Horses (Leaving Cert Agricultural Science): Revision Notes

Horses

Why horses appear in Leaving Cert Ag Science

Horses are not a principal examined enterprise on the LC Ag Science specification — the main animal enterprises are dairy, beef, sheep, pig and poultry. However, horses are relevant as:

• A significant part of the Irish agri-economy, particularly the Thoroughbred breeding industry.
• A useful comparison species for digestion (horses are hindgut fermenters, unlike ruminants or monogastrics).
• An example within cross-cutting topics like grassland management, parasite control, animal welfare and biosecurity.
• A valid subject for the Individual Investigative Study (IIS).

This note focuses on the science and Irish-industry content that could appear in those contexts, rather than day-to-day horse husbandry.

The Irish equine industry

Ireland has one of the most important horse industries in the world relative to population size, centred on Thoroughbred breeding and racing.

• Thoroughbred industry — Ireland is one of the top three Thoroughbred producers globally (alongside the USA and Australia). The industry is concentrated in Kildare, Tipperary and Meath, supported by the limestone-rich soils of the Curragh region which produce calcium-rich grass ideal for bone development in young stock.
• Key organisations:
  • Horse Racing Ireland (HRI) — governs horse racing and supports the Thoroughbred sector.
  • Horse Sport Ireland (HSI) — governs sport horse breeding and the Irish Sport Horse studbook.
  • The Irish National Stud at Tully, Co. Kildare — state-owned stud farm and training centre.
  • Coolmore Stud (Tipperary) — one of the largest Thoroughbred breeding operations in the world.
  • The Turf Club / Irish Horseracing Regulatory Board — integrity and regulation of racing.
• Economic significance — the sector contributes approximately €2 billion annually to the Irish economy and supports around 29,000 jobs directly and indirectly. It is a major source of export earnings through sales at Goffs (Kildare) and Tattersalls Ireland.

Irish horse breeds

• Thoroughbred — bred for flat and National Hunt racing; the keystone breed of the industry.
• Irish Draught — Ireland's native working horse; noted for bone, temperament and hardiness; a protected rare breed.
• Irish Sport Horse — a cross of Irish Draught × Thoroughbred (plus continental warmblood); Ireland's flagship showjumping and eventing horse.
• Connemara pony — native pony breed from the west of Ireland; hardy, versatile, popular for children's riding.

Horse digestion: the hindgut fermenter

This is the single most likely way horses appear in a science question — as a contrast with cattle and pigs.

The horse's digestive tract:

1. Mouth — powerful grinding teeth; horses chew thoroughly and produce a lot of saliva.
2. Oesophagus — one-way; horses cannot vomit.
3. Stomach — small (~8–15 L); acid digestion; food passes through quickly.
4. Small intestine — enzymatic digestion and absorption of starches, sugars, protein, fats and most vitamins.
5. Caecum and large colon — microbial fermentation of fibre into volatile fatty acids (the horse's main energy source from forage).
6. Small colon and rectum — water reabsorption; faeces formed.

Practical consequences of hindgut digestion

• Horses are trickle feeders — evolved to graze 16+ hours a day. Long gaps without forage cause gastric ulcers.
• Large grain meals are dangerous — undigested starch overflowing into the hindgut disrupts microbial balance, causing colic and laminitis. Concentrates must be fed little and often.
• Sudden diet changes (e.g. turnout onto lush spring grass) can trigger colic or laminitis — all changes should be gradual over 7–10 days.
• Horses get most of their energy from forage (grass, hay, haylage). Concentrates (oats, barley, compound feeds) are only added when workload or body condition demands.

Grassland and paddock management

This is where horse content overlaps most directly with the examinable syllabus.

