How it works
The science behind the numbers
Feedwise is a deterministic engine built on published animal-nutrition science. Every number — energy, protein, minerals, intake — traces to a named source, listed below. The maths is fixed equations from the published standards, run the same way every time.
AFRC energy & protein system
Requirements are built with the AFRC (1993) metabolisable-energy and metabolisable-protein framework — the same system professional nutritionists use — with New Zealand calibration from Beef+Lamb NZ and DairyNZ.
Law of the minimum
Achievable production is the smallest of what energy, protein and physical intake each allow — and capped at the animal’s realistic genetic potential. We tell you which one is holding things back.
The rumen-fill ceiling
Our point of difference: the rumen can only hold so much fibre. We cap intake by NDF rumen-fill, not just appetite, so a bulky diet shows its true limit instead of an optimistic number.
Checked against the experts
We cross-check the engine against professional formulation tools and real laboratory reports. On our reference cases its requirements land within a few percent of the expert figures across energy, protein and the key minerals.
Every number below is drawn from the published animal-nutrition science and, where useful, calibrated to New Zealand conditions. Each is tagged Established (a standard or NZ-calibrated value), Best estimate (our best-supported figure where direct data for that species is limited), or Design limit (a deliberately generous ceiling, not a measured requirement). The engine always runs on sourced defaults, and we keep refining them as better data lands.
Every number, and where it comes from
Nothing here is a black box. Open any group to see the values the engine uses and the source behind each. Some are exact published constants; others are calibrated to NZ conditions.
These are the engine’s coefficients — the numbers inside the equations. The composition of individual feeds is reference data rather than coefficients, and lives on feed values, with a source against each one.
Energy40 values
| Coefficient | Value | Source | Status |
|---|---|---|---|
| Gross energy of dry matter | 18.4MJ/kg DM | MAFF 1975/1984, adopted by CSIRO 2007 (§1) and NZ practice | Established |
| Efficiency of ME for maintenance (k_m) | 0.35·q + 0.503 | AFRC 1993 / ARC 1980 | Established |
| Efficiency of ME for lactation (k_l) | 0.35·q + 0.420 | AFRC 1993 | Established |
| Efficiency of ME for growth (k_g) | 0.78·q + 0.006 | AFRC 1993 | Established |
| Fasting metabolism (sheep)(sheep) | 0.25MJ/kg^0.75 | AFRC 1993 (young sheep 0.25; adults 0.23) | Established |
| Fasting metabolism (cattle)(cattle) | 0.294MJ/kg^0.75 | Calibrated to Beef+Lamb NZ / Nicol & Brookes 2007 (500 kg cow ~60 MJ/d) | Established |
| Basal activity allowance (sheep)(sheep) | 0.011MJ/kg LW | AFRC 1993 (range 0.0067–0.024) | Established |
| Basal activity allowance (cattle)(cattle) | 0.01MJ/kg LW | AFRC 1993 (0.0071–0.0095) | Established |
| Grazing-activity allowance (sheep)(sheep) | 0.21fraction over housed (rolling) | Nicol & Brookes 2007 / CSIRO 2007 (NZ rolling ~+20%) | Established |
| Grazing-activity allowance (cattle)(cattle) | 0.26fraction over housed (rolling) | Nicol & Brookes 2007 (NZ rolling ~+26%) | Established |
| Grazing-activity allowance (deer)(deer) | 0.21fraction over housed (rolling) | Nicol & Brookes 2007 (deer <100 kg as sheep-type) | Best estimate |
