Most horses eat hay and some form of concentrates a day, such as grain or pelleted feed. They generally get concentrates one to two times a day, with the amount and type varying with each horse.
The gastrointestinal tract in horses is designed to regularly be ingesting small amounts of food all throughout the day. Non- ruminant herbivores are designed to consume a high fiber, low starch diets by foraging throughout the day.
This unlike other herbivores, such as cows, sheep, goats, and deer, that chew their cud. A horse will produce 20-80 liters of saliva a day, to aid in the process of digesting.
The stomach also digests protein and regulates the food that passes into the small intestine. Once in the small intestine, more digestion of protein happens, in addition to simple carbohydrates and fats.
The colon works to absorb nutrients and water that comes with food through the digestive tract. Some of the most common causes for colic are excess gas build up in the colon, dehydration, parasites, excessive intake of sand, stress, changes in diet, blockage in the digestion track and too much grain intake.
Signs of colic include rolling, laying down, stretching, pawing, kicking, lack of fecal production, lack of interest in food and water, elevated heart rate and sweating. While waiting for the vet to arrive, it is a good idea to walk your horse, as this stimulates gut movement and prevents any injuries from excessive rolling.
A balanced diet and constant access to fresh water can help prevent colic in horses. A horse that receives regular exercise will also help its gut health.
Since horses are herbivores, their diet largely consists of hay and grass. Horses also typically eat grain or other concentrates to help meet their dietary needs, and they also enjoy many types of fruits and vegetables as treats.
Horses have a unique digestive system and it is very important for them to maintain a proper diet in order for them to be healthy. Each horse is unique and will have a different feeding plan based on their age, weight, and exercise.
Horses have a jawline that is perfect for eating raw plant material. Horses also have 12 premolars and 12 molars that help them grind tough leaves and stem.
Horses teeth grow throughout their lives as they get worn out from chewing tough plant matter. The digestive system of a horse has been designed to turn grass into energy.
Horses use bacteria in their cecum and large intestine to ferment and digest fiber. A horse’s hind gut also works as a large fluid reservoir as fiber binds with water.
The stomach of a horse can only hold a small amount and thus empties quickly. Food passes through their bodies at a rate of about one foot per minute, which is why horses graze for such a long period.
The grass is the natural food of horses and is great for their digestive system. However, when you leave out your horse to graze in the pasture, ensure that there are no harmful plants.
When pasture isn’t available, like in the cooler months, hay is the next best thing for your horse. Fruits and vegetables are great for horses as they add the necessary moisture to the feed.
Also, vegetables like turnips, potatoes, tomatoes, kale, broccoli, and cabbage must be avoided as they can make your horse gassy. Concentrates that are grains, like corn, oats, and barley, are good for your horse.
For instance, feeding horses dried fish is a common practice in winters in Iceland. The meat, apparently, provides them the extra protein needed to survive the harsh winters.
What horses really need is plenty of good quality roughage and clean water to keep them hale and hearty. The horse has one of the most complex, and arguably, the most frustrating, digestive systems of any grazing livestock species that owners/producers deal with.
Horses breakdown these structural components of roughage via a microbial population in a modified part of the digestive system called the cecum. Cattle, sheep, and other ruminants, have food deposited into the lumen first, where it goes through a microbial digestive process before moving onto other compartments such as the true stomach.
Before delving too deeply into the differences in ruminant and non- ruminant herbivores, perhaps we should give an overview of how a horse grazes and what happens to the forage once it enters the digestive system. Horses are spot grazers, they have specialized mouths to select and eat the tops of the plants that they like.
Because of the selective behavior, horses have a reputation as rough and detrimental on pastures and forage species. The esophagus has one-way peristaltic action which means that horses cannot regurgitate their food and therefore can’t chew their cud.
A horse’s stomach is approximately 4 gallons and is the smallest in relation to its size of any other livestock species. The horse’s large intestine accounts for 60% of the total volume of the digestive tract.
Bacterial breakdown of cellulose and other carbohydrates result in the production of volatile fatty acids (IFAS). The small colon is the primary site of water absorption and the rectum is where manure is expelled. Several of these attributes add up to making horses susceptible to digestive upsets.
Since the equine digestive system doesn’t have a lot of muscular contractions, adequate water is essential to keep things moving through the tract. However, the speed at which food moves through the digestive tract, makes non- ruminant herbivores more likely to be easy keepers than most ruminants.
Explain the difference between ruminants and hind gut fermentors Describe the production cycle of dairy cows, sheep, and dairy goats Describe the normal feeding behaviors of cattle, small ruminants, and horses Describe the anatomy and functions of the four chambers of the ruminant stomach Explain the production of volatile fatty acids (IFAS) in the lumen and the fate of the various types of IFAS produced Describe body condition scoring in cattle, small ruminants, and horses and how body condition score is expected to change with physiologic state Explain changes in amount or ration fed in dairy cows and in small ruminants through their production cycle Define a total mixed ration and list advantages Describe differences in bovine colostrum, transition milk, and whole milk Define failure of passive transfer (FPT) and how it is assessed in calves Describe assessment of colostrum quality Explain how much colostrum is fed to the average calf and how that volume is calculated Describe timing of colostrum feeding in ruminants Describe types and advantages / disadvantages of feeding raw colostrum, stored colostrum, colostrum replacement products, and heat-treated colostrum Describe changes in feeding for calves progressing through the three phases of calf development (PRE- ruminant to transition to ruminant) Describe how feeding may vary in small ruminants based on time of the year Describe creep feeding Describe use of coccidiostats when feeding small ruminants Describe feeding systems for cattle and small ruminants Describe anatomy of the equine GI tract Explain ideal percentages of forage and other types of feed for horses Describe disease conditions associated with improper nutrition / feeding of herbivores Once weaned, all ruminants ferment food in the lumen and have unique nutritional needs.
