Cattle Nutrition: Cattle Feed andTips for Optimal Animal Health

Practical feeding is the most controllable lever producers have to lift on-farm performance. In Australia, productivity and resilience flow from meeting clear nutrient requirements for each animal and production stage.

Animals need absolute amounts of water, energy, protein, minerals and vitamins — not just label percentages. Actual intake and diet composition decide whether requirements are met for growth, reproduction and health.

Environment and breed change needs. Heat, cold, mud, distance to water and pasture quality all affect feed intake and welfare. Producers must match forage and supplements to on-ground conditions, from temperate pastures to arid scrub and saltbush country.

This guide focuses on practical steps: aligning feed and water, using metrics like dry matter, DMI, NDF/ADF and net energy, and avoiding common gaps that limit production. The aim is simple — help producers make faster, better decisions this season with grounded, actionable advice.

Key Takeaways

• Feed and water management are the primary tools for improving production and animal health.
• Meet absolute nutrient amounts — intake matters more than label percentages.
• Adjust rations for environment, breed and stage to avoid shortfalls.
• Keep clean, continuous water access; even shortfalls reduce feed use and growth.
• Use dry matter and DMI metrics when matching forage and supplements to goals.

Why nutrition drives productivity and animal health

Genetics set the upper limit; everyday feed and the paddock decide how close animals get to that ceiling.

Phenotype reflects both heredity and environment. On-farm, diet is the largest controllable environmental factor. Meeting daily requirements determines growth, fertility and herd resilience.

Genetics, environment and phenotype

Breed and genotype set potential. Stock will only reach that potential when body size, age, stage and activity are matched by practical rations.

Weather and paddock conditions shift needs. Hot or cold snaps, mud and distance to water all change intake and daily requirements.

Core nutrients: water, energy, protein, minerals and vitamins

Five core nutrients underpin performance. Shortfalls for even a few days reduce growth, weaken immunity and cut milk or weight gain.

• Water — controls intake and rumen function.
• Energy — fuels daily activity and production.
• Protein — supports growth, pregnancy and milk.
• Minerals — key for reproduction and metabolism.
• Vitamins — support immunity and tissue repair.

Absolute daily delivery beats percentage labels. Measure dry matter intake and match the diet to class and season. Good planning buffers risk, steadies returns and lifts whole-herd production.

Cattle nutrition

Matching nutrient requirements to class, weight and stage

Age, weight and production stage set daily needs for growth and reproduction. Producers should map target gains and adjust rations by class rather than feeding the whole herd the same mix.

How needs change by class

Replacement heifers require steady gains to reach puberty by about 15 months and near 80% of mature weight before first calving. That drives higher protein and energy per kilogram of gain, even when dry matter intake is lower.

Lactation markedly increases daily demand; early postpartum cows need almost double the protein of dry cows. Underfeeding this window slows milk and delays rebreeding.

Late gestation also lifts requirements as the foetus grows rapidly. If the dam is short-fed, she will sacrifice body condition to support the unborn calf.

• Scale rations with body weight—larger-framed animals need more energy to maintain and grow.
• Set class-specific feeding plans for dry cows, late-pregnancy cows, lactating cows, weaners, yearlings and bulls.
• Adjust feeds seasonally to protect condition and production.

Understanding dry matter, intake and digestibility

Dry matter determines the usable fuel in every feed and is the starting point for all ration decisions.

Key measures and what they mean on-farm

DM is the feed minus water — the fraction that holds energy, protein, minerals and vitamins. Compare rations on a dry-matter basis, not as-fed.

DMI (dry matter intake) is the dry matter eaten each day, often expressed as a percentage of liveweight. It converts requirement numbers into what to offer the herd.

DMD and DOMD are simple markers of digestibility. Higher DMD raises metabolisable energy, boosts digestion speed and supports better production.

Why fibre fractions matter

NDF is structural fibre that limits voluntary intake. ADF is the least digestible fraction. As plants mature, NDF rises and farms see slower passage through the rumen and capped intake.

“Measure DM, DMD/DOMD, NDF and ADF regularly — it tells you when to top up supplements before performance slips.”

On-farm drivers of feed intake

• Plant diversity and palatability affect selection and feed intake.
• Secondary compounds and high salt in shrubs cut intake and change grazing patterns.
• Heat, cold and herd condition change daily appetite and passage rates.

Routine feed testing for DM, DMD/DOMD, NDF and ADF gives early warning. Use results to match supplements, set stocking and protect herd condition.