| Grazing-activity allowance (goat)(goat) | 0.27fraction over housed (rolling) | AFRC 1998 (goat MEm structurally higher than sheep) | Best estimate |
| Cold-stress uplift — cold/exposed | 1.15× maintenance | CSIRO 2007 cold-stress (Ecold); sustained-cold extension ~1%/°C below LCT | Best estimate |
| Cold-stress uplift — severe storm | 1.45× maintenance | CSIRO 2007 (wind + wet strip external insulation); DairyNZ dry-cow cold thresholds | Best estimate |
| Cold-stress uplift — cold, recently shorn (sheep)(sheep) | 1.3× maintenance | Elvidge & Coop 1974 (off-shears maintenance +18–24% in mild cold) | Best estimate |
| Cold-stress uplift — severe storm, recently shorn (sheep)(sheep) | 2× maintenance | Elvidge & Coop 1974 (exposed +76%); Symonds 1986 (shorn heat production +28%) — off-shears in a storm can double maintenance | Best estimate |
| Ewe milk energy(sheep) | 5.2MJ/L | Pulina; Brett et al. (ewe milk GE ~5.0–6.0 at 6.5% fat) | Established |
| Cow milk energy (default)(cattle) | 3.1MJ/L (net) | AFRC; refined by the entered fat/protein (Tyrrell-Reid lineage) | Established |
| Energy value of liveweight gain (sheep)(sheep) | (6.7+R) + (20.3−R)·ZF1, ZF1 = 1/(1+e^−6(LW/SRW−0.4)), R = 0.92·gain/(4·SRW^0.75)−1MJ/kg net | CSIRO 2007 (eq 1.30) / Nicol & Brookes 2007 / MPI NEMI | Established |
| Energy value of liveweight gain (cattle)(cattle) | (6.7+R) + (20.3−R)·ZF1, ZF1 = 1/(1+e^−6(LW/SRW−0.4)), R = 0.92·gain/(4·SRW^0.75)−1MJ/kg net | CSIRO 2007 (eq 1.30) / Nicol & Brookes 2007 / MPI NEMI | Established |
| Mature reference weight — finishing lamb(sheep) | 65kg | NZ Romney/composite ewe-line mature size | Established |
| Mature reference weight — ewe(sheep) | 72kg | Mature ewe liveweight | Established |
| Mature reference weight — hogget(sheep) | 65kg | Mature size of the hogget’s line | Established |
| Mature reference weight — growing cattle(cattle) | 550kg | NZ Angus/Hereford mature size (dairy-beef ~600–650) | Established |
| Mature reference weight — dairy cow(cattle) | 600kg | Friesian/dairy mature liveweight | Established |
| Mature reference weight — beef cow(cattle) | 550kg | NZ beef cow mature liveweight | Established |
| Milk energy to the lamb(sheep) | 4.5MJ ME/L | Ewe-milk GE ~4.8 MJ/L (39·fat+2090) × ~0.93 metabolisability | Established |
| Milk energy to the calf(cattle) | 2.9MJ ME/L | Cow-milk GE ~3.1 MJ/L × ~0.93 metabolisability | Established |
| Milk energy to the fawn(deer) | 5.7MJ ME/L | Red-deer milk GE ~6.0 MJ/L (Landete-Castillejos et al. 2003 energy equation; NZ composition Li et al. 2023) × ~0.95 | Best estimate |
| Milk energy to the kid(goat) | 3.6MJ ME/L | Boer/meat-doe milk GE ~3.8 MJ/L (Ferro, Tedeschi & Atzori 2017 — 907 kcal/kg) × ~0.95 | Best estimate |
| Fasting metabolism (deer)(deer) | 0.264MJ/kg^0.75 | Annual mean; Sika MEm 0.251/NEm 0.224 (PMC8476843); CSIRO AN10176 | Established |
| Basal activity allowance (deer)(deer) | 0.013MJ/kg LW | Free-living red deer ~20% > housed (no cervid factorial allowance) | Best estimate |
| Hind milk energy(deer) | 6MJ/L | Measured red-deer milk 5966 kJ/kg (Asher et al. 2022, PMC9411626) | Established |
| Mature reference weight — deer weaner (red)(deer) | 160kg | Red mid-frame mature size (hind ~110 / stag ~210; Nicol et al. 2003) | Best estimate |
| Mature reference weight — hind (red)(deer) | 110kg | Red mature hind ~90–120 kg (Wilson & Haigh; Nicol et al. 2003) | Established |