They are physiologically designed to consume large meals in a short amount of time. Unschooled feed is later regurgitated and chewed so that particle size is reduced for further passage down the digestive tract.
The reticulum is a specialized pouch of the lumen located adjacent to the heart but separated from it by the diaphragm. It also collects abnormal objects eaten by the cow and so is sometimes called “the hardware stomach.” The lumen lies on the left side of the abdomen.
Basically, it is a huge fermentation vat filled primarily with anaerobic bacteria. The oakum absorbs water and breaks down the ingest into small particles by passage through many closely connected layers (“plies”).
It secretes hydrochloric acid, much, pepsinogen, rennin (which clots casein, or milk proteins), and lipase (which breaks down fats). In the lumen, bacteria and protozoa break down the food into nutrients the cow can absorb.
Micro-organisms produce IFAS from digested feed; this is the cow’s primary energy source. The excess hydrogen is attached to carbon to make methane (CH 4), which is educated (burped) or passed into manure.
Starches and sugars are broken down to form 3-carbon IFAS (propitiate) that are converted by the liver to glucose. Prior to and at the peak, it is hard for a cow physically to eat enough to keep up with metabolic needs of milk production.
She will meet energy needs by mobilizing fat and, to a smaller extent, protein. After peak lactation, energy needs will gradually decrease until she is dried off two months before her next calf is due.
Cows cannot eat enough to take in sufficient energy to balance milk production. A big concern in early lactation is lumen acidosis, a common condition where there is overproduction of lactic acid in the lumen with a decrease in production of the more valuable IFAS previously described.
At peak milk production, intake again is limited by how much dry matter the cow can consume. Dry matter intake is associated with taking in enough nutrients to permit body condition to be restored.
Cows are pregnant during this phase so the diet provided must support the developing fetus. Cows receive a very different ration during this stage than they had as milking cows, with an increase in forage to prepare the lumen for the next lactation and feeding of a ration with lower energy density.
The diet is gradually shifted to that of the milking cow to give the lumen microflora time to adapt. Advantages of a Mr is that each mouthful is the same so there is better assurance of a balanced diet delivered to the lumen micro-organisms; there is less chance of a given cow selectively eating or avoiding a single type of feed; each individual cow can consume to her physical ability; and there are savings in labor and mechanization, especially in large operations.
COLOSTRUMTRANSITION Sinkhole MILKTotal Solids(%) 23.914.112.9 Protein (%) 14.05.13.1 Fat (%) 126.96.36.199 Total Minerals (%) 1.110.870.74 Egg (mg/mL) 48.015.00.6 Immunoglobulins cannot cross this placenta to the fetus so calves are born without circulating protective antibodies.
Passive transfer is absorption of antibodies by the newborn calf across the gut into the circulation (Egg, IGA, and IGM). Failure of passive transfer (FPT) is defined as concentration of Egg in calf serum of less than 10 mg/mL when measured in blood drawn between 24 and 72 hours of age.
In one study, 21% of United States dairy heifer calves had FPT. Benefits of having adequate passive transfer include reduced treatment and mortality rates in calves, improved growth rates and feed efficiency, decreased age at first calving, and increased first and second lactation milk production.
It is inexpensive, rapid, and simple to do but the instrument is fragile and the test must be performed at room temperature. Most people hedge their bets by giving a large enough volume to ensure that calves are receiving enough Egg.
If calves are fed 4 quarts of colostrum, this goal will be met 87% of the time. Calves are born with an open gut that is able to absorb large protein molecules intact, such as Egg.
Gut closure begins soon after birth with progressive loss of ability to absorb Egg. If there are many bacteria in colostrum, this may prevent Egg absorption from the calf’s GI tract and may directly cause disease.
Infection from the mammary gland or fecal contamination of skin on the teats This is best avoided by discarding milk from known diseased cows, not letting the calf suckle the dam, cleaning and sanitizing the udder before milk collection, and not pooling raw colostrum to be sure that colostrum containing bacteria from one cow does not adulterate good colostrum from other cows. On-farm monitoring of passive transfer requires bleeding of about 12 clinically normal calves between 1 and 7 days old and measuring total protein with a refractometer.
Goals are for calves to double birth weight by 56 days of age (average daily gain (ADG) of 1.6-1.8 lb/day) and for calves to develop a functional lumen so the calf can be weaned off a milk diet and onto solid feed by 7-8 weeks of age. They cannot digest solid feed and have limited lumen fermentation capacity.
Calves are dependent on a liquid diet (milk) as their major source of nutrients. Their diet consists of high-quality milk replaced, calf starter (pelleted grain), and water.
