How much do horses eat?
Grass/fresh forage
It is difficult to measure the fresh forage eaten by horses grazing (voluntary dry matter intake or VDMI). The NRC Nutrient Requirements of Horses 2007 suggests that estimated VDMI for grazing horses ranges from 1.5 to 3.1% of bodyweight, with lactating mares having the highest intake at an average of 2.8% , and other categories of horses eating around 2% of their bodyweight. The NRC 2007 suggests an intake of 2 - 2.55 % BW/d for grazing adult non-lactating horses.
Voluntary DM intakes of fresh forages by horses and ponies have been measured and values ranging from 1.5 - 5.2% BW/d reported - Marlow et al 1983 & as above. Higher values tend to be ponies. Horses are regarded as averaging 2.2% BW/d for mature horses and 2.5 - 3% BW/d for lactating mares.
Under some circumstances around 5% BW/d has been reported - see
Smith et al 2007
Longland et al 2011
Pratt-Phillips et al 2011
Dulphy et al. 1997 concluded that average DM intakes of forage were ~2% BW
It is difficult to measure the fresh forage eaten by horses grazing (voluntary dry matter intake or VDMI). The NRC Nutrient Requirements of Horses 2007 suggests that estimated VDMI for grazing horses ranges from 1.5 to 3.1% of bodyweight, with lactating mares having the highest intake at an average of 2.8% , and other categories of horses eating around 2% of their bodyweight. The NRC 2007 suggests an intake of 2 - 2.55 % BW/d for grazing adult non-lactating horses.
Voluntary DM intakes of fresh forages by horses and ponies have been measured and values ranging from 1.5 - 5.2% BW/d reported - Marlow et al 1983 & as above. Higher values tend to be ponies. Horses are regarded as averaging 2.2% BW/d for mature horses and 2.5 - 3% BW/d for lactating mares.
Under some circumstances around 5% BW/d has been reported - see
Smith et al 2007
Longland et al 2011
Pratt-Phillips et al 2011
Dulphy et al. 1997 concluded that average DM intakes of forage were ~2% BW
Equine Applied and Clinical Nutrition
P 409
Estimating grass intake is difficult. If a horse maintains bodyweight, this reflects adequate energy intake. It has been assumed that VDMI matches energy requirements, but research has shown that intake is highly variable.
VDMI is influenced by grass availability, palatability (plant species and composition) and digestibility/plant maturity (quality of grazing), grazing behaviour, quantity of grazing (sward height, stocking density), gender, age, breed, breeding status, herd dynamics and weather. VDMI will be greater on well managed pasture with a low stocking density compared to over-grazed or drought-damaged pasture.
Forage quality affects VDMI but a simple relationship has not been found in horses, with some horses increasing and some decreasing their VDMI when forage quality and dry matter digestibility decrease (Edouard et al 2008).
Edouard et al 2009 - horses chose longer grass in equal quality grass.
Rate of intake is affected by mouth and body size. Fleurance et al 2009 found that ponies increase their rate of intake by increasing bite size, but their overall intake is limited by the time to bite and chew, which increases with body size and is greater in large horses.
Ponies have been suggested to have a higher VDMI than horses, with almost 5% recorded for ponies stabled and offered ad lib fibre-based feed.
Dugdate et al 2011 found that ponies could consume a high proportion of their predicted VDMI when grazing time was restricted.
Ince et al 2011 reported that ponies ate almost 50% of their total daily dry matter intake during 3 hours of grazing, after acclimatization to restricted grazing.
VDMI of horses and ponies at grass varies widely between individuals. "Most estimates suggest a range of between 1.6-3.6% of bodyweight (NRC 2007) with lactating mares typically at the higher end of this range for VDMI (2.6-3.1%)."
P 409
Estimating grass intake is difficult. If a horse maintains bodyweight, this reflects adequate energy intake. It has been assumed that VDMI matches energy requirements, but research has shown that intake is highly variable.