| Wapiti maintenance uplift(deer) | 1.2× | Hybrid maintenance ME/kg^0.75 ~+20% (Judson & Nicol 1997); applied to pure wapiti | Best estimate |
| Wapiti-cross maintenance uplift(deer) | 1.2× | Hybrid maintenance ME/kg^0.75 ~+20% (Judson & Nicol 1997) | Established |
| Fasting metabolism (goat)(goat) | 0.244MJ/kg^0.75 | Saanen dairy; growing goats ≈ sheep for maintenance, NS (PMC11879033) | Established |
| Basal activity allowance (goat)(goat) | 0.013MJ/kg LW | Active browser ≥ sheep (engineering estimate; no clean goat partition) | Best estimate |
| Doe milk energy(goat) | 2.8MJ/L | NZ Saanen milk 667 kcal/kg = 2.79 MJ/L (PMC7204986); leaner than generic goat | Established |
Protein14 values
| Coefficient | Value | Source | Status |
|---|---|---|---|
| MP from microbial crude protein | 0.6375 | AFRC 1993 (0.75 true protein × 0.85 digestibility) | Established |
| Fermentable ME fraction (fallback) | 0.92 | AFRC 1993 (forage default; excludes fat/acids) | Established |
| Oil energy value (FME deduction) | 35MJ/kg oil | AFRC 1993 — feed oil GE ~35 MJ/kg; fat carries ME but is not fermented | Established |
| Silage fermentation-acid (FME deduction) | 1.8MJ/kg DM | AFRC/BAGCD grass silage FME/ME ≈ 0.71 (ME 11.0 → FME 7.8) net of oil | Established |
| MP maintenance (sheep)(sheep) | 2.5g/kg^0.75 | AFRC (basal endogenous + scurf/dermal ~2.3–2.9) | Established |
| MP maintenance (cattle)(cattle) | 2.5g/kg^0.75 | AFRC 1993 / NRC (range ~2.3–3.8) | Established |
| Milk true protein (ewe)(sheep) | 52g/L | Measured ewe milk (48–58) | Established |
| Milk true protein (cow)(cattle) | 38g/L | NZ milk true protein ~3.8% (NZ Dairy Statistics) | Established |
| Efficiency of MP for milk | 0.68 | AFRC 1993 (0.68; revised 0.67) | Established |
| ERDP / DUP (default fallback) | 0.70 / 0.10 of CPfraction | AFRC 1993 — now FEED-SPECIFIC (see Feed library) | Established |
| MP maintenance (deer)(deer) | 2.5g/kg^0.75 | Sika net protein maintenance 1.57 g/kg^0.75 → MP ~2.2–2.6 (PMC8476843) | Established |
| Hind milk protein(deer) | 67g/L | Measured 6.7% true protein (Asher et al. 2022) | Established |
| MP maintenance (goat)(goat) | 3g/kg^0.75 | NRC 2007 ~3.07 (the Saanen 3.8 rides a km=0.33 artefact) | Established |
| Doe milk protein(goat) | 29g/L | Saanen 2.94% true protein (PMC7204986) | Established |
Minerals19 values
| Coefficient | Value | Source | Status |
|---|---|---|---|
| Calcium true absorption (sheep)(sheep) | 0.38 | NZ forage (NASEM grass 0.30–0.40) | Established |
| Phosphorus true absorption (sheep)(sheep) | 0.5 | Forage ~0.50–0.58 (AFRC/INRA) | Established |
| Magnesium true absorption (sheep)(sheep) | 0.17 | ARC 0.17 (conservative); NASEM base 0.31 | Established |
| Sodium true absorption (sheep)(sheep) | 0.9 | ARC/NASEM 0.90–0.91 | Established |
| Calcium maintenance (sheep)(sheep) | 0.623·DMI + 0.228g/d | AFRC 1991 (per kg DM intake) | Established |
| Phosphorus maintenance (sheep)(sheep) | 0.693·DMI − 0.06g/d | AFRC 1991 (per kg DM intake) | Established |
| Sodium maintenance (sheep)(sheep) | 22mg/kg LW | ARC sheep net endogenous ~26 (obligatory salivary recycling) | Established |
| Sodium maintenance (cattle)(cattle) | 6mg/kg LW | ARC cattle ~6 (NOT the higher sheep figure) | Established |
| Calcium maintenance (cattle)(cattle) | 0.66·DMI + 0.0079·W − 0.74g/d | AFRC 1991 (cattle; within ~4% of NASEM 2021 0.90·DMI) | Established |