Calves are fed whole milk or milk replaced in a volume of 2-3 quarts twice daily in summer and 3-4 quarts twice daily in winter, when more energy is needed for cold stress; some producers feed three times on cold winter days. Some producers like to offer a small amount of dry hay but this does not contribute to lumen development prior to weaning.
Milk generally bypasses the lumen via the esophageal groove and empties directly into the aromas. The milk clot is slowly digested by pepsin and HCl and is released to the intestines.
Considerations include desired nutrient intake to meet health and growth targets, disease control, complexity of managing the feeding program, and cost-benefit analysis. Cons include cost of pasteurization and need for more intensive management and monitoring compared to conventional milk replaced programs.
During this phase, the calf begins to develop a functional lumen capable of digesting dry feed. Lumen development is accomplished by grain feeding to promote satyric and prop ionic acid production, lowering pH and increasing growth of micro-organisms.
This increases the size and muscularity of the lumen, and promotes development of papillae while the microflora is established. Grain feeding is required for development of the lumen in size and function.
21-23% crude protein (dry matter basis) Molasses content 5-8% Begin offering at 3 days and replace daily Provide free-choice fresh water Put in clean buckets Put in mouth after milk feeding Water is essential to maintain hydration status, especially during periods of heat stress and illness (diarrhea = scours).
In winter, offer warm water for 1 hour after each milk feeding, then dump it before it freezes. The typical dairy goat is bred in the fall while still lactating from her previous pregnancy.
The information below refers to goats but is applicable to sheep as well; the complete document from which this is drawn is in the External Resources folder for this section. The greatest asset of goats is the ability and tendency to use woody plants and weeds not typically consumed by other species of animals (cattle and sheep), converting them into a salable product.
Therefore, these plant species can be inexpensive sources of nutrients and make for a very profitable goat enterprise. Similarly, goats are believed to have a relatively high ability to detoxify absorbed anti-nutritional factors.
The adequacy of a nutritional program can be assessed by observing changes in body weight and condition of the animal. Animals should achieve a certain body condition during specific periods of the production cycle.
During times of limited forage availability or quality such as winter, or feeding poor quality hay or stockpiled forage, a supplement will be needed to supply deficient nutrients. The level of supplemental feeding should be adjusted with changes in animal requirements, such as increased needs of late pregnancy.
Sometimes it may be preferable to put an animal in a lot and feed a complete diet or one high in concentrate such as with dairy goats. There may be periods when nutrient requirements cannot be met, resulting in loss of body weight.
An example would be weight loss during early lactation because sufficient nutrients cannot be consumed. However, if the doe is in poor body condition, is a growing yearling, or has severe weight loss during this time, milk production will be depressed.
During a drought, it may be acceptable for open or early pregnant animals that are not lactating to lose weight. Decisions can then be made on the supplemental nutrition needed for the buck to achieve the desired BCS.
Feeding bucks high levels of grain (greater than 1.5% of body weight) for a long period of time makes them prone to urinary calculi. The four production periods of does are dry nonpregnant, pregnant, late gestation, and lactating.
Does that are open (nonpregnant) or in the early stage of pregnancy (< 95 days) have fairly low nutrient requirements. For open does, the goal is to gain a little weight to be in good condition for breeding.
Flushing refers to the practice of providing extra nutrition to does approximately 2 weeks prior to breeding and for a variable portion of the breeding period (e.g., 1-2 weeks) to increase the number of ovulation and have a greater proportion of twins and triplets. However, several controlled studies with Spanish goats in reasonable body condition (BCS 2.5 – 3.5) have shown no response in kidding or conception rate of meat goats to flushing with extra protein, energy, or both.
The goal of a wintering program is to economically provide the necessary nutrients to maintain a reasonable body condition, lose no weight, and keep them warm. Commonly used supplements include whole shelled corn (inexpensive source of energy), range cubes (inexpensive source of energy and protein), sweet feed, protein blocks, molasses blocks or tubs, and liquid feed.
In drier areas, the forage is well-preserved, but in a more humid climate quality declines rapidly, making the practice less satisfactory. Animals make much more efficient use of stockpiled forage when strip grazed (using temporary electric fence to limit animal access to an area containing a 1 to 3 day supply of forage) to minimize trampling.
Rescue is used in many temperate regions for stockpiling and retains its quality well into late winter even in humid areas. Most recommendations for stockpiling rescue include late summer fertilization, clipping, and deferred grazing.
Pregnancy toxemia is a metabolic disease usually caused by animals being too fat (body condition score greater than 4) prior to kidding, although very thin animals (body condition score less than 2) are subject to the disease also. It is caused by a high demand for nutrients by the growing fetus in late pregnancy that is not being met (excess fat in the body and the growing fetus limit room in the stomach for food, reducing intake of the diet).
This unmet nutrient demand causes a rapid breakdown of fat reserves, forming ketone bodies at high levels which are toxic. Treatments include administration of propylene glycol, large doses of B vitamins, glucose given intravenously, and possibly C-section.
Do NOT sharply reduce feed in late gestation as this may cause pregnancy toxemia. Does can be encouraged to exercise by separating hay, feed and water at a substantial distance, forcing them to walk more.
During lactation, the doe can consume nearly enough nutrients if an abundant supply of high quality pasture is available, such as in spring or early summer. Kidding should take place when there is an adequate supply of high quality pasture.
