MHU/HQ September 2012: Digestive Anatomy
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MHU/HQ September 2012: Digestive Anatomy






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  • Prehension Lips/incisors Allows for selectivity of feeds
  • Microbial fermentation promoted by: Buffering effect of bicarbonate and Na derived from SI Anaerobic environment Normal motility Acetic and butyric acids are products of fiber digestion Propionate is product of starch digestion Optimum pH of microbial fermentation is 6.5 Gas production is byproduct – CO2, methane, H Protein digestion is a hot debate

MHU/HQ September 2012: Digestive Anatomy MHU/HQ September 2012: Digestive Anatomy Presentation Transcript

  • My Horse University and eXtension’s HorseQuest welcome you to this live Webcast. Digestive Anatomy:Why We Feed Horses the Way We Do Dr. Carey Williams Rutgers University
  • Meet our presenter: Dr. Carey Williams Rutgers UniversityQuestion facilitator: Danielle Smarsh, Doctoral Candidate Rutgers University
  • FOREGUT:• Mouth• Stomach• Esophagus• Small IntestineHINDGUT:• Cecum• Large Colon• Small Colon• Rectum
  • Mouth• Function: – Selection – Chewing – Saliva – Swallowing• Teeth: – Incisors: shear forage – Molars: grind food
  • Teeth Floating(Hill, 1997. Horse Health Care)
  • ChokeEndoscopy ofan esophageal obstruction
  • Stomach• Small stomach capacity, only 2-4 gallons for a 1100 lb horse – Secretes HCl and Pepsin to begin the breakdown of food – Unable to regurgitate food • Sphincter between esophagus and stomach only allows passage of food one way • Horses Can’t Throw Up!
  • Small Intestine• Small intestine is 50-70 ft long and holds 10- 23 gallons – Most of the nutrients (protein, some CHO and fat) are digested here – Most of the vitamins and mineral are absorbed here – Water is not absorbed here but helps move the food through
  • Accessory Organs• Pancreas: – Production/secretion of pancreatic juices for protein, starch, fiber digestion• Liver: – Production of bile – Emulsification of fat – Bile secreted continuously by the liver – NO GALL BLADDER!
  • Large Intestine• Large Intestine: • Cecum • Large and Small colon • Rectum – Forage fermentation – Water absorption
  • Cecum• Liquids are passed to the cecum – 3-4 ft long and holds 7-8 gallons – No detoxification of toxic substances until they reach the cecum – Contains bacteria to digest the fiber and some carbohydrates
  • Cecum• Functions: – Microbial Fermentation: • Volatile fatty acids: acetic, propionic, butyric • B-Vitamins, Vitamin K, Gas – Absorption: • Protein and fermentation products• Transit time: – Slow- 38 to 48 h – Liquids- 5 h
  • Microbial Digestion Microbes Fiber from forage & other undigested residualsVFA’s, B-vitamins, Vitamin K, Gas
  • Avoid Abrupt Changes
  • Large Colon• Large colon is 10-12 ft. long and holds 14-16 gallons – Four parts: • right ventral colon • sternal flexure to left ventral colon • pelvic flexure to left dorsal colon • diaphragmatic flexure to the right dorsal colon – Sternal and diaphragmatic flexures are a common place for impaction
  • Large Colon
  • Small Colon• Small colon leads up to the rectum – It is 10 ft long and only holds 5 gallons – Smaller diameter than large colon – Functions: • Water absorption • Formation of fecal balls• Rectum 1 ft in length – Function: Storage reservoir
  • NutrientsSite of: Digestion AbsorptionWater ------- ColonProtein Stomach & SI SILipid SI SICHOs Simple SI SI Complex Starch SI SI Structural LI LI
  • MonogastricsMouthStomach Protein digestion SI Prot absorption, lipid dig/absorp, Simple CHO dig/absorpCecum Complex CHO fermentationColon Complex CHO fermentation Absorption of water
