Beef Cattle

Digestive Physiology: Adult Ruminant vs Preruminant and Monogastric

The Adult Ruminant Stomach

An adult bovine stomach comprises four distinct compartments operating in sequence: rumen → reticulum → omasum → abomasum.

• Rumen: A large fermentation vat holding up to 150–200 litres. It hosts billions of symbiotic microorganisms (bacteria, protozoa, and fungi). Microbes secrete the enzyme cellulase to break down cellulose and hemicellulose in grass and silage—an enzyme mammals cannot produce.
• Reticulum: A honeycomb-textured chamber that traps dense foreign material (such as wire or stones) and collects coarse digesta into boluses for regurgitation during rumination (chewing the cud).
• Omasum: Composed of numerous thin muscular sheets (the 'manyplies' or leaves) that reabsorb water, squeeze fine digesta, and absorb residual minerals and volatile fatty acids.
• Abomasum: The 'true stomach', operating identically to a monogastric stomach by secreting gastric juice containing hydrochloric acid and pepsin to digest microbial and bypass proteins.

Functions of Rumen Microorganisms

1. Volatile Fatty Acid (VFA) Synthesis: Microbes ferment dietary plant fibre and starches into three primary volatile fatty acids: acetic acid, propionic acid, and butyric acid. These are absorbed directly through the rumen papillae into the bloodstream, providing roughly 70% of the cow's total metabolic energy.
2. Microbial Protein Synthesis: Microbes convert non-protein nitrogen (such as urea) and poor-quality plant proteins into high-quality microbial protein. As microbes pass into the abomasum and small intestine, they are digested, providing essential amino acids.
3. Vitamin Synthesis: Rumen microbes synthesise all required B vitamins (including B12) and vitamin K.
4. Fermentation By-products: Large volumes of carbon dioxide ($CO_2$) and methane ($CH_4$) are produced as by-products of anaerobic fermentation. The animal expels these gases via eructation (belching). Rumen methane emissions represent a primary target for greenhouse gas mitigation.

Rumination and Rumen Buffering

During rumination, the animal regurgitates cud, re-chews it to reduce particle size, and re-swallows it. This stimulates the production of vast amounts of alkaline saliva rich in sodium bicarbonate, which buffers rumen pH between 6.2 and 6.8, preventing rumen acidosis.

Contrast with a Monogastric Animal

A monogastric animal (such as a pig) possesses a single, non-compartmentalised, acid-secreting stomach. Lacking a pre-gastric fermentation chamber, pigs cannot digest fibrous cell walls efficiently and require easily digestible, concentrate-based rations containing pre-formed essential amino acids (such as lysine and methionine).

Cattle Breeds, Classification, and Genetic Selection

Cattle Breed Identification

• Holstein-Friesian: Large-framed dairy breed. Black and white coat. Capable of high milk yields with moderate solids percentages. (The Friesian originated in the Netherlands; the Holstein strain was developed in North America for higher volume).
• Jersey: Small Channel Island dairy breed with a fawn or light-brown coat and a dished face. Low volume, but high butterfat (~5.0%) and protein (~3.8%).
• Aberdeen Angus: Early-maturing British beef breed. Naturally polled (hornless) with a solid black (or red) coat. Renowned for docility, easy calving, and intramuscular fat marbling.
• Hereford: Early-maturing British beef breed. Red-brown body with a characteristic white face, white crest, and white underline. Docile, finishes rapidly on grass.
• Shorthorn: Early-maturing breed with a red, white, or roan coat. Historically dual-purpose, now bred as maternal suckler dams and pedigree beef.
• Charolais: Late-maturing French continental breed. Cream or white coat with heavy muscle conformation. Widely used as a terminal sire for rapid growth.
• Limousin: Late-maturing continental breed. Golden-red coat with lighter shading around the muzzle and eyes. Prized for lean meat yield and high kill-out percentage.
• Belgian Blue: Extreme late-maturing continental breed. White or blue-roan coat. Exhibits muscular hypertrophy (double muscling), requiring careful calving supervision.
• Simmental: Continental dual-purpose breed. Red, gold, and white patches with a white face. Valued in suckler herds for high milk yield and fast calf growth.