| Phosphorus maintenance (cattle)(cattle) | 1.0·DMI (growing 0.8)g/d | NASEM 2021 Dairy (adult) / NASEM 2016 Beef (growing) | Established |
| Milk calcium (ewe)(sheep) | 1.9g/L | Measured ewe milk 1.6–1.9 | Established |
| Mg–K antagonism: K threshold | 2.5% DM K | NRC/CSIRO/NZ (Mg uptake falls above ~2.5–3% K) | Established |
| Mg–K antagonism: max reduction | 0.4fraction | Literature ~20–40%+ | Established |
| Calcium true absorption (deer)(deer) | 0.4 | No cervid factorial study — anchored to forage cattle 0.40 (conservative) | Best estimate |
| Phosphorus true absorption (deer)(deer) | 0.65 | Anchored to cattle 0.65 (deer are efficient P recyclers) | Best estimate |
| Sodium maintenance (deer)(deer) | 9mg/kg LW | Sheep/cattle-anchored (no cervid factorial Na balance study) | Best estimate |
| Calcium true absorption (goat)(goat) | 0.3 | NRC 2007 goat maintenance true-absorption 0.30 | Established |
| Phosphorus true absorption (goat)(goat) | 0.65 | NRC 2007 / Meschy goat P absorption 0.65–0.70 | Established |
| Sodium maintenance (goat)(goat) | 6mg/kg LW | Boer×Saanen kid balance (Mendonça 2017); Saanen Na not separately measured | Established |
Intake8 values
| Coefficient | Value | Source | Status |
|---|---|---|---|
| NDF-fill ceiling (lamb)(sheep) | 0.021fraction of LW | Cannas et al. (sheep NDF intake 5.4442·BW^-0.25) | Established |
| NDF-fill ceiling (ewe, non-lactating base)(sheep) | 0.017fraction of LW | Cannas et al. (×1.1 lactation uplift = lactating value) | Established |
| NDF-fill ceiling (cow, non-lactating base)(cattle) | 0.011fraction of LW | Mertens 1987/1994 (×1.1 = the 1.2% dairy benchmark) | Established |
| Lactation NDF-capacity uplift | 1.1× | Physiology (larger functional rumen, faster passage) | Best estimate |
| Late-pregnancy intake depression (cattle/deer/goat) | 0.15max fraction | Beef cow ~14% near term (suckler, last ~15 d); deer/goat by analogy (no species gestation-intake study). Sheep use the litter-split values below. | Established |
| Late-pregnancy intake depression (ewe, single)(sheep) | 0.12max fraction | Gallo & Tedeschi 2021 (Sci. Agric. 78:e20190291): single / ≤4 kg litter ~12% at term; lineage Pulina 1996 / INRA 1988 | Established |
| Late-pregnancy intake depression (ewe, twin/triplet)(sheep) | 0.18max fraction | Gallo & Tedeschi 2021 (Sci. Agric. 78:e20190291): multiple / >4 kg litter ~18% at term; lineage Pulina 1996 / INRA 1988 | Established |
| Appetite ceiling (ewe)(sheep) | 0.045fraction of LW | Lactating ewes 4.0–5.5% BW | Established |
Lactation curve33 values
| Coefficient | Value | Source | Status |
|---|---|---|---|
| Rearing ewe — early intake(sheep) | 0.8× | Physiological ewe lactation curve, suckling (Pulina; AFRC) | Established |
| Rearing ewe — early milk ceiling(sheep) | 1× | Physiological ewe lactation curve, suckling (Pulina; AFRC) | Established |
| Rearing ewe — mid intake(sheep) | 1× | Physiological ewe lactation curve, suckling (Pulina; AFRC) | Established |
| Rearing ewe — mid milk ceiling(sheep) | 0.78× | Physiological ewe lactation curve, suckling (Pulina; AFRC) | Established |
| Rearing ewe — late intake(sheep) | 0.9× | Physiological ewe lactation curve, suckling (Pulina; AFRC) | Established |
| Rearing ewe — late milk ceiling(sheep) | 0.5× | Physiological ewe lactation curve, suckling (Pulina; AFRC) | Established |