Water: the most important nutrient in Australian conditions

Access to clean, cool water is the single management action that most quickly lifts herd performance on Australian properties.

Typical intake and key drivers

Rule of thumb: expect 0.06–0.20 L/kg bodyweight, roughly 15–300 L per day depending on size, lactation and heat. Lactation and hot weather push animals to the top end.

Drivers include liveweight, milk yield, genetics, activity, daily feed composition and climate. Plan trough numbers and flow to meet peak demand.

Quality risks and testing

Screen every source for salinity, nitrates and toxic elements (Al, As, B, Cd, Cr, Co, Cu, F, Pb, Mn, Hg, Ni, Se, V, Zn). Salinity thresholds: 4,000 mg/L for growth, 5,000 mg/L to maintain condition and 10,000 mg/L maximum. Note 1,000 mg/L ≈ 1,785 EC.

Managing restriction and high-moisture feedstuffs

• Never abruptly remove access; if restriction occurred, reintroduce gradually to avoid overconsumption and scours.
• High-moisture feedstuffs can cause loose dung — offer low-moisture dry hay to slow passage and stabilise manure.
• Saline water and saltbush diets raise thirst; summer saline drinking can boost use by ~80%.

Keep troughs shaded and clean; livestock avoid warm, dirty water and reduce feed intake and production. Maintain pumps, floats and lines ahead of heatwaves to protect supply and meet requirements.

Feed intake and energy requirements across seasons

Seasonal swings change how much usable energy herds can and will eat each day.

From TDN to net energy: use TDN as a rough check but plan rations on a net energy basis for maintenance, growth and milk. Aim to keep total diet energy balanced so animals meet targets without rumen upset.

Practical checks and the 65–70% TDN rule

Intake peaks at roughly 65–70% TDN. Above that level, animals often cut voluntary intake to avoid digestive issues. Include enough roughage to keep rumen function steady when using high-energy supplements.

Season, body score and feed intake effects

Forage intake capacity varies with quality and stage. Typical dry-matter intake runs 1.8–2.7% of liveweight; lactating stock sit at the top end.

Heat depresses intake and lowers production; cold raises demand. A 1,200 lb cow at 20°F with wind can need about 28% more energy than at 32°F with no wind. Lactation increases energy need by ~50% over maintenance.

Body condition matters. Fleshy animals tend to eat 2.5–5% less than thinner animals on the same forage, so adjust feeding rates and paddock rotations to keep condition stable.

“Match net energy to the animal’s stage and season — support early lactation and lift energy or DMI through cold snaps to protect rebreeding and weight.”

• Convert TDN checks into net energy targets when building rations.
• Use the 65–70% TDN guide to avoid suppressing intake with overly dense feeds.
• Plan supplements and rotations to cover seasonal dips in feed intake and rising energy requirements.

Protein, crude protein and metabolizable protein systems

Getting the right balance of degradable and bypass protein keeps rumen function steady and production on track.

Crude protein (CP) is a lab measure: nitrogen × 6.25. It tells total N, not how the animal uses it.

Metabolizable protein (MP) splits into microbial protein made in the rumen plus rumen undegradable protein (RUP) that reaches the small intestine.

RDP vs RUP: balancing rumen degradable and undegradable protein

Rumen degradable protein (RDP) feeds microbes. They convert fibre to volatile fatty acids and microbial protein.

RUP bypasses the rumen and is digested in the small intestine to support growth, milk and fertility.

• Why both matter: RDP sustains fermentation and energy extraction; RUP supplies amino acids post-rumen.
• High-performing stock benefit from added RUP; low forage quality often needs extra RDP.

Calculating RDP as a proportion of TDN intake

Use 10–13% of daily TDN as the RDP rule of thumb.

“Example: 25 lb DM at 50% TDN = 12.5 lb TDN; RDP need ≈ 1.25 lb (10%).”

If hay is 6% CP and 65% of CP is RDP, that hay supplies about 0.98 lb RDP. The gap is 0.27 lb RDP — the amount to top up with a supplement.

Practical action: test CP and degradability, convert percentages to kilograms of RDP, then plug any shortfall with a targeted supplement. Without enough RDP, fermentation and intake fall, and energy extraction suffers.

Mineral requirements and interactions that matter

Minerals steer growth, fertility and immune function more quietly than energy but with equal impact.

Macro and trace minerals: ranges and roles

Key macro ranges per kg dry matter: P 1.0–3.8 g; S ~2.0 g; Ca 2.0–11.0 g; Na 0.8–1.2 g; Mg 1.3–2.2 g; K 5.0 g; Cl 0.7–2.4 g.