When feeding high levels of grain, the animal should go through an adjustment period of two to three weeks during which time the grain portion of the diet is gradually increased to prevent digestion and other problems from occurring. Feeding a dairy ration and hay to a doe during late gestation and the lactating period will cost approximately $30 per animal.
Utilizing available pasture as a feed source is a much cheaper alternative. Nutrient requirements decline as stage of lactation advances, enabling the doe to maintain body condition or even increase it on pasture alone.
This is accomplished by fencing around a feeder and using a creep gate that has holes about 5 inches wide by 1 ft high. A commercial creep feed with at least 16% crude protein that is medicated with a coccidiostat should be used.
It requires about 6 lbs of feed to produce 1 lb of animal gain. The more rapid growth from creep feeding may be beneficial for producing show prospects.
This may have application for goats using high quality pastures (crabgrass or supergrass that is planted for the kids). Thus, during that time it makes sense to supply nutrients from an inexpensive source, typically pasture.
A major consideration in determining the date to kid is level of forage production at that time. Some markets provide a substantial price premium from kidding at a specific time of the year, such as producing prospect show withers or registered animals.
However, it may take a considerable market premium to cover the cost of purchased feed, so general reliance on pastures and forages is best. Colostrum contains antibodies that strengthen the immune system for the first months of life.
This does take some practice, but obtaining colostrum is critically important to kid survival. Kids are very susceptible to bloating and other gastrointestinal problems from milk replaces that contain a high level of lactose due to use of dried whey in their formulation.
A calf starter feed (with a coccidiostat such as Dimension or Dec cox, sometimes called medicated) and high quality hay should be made available the second week of life. After 4 weeks of life, kids can be limit fed milk at one pint in the morning and also in the afternoon.
Kids can be weaned after 8 weeks of age if they are consuming 2 ounces of starter per day and weigh two and a half times their birth weight (about 18 lbs). Weaning shock can be reduced by going to once daily milk feeding for several days to encourage consumption of the starter.
Rations should be balanced not only for protein and energy, but calcium and phosphorus contents should be calculated, macro minerals supplemented, and a trace mineralized salt used to provide micro minerals. If the ration is being fed at high levels, sufficient fiber should be included in the diet to prevent acidosis.
Dried brewers yeast and probiotics are often used in rations fed to animals at high levels to help prevent them from going off feed. Management considerations to reduce coccidiosis incidence include sanitation, cleanliness, and dry housing.
Feeds should be offered in such a way to minimize mold growth or fecal contamination that reduces intake. Mineral mixes must remain dry and should be replenished at 2-week intervals to avoid caking.
Wild horses are nomadic, following the food, and don’t defend a set territory. They are grazers or trickle feeders, designed to eat numerous small meals throughout the day.
Horses pretend with their tongue and incisors, moving the bolus to the back of the mouth where it is ground by the cheek teeth (premolars and molars). Intense mastication by the cheek teeth leads to reduction in particle size and stimulates production of saliva, which is 99% water and serves primarily as a lubricant.
There are virtually no digestive enzymes in equine saliva but it does provide buffering of gastric contents. The esophagus is 1.2-1.5 meters (4-5 ft) long from the pharynx to the cardiac of the stomach with upper and lower esophageal sphincters.
The small intestine is the only site of calcium absorption in the equine GI tract. A huge resident microbial population is responsible for digestion of fibrous matter and includes bacteria, fungi, and protozoa.
IFAS, fractals (complex sugars), nitrogen, sodium, chloride, and water are absorbed. Need is heavily influenced by life stage, body condition, and ambient temperature.
It is obtained from feed and is digested and absorbed primarily in the small intestine. Digestion of protein is initiated in the stomach through the actions of HCl and pepsinogen and is completed in the small intestine.
Essential (also called indispensable) amino acids cannot be synthesized and must be obtained in the diet. For conditionally indispensable amino acids, pathways exist but at times the body cannot make them in sufficient quantities.
Benefits of fat supplementation are increased energy density for weight gain and replacing carbohydrates as sources of calories. Macro minerals that are required in the diet include calcium, phosphorus, sodium, chloride, magnesium, and potassium.
Vitamin D plays a smaller role in Ca:P homeostasis in horses than in other species. High calcium can negatively impact phosphorus absorption and vice versa.
Micro minerals that are required in the diet include copper, zinc, iron, selenium, manganese, cobalt, and iodine. Selenium deficient soils exist in different parts of the United States, so having an understanding of local growing conditions (and/or a hay analysis) is key to making good decisions about supplementation.
The maximum tolerable concentration is 2 mg/kg DM; selenium toxicity is a clinical concern. Cereal grains such as corn, oats, barley, wheat, rye, and millet.
These may be pelleted, and may be cereal grains, and supplemental protein or vitamins/minerals, for example Purina Cultism. Ration balancers are very concentrated sources of vitamins and minerals designed to be fed with either grass forage or alfalfa forage, for example Nutrient Empower Grass Balancer.
Complete feeds are designed to be fed as the sole source of nutrition in the absence of forage. These are forage-based and often are pelleted and softened by the addition of water, for example, Purina Equine Senior.