• Horse pasture differs from cattle pasture — horses are selective grazers that create "lawns" (grazed short) and "roughs" (latrine areas, ungrazed). Mixed or rotational grazing with cattle/sheep helps even out the sward and breaks parasite life-cycles (equine worms don't survive passage through ruminants).
• Species selection — hardy grasses like perennial ryegrass and timothy, with less clover (high-clover pasture can contribute to laminitis).
• Poaching — horses' weight and small hooves cut up wet ground badly; rotation and dry lying areas are important.
• Ragwort (Senecio jacobaea) — Ireland's most important toxic pasture weed. Contains pyrrolizidine alkaloids that cause cumulative, irreversible liver damage. Toxic fresh and dried (especially dangerous in hay, where horses can't selectively avoid it). Control is a legal requirement for landowners under the Noxious Weeds Act 1936. Managed by pulling, cutting before seed-set, or targeted herbicide.
• Other toxic plants on Irish pasture: yew, rhododendron, acorns/oak, bracken, sycamore seeds (atypical myopathy).

Parasite control — modern approach

The old "worm every 6–8 weeks" rotational dosing approach is now outdated and actively harmful — it has driven widespread anthelmintic resistance in equine worms.

This mirrors the drive toward responsible antimicrobial and antiparasitic use across the livestock sectors and is a good example of science informing practice.

Animal welfare and regulation

• Animal Health and Welfare Act 2013 — the main Irish legislation covering all farmed and kept animals including horses; enforced by the Department of Agriculture, Food and the Marine (DAFM). Requires owners to provide for animals' needs and prohibits unnecessary suffering.
• Control of Horses Act 1996 — local authority powers to deal with stray, wandering and illegally kept urban horses; still highly relevant in parts of Ireland.
• Equine passport and microchip — every horse in Ireland and the EU must have an equine passport, issued by an approved Passport Issuing Organisation (PIO), from no later than 6 months of age or by 31 December of its year of birth, whichever is later. Passports contain the horse's identity, microchip number, ownership details and a medicines record declaring whether the horse is intended for the human food chain.
• Five Freedoms apply to horses as to any other kept animal (freedom from hunger/thirst, discomfort, pain/injury/disease, fear/distress, and freedom to express normal behaviour).

Notifiable and significant equine diseases

Useful as examples in biosecurity and disease-control questions.

• Equine Infectious Anaemia (EIA, "swamp fever") — notifiable viral disease; blood-borne; no cure or vaccine; infected horses are euthanised under DAFM control.
• Contagious Equine Metritis (CEM) — notifiable bacterial venereal disease; major concern in the Thoroughbred breeding industry; controlled by pre-breeding swabbing.
• African Horse Sickness — notifiable, exotic, midge-borne; not present in Ireland but monitored.
• Equine Influenza — respiratory virus; vaccination is mandatory for racing and competition horses under HRI / FEI rules; was the cause of the 2019 UK racing shutdown.
• Equine Herpes Virus (EHV-1) — respiratory disease, abortion and occasionally neurological disease in breeding stock.
• Strangles (Streptococcus equi) — highly contagious bacterial upper-respiratory infection; swollen submandibular lymph nodes ("abscesses"); controlled by strict isolation and yard biosecurity rather than by mass treatment.

Standard yard biosecurity (quarantine of new arrivals, separate equipment, hand hygiene, isolation of sick animals) is the main defence against all of these — the same principles used in commercial pig and poultry units.

Horse ownership at a glance

• Horses live 25–30 years — a long-term commitment.
• Need roughage as the basis of the diet (grass, hay, haylage), with concentrates added only as required; rough rule of thumb 1.5–2% of bodyweight in total daily feed.
• Need 25–45 L of water per day in warm weather, more when working.
• Need farrier attention every 6–8 weeks and annual (or more frequent) dental checks by a qualified equine dental technician or vet.
• Need companionship — horses are herd animals and suffer when kept alone.
• Common health problems — colic (any digestive disorder; can be rapidly fatal), laminitis (painful inflammation of the hoof laminae, often triggered by overfeeding rich grass or grain), sweet itch (midge allergy), and lameness.

Remember!