| Milked ewe — early intake(sheep) | 0.75× | Dairy-sheep intake (AFRC / Cannas) | Established |
| Milked ewe — early milk ceiling(sheep) | 0.95× | NZ dairy-sheep lactation (Hempstead et al. 2023) | Established |
| Milked ewe — mid intake(sheep) | 0.85× | Dairy-sheep intake (AFRC / Cannas) | Established |
| Milked ewe — mid milk ceiling(sheep) | 0.85× | NZ dairy-sheep lactation (Hempstead et al. 2023) | Established |
| Milked ewe — late intake(sheep) | 0.82× | Dairy-sheep intake (AFRC / Cannas) | Established |
| Milked ewe — late milk ceiling(sheep) | 0.55× | NZ dairy-sheep lactation (Hempstead et al. 2023, ~56% persistency) | Established |
| Dairy cow — early intake(cattle) | 0.78× | NASEM 2021 Dairy (DMI lags milk into early lactation) | Established |
| Dairy cow — early milk ceiling(cattle) | 0.92× | Wood 1967 lactation curve (peak ~wk 4–8) | Established |
| Dairy cow — mid intake(cattle) | 1× | NASEM 2021 Dairy (DMI peaks mid-lactation) | Established |
| Dairy cow — mid milk ceiling(cattle) | 0.97× | Wood 1967 lactation curve | Established |
| Dairy cow — late intake(cattle) | 0.98× | NASEM 2021 Dairy (intake stays high as milk falls) | Established |
| Dairy cow — late milk ceiling(cattle) | 0.75× | NZ 305-day persistency (Tong et al. 2016, ~76–90% OAD/TAD) | Established |
| Dairy goat — early intake(goat) | 0.82× | Goat lactation physiology (DMI peaks ~8–12 wk, after the milk peak) | Established |
| Dairy goat — early milk ceiling(goat) | 0.92× | Saanen lactation curve (peak ~day 50–80; Montaldo & Manfredi) | Established |
| Dairy goat — mid intake(goat) | 1× | Lactating dairy-goat DMI ~5% BW at peak (NRC 2007) | Established |
| Dairy goat — mid milk ceiling(goat) | 0.92× | Saanen lactation curve (flat plateau near peak) | Established |
| Dairy goat — late intake(goat) | 0.92× | Goat intake stays high through a persistent lactation (NRC 2007) | Established |
| Dairy goat — late milk ceiling(goat) | 0.8× | Saanen ~86% persistency (Montaldo & Manfredi); NZ extended lactation (Bauer et al. 2023) | Established |
| Beef cow — early intake(cattle) | 0.82× | Suckler early-lactation DMI suppressed ~18% (Teagasc/AHDB) | Established |
| Beef cow — early milk ceiling(cattle) | 0.9× | Ferreira et al. 2021 (Wood fit, peak ~wk 5.9) | Established |
| Beef cow — mid intake(cattle) | 1× | Lactating suckler DMI ~2.6% BW vs ~2.0% dry (NASEM-derived) | Established |
| Beef cow — mid milk ceiling(cattle) | 0.93× | Ferreira et al. 2021 (near-peak through mid lactation) | Established |
| Beef cow — late intake(cattle) | 0.92× | Intake eases as milk demand falls toward weaning (NASEM-derived) | Established |
| Beef cow — late milk ceiling(cattle) | 0.55× | Midpoint of Wood (~0.64–0.74) and Jenkins-Ferrell/NASEM (~0.27–0.45) beef fits | Best estimate |
| Hind — early milk ceiling(deer) | 1× | Red-deer lactation peak wk 2–4 (García et al. 1999 Type-I) | Best estimate |
| Hind — mid milk ceiling(deer) | 0.8× | Red-deer post-peak decline (García et al. 1999; Landete-Castillejos et al. 2000) | Best estimate |
| Hind — late milk ceiling(deer) | 0.55× | Decline toward pre-rut weaning at 3–4 months (Deer NZ; García et al. 1999) | Best estimate |
Pregnancy7 values
| Coefficient | Value | Source | Status |
|---|---|---|---|
| Pregnancy ME per foetus (ewe, at term)(sheep) | 7.75MJ/d | AFRC 1993 conceptus equation; Kenyon et al. 2019 NZ lamb birth weights | Established |