VDMI is influenced by grass availability, palatability (plant species and composition) and digestibility/plant maturity (quality of grazing), grazing behaviour, quantity of grazing (sward height, stocking density), gender, age, breed, breeding status, herd dynamics and weather. VDMI will be greater on well managed pasture with a low stocking density compared to over-grazed or drought-damaged pasture.
Forage quality affects VDMI but a simple relationship has not been found in horses, with some horses increasing and some decreasing their VDMI when forage quality and dry matter digestibility decrease (Edouard et al 2008).
Edouard et al 2009 - horses chose longer grass in equal quality grass.
Rate of intake is affected by mouth and body size. Fleurance et al 2009 found that ponies increase their rate of intake by increasing bite size, but their overall intake is limited by the time to bite and chew, which increases with body size and is greater in large horses.
Ponies have been suggested to have a higher VDMI than horses, with almost 5% recorded for ponies stabled and offered ad lib fibre-based feed.
Dugdate et al 2011 found that ponies could consume a high proportion of their predicted VDMI when grazing time was restricted.
Ince et al 2011 reported that ponies ate almost 50% of their total daily dry matter intake during 3 hours of grazing, after acclimatization to restricted grazing.
VDMI of horses and ponies at grass varies widely between individuals. "Most estimates suggest a range of between 1.6-3.6% of bodyweight (NRC 2007) with lactating mares typically at the higher end of this range for VDMI (2.6-3.1%)."
Martinson KL, Siciliano PD, Sheaffer CC, McIntosh BJ, Swinker AM, Williams CA
A Review of Equine Grazing Research Methodologies
Journal of Equine Veterinary Science Volume 51, April 2017, Pages 92-104
Harrison R, Murray JMD
A preliminary study of grazing intakes of ponies with and without a history of laminitis
Livestock Science 2016, 186 pp. 2-5
Osoro et al 2017 followed 5 crossbred (mostly Cabalo Galego de Monte/Galician pony) mares with suckling foals sharing 22.3 ha 76% heathland and 24% improved pasture (white clover, perennial ryegrass, Agrostis capillaris) in north west Spain from April to autumn in 2004 and 2005 (there was a severe drought in 2005). Dry matter intake (DMI was calculated in June 2004 268.2, Sept 2004 134.3 and June 2005 251.3, giving an average of 217.9 g DM/kg BW. (From Harris et al. 2017: Average DM intake was 2.7% of BW, and intake rate 11 min/kg).
Osoro K, Ferreira LMM, Garcia U, Martinez A, Celaya R
Forage intake, digestibility and performance of cattle, horses, sheep and goats grazing together on an improved heathland
Animal Production Science 2017, 57, 102-109. doi: 10.1071/A15153. Published online by CSIRO Publishing 22 Sept 2015 (full paper on ResearchGate)
Bott RC, Greene EA, Kock K, Martinson KL, Siciliano PD, Williams C, Trottier NL, Burk A, Swinker A
Production and Environmental Implications of Equine Grazing
Journal of Equine Veterinary Science Volume 33, Issue 12, December 2013, Pages 1031-1043 (DeepDyve)
Ferreira et al 2012 also looked at 5 mares grazing heathland/improved pasture in north west Spain (presumably the same project as Osoro et al. 2017 above, so presumably these mares were suckling foals, not sure if this paper presents different data or not). Ponies grazed for an average of 621 minutes/day (10 hours 21 minutes). Daily feed intake was 233 g DM/kg LW0.75 in June and 119 g DM/kg LW0.75 in September.