Crossbreeding and Dominant Traits

Crossbreeding is the mating of animals from two distinct pure breeds (for example, a purebred Hereford bull on a Holstein-Friesian cow). Using a purebred sire ensures predictable, uniform traits in the offspring. Crossbred calves benefit from hybrid vigour (heterosis), displaying superior hardiness, fertility, and growth over parental averages.

• Crossing a Hereford onto a Friesian yields a black calf with a white face, as both black coat colour and the white face trait are genetically dominant.
• Crossing an Aberdeen Angus yields polled calves, because the polled gene is dominant over horned.

Breeding Indices and Selection Principles

• Economic Breeding Index (EBI): Single-figure monetary index estimating the extra profit (€) a dairy bull's daughters will generate per lactation compared to a base cow. It includes sub-indices: Milk Production, Fertility, Calving Performance, Beef Carcase, Maintenance, Management, Health, and Carbon.
• Beef Euro-Star Index: Divided into the Replacement Index (maternal milk, fertility, and calving ease for breeding suckler replacements) and the Terminal Index (growth rate, carcase weight, and conformation for slaughter animals).
• Performance Testing: Evaluating a young sire's own growth rate, muscle conformation, and feed efficiency under standardised conditions at a central testing station.
• Progeny Testing: Assessing a sire's true genetic merit by recording the physical traits, milk yield, health, and slaughter data of a large cohort of his offspring across commercial farms.
• Genomic Selection: Profiling an animal's DNA from tissue tags or hair follicles at birth to predict future breeding values, reducing generation intervals.
• Visual Selection (Physical Traits): Selecting breeding stock based on conformation, feet, legs, udder shape, frame, and docility. Effective for highly heritable physical traits.
• Natural Selection vs Artificial Selection: Natural selection favoured hardiness and disease tolerance in native breeds (such as the Kerry cow). In farming, artificial selection replaces this, as the breeder selects parents for economic traits.
• Genetic Engineering: Direct modification or editing of an animal's genome (e.g., introducing the polled gene into dairy genetics to remove the need for dehorning). Subject to stringent EU regulations.

Beef Production Systems, Carcase Grading, and Feed Efficiency

Beef Systems Comparison

Irish beef systems are predominantly grass-based, relying on high-DMD grazed pasture and winter grass silage.

• Suckler-to-Beef / Weanling: A beef cow suckles her own calf until weaning at 7–9 months. Calves graze alongside dams and receive creep concentrates pre-weaning. While producing high-quality continental carcases, suckler enterprises incur high cow maintenance costs and generate lower stocking rates.
• Dairy Calf-to-Beef: Surplus dairy-bred calves (Holstein-Friesian bullocks, Angus or Hereford crosses) are purchased at 2–3 weeks of age, artificially reared, and finished at 20–24 months. This system features lower calf purchase costs and higher stocking rates, but carcases display lower conformation grades.

Nutritional Principles in Beef Production

• Nutritive Properties of Food Constituents:
• Carbohydrates: Provide the primary source of dietary energy; sugars and starches fuel daily metabolism, while structural fibre (cellulose) maintains rumen function and stimulates cud-chewing.
• Proteins: Supply essential amino acids for muscle and tissue growth, cellular repair, enzyme production, and foetal development.
• Lipids (Fats): Act as a concentrated energy store, supplying over twice the energy of carbohydrates per gram.
• Minerals: Macro-minerals (calcium and phosphorus) are required for skeleton formation and milk production; magnesium is critical for nerve and muscle function (preventing grass tetany). Micro-minerals (trace elements like cobalt, copper, and selenium) support fertility and enzyme activity.
• Vitamins: Fat-soluble vitamins A, D, and E support vision, bone formation, and immunity; water-soluble B vitamins and vitamin K are synthesised directly by rumen microbes.
• Water: Essential for hydration, nutrient transport, waste excretion, and biochemical reactions.
• Dry Matter Digestibility (DMD): The percentage of dry matter in a feed that is digested by the animal. Silage cut in late May averages ~75% DMD, while overgrown late-June silage drops to ~60% DMD due to stem lignification. High-DMD silage increases voluntary intake, daily liveweight gain (DLG), and reduces concentrate requirements.
• Compensatory Growth: The accelerated, highly efficient growth rate exhibited by cattle when placed on an abundant, high-quality diet (such as spring pasture) following a period of restricted nutritional intake (such as a low-cost, store winter period).
• Ration Balancing: A ration combines feeds to supply these constituents to match the animal's stage of development: young stock require high-protein rations (16–18% crude protein) for skeletal and muscle development, while finishing cattle require high-energy, starch-rich diets (barley-based, 12–14% crude protein) to deposit fat cover.