Protein may be added to improve quality of forage and to aid in building muscle, hair and hooves. Owners can use as a protein supplement, a complete feed, or alfalfa (forage or pellets).
Loose salt may be added to the bucket to encourage water consumption (1-3 tsp BID). Trace mineral blocks are okay if only one horse has access but it is hard to guarantee adequate consumption.
Horses selectively graze areas where they have not defecated and remove the tops of plants that are actively growing. Continuous grazing maximizes saliva production, and decreases risk of gastric ulcers, colic, and vices.
Have the same person do the measurements each time, use consistent landmarks, and take digital photos. Key areas to evaluate are the neck, shoulder, barrel (ribs), and tail head.
From time immemorial, they have been used as a source of food, transport, entertainment, and companionship. Although they can survive solely on grass, hay, and plants, people still have their confusion about whether they’re herbivores, carnivores, or omnivores.
Studies show that some species rely on others as their source of food, and some eat other animals. Unlike many other animals, horses rely on plants as their primary source of food.
Animals have different jawlines, and the shape of their skulls and teeth can tell you what dietary habits they’re inclined to. They also have big canines that make it easier to grip the flesh and cut through it quickly.
They follow their prey and get as close to them as possible, and they make a sudden sprint to attack them. A predator’s jaws are created in a manner that gives them a significant advantage when it comes to hunting.
Their jaws are equipped with sharp incisors and large canines that help in crushing and breaking down the fibers into digestible form. Most omnivores show the behaviors of stealth when it comes to hunting, but they are also able to forge, dig, browse, and gather plant material.
Herbivores have a totally different jawline as their bodies are adapted to eating only pure, raw plant material. They’re easily able to cut, nip through the gross, or hold on as they pull back at branches of trees.
Herbivores animals have some common traits like alertness and the ability to run very fast as it’s their primary way to survive. They’re bred so that they’re able to run races, pull heavy loads, or jump high and give performances.
The digestive system of horses is very well-equipped at turning grass into energy. Since canines are mostly used for chewing and tearing flesh, horses aren’t equipped to do that.
A horse’s stomach can hold a small amount and empty it quickly as it passes through their bodies at a rate of about 1 foot per minute. Horse breeders provide them with alternative sources of energy like grains.
The grain helps to give them a boost, which enhances their energy and makes them work harder. Horses hold a great deal of water and mass that fills up their enormous gut.
Meats and animal products go bad very quickly, and they have toxins that don’t always get destroyed by cooking. These can be contracted via food that could possibly be contaminated with bird or rodent carcasses.
Hence, consuming meat once or twice may not hurt them but doesn’t mean it is the perfect addition to a horse’s diet. Herbivores, including horses, have evolved in a way that they can graze continuously throughout the day.
But at times when pasture isn’t available around the year, there are a few alternatives that one can give to their horses. Grains are meant to supplement hay and prove to be a rich source of vitamins and minerals.
Did you know an average horse can drink up to 5-10 gallons of fresh water a day? An average horse needs to consume hay, which is about 2% of their body weight in one day.
The time, environment, conditions, and harvesting process all have a significant impact on the quality of the hay. When serving them feed, you should allow your horse to enjoy hay first before consuming rich, calorie-dense grains.
It is crucial to ration the amount of grain, based on how much your horse requires. Grain portions should be based on your horse’s weight and activity level.
If you’re giving your horse too little a quantity of grains, it means you’re depriving them of some essential nutrients that could be beneficial for them. Small, frequent meals help in recreating the sort of experience a horse will have in nature.
However, this may not be fulfilling for them as it would be better to feed them at least three times a day with a gap of 8 hours in between each mealtime. Consistent feeding helps horses feel used to the surroundings, and a lack of this could also trigger health issues and stress.
The herbivorous nature of horses, and them being the PRE animal, helps us understand some of their behaviors and traits. They are not omnivores. We can understand that when a horse encounters danger, their steady response is to flee from the situation.
They’re equipped with speed and alertness, which helps them avoid risk and understand when they’re facing danger. Some studies have also shown that due to the fear of predators, prey chooses to live together in groups.
Equine digestive systems are incredibly delicate and are best suited for plant matter and not meat. Their jaws are designed in a way that helps them to grind and break down complex fibers instead of flesh.
Since they cannot vomit, toxins from these foods can build in their systems, which can prove to be fatal. Certain other herbivores have also adopted this “caudal fermentation” lifestyle, most notably rabbits and rodents.
However, the equine large intestine is massive and anatomically complex in comparison to most other animals. The cecum and ascending colon have bands of smooth muscle (tenure) which cause these organs to form pouches called austral.
Additionally, every few minutes the strong, mass movement-type contraction occurs that forces some cecal contents through the economic orifice into the ascending colon. Within the ascending colon occurs segmentation and austral contractions that efficiently mix ingest and expose it to the mucosa for absorption of water, electrolytes and volatile fatty acids produced through fermentation.
Fermentation and Physiology of the Equine Hind gut Digestive function in the stomach and small intestine of horses occurs pretty much as in any other monogastric animal. Cellulose and related molecules pass through the small gut intact, although such plant material may be softened and swollen prior to entry into the cecum.
Most importantly, horses survive as herbivores because volatile fatty acids are produced in large quantities, absorbed through the cecal and colonic epithelium, and distributed for use throughout the body. One significant difference from the ruminant strategy is that that large quantity of microbial protein generated in the equine large gut is wasted because there is no opportunity there for significant absorption of amino acids.