Ferreira L.M.M. et al. (2012)
Foraging behaviour of equines grazing on partially improved heathlands
In: Saastamoinen M., Fradinho M.J., Santos A.S., Miraglia N. (eds) Forages and grazing in horse nutrition. Forages and grazing in horse nutrition, vol 132. Wageningen Academic Publishers, Wageningen
Dowler LE, Siciliano PD, Pratt-Phillips SE, Poore M
Determination of Pasture Dry Matter Intake Rates in Different Seasons and Their Application in Grazing Management
Journal of Equine Veterinary Science Volume 32, Issue 2, February 2012, Pages 85-92
Estimation of Pasture Dry Matter Intake and its Practical Application in Grazing Management for Horses - Paul D Siciliano
A Review of Equine Grazing Research Methodologies
Journal of Equine Veterinary Science Volume 51, April 2017, Pages 92-104
Harrison R, Murray JMD
A preliminary study of grazing intakes of ponies with and without a history of laminitis
Livestock Science 2016, 186 pp. 2-5
Osoro et al 2017 followed 5 crossbred (mostly Cabalo Galego de Monte/Galician pony) mares with suckling foals sharing 22.3 ha 76% heathland and 24% improved pasture (white clover, perennial ryegrass, Agrostis capillaris) in north west Spain from April to autumn in 2004 and 2005 (there was a severe drought in 2005). Dry matter intake (DMI was calculated in June 2004 268.2, Sept 2004 134.3 and June 2005 251.3, giving an average of 217.9 g DM/kg BW. (From Harris et al. 2017: Average DM intake was 2.7% of BW, and intake rate 11 min/kg).
Osoro K, Ferreira LMM, Garcia U, Martinez A, Celaya R
Forage intake, digestibility and performance of cattle, horses, sheep and goats grazing together on an improved heathland
Animal Production Science 2017, 57, 102-109. doi: 10.1071/A15153. Published online by CSIRO Publishing 22 Sept 2015 (full paper on ResearchGate)
Bott RC, Greene EA, Kock K, Martinson KL, Siciliano PD, Williams C, Trottier NL, Burk A, Swinker A
Production and Environmental Implications of Equine Grazing
Journal of Equine Veterinary Science Volume 33, Issue 12, December 2013, Pages 1031-1043 (DeepDyve)
Ferreira et al 2012 also looked at 5 mares grazing heathland/improved pasture in north west Spain (presumably the same project as Osoro et al. 2017 above, so presumably these mares were suckling foals, not sure if this paper presents different data or not). Ponies grazed for an average of 621 minutes/day (10 hours 21 minutes). Daily feed intake was 233 g DM/kg LW0.75 in June and 119 g DM/kg LW0.75 in September.
Ferreira L.M.M. et al. (2012)
Foraging behaviour of equines grazing on partially improved heathlands
In: Saastamoinen M., Fradinho M.J., Santos A.S., Miraglia N. (eds) Forages and grazing in horse nutrition. Forages and grazing in horse nutrition, vol 132. Wageningen Academic Publishers, Wageningen
Dowler LE, Siciliano PD, Pratt-Phillips SE, Poore M
Determination of Pasture Dry Matter Intake Rates in Different Seasons and Their Application in Grazing Management
Journal of Equine Veterinary Science Volume 32, Issue 2, February 2012, Pages 85-92
Estimation of Pasture Dry Matter Intake and its Practical Application in Grazing Management for Horses - Paul D Siciliano
Dugdale AH, Curtis GC, Cripps PJ, Harris PA, Argo CM.
Effects of season and body condition on appetite, body mass and body composition in ad libitum fed pony mares.
Vet J. 2011 Dec;190(3):329-37. Epub 2010 Dec 10 (full paper on DeepDyve)
Annette Longland presented at the Equine Science Society 2011: mature ponies not in work ate an average of 3.8% BW DM mixed grass/legume pasture over 6 weeks - from 3.4% BW higher quality pasture (DE 2.9 Mcal/kg) to 4.2% lower quality pasture (DE 2.3 Mcal/kg) - however, these were estimated figures calculated from changes in body weight.
Longland AC, Ince J, Harris PA
Estimation of pasture intake by ponies from liveweight change during six weeks at pasture
Journal of Equine Veterinary Science May–June, 2011 Volume 31, Issues 5-6, Pages 275–276 (full paper on DeepDyve)
Dugdale et al 2010
Smith et al 2007
Crawford et al 2007: It has been calculated from some studies of pasture consumption (Longland and Byrd, 2006) that horses can commonly consume between 2.1 and 3.5 kg of fructans per d (4.2 to 7.0 g/kg of BW) for a 500-kg animal. This calculation was based on DM intakes of between 1.5 and 3% of BW per day, and a peak fructan content of around 25 to 30% of DM, although greater DM intakes have been reported (Longland and Byrd, 2006). Therefore, even at the lower end of this range of DM intakes, the total intake of fructan at certain times of the year on certain pastures could be considerable.