| Pregnancy ME per foetus (cow, at term)(cattle) | 42MJ/d | Beef+Lamb NZ FS90 Table 1.2 (above maintenance, at calving: 34 for a 30 kg calf, 45 for 40 kg) | Established |
| Pregnancy MP per foetus (ewe, at term)(sheep) | 45g/d | AFRC 1993 Table 9 (increment ~39–57) | Established |
| Pregnancy ME per foetus (hind, at term)(deer) | 5MJ/d | Cambridge red-deer model (late-term ramp 1.7→5.0 MJ/d; 55 MJ/kg birthweight) | Established |
| Pregnancy MP per foetus (hind, at term)(deer) | 45g/d | Sheep/cattle-scaled (no measured deer conceptus N) | Best estimate |
| Pregnancy ME per foetus (doe, at term)(goat) | 6.31MJ/d | AFRC 1998 goat (single kid at term; via Cannas et al. 2000); multiples per Härter et al. 2016 | Established |
| Pregnancy MP per foetus (doe, at term)(goat) | 32g/d | AFRC 1998 goat (single kid at term; via Cannas et al. 2000) | Best estimate |
Genetic ceiling13 values
| Coefficient | Value | Source | Status |
|---|---|---|---|
| Genetic ceiling — lamb gain(sheep) | 400g/day | NZGA / Beef+Lamb NZ (best NZ mobs ~409; finishing ~350) | Design limit |
| Genetic ceiling — cattle gain(cattle) | 1600g/day | Beef+Lamb NZ (observed max ~1.48–1.55 kg/d) | Design limit |
| Genetic ceiling — ewe milk(sheep) | 6L/day | East Friesian peak ~5–6 L | Design limit |
| Genetic ceiling — cow milk(cattle) | 50L/day | NZ pasture peaks ~30–40; 50 = generous ceiling | Design limit |
| Genetic ceiling — deer gain(deer) | 400g/day | DINZ (reds ~320–350; elk-cross higher) — season-scaled in winter | Design limit |
| Genetic ceiling — hind milk (red)(deer) | 2.5L/day | Red-deer peak ~2.5 L/d at ~day 40 (Loudon et al. 1983 ~2.2; Arman et al. 1974 1.4–2.0) | Design limit |
| Wapiti hind milk-ceiling factor(deer) | 1.6× | Wapiti hind peak ~4.0 L/d vs red 2.5 (cervid lactation review) | Design limit |
| Wapiti-cross hind milk-ceiling factor(deer) | 1.3× | Interpolated red↔wapiti — no direct hybrid milk citation | Design limit |
| Wapiti weaner growth-ceiling factor(deer) | 1.125× | Larger frame → higher growth potential than red (DINZ; Nicol et al. 2003) | Design limit |
| Wapiti-cross weaner growth-ceiling factor(deer) | 1.125× | Cross spring gain ~345 g/d per-head, +29% vs red (Judson 2003 / Nicol et al. 2003) | Design limit |
| Genetic ceiling — doe milk(goat) | 5L/day | Saanen peak ~5 L/day (NZ average ~2.7) | Design limit |
| Genetic ceiling — meat-doe milk(goat) | 2L/day | Suckled Boer/meat doe peak ~1.5–2.5 L/day (Casey & Van Niekerk 1988; Bekele et al. 2025) | Design limit |
| Genetic ceiling — meat-goat gain(goat) | 250g/day | Boer feedlot top-end (192–217 typical; elite ~250–340) | Design limit |
Rumen health2 values
| Coefficient | Value | Source | Status |
|---|---|---|---|
| Rumen NDF minimum (ewe)(sheep) | 30% DM | Extrapolated (NRC defines no sheep NDF requirement) | Best estimate |
| Rumen NDF minimum (dairy cow)(cattle) | 27% DM | NRC (min total NDF ~25%, 19% forage) | Established |
Risk indices5 values
| Coefficient | Value | Source | Status |
|---|---|---|---|
| Grass-staggers danger ratio | 2.2K/(Ca+Mg) meq | Kemp & 't Hart 1957 | Established |
| DCAD milk-fever threshold (dry/transition) | 300meq/kg | NRC/NASEM; DAIReXNET (lactating optimum is +250–340) | Established |
| Equivalent weights (DCAD/staggers) | Na 435, K 256…meq/% DM | Standard atomic equivalent weights | Established |
| Dietary sulfur — PEM watch / risk | 0.40 / 0.50% S of DM | NRC Mineral Tolerance of Animals 2005 / NASEM Beef 2016 (max tolerable 0.30% high-concentrate, 0.50% high-forage; 0.40% general hazard line) | Established |