Carcase Classification: The EUROP Grid

Carcase value is determined using two objective factory scales:

• Conformation: Evaluated on the EUROP scale (E = excellent/convex profile, U = very good, R = good, O = fair, P = poor/concave profile). Each class is subdivided into +, =, and −.
• Fat Score: Evaluated on a scale from 1 (leanest) to 5 (fattest), also subdivided into +, =, and −.
• Typical Scores: A late-maturing continental steer grades E or U with fat 2 to 3 (e.g., U+ 3=). An early-maturing British crossbred steer (e.g., Angus × Friesian) finishes faster, typically grading R or O with fat 3 to 4 (e.g., R= 4−).

Kill-Out Percentage Benchmarks

• Holstein-Friesian dairy steers: ~50%–52%
• Angus / Hereford beef-cross steers: ~52%–55%
• Continental beef steers: ~56%–60%
• Continental bulls: ~58%–62%

Animal Health, Biosecurity, and Safe Farmyard Design

Cattle Diseases, Transmission, and Control

• Hoose (Lungworm): Larvae eaten from pasture migrate to the bronchi. Causes persistent coughing and pneumonia in first-season grazing calves. Controlled by anthelmintic dosing and leader-follower grazing.
• Stomach Worms (Ostertagia):* Larvae damage the abomasal mucosa, causing profuse watery scour and stunting. Controlled by strategic dosing and pasture rotation.
• Liver Fluke (Fasciola hepatica): Requires the mud snail (Galba truncatula*) as an intermediate host on poorly drained ground. Causes anaemia and weight loss. Controlled by fencing off wet drains and dosing flukicides in autumn/winter.
• Bovine Viral Diarrhoea (BVD): Virus causing immunosuppression and congenital defects. Persistently Infected (PI) calves shed massive viral loads. Controlled by national mandatory tag-tissue testing, culling PI calves, and biosecurity.
• Milk Fever (Hypocalcaemia): Sudden metabolic calcium drop at calving. Symptoms: muscle tremors, cold ears, sternal recumbency ('downer cow' with head tucked into flank). Treated with calcium borogluconate injected intravenously or subcutaneously.
• Grass Tetany (Hypomagnesaemia): Acute blood magnesium drop on lush spring pasture high in potassium. Can be rapidly fatal if untreated. Treated immediately with magnesium sulphate injected subcutaneously.
• Zoonoses: Pathogens transmissible from cattle to humans, including TB, brucellosis, leptospirosis (via infected urine), ringworm (fungus via direct skin contact), and Cryptosporidium (via calf faeces).
• Notifiable Diseases: Diseases posing extreme national or economic risk that must be reported to the Department of Agriculture, Food and the Marine (DAFM) immediately: Bovine TB, Brucellosis, BSE, Foot-and-Mouth Disease, and Anthrax. DAFM places immediate herd movement restrictions (lock-up).

Animal Welfare, Handling, and Food Traceability

• Animal Welfare Principles (The Five Freedoms): Good husbandry requires fulfilling five core welfare freedoms:

1. Freedom from hunger and thirst (constant access to clean water and a balanced diet).
2. Freedom from discomfort (sheltered housing, dry bedding, and sufficient space to rest).
3. Freedom from pain, injury, and disease (preventative healthcare, vaccination, and prompt veterinary treatment).
4. Freedom to express normal behaviour (adequate space, good lighting, and company of herd-mates).
5. Freedom from fear and distress (calm management and avoiding conditions that cause mental suffering).

• Handling and Housing for Welfare: Animal handling must be low-stress and calm. Facilities require non-slip grooved concrete floors, well-designed handling races, anti-backing ratchets, and secure restraining crushes. Housing requires adequate lying space and sufficient ventilation to remove excess heat, moisture, and noxious gases without creating draughts.
• Food Safety and Traceability Systems: Robust traceability protects human consumers and Irish export markets:
• Every calf must receive two official ear tags (one in each ear) within 20 days of birth.
• Births are registered to obtain an individual bovine passport (blue card).
• All animal movements, sales, and deaths are logged on DAFM's Animal Identification and Movement (AIM) database, allowing any beef carcase or milk consignment to be traced back to the farm of origin.
• Traceability compliance is audited via Bord Bia Sustainable Quality Assurance Schemes, guaranteeing verified standards to consumers.