Mastication halters record the movements of the mouth and automatically differentiate between eating and ruminating. For ruminants such as cows, sheep, goats, deer, llamas or camels, eating and ruminating are two different processes: Some time after feeding, they regurgitate part of their food and chew it again with particularly even, rhythmic movements.
In their study with horses, cows and camels, they use special mastication halters, which can record the movements of the mouth and automatically differentiate between eating and ruminating. In the case of cows and camels, the mastication rhythms differ clearly in a predictable manner.
For Marcus Claus's, professor at the Clinic for Zoo Animals, Exotic Pets and Wildlife of the University of Zurich, the similarity in the chewing rhythm of such different animal groups is understandable: Horses do not have a second chance to re-chew something that is hard to digest. The researchers have an interesting theory: When grazing in the wild, herbivores also take in dust, dirt or earth, which addition-ally abrades the teeth while eating.
Ruminants, on the other hand, can postpone thorough mastication after the initial eating process until later after the food has been cleaned of such contamination in the lumen. “The irregular incentive mastication of cows could therefore have developed in order to protect the teeth while eating,” Claus's says.
More information: Marie T. Pittman et al., Incentive mastication in horses resembles rumination but not incentive mastication in cattle and camels, Journal of Experimental Zoology Part A: Ecological and Integrative Physiology (2017). Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission.
Equestrians are also abuzz about the book Deadly Equines: The Shocking True Story of Meat-Eating and Murderous Horses. Their entire digestive system is designed to process plant matter.
We tend to organize everything into neat, tidy categories in our minds, so anything that deviates from the norm seems exciting. While many of these stories in Deadly Equines should be taken with a grain of salt, there is no denying meat is not off the table for horses (pun intended).
Viral videos of a horse eating a chick and a deer eating a bird, as well as the news story of deer scavenging on human corpses at a body farm in Texas, have understandably made a lot of people curious about what is going on. There are also omnivores that eat a little of everything and autotrophs, like plants and algae, that produce their own food.
In general, herbivores have flat teeth for grinding and long digestive systems, carnivores have sharper teeth for tearing meat and shorter digestive systems, and omnivores are somewhere in between. Lean, Mean, Green-Processing Machines The equine digestive system is excellent at turning grass into energy.
Horses teeth continually “erupt” throughout their life, as they are worn down from chewing tough plant matter. Ruminants, like cattle and sheep, use bacteria in their Rubens, a digestive chamber before the stomach, to ferment plant fiber.
In fact, horse stomachs hold a surprisingly small amount, empty quickly, and food passes through their bodies at a rate of about 1 foot per minute. Humans sometimes provide horses with alternate sources of energy, like grain, to give them a boost for harder work.
A typical 1,000-pound horse that is just working on maintaining her body condition needs roughly 15,000 calories a day. A lush, green pasture averages 245 calories per pound, so you can see why horses can spend up to 17 hours per day grazing.
So, how come horses can’t simply eat less food overall if it has a higher calorie and nutrient density? Besides providing energy and nutrients, all of this roughage holds a great deal of water and the sheer mass fills up the horse’s enormous gut.
When a horse’s digestive tract is empty, they are more prone to twisting of the intestines and colic. They can also lose their water reservoir and develop diarrhea, which can result in dehydration.
Since horses were made to be constantly consuming forage, they aren’t set up to handle the feeling of an empty stomach, and they are not sure what to do with all that time they spend not chewing. This can result in sand colic, where the desperate horse spends time sweeping the surrounding ground in an effort to relieve hunger and boredom.
Horses may also turn to chewing wood or other vices like cribbing and weaving. If they were to consume something dangerous or poisonous, it would require prompt veterinary attention.
Sure, they “can” process meat and get some energy and nutrients from it, but they have teeth that need grinding and a belly that needs to be kept full of fiber. The occasional snack of a bit of hot dog or slow chick with poor decision-making probably will not hurt them, but meat cannot be the foundation of a horse’s diet.
If horses are herbivores with a digestive system meant for plants, why are some of them eating meat? Many hooked animals, like cows and deer, are known to eat bones or antlers and some science points to a need for calcium as an explanation for this behavior.
Horses may eat sand, wood, manes/tails, and manure due to boredom or inadequate nutrients. Due to horses willingness to try different foods, they have been fed meat and animal products all over the world throughout history.
While horses in Iceland are generally kept on pasture, in the winter with supplemental hay, farmers may also place barrels of salted herring out for them. Exploration of Antarctica in the early 1900s made use of Siberian and Manchurian ponies to transport supplies.
These ponies were said to have eagerly eaten dried fish, blubber, and raw seal meat. Multiple reports of Tibetan horses from the 1800s through the 1900s said they were fed meat regularly and ones trained to eat it were more valuable.
Lawn clippings can contain dangerous chemicals or weeds that the horse cannot pick out. Horses also have a tendency not to chew clippings, which can lead to choke, colic, or laminates.
Horses are lactose intolerant and dairy products run the risk of causing digestive upset. Like other safe fruits they should only be given as a treat and not make up a large part of their diet.