| Brassica share of diet — watch | 70% of diet DM | DairyNZ (brassicas feed best <70% of the diet, ≥30% fibre, ≥10-day transition) | Established |
Emissions6 values
| Coefficient | Value | Source | Status |
|---|---|---|---|
| Methane yield — cattle(cattle) | 21.6g CH₄/kg DM eaten | NZ Greenhouse Gas Inventory (Clark, Brookes & Walcroft 2003); IPCC 2019 Eq 10.21a | Established |
| Methane yield — adult sheep(sheep) | 20.9g CH₄/kg DM eaten | NZ Greenhouse Gas Inventory (adult sheep >1 yr); IPCC 2019 Eq 10.21a | Established |
| Methane yield — young sheep (lambs/hoggets)(sheep) | 16.8g CH₄/kg DM eaten | NZ Greenhouse Gas Inventory (sheep <1 yr; Swainson, Muetzel & Clark 2015 — ~20% lower) | Established |
| Methane yield — deer(deer) | 21.3g CH₄/kg DM eaten | NZ Greenhouse Gas Inventory deer proxy (mean of cattle + sheep); measured NZ comparison (Swainson et al. 2007) sits in this mid-range | Best estimate |
| Methane yield — goats(goat) | 20.9g CH₄/kg DM eaten | Sheep figure used as the goat proxy (IPCC groups sheep + goats); IPCC 2019 goat Ym 5.5% as a cross-check | Best estimate |
| Methane → CO₂-equivalent (GWP100) | 28kg CO₂e per kg CH₄ | IPCC AR5 GWP100 — NZ official accounting metric | Established |
Trading4 values
| Coefficient | Value | Source | Status |
|---|---|---|---|
| Dressing-out % — prime lamb(sheep) | 0.44carcass ÷ liveweight | MPI 2963 "Review of dressing-out % in NZ livestock" — recommends 0.44 (Muir 6,200-lamb mean 0.438) | Established |
| Dressing-out % — prime beef(cattle) | 0.54carcass ÷ liveweight | MPI 2963 — recommends 0.54 for steers/heifers/bulls (NZ steer literature mean 0.533, lifted for heavier modern stock) | Established |
| Dressing-out % — venison (red deer)(deer) | 0.56carcass ÷ liveweight | MPI 2963 — red-deer mean 0.559, recommends 0.56; Te Ara/DINZ corroborate 0.54–0.60 | Established |
| Dressing-out % — meat goat(goat) | 0.5carcass ÷ liveweight | NZ Massey/Stafford Capretto–Chevon kid studies (Boer 0.50–0.57; kids 0.50–0.55) — not covered by MPI 2963 | Best estimate |
Feed budgeting7 values
| Coefficient | Value | Source | Status |
|---|---|---|---|
| Pasture utilisation | 0.85fraction of grown pasture eaten | DairyNZ Comparative Stocking Rate (pasture eaten ÷ 0.80 = grown); B+LNZ rotational-grazing default ~0.90 | Established |
| Minimum average cover | 1900kg DM/ha (whole-farm average) | DairyNZ — target balance-date APC 1900–2100 kg DM/ha is the lowest the average should reach all year; growth limited below ~1800–1900 | Established |
| Liveweight per condition score — ewe(sheep) | 7.74kg LW / BCS unit (1–5) | Morel et al. 2016 (Small Ruminant Research 143) — NZ Romney-cross body composition | Established |
| Liveweight per condition score — dairy cow(cattle) | 6.58% of liveweight (≈33 kg at 500 kg)kg LW / BCS unit (1–10) | DairyNZ Body Condition Scoring reference guide (6.58% of liveweight per BCS unit) | Established |
| Liveweight per condition score — beef cow(cattle) | 40kg LW / BCS unit (1–10) | B+LNZ Fact Sheet 90 (Nicol & Brookes 2007) — ~40 kg per unit on the 1–10 scale | Established |
| Liveweight per condition score — hind(deer) | 9kg LW / BCS unit (1–5) | Deer Industry NZ / Audigé, Wilson & Morris 1998 (NZ J Ag Res 41) — 8–10 kg per unit | Best estimate |