Farm Safety and Yard Layout Sketch

When producing a farmyard sketch for assessment, students must account for health and safety, economic efficiency, and environmental sustainability:

1. Dwelling House (Social / Health & Safety): Completely fenced off from livestock movement and machinery routes to provide a secure, child-safe perimeter.
2. Economic Layout Practice: Short, direct transit routes between livestock housing, feed storage, and the milking parlour or handling yard save labour and machinery operating time. Grouping buildings enables shared services (water, electricity) and allows slurry and drainage to flow by gravity, lowering capital construction and ongoing operating costs.
3. Livestock Handling Yard: Centrally located handling crush with an anti-backing bar, non-slip concrete grooving, and an integrated calving gate with a headstock restraint to protect handlers.
4. Machinery & PTO Safety: Dedicated tractor transit routes kept separate from animal races; separate locked, bunded stores for agrochemicals and veterinary medicines; PTO guards fitted on all drive shafts.
5. Slurry Storage & Gas Hazard: Slurry produces hydrogen sulfide ($H_2S$), a dense gas that deadens the sense of smell and kills within a single breath. Slurry tanks must have external agitation points located outside sheds. Agitation must only occur on windy days with all shed doors open and stock fully evacuated for at least 30 minutes.
6. Silage Slab & Effluent Management: Silage effluent has a Biochemical Oxygen Demand (BOD) over 200 times that of raw domestic sewage. Slabs require leak-proof concrete perimeter channels directing effluent directly into underground collection tanks to prevent waterway eutrophication.

Environmental Implications, Slurry Management, and Sustainable Intensification

• Environmental Impacts of Cattle Production:
• Greenhouse Gas Emissions: Enteric fermentation in the rumen produces methane ($CH_4$), while nitrogen excreted in dung and urine produces nitrous oxide ($N_2O$). Both are potent greenhouse gases contributing to climate change.
• Air Quality: Slurry agitation and surface spreading release ammonia ($NH_3$), which contributes to air pollution and soil acidification.
• Water Quality: Leaching of nitrates and surface runoff of phosphorus into waterways trigger algal blooms and eutrophication, depleting aquatic oxygen.
• Slurry and Farmyard Manure (FYM) Best Practice:
• Storage Capacity: Provide adequate storage capacity (statutory 16–22 weeks depending on zone) to eliminate the risk of winter tank overflow.
• Prohibited Spreading Periods: Never spread slurry during the winter closed period, on waterlogged, flooded, snow-covered, or frozen ground, or on steep slopes near water.
• Low-Emission Slurry Spreading (LESS): Use trailing shoe or dribble bar equipment instead of splash plates. LESS places slurry directly under the grass canopy, drastically reducing ammonia volatilisation and increasing nitrogen recovery.
• Buffer Zones and Nutrient Planning: Maintain unfertilised buffer zones along watercourses and apply slurry strictly in accordance with soil test results.
• Sustainable Intensification: Producing higher agricultural output per hectare (such as increased milk solids or carcase output) without increasing environmental degradation, carbon footprint, or resource depletion.

Livestock Lifecycle Stages and Nutritional Management

Managing livestock successfully means matching feed to the animal's changing needs as it grows, reproduces, and produces milk or meat.

