Equine Nutrition

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Equine Nutrition

• Digestion anatomy
• physiology

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Anatomy of the equine digestive system

• Teeth
• Strong teeth and jaws enable the horse to eat its
  feedstuff.
• The high-crowned teeth are held in the bone
  structures of the premaxilla and maxilla and the
  mandible.

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Anatomy of the equine digestive system
Teeth

• Adult horses usually have 40 teeth
• 12 incisors
• 4 canines
• 12 premolars
• 12 molars
• In females the canines may be small or absent.

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Anatomy of the equine digestive system
Upper jaw Maxilla
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Anatomy of the equine digestive system
Lower Jaw Mandible
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Anatomy of the equine digestive system
Erosion of central incisor
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Anatomy of the equine digestive system
Development of Galvaynes Groove
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Anatomy of the equine digestive system

• Teeth - refer to handout
• Lips - prehension
• Tongue - tactile
• - used for mastication wallowing - drives
  the food (bolus) into pharynx
• Pharynx - connects mouth w/ esophagus and
  nasal cavity w/ larynx
• - muscular passage
• - unimuscular

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Anatomy of the equine digestive system

• Epiglottis - passively covers the laryngeal
  opening during swallowing
• Esophagus - 50 to 60 in length
• - connects pharynx w/ stomach
• - has circular muscles which force
  food water down by peristalsis

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Anatomy of the equine digestive system

• Oral cavity

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Anatomy of the equine digestive system
Swallowing
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Anatomy of the equine digestive system
Salivary Glands

• - essential for digestion
• - secretion from these glands are highly
  variable in chemical composition
• - moistens, lubricates, protects and
  partially digests food via salivary
  amylase.
• - serves as a buffer in the ingesta

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Anatomy of the equine digestive system
Salivary glands

• 1. Parotid glands
• - largest, 8-10 long 1 thick
• - located below the ear behind the jaw
• - secretes water mucus
• - may cause compaction if not functioning
• 2. Submaxillary glands
• - are long and narrow
• - one is located on each side partly under
  the parotid gland
• - secretes water
• 3. Sublingual gland
• - located beneath the oral mucous membrane,
  between the tongue and the mandible
• - has many ducts opening orally along the
  length of the sublingual fold
• - 5 to 6 long secretes water

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Anatomy of the equine digestive system
Stomach

• - resembles that of a kidney bean
• - 2 to 4 gal cap. (8 of total GI)
• - esophagus enters stomach at sharp angle
• - water passes quickly
• - rate of passage of feed depends largely on
  the nutrient composition of the ration
• - initial stage of digestion is provided by
  gastric secretions

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Anatomy of the equine digestive system
Stomach

• Esophagus
• Stomach
• Greater curvature
• Lesser curvature
• Pyloric region
• Duodenum

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Anatomy of the equine digestive system
Stomach

• Esophagus
• Cardiac orifice
• Esophageal region
• Plicated margin
• Cardiac gland region
• Fundic gland region
• Pyloric gland region
• Pylorus

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Anatomy of the equine digestive system

• Digestion is more complete when stomach is not
  completely full.
• - two types of motility
• 1. peristalsis
• 2. tonic contraction
• Feed small quantities more often and feed hay
  before grain.
• Water before feeding (if not free choice).

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Anatomy of the equine digestive system

• Newborn
• - dont produce HCL.. no pepsin
• - spares milk break down
• - spares antibodies from break down
• - allows antibodies to enter S.I.
• permeable 1st moments of life

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Anatomy of the equine digestive system

• Small Intestine (S.I.)
• - abt. 70 in length
• - 2 to 3 in diameter
• - 27 capacity of GI tract (10-12 gal)
• - 3 sections
• 1. duodenum
• 2. jejunum
• 3. ileum

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Anatomy of the equine digestive system

• 1. duodenum
• - originates at pyloric sphincter
• - before mesenteric artery
• - both bile and pancreatic fluids are
  emptied in this segment
• 2. jejunum and ileum
• - no clear demarcation
• - more muscular and constricted
• - helps prevent back flow from cecum

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Anatomy of the equine digestive system

• 3 types of motility
• 1. pendular motion a localized shortening
  and lengthening of the intestine which
  produces a mixing action.
• 2. segmentation contraction ring-like
  contractions at regular intervals which
  periodically relax, whereupon the area that
  had been previously relaxed contracts.
• 3. peristalsis providing a means for
  movement of chyme down the tract.

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Anatomy of the equine digestive system

• Cecum
• - pouch at the junction of the S.I. And colon
• - about 4 and holds 6 - 8 gal.
• - content is usually 6 to 10 DM
• - 18 of total capacity of GI tract

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Anatomy of the equine digestive system

• Cecum
• - extends from R flank downward toward the
  diaphragm.
• - chyme from SI and H2O are mixed by
  contraction and relaxation of the 4
  longitudinal bands called taeniae coli.
• - microbial population similar to that of
  cattle.

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Anatomy of the equine digestive system

• Base of the cecum
• Body of the cecum
• Apex of the cecum

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Anatomy of the equine digestive system

• Cecum
• - formation of Fatty Acids (VFA) some
  vitamins.
• - mucosa layer similar to SI but w/o villi.
• - main area of fiber digestion.
• - can not use VFA as well as cattle.
• WHY?

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Anatomy of the equine digestive system

• Cecum
• - VFAs are easily absorbed from the cecum
  and used for energy production.
• - microbial population produces many
  B- Vitamins.
• - horses at work may benefit from B vit.
  supplement.
• Why?

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Anatomy of the equine digestive system

• Large Colon
• - approx. 10-12 in length 8-10 dia.
• - divided into
• 1. right ventral colon
• 2. sternal flexure to left ventral colon
• 3. pelvic flexure to the left dorsal colon
• 4. diaphragmatic flexure to the right
  dorsal colon

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Anatomy of the equine digestive system
1. right ventral colon 2. left ventral colon 3.
left dorsal colon 4. right dorsal colon
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Anatomy of the equine digestive system

• Ingesta must pass through three major flexures
• sternal flexure
• pelvic flexure
• diaphragmatic flexure

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Anatomy of the equine digestive system

• Large colon
• - some digestion water absorption and
  fermentation.
• - 36 of GI tract
• - holds approx. 14-16 gal

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Anatomy of the equine digestive system

• 1. ventral colon
• - 4 in length
• - 3 to 3.5 in diameter
• - 3 bands
• - haustrae- sacculations throughout the colon
• 2. dorsal colon
• - 6 long 8 to 18 in diameter
• - content finer and darker
• - largest part of GI tract

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Anatomy of the equine digestive system

• 3. transverse colon
• - 17 and 18th vertebrae
• - lies R to L
• 4. Small colon
• - 10 to 12 long
• - 3 to 4 in diameter 5 gal
• - formation of dung

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Anatomy of the equine digestive system

• Motility in the colon
• 3 types
• 1. Haustral contractions mixing action
• localized contractions in various portions
  of the colon.
• 2. Massive peristalsis slow, strong,
  aboral waves that propel the ingesta.
• 3. Reverse peristalsis aids in the
  mixing of digesta as well as the
  absorption of nutrients.
• Rectum
• - excretion