  • Grains and Forages for Horses
  • Roughages vs. Concentrates Roughage ConcentrateFiber High LowEnergy Low HighProtein Variable VariableCost Lower VariableDensity Low (bulky) High
  • Roughage• Pasture and Hay:• Horses should consume AT LEAST 1 % of their BW per day – 1000 lb horse = 10 lb hay• Nutrient intake depends on forage quality• Feeding quality forage can reduce cost of feeding grain
  • Pasture• Grasses:• Cool season: – bluegrass – orchardgrass – timothy – tall fescue Timothy Orchardgrass• Warm season: – bermuda – bluestem – sudan
  • PastureLegumes:• Alfalfa• Clover
  • Hay• Hay:• Grasses and legumes are cut to make hay• Orchardgrass/Alfalfa• Legumes have higher: • protein • energy • TDN • COST!
  • Hay Quality• Never feed dusty or moldy hay!• Quality depends on: – Plant Maturity • No seed heads – Leafiness • Smaller stem size – Smell – Color – Weeds/Debris
  • Hay Guidelines• Hay requirement: – Feed at least 50 % of the total ration as forage (pasture and/or hay) • E.g. 1000 lb horse will eat 15 to 30 lb of food • If feeding 20 lb; at least 10 lb should be forage – High quality grass hay or alfalfa/grass mix – Caution with straight Alfalfa • Creates Ca:P ratio imbalance • Diet too high in protein
  • Concentrates• Grains:• Fiber - low (2 -10%)• Energy - high• Protein - low (8 to 10%)• Cost - reasonable – Examples • Corn • Oats • Barley • Sorghum
  • - most popular OATS - lower energy value CORN - higher fiber - more palatable and digestible - can be expensive - palatable - 2 x energy as oats - low in fiber- mostly for humans - small hard kernel - easy to over feed- expensive - not palatable - moldy is lethal- small hard kernels - used in grain- high energy mixes - high energy - hard hulls- low palatability - low fiber - medium fiber & energy WHEAT MILO BARLEY
  • - byproduct of grain processingis oil- 35 % protein- 85 % is digestible FLAXSEED RYE - high-energy ingredient - usually as part of a mixture - kernel has high nutritional value - the plant itself is a good roughage source
  • Feeding Guidelines• Forage is the base – Always try to feed the most forage possible• Feed about 2% of the horses BW – 1000 lb horse = 20 lb• Feeding a 1000 lb horse at maintenance: – If 5-6 lbs grain; – then no less than 15 lbs of hay
  • Feeding Guidelines• Horses should be fed to meet their immediate needs – I.e. cut grain on rest days• Horses’ stomachs are small so feed at least 2 x a day – More times a day the better
  • Feeding Guidelines• Feed by weight not volume! – 1 lb oats is not 1 lb of corn• Monitor condition scores – Score of 5 is appropriate
  • Feeding Guidelines• Store feed properly, no mold or rodent contamination• Feed on a set schedule – Horses are creatures of habit – They easily upset by changes in routine• Change feeds gradually – Horses stomachs cannot cope with drastic change – It upsets the microbes in the GI tract causing colic
  • Feeding Guidelines• Be aware of the pecking order – Are they getting their food?• Regularly de-worm – Most common cause of a thin horse• Regularly examine teeth – Can they chew food?• Feed off the ground in hay racks or tubs – Prevents dust inhalation
  • Thank You!Carey Williams, Ph.D.Equine Extension Equine Science Center Better horse care through research & education
  • Give us your feedback!• You will receive a survey by email in 1-2 days. Please take a few minutes to give us your feedback on this webcast. It will help us to better serve you!
  • Upcoming Webcasts• Protein Requirements for Horses October 23, 2012 | 7PM EDT• Equine Energetics November 27, 2012 | 7PM EDT
  • Thank you for attending this live web presentation! For more information about My Horse University please visit us at: | | 517-353-3123