Crawford C, Sepulveda MF, Elliott J, Harris PA, Bailey SR
Dietary fructan carbohydrate increases amine production in the equine large intestine: Implications for pasture-associated laminitis
J ANIM SCI November 2007 vol. 85 no. 11 2949-2958
Comment..
Argo et al 2002
Holland et al 2000
Intakes of pasture range from 1.5 to 3.3% of bodyweight per day.
McMeniman 2000
Dulphy et al 1997 looked at mature light horses eating first cut fresh pasture VDMI 18 g DM/kg BW (so 1.8% BW), and eating second cut fresh pasture VDMI 20 (so 2.0% BW) source NRC 2007 p145.
Harris et al. 2017 reports this as: WM intake per 500 kg horse was 63, average DM intake was 2% BW, intake rate 10 min/kg and mean intake time 10.57 hours/24.
Houbiers and Smolders 1990 looked at 12 thoroughbreds/trotters eating fresh cut long summer grass (16% DM). WM intake per 500 kg horse was 80, average DM intake was 2.1% BW, intake rate 10 min/kg and mean intake time 13.37 hrs/24.
For the same horses eating fresh cut short spring grass (DM 14%), WM intake per 500 kg horse was 84, average DM intake was 2.3% BW, intake rate 8 min/kg and mean intake time 11.16 hrs/24.
Houbiers and Smolders 1990 also looked at 12 warmbloods eating fresh cut long summer grass (16% DM). WM intake per 500 kg horse was 85, average DM intake was 2.1% BW, intake rate 10 min/kg and mean intake time 14.15 hrs/24.
For the same horses eating fresh cut short spring grass (DM 14%), WM intake per 500 kg horse was 90, average DM intake was 2.4% BW, intake rate 8 min/kg and mean intake time 11.95 hrs/24. (From Harris et al. 2017).
Chenost and Martin-Rossett 1985 looked at thoroughbreds eating fresh cut hybrid ryegrass (20% DM). WM intake per 500 kg horse was 52, average DM intake was 2.6% BW, intake rate 12 min/kg and mean intake time 10.36 hrs/24 (from Harris et al. 2017). NRC 2007 p145 reports this as mature trotters ate fresh cut grass (4 species) and alfalfa at 98.6 g DM/kg BW0.75.
Marlow CH, van Tonder EM, Hayward FC, van der Merwe SS, Price LE
A report on the consumption, composition and nutritional adequacy of a mixture of lush green perennial ryegrass (Lolium perenne) and cocksfoot (Dactylis glomerata) fed ad libitum to Thoroughbred mares
J S Afr Vet Assoc. 1983 Sep;54(3):155-7
Non-lactating Thoroughbred mares ate 1.5-2.2% of their bodyweight in fresh cut perennial ryegrass/cocksfoot mix.
Hay, haylage and other non-fresh forage
Hay (85% DM)
Staniar et al 2014 looked at quarter horses eating teff hay (40% ADF). WM intake per 500 kg horse was 9.1, average DM intake was 1.7% BW, intake rate 45 min/kg and mean intake time 7 hrs/24.
Dulphy et al 1997 collated data from various authors including light horses eating lucerne hay. WM intake per 500 kg horse was 13, average DM intake was 2.2% BW, intake rate 45 min/kg and mean intake time 9.55 hrs/24.
Light horses eating grass hay had WM intake per 500 kg horse 13, average DM intake 2.2% BW, intake rate 35 min/kg and mean intake time 7.42 hrs/24 (Harris et al 2017).
Dulphy et al. 1997 concluded that average DM intakes of forage were ~2% BW:
Dulphy JP, Martin-Rosset W, Dubroeucq H, Ballet, JM, Detour A, Jailler M
Compared feeding patterns in ad libitum intake of dry forages by horses and sheep
Livestock Production Science Volume 52, Issue 1, 15 November 1997, Pages 49-56
Adult gelding saddle horses, weighing 500 kg, were offered grass hay (4), lucerne hay (1) and straw (1). On average, horses ingested 20.0 g DM/kg live weight, or 2% bodyweight, and ate more grass hay than lucerne hay or straw.