Meat does not have the correct nutrients to make up a significant portion of their diet. Apple seeds produce hydrogen cyanide when chewed, which can be deadly in high enough doses.
Carrots make an excellent treat, but should only be given in moderation since they do not contain the correct nutrient profile for horses to stay healthy. Horses have herbivore digestive tracts and don’t need meat to survive.
Horses may need up to 12 gallons of water per day, depending on their diet and environment. (Source) Some horses might avoid drinking dirty, icy, or strange tasting water, and they run the risk of developing impaction colic.
Keep your horse’s water clean, easy to access, and at a reasonable temperature. What horses DO require is plenty of good quality roughage and clean water to keep their digestive systems running smoothly.
The process, which takes place in the front part of the digestive system and therefore is called fore gut fermentation, typically requires the fermented ingest (known as cud) to be regurgitated and chewed again. The process of rec hewing the cud to further break down plant matter and stimulate digestion is called rumination.
The word ruminant comes from the Latin ruminate, which means “to chew over again”. Hoffmann and Stewart divided ruminants into three major categories based on their feed type and feeding habits: concentrate selectors, intermediate types, and grass/roughage eaters, with the assumption that feeding habits in ruminants cause morphological differences in their digestive systems, including salivary glands, lumen size, and lumen papillae.
However, Woodall found that there is little correlation between the fiber content of a ruminant's diet and morphological characteristics, meaning that the categorical divisions of ruminants by Hoffmann and Stewart warrant further research. However, their anatomy and method of digestion differs significantly from that of a four-chambered ruminant.
A, dog; B, Mus documents ; C, Mus muscles ; D, weasel; E, scheme of the ruminant stomach, the arrow with the dotted line showing the course taken by the food; F, human stomach. A (in E and G), aromas; Ca, cardiac division; O, psalteries; OE, esophagus; P, pylorus; R (to the right in E and to the left in G), lumen; R (to the left in E and to the right in G), reticulum; Sc, cardiac division; Sp, pyloric division; WZ, water-cells.
Fermentation is crucial to digestion because it breaks down complex carbohydrates, such as cellulose, and enables the animal to utilize them. Microbes function best in a warm, moist, anaerobic environment with a temperature range of 37.7 to 42.2 °C (100 to 108 °F) and a pH between 6.0 and 6.4.
Without the help of microbes, ruminants would not be able to utilize nutrients from forages. The food is mixed with saliva and separates into layers of solid and liquid material.
Solids clump together to form the cud or bolus. The cud is then regurgitated and chewed to completely mix it with saliva and to break down the particle size.
Smaller particle size allows for increased nutrient absorption. Protein and nonstructural carbohydrate (pectin, sugars, and starches) are also fermented.
Saliva is very important because it provides liquid for the microbial population, recirculates nitrogen and minerals, and acts as a buffer for the lumen pH. The type of feed the animal consumes affects the amount of saliva that is produced.
Though the lumen and reticulum have different names, they have very similar tissue layers and textures, making it difficult to visually separate them. The degraded digest, which is now in the lower liquid part of the reticulorumen, then passes into the next chamber, the oakum.
It keeps the particle size as small as possible in order to pass into the aromas. The oakum also absorbs volatile fatty acids and ammonia.
The aromas is the direct equivalent of the monogastric stomach, and digest is digested here in much the same way. This compartment releases acids and enzymes that further digest the material passing through.
Digest is finally moved into the small intestine, where the digestion and absorption of nutrients occurs. The small intestine is the main site of nutrient absorption.
The surface area of the digest is greatly increased here because of the villi that are in the small intestine. This increased surface area allows for greater nutrient absorption.
Microbes produced in the reticulorumen are also digested in the small intestine. The major roles here are breaking down mainly fiber by fermentation with microbes, absorption of water (ions and minerals) and other fermented products, and also expelling waste.
Fermentation continues in the large intestine in the same way as in the reticulorumen. Only small amounts of glucose are absorbed from dietary carbohydrates.
The glucose needed as energy for the brain and for lactose and milk fat in milk production, as well as other uses, comes from nonsugar sources, such as the Via propitiate, glycerol, lactate, and protein. The Via propitiate is used for around 70% of the glucose and glycogen produced and protein for another 20% (50% under starvation conditions).
Wild ruminants number at least 75 million and are native to all continents except Antarctica. Species inhabit a wide range of climates (from tropic to arctic) and habitats (from open plains to forests).
Ruminating animals have various physiological features that enable them to survive in nature. During grazing, the silica content in forage causes abrasion of the teeth.
This abrasion is compensated for by continuous tooth growth throughout the ruminant's life, as opposed to humans or other nonruminants, whose teeth stop growing after a particular age. Most ruminants do not have upper incisors; instead, they have a thick dental pad to thoroughly chew plant-based food.
Another feature of ruminants is the large luminal storage capacity that gives them the ability to consume feed rapidly and complete the chewing process later. This is known as rumination, which consists of the regurgitation of feed, rec hewing, resalivation, and res wallowing.
Rumination reduces particle size, which enhances microbial function and allows the digest to pass more easily through the digestive tract. Vertebrates lack the ability to hydrolyze the beta glycosidic bond of plant cellulose due to the lack of the enzyme cellulose.