Trace targets (mg/kg DM): Cu 4–14; Co 0.07–0.15; Se 0.04; Zn 9–20; I 0.5; Fe 40; Mn 20–25.

Why these matter: they support growth, bone strength, fertility and immunity. Lack or excess shows up as slow gains, poor conception and weakened disease resistance.

Common antagonisms and seasonal risks

Some elements interact. High sulphur reduces copper availability. Molybdenum with sulphur and iron also ties up copper.

High potassium — often from lush spring pasture — combined with high calcium and protein can limit magnesium uptake and cause grass tetany risks.

“Water can be a hidden mineral source; bore and saline supplies may push elements above safe limits.”

Practical checks and actions

• Test both feedstuffs and water for mineral content before setting loose licks or blocks.
• Adjust supplements for local antagonisms — add available copper where molybdenum is high, but stay within safe limits.
• Watch seasons: lush pasture raises K and protein; drought concentrates salts in water.
• Keep trace elements within known safe ranges; low-dose essentials can be toxic in excess.

Takeaway: design mineral programs that include water analysis, monitor for antagonisms, and review supplement formulas each season to keep stock in good condition.

Vitamins for grazing cattle: practical considerations

Vitamins play a quiet but vital role in herd resilience, especially on pasture-based systems.

Focus on fat-soluble A, D and E and water-soluble B complexes. Green forage supplies most provitamin A and vitamin E. When pastures dry off, or when animals eat stored hay, those supplies fall and targeted supplementation is needed.

Why it matters: vitamin status links directly to immune response, reproductive success and recovery from heat or transport stress. Young stock and first‑calvers are the highest risk group.

• Check requirements against NASEM guidelines and avoid exceeding maximum tolerable levels.
• Match vitamin inclusion with mineral programs to prevent imbalances and wasted cost.
• Use injectable or oral boluses only when testing or risk justifies them.

“Clean, continuous water supports vitamin and mineral uptake and is essential for calf performance.”

Practical tip: work with a nutritionist to design a cost‑effective vitamin plan that fits your feed base, protects production and keeps young stock growing.

Rumen function and fermentation fundamentals

The rumen is a living fermentation vat. It converts fibre and forage into volatile fatty acids that supply about 60–80% of daily energy for grazing stock.

VFAs, microbes and the small intestine

Microbes in the rumen digest structural matter and ferment carbohydrates to produce acetate, propionate and butyrate. These VFAs are the main energy source for maintenance and production.

Microbial protein forms from rumen microbes using true protein and non-protein nitrogen (for example urea). When microbes pass to the abomasum and then the small intestine, they release high‑quality protein for absorption.

Rumen undegradable protein (RUP) bypasses fermentation and is digested lower in the gut. High‑performing animals often need added RUP to meet amino acid demands.

“Cud chewing and eructation keep the rumen stable—disruption of these behaviours signals rapid trouble.”

• Keep effective fibre length and water access to support steady fermentation and intake.
• Use non‑protein nitrogen safely only when fermentable energy is present to capture it into microbial protein.
• Monitor behaviour—reduced cud or bloat risk harms digestion and health quickly.

Forage quality, plant selection and grazing behaviour

Pasture mix and plant stage shape what stock pick at each bite and drive daily intake.

Palatability comes from leafiness and protein content. In arid country, grasses and forbs supply the bulk of dry matter early in the season. When those plants mature, digestibility falls and NDF rises, cutting voluntary intake and performance.

How bite mechanics and plant mix shape selection

Bite mechanics favour soft leaves and stems. Animals reject twigs and coarse stems, so selective grazing concentrates use on leafy species and can reduce their persistence over time.

“Regular, light grazing encourages fresh leaf and faster regrowth; heavy, late grazing leaves stems that lower herd intake.”

• Species mix, maturity and leafiness dictate palatability and day-to-day feed choice.
• As plants age, digestibility drops and NDF increases — supplement when quality falls.
• Diverse pastures buffer seasonal shortfalls and support steadier production.
• Shrubs such as saltbush help maintain condition in dry spells but rarely drive strong weight gain alone.
• Targeted grazing and strategic spelling keep pastures leafy and productive.

Australian realities: arid zones, saltbush and saline water

When water carries salts, watering systems and shade become primary production tools. In arid zones, salt in troughs and shrubs changes daily needs and how stock use the paddock.