Vermorel et al 1997 looked at standardbreds eating late cut hay. WM intake per 500 kg horse was 10, average DM intake was 1.7% BW, intake rate 40 min/kg and mean intake time 6.42 hrs/24. For medium cut hay, WM intake per 500 kg horse was 11, average DM intake was 1.9% BW, intake rate 40 min/kg and mean intake time 7.05 hrs/24.
Martin-Rosset and Dulphy 1987 looked at heavy horse yearlings eating medium quality hay. WM intake per 500 kg horse was 12, average DM intake was 2% BW, intake rate 40 min/kg and mean intake time 7.75 hrs/24. (From Harris et al. 2017).
Staniar et al 2014 looked at quarter horses eating teff hay (40% ADF). WM intake per 500 kg horse was 9.1, average DM intake was 1.7% BW, intake rate 45 min/kg and mean intake time 7 hrs/24.
Dulphy et al 1997 collated data from various authors including light horses eating lucerne hay. WM intake per 500 kg horse was 13, average DM intake was 2.2% BW, intake rate 45 min/kg and mean intake time 9.55 hrs/24.
Light horses eating grass hay had WM intake per 500 kg horse 13, average DM intake 2.2% BW, intake rate 35 min/kg and mean intake time 7.42 hrs/24 (Harris et al 2017).
Dulphy et al. 1997 concluded that average DM intakes of forage were ~2% BW:
Dulphy JP, Martin-Rosset W, Dubroeucq H, Ballet, JM, Detour A, Jailler M
Compared feeding patterns in ad libitum intake of dry forages by horses and sheep
Livestock Production Science Volume 52, Issue 1, 15 November 1997, Pages 49-56
Adult gelding saddle horses, weighing 500 kg, were offered grass hay (4), lucerne hay (1) and straw (1). On average, horses ingested 20.0 g DM/kg live weight, or 2% bodyweight, and ate more grass hay than lucerne hay or straw.
Vermorel et al 1997 looked at standardbreds eating late cut hay. WM intake per 500 kg horse was 10, average DM intake was 1.7% BW, intake rate 40 min/kg and mean intake time 6.42 hrs/24. For medium cut hay, WM intake per 500 kg horse was 11, average DM intake was 1.9% BW, intake rate 40 min/kg and mean intake time 7.05 hrs/24.
Martin-Rosset and Dulphy 1987 looked at heavy horse yearlings eating medium quality hay. WM intake per 500 kg horse was 12, average DM intake was 2% BW, intake rate 40 min/kg and mean intake time 7.75 hrs/24. (From Harris et al. 2017).
Haylage (DM56-65%)
Bergero et al 2002 looked at ponies at rest eating early cut haylage (DM 56%). WM intake per 500 kg horse was 19, average DM intake was 2.7% BW, intake rate 30 min/kg and mean intake time 9.36 hrs/24.
Ponies in light work eating late cut haylage (DM 63%) had WM intake per 500 kg horse 17, average DM intake 2.8% BW, intake rate 30 min/kg and mean intake time 8.52 hrs/24.
Ponies in medium work eating late cut haylage (DM 65%) had WM intake per 500 kg horse 19, average DM intake 3.1% BW, intake rate 30 min/kg and mean intake time 9.3 hrs/24. (From Harris et al 2017).
Bergero et al 2002 looked at ponies at rest eating early cut haylage (DM 56%). WM intake per 500 kg horse was 19, average DM intake was 2.7% BW, intake rate 30 min/kg and mean intake time 9.36 hrs/24.
Ponies in light work eating late cut haylage (DM 63%) had WM intake per 500 kg horse 17, average DM intake 2.8% BW, intake rate 30 min/kg and mean intake time 8.52 hrs/24.
