(a) Development of bone, fat and muscle tissues in mammalian embryo (10 marks) (b) Vitamin B complex deficiency in poultry (10…

(a) Development of Bone, Fat and Muscle in the Mammalian Embryo All three arise from mesoderm-derived mesenchyme: trunk skeleton and muscle from paraxial mesoderm (sclerotome forms vertebrae and ribs, myotome forms muscle), limb bones from lateral plate mesoderm, and facial bones from neural crest.

Bone: in intramembranous ossification (flat skull and face bones) mesenchymal cells become osteoblasts directly. In endochondral ossification (long bones, vertebrae) a hyaline cartilage model forms first, then a primary centre in the diaphysis, vascular invasion, and later epiphyseal centres. Osteoblasts lay down mineralising matrix; osteoclasts remodel it.

Muscle: myoblasts fuse into multinucleated myotubes, then fibres. Primary myogenesis forms a few early fibres, secondary myogenesis the bulk. Fibre number is fixed around birth; later growth is by hypertrophy.

Fat: mesenchymal cells become lipoblasts, then adipocytes. Brown fat appears earlier; white fat appears late in gestation and expands after birth. BMPs, FGFs, MyoD, myogenin and PPARγ regulate these steps.

(b) Vitamin B Complex Deficiency in Poultry B vitamins are coenzymes of energy and protein metabolism, and birds, with limited gut synthesis, show deficiency signs quickly on poorly supplemented maize-soybean rations.

• Thiamine (B₁): anorexia and polyneuritis, with "star-gazing" head retraction (opisthotonos).
• Riboflavin (B₂): curled-toe paralysis in chicks, with swollen sciatic nerves, poor growth and low hatchability, and "clubbed down" in embryos.
• Pantothenic acid: dermatitis with scabs at the beak angle and eyelids, and feathering problems.
• Niacin: poor growth, bowed legs and enlarged hocks.
• Pyridoxine (B₆): excitability, convulsions, poor growth.
• Biotin: foot pad dermatitis, perosis and fatty liver and kidney syndrome.
• Folic acid: anaemia, poor feathering and perosis.
• Cobalamin (B₁₂): anaemia, poor growth and embryonic death around day 17.

Perosis (slipped tendon) can also be caused by choline and manganese deficiency.

Treatment and prevention: correct the ration, add a B-complex premix to feed or water, and use injections for individual birds.

(c) Time of Death in Veterolegal Cases Estimation relies on several changes, because no single sign is exact.

• Algor mortis: body cooling, depending on ambient temperature, coat, body size and condition; the rectal temperature falls roughly 1°C per hour in the first hours.
• Rigor mortis: stiffening as ATP is lost, starting in the head and neck and spreading to the limbs (Nysten's rule), commonly beginning in a few hours and passing off after one to two days; it comes and goes sooner in hot weather.
• Livor mortis: hypostasis settles on the lower side and fixes after some hours.
• Decomposition: bloat, discolouration and putrefaction, faster in hot climates.
• Stomach and rumen contents, giving time since last feed.
• Vitreous humour potassium, which rises with time after death.
• Forensic entomology: blowfly (Calliphoridae) egg laying, larval instar and pupation timing.

Environmental factors, such as temperature, humidity, season and scavengers, must be considered for the estimate.

(d) Packaging of Milk and Milk Products Packaging protects against contamination, light, oxygen and loss of flavour, and extends shelf life.

• Pasteurised milk: LDPE/LLDPE co-extruded pouches (with black-white film to block light), HDPE bottles, glass bottles, and paperboard cartons.
• UHT milk: aseptic carton such as Tetra Pak, with layers of polyethylene, paperboard and aluminium foil, giving long ambient shelf life.
• Curd and yoghurt: polypropylene cups, sealed with foil.
• Paneer, cheese: vacuum or modified-atmosphere packs of multilayer film.
• Butter: parchment or foil laminate; ghee: tin, glass, PET or laminated pouches.
• Milk powder: laminated pouches, cans or foil-lined bags, flushed with nitrogen. Packaging must be of food grade, with limited migration, and labelled under FSSAI Labelling and Display Regulations (batch, date, vegetarian logo, nutritional information).

(e) Eating Quality of Meat Eating quality is the combination of tenderness, juiciness, flavour and colour.

Tenderness: depends on connective tissue (collagen amount and cross-links, rising with age), sarcomere length (cold shortening reduces it), muscle fibre type, marbling, and post-mortem ageing, in which calpains degrade myofibrillar proteins. Rigor and rapid chilling can toughen meat.

Juiciness: depends on water-holding capacity and intramuscular fat. Ultimate pH of about 5.4–5.7 gives good water binding; low pH with high temperature causes PSE, and high pH causes DFD.

Flavour: arises on cooking, from Maillard reactions between amino acids and sugars, and breakdown of lipids, with species flavour in fat (mutton, goat).

Colour: depends on the myoglobin state (purple deoxymyoglobin, bright red oxymyoglobin, brown metmyoglobin).

Breed, age, sex, feeding, stress before slaughter, and cooking method also matter. Evaluation uses a trained taste panel and objective shear force (Warner-Bratzler).