Since the environment inside a lumen is anaerobic, most of these microbial species are obligated or facultative anaerobes that can decompose complex plant material, such as cellulose, hemicellulose, starch, and proteins. The hydrolysis of cellulose results in sugars, which are further fermented to acetate, lactate, propitiate, literate, carbon dioxide, and methane.
As bacteria conduct fermentation in the lumen, they consume about 10% of the carbon, 60% of the phosphorus, and 80% of the nitrogen that the ruminant ingests. To reclaim these nutrients, the ruminant then digests the bacteria in the aromas.
The enzyme lysosome has adapted to facilitate digestion of bacteria in the ruminant aromas. Pancreatic ribonuclease also degrades bacterial RNA in the ruminant small intestine as a source of nitrogen.
The role of saliva is to provide ample fluid for lumen fermentation and to act as a buffering agent. After digest pass through the lumen, the oakum absorbs excess fluid so that digestive enzymes and acid in the aromas are not diluted.
Tannins are phenolic compounds that are commonly found in plants. Found in the leaf, bud, seed, root, and stem tissues, tannins are widely distributed in many species of plants.
Depending on their concentration and nature, either class can have adverse or beneficial effects. Tannins can be beneficial, having been shown to increase milk production, wool growth, ovulation rate, and lambing percentage, as well as reducing bloat risk and reducing internal parasite burdens.
Tannins can be toxic to ruminants, in that they precipitate proteins, making them unavailable for digestion, and they inhibit the absorption of nutrients by reducing the populations of proteolytic lumen bacteria. Very high levels of tannin intake can produce toxicity that can even cause death.
Animals that normally consume tannin-rich plants can develop defensive mechanisms against tannins, such as the strategic deployment of lipids and extracellularpolysaccharides that have a high affinity to binding to tannins. Some ruminants (goats, deer, elk, moose) are able to consume feed high in tannins (leaves, twigs, bark) due to the presence in their saliva of tannin-binding proteins.
The verb 'to ruminate' has been extended metaphorically to mean to ponder thoughtfully or to meditate on some topic. In psychology, “rumination” refers to a pattern of thinking, and is unrelated to digestive physiology.
In 2010, enteric fermentation accounted for 43% of the total greenhouse gas emissions from all agricultural activity in the world, 26% of the total greenhouse gas emissions from agricultural activity in the U.S., and 22% of the total U.S. methane emissions. The meat from domestically-raised ruminants has a higher carbon equivalent footprint than other meats or vegetarian sources of protein based on a global meta-analysis of lifecycle assessment studies.
Methane production by meat animals, principally ruminants, is estimated 15–20% global production of methane, unless the animals were hunted in the wild. The current U.S. domestic beef and dairy cattle population is around 90 million head, approximately 50% higher than the peak wild population of American Bison of 60 million head in the 1700s, which primarily roamed the part of North America that now makes up the United States.
^ a b c Fernández, Manuel Hernández; VBA, Elisabeth S. (2005-05-01). “A complete estimate of the phylogenetic relationships in Ruminants: a dated species-level super tree of the extant ruminants”.
Chapter 1 General Biology and Evolution addresses the fact that came lids (including camels and llamas) are not ruminants, pseudo-ruminants, or modified ruminants. ^ Richard F. Kay, M. Susana Cargo, Early Miocene Paleo biology in Patagonia: High-Latitude Paleo communities of the Santa Cruz Formation, Cambridge University Press, 11/10/2012 ^ “Suborder Ruminating, the Ultimate Ungulate”.
“Evolutionary steps of physiological and diversification of ruminants: a comparative view of their digestive system”. Functional Anatomy and Physiology of Domestic Animals, pages 357–358 ISBN 978-0-7817-4333-4 ^ Colorado State University, Hypertext for Biomedical Science: Nutrient Absorption and Utilization in Ruminants ^ a b c d Hickman.
Ruminant ecology and evolution: Perspectives useful to livestock research and production”. Journal of Dairy Science, 93:1320–1334 ^ “Dental Anatomy of Ruminants”.
“Reconstructing the evolutionary history of the artiodactyl ribonuclease super family” (PDF). “Some physical and chemical properties of Bovine saliva which may affect lumen digestion and synthesis”.
“Old world ruminant morphophysiology, life history, and fossil record: exploring key innovations of a diversification sequence” (PDF). ^ a b c B. R Min, et al. (2003) The effect of condensed tannins on the nutrition and health of ruminants fed fresh temperate forages: a review Animal Feed Science and Technology 106(1):3–19 ^ Bate-Smith and Swain (1962).
^ Leviticus 11:3 ^ Asama, Nariño; Minamoto, MIA; Hind, Tune (1999). “Effect of the Addition of Fumarate on Methane Production by Luminal Microorganisms in Vito”.
8–58 (PDF) ^ Shin dell, D. T.; Faludi, G.; Koch, D. M.; Schmidt, G. A.; Unger, N.; Bauer, S. E. (2009). ^ Shin dell, D. T.; Faludi, G.; Koch, D. M.; Schmidt, G. A.; Unger, N.; Bauer, S. E. (2009).
^ Ripple, William J.; Pete Smith; Helmut Haber; Stephen A. Montana; Clive McAlpin & Douglas H. Boucher. Wiki source has the text of the 1905 New International Encyclopedia article Ruminant “.