not-fat (usually skim milk powder) with water, so that the fat has to be emulsified back into the milk.

Manufacturing process

1. Water: use potable, soft water, heated to about 40–50°C for rapid dissolution.
2. Mixing: add the powder through a high-shear mixer, powder funnel or tri-blender, avoiding lumps and foaming; about 100 g of skim milk powder per litre gives skim milk of about 9% solids-not-fat.
3. Hydration: hold the mix for about 1–2 hours (or overnight chilled) so that proteins fully hydrate, which removes the chalky taste.
4. Deaeration: remove air incorporated during mixing.
5. Fat addition (for recombined milk): melt butter oil or anhydrous milk fat at about 45–50°C and meter or inject it into the warm skim base.
6. Homogenisation: two-stage homogenisation (about 150–200 bar) is essential for recombined milk, to create stable fat globules coated with protein and prevent creaming; it is also used for reconstituted whole milk.
7. Heat treatment and packing: pasteurise (HTST 72°C for 15 seconds) or UHT-treat, cool to below 5°C, and pack; standardise fat and SNF to the FSSAI standard for the declared class (for example toned or standardised milk).

Comparison

• Raw materials: reconstituted milk uses powder and water only; recombined milk uses SMP, milk fat and water, and sometimes fresh milk as well.
• Fat: in reconstituted milk, any fat comes from whole milk powder; in recombined milk it is added separately and can be adjusted to any level.
• Homogenisation: this is optional for reconstituted milk but essential for recombined milk.
• Flavour: both may have a slight cooked or powdery flavour. Reconstituted whole-milk powder may give an oxidised flavour on storage, while recombined milk made with fresh milk fat tastes closer to fresh milk.
• Storage of raw materials: SMP and butter oil keep longer than whole milk powder, whose fat oxidises, so recombining gives flexibility.
• Cost and use: both let dairies use flush-season surplus, stored as powder and butter oil, to meet lean-season demand, and supply regions with little fresh milk. In India, the toned milk pioneered at Aarey (Mumbai) blends high-fat buffalo milk with reconstituted skim milk, and dairies reconstitute or recombine milk in the lean summer season.
• Nutrition: both are nutritionally close to fresh milk, although heat-sensitive vitamins fall slightly; fortification with vitamins A and D is common.
• Labelling: consumers should be told when milk is reconstituted or recombined.

(c) Stunning Techniques for Humane Slaughter Stunning makes the animal unconscious and insensible to pain, instantly or without distress, until death by bleeding. It is required by the WOAH Terrestrial Animal Health Code and by India's Prevention of Cruelty to Animals (Slaughter House) Rules, 2001, while Section 28 of the PCA Act, 1960 saves slaughter in a manner required by religion.

1. Mechanical (percussive) stunning

• Penetrating captive bolt: a bolt driven by a blank cartridge or compressed air (pneumatic) enters the skull and damages the cerebral cortex and brain stem, causing immediate unconsciousness. It is used in cattle, buffaloes, sheep, goats and horses. In cattle the bolt is placed at the frontal position, where lines from each eye to the base of the opposite horn cross; in horned sheep and goats it is placed behind the horns, aimed towards the throat.
• Non-penetrating (mushroom-head) captive bolt: it causes concussion without penetration, and is used for calves, sheep and poultry; it is less reliable in adult cattle.
• Firearms: used for large or dangerous animals in the field.

2. Electrical stunning

• Head-only: electrodes (tongs) are placed on either side of the head so that current passes through the brain and causes an epileptic seizure and unconsciousness. It is reversible, so the animal must be bled within about 15 seconds. Minimum currents are about 1.0 A for sheep and goats, 1.3 A for pigs and 1.28 A for adult cattle, applied for at least a few seconds.
• Head-to-body (head-to-chest): current passes through the brain and then the heart, causing cardiac fibrillation, so the animal does not recover. It is better for welfare.
• Poultry water-bath stunning: birds are shackled and their heads pass through electrified water, needing about 100 mA per bird for broilers; shackling itself is stressful.

3. Controlled atmosphere (gas) stunning

• Carbon dioxide: at 80–90% or more, for pigs, groups of which are lowered into the gas in gondolas; it causes unconsciousness through brain acidosis, but high concentrations are aversive and cause breathlessness before unconsciousness.
• Inert gases: argon or nitrogen (with less than 2% oxygen) cause unconsciousness by anoxia with less aversion.
• Multi-phase CO2 and low atmospheric pressure stunning (LAPS): used for poultry in crates, avoiding live shackling.

Assessment of effective stunning and welfare: an effectively stunned animal collapses immediately and shows no rhythmic breathing, no corneal or palpebral reflex, fixed dilated pupils, a relaxed jaw with the tongue hanging out, and no vocalisation or righting attempt. Tonic spasm followed by involuntary paddling is normal after captive bolt or electrical stunning. Bleeding (sticking) should follow quickly: within about 60 seconds for captive bolt and about 15 seconds for head-only electrical stunning. Welfare also depends on calm handling, restraint, trained operators, well-maintained equipment with backup, and monitoring for signs of returning sensibility. Stunning improves meat quality as well, by reducing stress, bruising and blood splash.