Cattle Lifecycle Stages

• Calf stage (0–8 weeks): Calves are born without antibodies because the cow's placenta prevents immunoglobulins passing to the calf in the womb. The calf must get colostrum (first milk) quickly to absorb antibodies directly across the gut wall into the blood. This gives the calf passive immunity. Gut absorption falls sharply after birth and is almost completely gone by 24 hours. Follow the 1-2-3 rule: use colostrum from the 1st milking, feed it within 2 hours of birth, and give at least 3 litres. Newborn calves are functionally monogastric: the oesophageal groove closes when the calf drinks, channelling milk directly into the abomasum and bypassing the undeveloped rumen. To build rumen microbes and grow the rumen wall, offer clean water, straw, and coarse calf starter concentrates from the first week.
• Weanling stage (2–12 months): Once off milk, calves rely on the rumen to ferment grass and forage into volatile fatty acids. Feed a 14–16% crude protein diet with leafy grass or top-quality silage to support bone and muscle growth.
• Replacement heifers (12–24 months): Dairy replacement heifers must grow steadily to reach about 60% of their mature body weight by 15 months, so they can be mated to calve down at 24 months. Do not overfeed heifers before puberty (around 3 to 9 months of age), as this causes fat to build up in the developing udder, reducing milk-producing tissue and lowering later milk yields.
• Lactating cow: In early lactation, milk output rises faster than feed intake, putting the cow into a negative energy balance. She milks off her own body fat to cover the gap. If underfed, she may develop ketosis.
• Dry cow (60-day dry period): This rest period lets udder tissue regenerate and restores Body Condition Score (BCS) before calving. Calving target BCS is 3.0 to 3.25 for dairy cows and 2.5 to 3.0 for sucklers. Feed dry-cow minerals: milk fever is caused by low blood calcium (hypocalcaemia) at calving. Supplying magnesium in the dry cow diet and avoiding high-calcium, high-potassium feeds helps the cow mobilise calcium from her bones. Low magnesium on its own causes grass tetany.

Sheep and Pig Nutrition

• Ewes in late pregnancy: Roughly 70% of foetal lamb growth takes place during the last 6 to 8 weeks of pregnancy. Farmers scan ewes and feed extra concentrates based on litter size to prevent twin-lamb disease (pregnancy toxaemia) in twin- and triplet-bearing ewes.
• Pig diets change with age: Young weaned pigs build lean muscle quickly and require rations with 16–18% crude protein (usually from soya bean meal). As pigs grow towards finishing, their protein requirement drops to about 14%. Extra protein is expensive, wasted, and excreted as nitrogen in slurry. Cereals (barley and wheat) provide energy. Pigs are monogastric and lack rumen microbes to digest cellulose, which is why they cannot digest grass.

Evaluating Animal Performance: DLG and Feed Conversion Ratio

Farmers measure animal growth and feed efficiency to check whether a feeding regime or enterprise is paying off.

Daily Liveweight Gain (DLG)

Daily Liveweight Gain (DLG) is the average liveweight an animal puts on each day over a given period:

If an exam question asks for DLG from birth to slaughter and provides only the final weight and age in days, divide the slaughter weight by the age in days (for example, $725\text{ kg} \div 654\text{ days} = 1.11\text{ kg/day}$). This calculation ignores birth weight, but it is the method expected when a question gives only final liveweight and age (e.g. 2025 Q16).

Food / Feed Conversion Ratio (FCR)

Feed Conversion Ratio (FCR) is the amount of feed (in kg) needed to produce 1 kg of liveweight gain:

A lower FCR means the animal is more efficient, as it requires less feed to put on each kilogram of weight.

(Slow-growing store animals have a higher, poorer FCR because a greater proportion of their daily feed intake is used for body maintenance rather than liveweight gain.)

*Pigs have a lower FCR than cattle because they are fed a dry, concentrated, easily digested meal and lose no energy to enteric methane gas. However, cattle and sheep convert grass and silage—forage that humans and pigs cannot eat—into high-quality milk and meat. That grass-converting ability is Ireland's core farming advantage.

Animal Husbandry, Welfare, and Fertility Targets

The Animal Health and Welfare Act (2013) places a legal duty of care on farmers to ensure animals are looked after properly. Animal welfare is evaluated using the Five Freedoms:

1. Freedom from hunger and thirst (fresh water and a balanced diet).
2. Freedom from discomfort (shelter, dry lying areas, and good ventilation).
3. Freedom from pain, injury, and disease (prevention, rapid treatment, and handling units).
4. Freedom to express normal behaviour (sufficient space, social contact with other stock).
5. Freedom from fear and distress (calm handling, no rough treatment).

Sheep Breeding-Season Management

• Body Condition Score: Ewes should be at BCS 3.0–3.5 at mating.
• Flushing: Putting ewes on a higher plane of nutrition (fresh leafy grass or meal) for 3 weeks before and during mating. This increases ovulation rate, leading to more twin births.
• Health checks: Cull broken-mouthed, infertile, or chronically lame ewes; check rams 6–8 weeks before breeding (feet, teeth, testicles).
• Raddling: Fit a raddle harness with coloured crayon to the ram (ratio of roughly 1 ram per 40 ewes). As the ram mounts, he marks the ewe's rump. Change the raddle colour every 16–17 days (the length of the ewe's oestrous cycle). Ewes marked with the first colour and then re-marked with the new colour have returned to heat, so they did not conceive at the first mating. Unmarked ewes have not been mated. The raddle dates also let you predict lambing.

