Kashif Ishaq PhD; DVM Hind gut fomenters Stomach is not chambered Other animals are donkey, rabbits Parts of Digestive System Mouth Esophagus Stomach Small intestine is 21 m long Large intestine 40-50 % 1
Horses are classified as herbivores, or roughage eaters. Grazing animals with digestive systems designed for constant consumption of plant food. Unlike most other herbivores, the digestive system of the horse is considered monogastric Digestive organs include the stomach, small intestine and large intestine. The stomach and small intestine are commonly referred to as the upper gut, and are where most of the protein, fat, vitamins and minerals contained in feed are digested and absorbed. Horse lacks the complex fore stomach of a ruminant, unique characteristics of its large intestine, or hindgut, allow the horse to utilize cellulose and other fermentable substrates in much the same way as ruminants. The large intestine of the horse has a greatly enlarged cecum which serves as a fermentation vat. Billions of bacteria and protozoa produce enzymes that break down plant fibre. This fermentation process occurs posterior to the area where most nutrients are absorbed, and as a result, horses do not obtain all of the nutrients synthesized by microorganisms in its large intestine. 2
1- Esophagus 2-Stomach 3-Small Intestine 4-Cecum (large intestine) 5-Colon (large intestine) 6-Rectum The stomach stores, mixes, digests and propels feed into the small intestine. Very little of the feed nutrients are absorbed in the stomach. Proteins and carbohydrates are only partially digested in the stomach, and fats are only slightly hydrolyzed before the food passes into the intestine. The stomach of the horse contains about 10% of the capacity of the intestinal tract compared to about 70% for ruminants. Stomach has only 14% the capacity for feed as the mature ruminant and cannot handle large amounts of feed at one time. On the other hand, if the stomach remains empty, the excess gas produced can cause the stomach to rupture, leading to death. 3
The horse must eat frequent, small portions of feed to avoid overeating and possible injury from colic, founder, or damage to the stomach. Feeding a large meal limits the mixing action of the stomach and may prevent feed from coming into sufficient contact with gastric secretions in the stomach. This can have a negative effect on feed digestion. The small intestine contains about 30% of the total weight of the digestive tract of the horse, and is where most feed nutrients are digested and absorbed. The rate of passage of feed through the stomach and small intestine is very rapid. Grinding or chopping feed increases the rate of passage and decreases absorption of nutrients. Since the upper gut comprises only 40% of the digestive tract and feed moves through rapidly, it is relatively easy to overwhelm the digestive capacity of the stomach and small intestine. 4
The horse has the largest and most complex large intestine of any domestic animal. Its large intestine is made up of two large organs: the cecum and the colon. Together they represent about 60% of the horse's digestive tract. The cecum makes up about 25-30% of the large intestine. The horse's large intestine is designed to utilize plant fiber. The rate of feed movement through the colon is relatively slow. Because the colon folds back on itself several times and its diameter varies. 5
The horse's digestive system is susceptible to impaction, twisting and other types of colic. Colic can result from the formation of gaseous products derived from microbial fermentation. If large amounts of soluble carbohydrates, such as starch, reach the microorganisms in the hindgut, large amounts of gaseous compounds are produced. These gases are being produced faster than they can be absorbed or released, swelling occurs. This swelling can, and often does, cause the horse to develop colic Processing of feeds Level of intake Frequency of feeding Work Individuality Associative effects Time watering 6
10 day 3 week age begin nibble grain 16-18 % CP Maize, 37.4%, soy bean 33 %, oat 23 %, molasses 3.5 % Resting Adults 1.5 M cal/45.5 kg/day (9 kg good grass/graze 14hr/day) Working Adults Key factors are duration of work, speed 500 kg horse require 16.4 M cal, CP 656 gm Give additional mineral when feeding hay 225-450 gm grains for pleasure riding 900 1300 gm moderate work, 1.8 kg hard work Grains are good source of fat 7
Pregnancy: 1 st 8 month 1.65 M cal/45.5 kg/day, 8 % CP For 500 kg, 18.2 M cal, 810 gm CP Last trimaster 19.7 M cal, 866 gm CP Lactating 1 st 3 mo: 500 kg mare require 28.6 M cal, 1430g CP Last 2 mo: 500 kg (24.5 M cal, 1050 gm CP) (Ca 40-60 g/day) Weanling Require 3.8 M cal/45.5 kg, 14.5 % CP Yearling to 2 year 12.5 % CP, 2.25 M cal/45.5 kg 2-4 year 1.5 1.9 M cal/45.5 kg, 8-11 CP Senior horse 1.5 M cal/45.5 kg, CP 10% 8
Feeding at regular intervals Small frequent feeding: avoid problems of digestion, Fat and rest are two enemies of horse Change in feeding must be gradual Avoid mouldy feed Cleaning and sanitation Inspection of teeth Proper exercise and parasite control Ration of Light Draught Horse Gram 0.9 kg, barley 0.90 kg, bran 0.90 kg Green Lucerne 13.60 kg For ponies gram 0.68 kg, barley 0.68 kg, bran 0.90 kg Green Lucerne 13.60 kg Ration of Light Draught Horse without fodder Gram 1.40 kg, barley 1.80 kg, bran 0.90 kg Hay 8.00 kg For ponies gram 1.10 kg, barley 1.60 kg, bran 0.90 kg Hay 8.00 kg 9
Ration of thoroughbred stallion Winter: oats 2.70 kg gram 0.90 kg, Bran 0.90 kg, Lucerne hay 4.50 kg, green fodder 18.0 kg (TDN 8.41 kg, DP 0.97 kg) Summer: oats 2.27 kg gram 0.45 kg, Bran 0.90 kg, Lucerne hay 4.50 kg, green fodder 13.60 kg (DM 10.78 kg, TDN 8.41 kg, DP 0.97 kg) Ration for mares Winter: oats 0.65 kg gram 0.65 kg, Bran 0.65 kg, Lucerne hay 3.60 kg, green fodder 9.0 kg, wheat straw chaffed 3.6 kg (DM 9.6 kg, TDN 5.75 kg, DP 0.97 kg) Summer: oats 1.8 kg, Bran 1.80 kg, Lucerne hay 2.50 kg, green fodder 22.70 kg (DM 9.6 kg, TDN 6.8 kg, DP 0.66 kg kg) Tonga Pony Ration Requirement for Maintenance:TDN 2.04 kg,145 gdp Requirement for Work : TDN 2.27 kg, 363 g DP SUMMER RATION: Gram 2.7kg, bran 0.9 kg, Chaffed WS 0.9kg, Grass 13.6 kg WINTER RATION: Gram 2.7 kg, bran 0.9kg, chaffed wheat straw 0.9 kg, lucerne green 9.0 kg 10
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