| Liveweight per condition score — goat(goat) | 8kg LW / BCS unit (1–5) | International caprine condition scoring (Ontario Goat; Langston University) — 7–10 kg per unit; not NZ-specific | Best estimate |
Animal health9 values
| Coefficient | Value | Source | Status |
|---|---|---|---|
| Pasture copper band | 5 low / 7 adequate / 15 highmg/kg DM | Grace & Knowles (2012) — mineral & trace-element nutrition of NZ grazing livestock | Established |
| Simple copper deficiency | 4mg/kg DM | B+LNZ Fact Sheet 95 — <4 = simple deficiency; 5–6 adequate only when Mo <1 | Established |
| Molybdenum band | >1 antagonises copper / >3 highmg/kg DM | Grace & Knowles (2012) | Established |
| Molybdenum copper-lockup threshold | 3mg/kg DM | Grace & Knowles (2012) — "Mo >3 mg/kg DM reduces the efficacy of oral Cu supplements by 30–50%" | Established |
| Sulphur compounding copper lockup | 0.4% DM | Grace & Knowles (2012) — S works with Mo to form thiomolybdates | Established |
| Pasture cobalt band | 0.06 low / 0.1 adequatemg/kg DM | Grace & Knowles (2012) — cattle ≥0.06, lambs ≥0.10 | Established |
| Pasture selenium band | 0.03 low / 0.05 adequatemg/kg DM | Grace & Knowles (2012); NZ pasture median ~0.05 | Established |
| Liver copper dry→wet conversion | ÷ 3.3dry basis → wet basis | Liver ≈ 30% DM; NZ labs report on a wet basis | Established |
| Facial eczema — preventive zinc | 20 mg Zn/kg LW/day (zinc oxide is 80% Zn) | DairyNZ / NZ veterinary guidance — the widely-cited preventive rate | Established |
Nutrient8 values
| Coefficient | Value | Source | Status |
|---|---|---|---|
| Lime to lift pH | 0.7t/ha per 0.1 pH unit | Edmeades et al. (2018) — 126-trial midpoint (range ~0.5–0.9) | Established |
| Lime buffering by soil type | sedimentary / ash / pumice 1× · peat 1.3×multiplier | FANZ (2024) + Edmeades et al. (2018) — mineral-soil buffering differences not significant; peat needs more | Established |
| Capital P per Olsen P unit | sed 5 · ash 11 · pumice 7 · peat 8kg P/ha per Olsen unit | FANZ (2024) p.25 averages; peat corroborated by O’Connor et al. (2001) | Established |
| Capital K per QTK unit | sed 50 · ash 60 · pumice 45 · peat 45kg K/ha per QTK unit | FANZ (2024) p.26 averages | Established |
| Annual sulphur rate | sed 35 · ash 25 · pumice 45 · peat 30kg S/ha/yr | FANZ (2024) p.27 | Established |
| Nutrient removed per 1000 kg milksolids | P 9 · K 15kg per 1000 kg MS | Overseer milk-mineral basis (milk P ~0.9, K ~1.5 g/L) | Established |
| Annual maintenance loss / immobilisation | P sed 21 / ash 29 · K sed 10 / ash 12kg/ha/yr, added to removal | FANZ (2024) p.28; peat from O’Connor et al. (2001) Proc. NZGA 63 Table 3 | Established |
| Default production for the maintenance estimate | 1100kg MS/ha/yr | NZ dairy average — a starting assumption, not a measurement | Established |
Primary sources
- AFRC (1993) — Energy and Protein Requirements of Ruminants
- CSIRO (2007) — Nutrient Requirements of Domesticated Ruminants
- NRC / NASEM — Nutrient Requirements of Sheep, Beef Cattle, and Dairy Cattle
- Beef + Lamb New Zealand — feed fact sheets (Nicol & Brookes 2007)
- DairyNZ — Facts & Figures; feed and pasture guidance
- Grace & Knowles — mineral & trace-element nutrition of NZ grazing livestock
- Feedipedia (INRAE / CIRAD / FAO) — feed composition & protein degradability
Feedwise gives indicative models for decision support. It is not a substitute for a nutritionist or veterinarian — for animal-health decisions, talk to your vet.