Suckler Herd Fertility Targets (KPIs)

• Calving interval: The time in days between two calvings of the same cow. Target is 365 days (one calf per cow per year).
• 6-week calving rate: Target is 80% of the herd calved within the first 6 weeks of the calving season.
• Calves per cow per year: Target is 0.95.

To hit these targets, keep cows at BCS 2.5–3.0 at breeding, feed replacement heifers to reach target weights, use a fertility-tested bull or heat-detection tools (tail paint, scratch cards, activity collars), cull infertile cows, and feed colostrum to every calf within 2 hours to keep calf mortality low.

Housing, Farmyard Layout, and Farm Safety

A farmyard sketch in an exam must balance animal handling, operator safety, and environmental protection.

Farmyard Layout Essentials

• Clean and dirty water separation: Roof gutters and clean yard areas must channel clean rainwater directly into soakaways or streams. Soiled yard water and effluent from the dungstead or silage pit must drain into sealed underground slurry tanks. Mixing clean roof water into slurry tanks wastes valuable tank storage and increases spreading costs.
• Handling units: Races and crushes should feature solid curved walls, non-slip concrete floors, anti-backing bars, and a sturdy head-gate. Cattle naturally circle and move toward light; curved walls keep them moving forward without seeing handlers standing ahead. A separate calving gate allows one person to safely assist a calving cow or perform a caesarean section without danger.
• Yard layout best practice: Locate the silage pit and slurry tanks away from streams; keep the farm dwelling separated from working machinery routes; provide good yard lighting; store veterinary medicines and chemicals in a locked shed.

Farm Safety and Hazard Controls

• Machinery hazards: Tractors and machinery cause the highest number of farm deaths. Always apply the 'Safe Stop' procedure: handbrake on, controls in neutral, engine stopped, and key removed before leaving the cab. Ensure PTO shafts are covered by a fully intact, chained PTO shield.
• Livestock hazards: Freshly calved cows and breeding bulls are dangerous. Use a bull pen with an exterior service passage, fit a nose ring to the bull, and never turn your back on a cow with a newborn calf.
• Biological hazards (Zoonoses): A zoonosis is an infection passed from animals to humans.
• Leptospirosis: Spread through infected cattle urine and calving fluids; causes severe flu-like illness and meningitis in humans. Prevent by herd vaccination, wearing gloves and eye protection when assisting calvings or milking.
• Ringworm: Fungal skin infection transmitted by touching infected cattle or timber gates; causes itchy circular lesions.
• Orf: Viral skin infection from sheep; causes painful blisters and scabs on hands. Prevent by wearing gloves and vaccinating the flock.
• Salmonella: Bacteria spread through manure; causes severe gastroenteritis.

Slurry Gas Dynamics and Safety Protocol

Slurry stored anaerobically in tanks produces four gases:

1. Hydrogen sulphide ($H_2S$): Heavier than air, highly toxic, flammable. At low levels it smells like rotten eggs, but at higher concentrations it rapidly deadens the human sense of smell. One or two breaths can cause collapse, respiratory failure, and death.
2. Carbon dioxide ($CO_2$): Heavier than air, colourless, odourless; displaces oxygen and causes suffocation.
3. Methane ($CH_4$): Lighter than air, colourless, odourless; highly explosive when mixed with air at 5–15%.
4. Ammonia ($NH_3$): Lighter than air, sharp stinging smell; irritates eyes and lungs.

Agitation Safety Protocol: Gas release peaks in the first 30 minutes of agitation. Follow these rules:

1. Choose a windy day so gases blow away quickly.
2. Evacuate all people and livestock from the building.
3. Open all shed doors and ventilation flaps.
4. Connect the agitator externally, start it, and leave the building immediately for at least 30 minutes.
5. If the pump is moved or the jet direction changed, leave the building again for at least 30 minutes.
6. Never enter or lean over a slurry tank, never work alone, and use a handheld gas monitor.