(a) (i) Describe the factors responsible for colic in horses and its treatment. (10 marks) (ii) What is the importance of DNA…

(a)(i) Etiology and Management of Equine Colic Colic in horses is a clinical syndrome of abdominal pain, primarily arising from gastrointestinal dysfunction. The etiology is multifactorial. Dietary factors, such as sudden changes in feed composition or inadequate forage intake, disrupt gut motility and microbial balance. Management errors, including prolonged stall confinement and restricted water access, exacerbate impaction risks. Parasitic burden, particularly from Strongylus vulgaris, causes verminous arteritis leading to intestinal ischemia. Anatomically, the horse’s large colon is mobile, loosely attached and narrows sharply at the pelvic flexure, predisposing it to impaction, displacement and torsion, while horses cannot vomit to relieve gastric distension. Treatment follows a stepwise protocol. Initial medical management involves fluid therapy to correct dehydration and electrolyte imbalances, analgesics like flunixin meglumine for pain control, and antispasmodics such as N-butylscopolammonium bromide (Buscopan) to relieve smooth muscle spasm. Lubricant laxatives, such as mineral oil, are used for impaction, distinct from osmotic agents like magnesium sulfate. If medical management fails, or if signs of strangulation (e.g., severe pain, tachycardia, absent gut sounds) persist, surgical intervention via celiotomy is critical to correct displacement or resect necrotic tissue.

(a)(ii) DNA Fingerprinting in Disease Investigation DNA fingerprinting is pivotal in epidemiological investigations by providing molecular evidence of disease origins and transmission. It utilizes techniques like Restriction Fragment Length Polymorphism (RFLP), PCR-based microsatellite analysis, and Amplified Fragment Length Polymorphism (AFLP) to generate unique genetic profiles. In outbreaks, such as Foot-and-Mouth Disease (FMD) in India, these methods trace viral lineages to specific reservoirs, distinguishing between local circulation and imported strains. This capability maps transmission pathways, identifying key nodes in the spread network. Furthermore, it facilitates vaccine strain matching, ensuring that deployed vaccines correspond to the circulating field strains. Similarly, spoligotyping and other fingerprinting of Mycobacterium bovis isolates link bovine tuberculosis cases on different farms. By analyzing the wildlife-livestock interface, DNA fingerprinting elucidates zoonotic spillover events, thereby supporting One Health strategies for disease control.

(b) Functional Anatomy of Female Fowl The female fowl possesses a unique asymmetrical reproductive system, with the right ovary and oviduct regressing during embryonic development. The right oviduct (a Müllerian duct) regresses under anti-Müllerian hormone because, unlike the left, it lacks oestrogen-receptor protection, while the right ovary fails to develop owing to asymmetric gene expression (e.g., PITX2). The left ovary contains follicles in various stages of maturation. In a laying hen, a hierarchy of follicles exists where the largest (preovulatory) follicle releases the oocyte. The oviduct consists of five functional regions: the infundibulum, where fertilization occurs; the magnum, which secretes the bulk of the albumen; the isthmus, responsible for forming the inner and outer shell membranes; the uterus (shell gland), where shell calcification begins and pigmentation occurs; and the vagina, which serves as the copulatory organ and birth canal. Sperm-host glands are located at the utero-vaginal junction. Hormonally, FSH recruits follicles, an LH surge (triggered by progesterone from the largest follicle) causes ovulation, and oestrogen develops the oviduct and medullary bone that supplies shell calcium. Reproductive status dictates anatomical changes: in immature hens, the oviduct is rudimentary; in laying hens, it is fully developed and active; during molting or broodiness, the oviduct regresses due to reduced estrogen and progesterone levels, leading to a temporary cessation of egg production.

(c) Environmental Effects on Production and Health Environmental factors profoundly influence animal physiology through the hypothalamic-pituitary-gonadal (HPG) axis. Thermal stress, quantified by the Temperature-Humidity Index (THI) which combines ambient temperature and humidity, disrupts thermoregulation. High THI leads to heat stress, reducing feed intake and diverting energy from production to cooling mechanisms, thereby lowering milk yield and growth rates. Reproductively, heat stress shortens and weakens oestrus expression, lowers conception rates through poor oocyte and early embryo quality, and reduces semen quality in males. In poultry, heat stress increases embryonic mortality and reduces hatchability. Photoperiod is a critical environmental cue for seasonal breeders; manipulating light exposure can extend breeding seasons in sheep and goats. Humidity interacts with environmental contaminants; high humidity promotes the growth of molds producing mycotoxins, which compromise immune function and reproductive health. Shelter design plays a vital role in mitigating these effects by providing ventilation, shade, and insulation, thereby maintaining the thermal neutral zone.