Equine Nutrition- The industry o Extremely diverse o Made into a leisure animal Not so much about work like it use to be (draft horses) more about performance and leisure - Research and developmento Nutritiono Reproo Exercise physiology o Meat scienceo Cloning and stem cell research- The way we feed our horses today differs greatly from that of 100 years ago o Because mainly of the use of horses these days o We know a lot more about what the animal actually needs - Introduction informationo Horses are herbivorous grazers they continue to consume all day Important to keep hay or something in front of them at all times o Hindgut fermenterso Adapted to meal consumptiono Production of VFA’s 30% of energy needs – cecum, colon (NRC, 2007)- Fermentation of forages in the cecum is so important in producing the VFA’s for energy.o Gut transit time  1-2 dayso Transition to new diet  7-14 days Gut transition time is so slow you have to be mindful of this o Digestible energy (DE) standard in the industry - Digestive anatomyo Esophagus Cant vomit, strong cardiac sphincter muscle in stomach prevents this.- This is what makes it so important for nutritionist to get the most out of the hind gut.  Digestive upset = colic many different forms this is just a broad termfor it.  Passage rate of digesta- 20%/hour- Rumen= 2-8%/hour Choke- Obstruction within esophagus- Fast eaters o Colonic vs. cecum fermenters (chart from slide)  Cecum fermeters have a much larger cecum  Most of the horses’ fermentation happens in the colon o Stomach  Stomach- - Small frequent meals; initiates digestion, like non-ruminanto 10% of tracto Limited digestiono Gastric ulcers – seen mostly in high performance animals Fed once a day, under high stress etc.  This is where feeding your animal small amountsthrough out the day is the best o Small intestine 30% of tract volume, 75% of GIT length  Digestion of - Starch- 65-75%- Protein, AA’s-60-70%- Fat- 90%- Ca absorption-95-99%- Phosphorous-20-25% Fast rate of passage No gall bladder- The liver continuously produces bile and doesn’t need anywhere to store it- THIS IS WHY IT IS IMPORTANT FOR HORSES TO EAT ALL DAYo Colon Large colon- Absorbso H2O- major site of this The forages pull water in as they are being digestedo VFA’so AAo Phosphorous, 50%o NaCl Small - Absorption of H2O- Fecal ball formationo Comparisons of digestion (chart from slide) Most of it happens in that hind gut from equine! Look at the comparisons- Digestion-Microbial Florao Fermentable carbohydrates (i.e. cellulose, hemicellulose from forages) cannotbe digested by mammalian enzymes, but can be fermented by microbes within the cecum and colon. o Hydrolyzable carbohydrates (i.e. sugars, starch) digested in the intestine This is where we can encounter problems feeding a lot of grain (high in starch and sugar) o Horses on high grain diets Are less efficient at digesting hay because of the microbial populationo The same goes for horses on a high forage dieto This is why abrupt changes in the diet may cause problems! Gradual change in diets is suggested - Absorptiono VFA- large colono Fats- SIo Protein- SIo Hydrolyzable carbohydrates- SIo Water Largest amount is absorbed at the ileocelcal junction- Water content of SI digesta amounts to 87-93%- Feces of healthy horse contains 58-62% water o Little is known about where and when gastric fermentation products are absorbedo However, absorption of VFA’s produced in the cecum and colon require mucosal Na+/H+ exchangeo Water and electrolyte balance are important  Helps to restore things back to normal - Nutrientso Water  Essential Temperature regulation Digestion Quantity:- Physiological state- Ambient temp (not too cold or hot) they are picky the actual temp doesn’t effect them it is just how picky they are- Feed quality o Long stem roughage will cause it to need more water- Forage - Minimum 1 gal/100 lbs of BW/dayo Fat  Energy density- ~9 Mcal/kg energy- 3x more dense than carbohydrate sources Not all fats are created equal you have to know what you are feeding.  You have to incorporate it depending on what your horse is doing  Why do we feed fat- Palpability- typically over 15% makes it unpalpabitable - Energy o Carbohydrates Main energy source ~3 Mcal/kg Structural vs. nonstructural - 0.5% BW/d- 1-1.5% BW/d Feeding concerns- pH - Lactic acid- Laminitis- the detachment in the hoof wall and rotation of the hoof  nasty stuff Hydrolysable carbohydrates- Small intestine is actually not very efficient at digesting and absorbing hydrolysable carbohydrateso Overflow into the cecum and colono Fermentation- lactic acido Microbial population change- endotoxin releaseo Reduce blood flow and inflammation to hood laminaeo Proteins Important for - Growth and maintenance- Muscle development  Protein fed at 8-10% in the ration - 14% in weanling diets Consideration for growth and lactation Protein in feeds - Expensive  High protein problems - They are not efficient in low quality proteins or nonprotein nitrogen like a ruminant is - In endurance horses- fed low protein dietso Increased urination or adverse effects on fluid balance- kidney function  Limiting amino acids- Body needs EAA as they cannot be made- Limiting EAA= an EAA that is present in less than adequate amounts- Limits protein synthesiso Like vowels in words- cant make many without them - 1st is lysine- 2nd is threonineo Or maybe it is methionine?o We do not really know a lot about this Protein as energy - Technically yes, but energetically expensive- Amino acids must be deaminated first o Release ammonia- excreted in urine Cost energyo Carbon skeleton is converted to energy- producing intermediates Cost energy- Not metabolically efficient energy source Horse vs. ruminants- Microbial protein generated in the equine hindgut is not absorbed efficiently enough to contribute to AA pool - Ruminants rely on MCP to meet their protein and AA requirements- Horse are sensitive to the quality of protein in the diet where asruminants aren’t always  Non-protein nitrogen - Ureao High in N (46%)o Can be toxic in horseso Little to no nutrition benefit to horses- Crystalline amino acidso Lys, Meth, Threonineo Often added to feeds for young horseso Reduces total CP by increasing limiting AAo Not done- Common feedstuffso Complete feeds-  What we