Practical salinity limits: keep source salinity under 4,000 mg/L for growth and under 5,000 mg/L to maintain condition. Ten thousand mg/L is an absolute maximum.

Salinity thresholds and managing high-salt diets

High-salt pastures, like saltbush, add a salt load that raises water requirements. Summer saline drinking can increase consumption by about 80%.

• Test each water source for salts and compare to the thresholds below.
• When levels push above growth thresholds, dilute with fresh supply or limit access time and offer low-salt feed.
• Match loose licks to the salt load so mineral requirements stay balanced.

Shade, distance to water and summer water management

Shade near troughs lowers body heat and reduces overall water use. Cooler, clean water keeps animals drinking and supports feed use and production.

Keep water points within manageable walking distances to avoid wasted energy and to protect water intake per day. In heat, ensure trough capacity and flow let every animal drink when needed.

Maintenance routines before hot spells save stock:

• Check pumps, floats and pipes weekly in summer.
• Clean troughs and remove algal build-up so source content stays acceptable.
• Have backup tanks or an emergency pumping plan to stop shortfalls that quickly cut feed intake.

“A reliable, cool water source near shade is often the simplest improvement that lifts herd condition in dry country.”

Classes of cattle and stage-specific nutrient needs

Practical feeding begins by grouping stock and matching daily delivery to stage. That approach protects production, condition and future fertility.

Lactating cows

Lactation roughly doubles protein needs versus a dry cow. An average beef cow peaks near 25 lb milk per day; higher-milk lines require more feed and denser diets.

Prioritise energy and protein to protect milk production and timely rebreeding. Increase dietary density gradually to avoid rumen upset.

Late pregnancy

Two-thirds of fetal growth happens in the last third of gestation. Raise both energy and protein in this window so the dam keeps body condition and the calf gets nourishment.

Growing young stock

Replacement heifers should gain about 1–1.5 lb/day to hit puberty and frame targets. Lower dry matter intake means higher protein concentration in the diet is needed to support growth and muscle.

“Match supplements to milking ability and track body condition — small, steady gains beat big swings.”

Weighing and condition scoring are non-negotiable. Use these checks to adjust rations, time transitions and meet breeding weight and growth targets without disrupting the rumen.

Building rations and supplementation programs

Good rations begin with a clear picture of dry matter, digestibility and the mineral load in every feed.

Start with the forage base: test hay and pasture for DM, DMD/DOMD, NDF/ADF and mineral content. Plug results into a simple ration plan to map shortfalls against nutrient requirements.

Check energy and crude protein targets by class. Verify RDP meets 10–13% of daily TDN from the measured TDN; add protein meals or urea where safe to close gaps.

Practical rules

• Match net energy density to production goals but keep effective fibre so intake does not fall.
• Choose mineral mixes after testing both feed and water; water can be a hidden source that alters mineral balance.
• In arid country, budget higher water use and account for sodium from shrubs when selecting licks and buffers.

“A tested feed base makes supplementation efficient and lowers cost per kilo of gain.”

Monitoring performance, water and feed quality

Early detection of changes in feed and water prevents drops in weight and production.

Screen every water source before the hot months. Test for salinity, nitrates and key toxic elements. Dirty or warm water slows growth and hits calves hardest.

Practical checks and seasonal adjustments

Track feed intake, manure consistency and body weight trends to spot problems fast. Forage capacity varies with quality and stage (about 1.8–2.7% BW). Implants or Rumensin can slightly reduce voluntary intake — factor that into plans.

• Set a routine for water testing—salinity, nitrates, toxic elements—before summer.
• Re-check mineral content in feed and water when changing paddocks or sources.
• Adjust rations for heat (lower DMI) and cold (higher energy need).
• Calibrate supplements by monitoring actual intake per day to avoid waste.
• Keep records of forage and water tests plus performance to refine decisions.

“Clean, cool water and simple, regular checks protect herd condition and lift production.”

Conclusion

A practical feeding plan lines forage and supplements to each class so animals meet daily requirements without wasted cost. Match feed quality and dry matter offers to target gains, fertility and herd resilience.

Water remains the single most powerful lever. Clean, cool supply and easy access keep intake steady and protect on‑farm production.

Test feed and water regularly for salts, minerals and vitamin levels. Use NASEM frameworks and local results to build cost‑effective rations suited to Australian conditions.

Plan for seasons. Adjust energy and protein delivery to suit heat, cold and stage without risking rumen function. Small, steady improvements in monitoring and supplementation deliver reliable gains in animal health and on‑farm profit.