Ponies in medium work eating late cut haylage (DM 65%) had WM intake per 500 kg horse 19, average DM intake 3.1% BW, intake rate 30 min/kg and mean intake time 9.3 hrs/24. (From Harris et al 2017).
Straw (DM 88%+)
Pearson et al 2001 looked at ponies eating oat straw. WM intake per 500 kg horse was 12, average DM intake was 2.2% BW, intake rate 45 min/kg and mean intake time 9 hrs/24.
Dulphy et al 1997 collated data from various authors including light horses eating straw. WM intake per 500 kg horse was 7, average DM intake was 1.3% BW, intake rate 50 min/kg and mean intake time 5.88 hrs/24. (From Harris et al. 2017).
Pearson et al 2001 looked at ponies eating oat straw. WM intake per 500 kg horse was 12, average DM intake was 2.2% BW, intake rate 45 min/kg and mean intake time 9 hrs/24.
Dulphy et al 1997 collated data from various authors including light horses eating straw. WM intake per 500 kg horse was 7, average DM intake was 1.3% BW, intake rate 50 min/kg and mean intake time 5.88 hrs/24. (From Harris et al. 2017).
Mean concentrate/pellet/chaff diets
Dugdale et al. 2011 looked at overweight ponies eating a chaff diet. WM intake per 500 kg horse was 12, average DM intake was 2.3% BW, intake rate 60 min/kg and mean intake time 11.6 hrs/24.
Argo et al. 2002 looked at welsh ponies eating a chaff-pellet mix. WM intake per 500 kg horse was 21, average DM intake was 3.2% BW, intake rate 25 min/kg and mean intake time 8.61 hrs/24. Eating only pellets, WM intake per 500 kg horse was 25, average DM intake was 4.4% BW, intake rate 18 min/kg and mean intake time 7.43 hrs/24, and for the maximum intake on the pellet diet, WM intake per 500 kg horse was 28, average DM intake was 4.9% BW, intake rate 18 min/kg and mean intake time 8.4 hrs/24. (From Harris et al. 2017).
Dugdale et al. 2011 looked at overweight ponies eating a chaff diet. WM intake per 500 kg horse was 12, average DM intake was 2.3% BW, intake rate 60 min/kg and mean intake time 11.6 hrs/24.
Argo et al. 2002 looked at welsh ponies eating a chaff-pellet mix. WM intake per 500 kg horse was 21, average DM intake was 3.2% BW, intake rate 25 min/kg and mean intake time 8.61 hrs/24. Eating only pellets, WM intake per 500 kg horse was 25, average DM intake was 4.4% BW, intake rate 18 min/kg and mean intake time 7.43 hrs/24, and for the maximum intake on the pellet diet, WM intake per 500 kg horse was 28, average DM intake was 4.9% BW, intake rate 18 min/kg and mean intake time 8.4 hrs/24. (From Harris et al. 2017).
References
Harris PA, Ellis AD, Fradinho MJ, Jansson A, Julliand V, Luthersson N, Santos AS, Vervuert I
Review: Feeding conserved forage to horses: recent advances and recommendations
Animal. 2017 Jun;11(6):958-967. doi: 10.1017/S1751731116002469. Epub 2016 Nov 24 (Full paper on ResearchGate)
Martinson KL, Siciliano PD, Sheaffer CC, McIntosh BJ, Swinker AM, Williams CA
A Review of Equine Grazing Research Methodologies
Journal of Equine Veterinary Science Volume 51, April 2017, Pages 92-104
Harris PA, Ellis AD, Fradinho MJ, Jansson A, Julliand V, Luthersson N, Santos AS, Vervuert I
Review: Feeding conserved forage to horses: recent advances and recommendations
Animal. 2017 Jun;11(6):958-967. doi: 10.1017/S1751731116002469. Epub 2016 Nov 24 (Full paper on ResearchGate)
Martinson KL, Siciliano PD, Sheaffer CC, McIntosh BJ, Swinker AM, Williams CA
A Review of Equine Grazing Research Methodologies
Journal of Equine Veterinary Science Volume 51, April 2017, Pages 92-104