Functions of various parts of the digestive tract: Mouth, Oesophagus

Mouth:

The primary function of the mouth include prehension (grasping), mastication (chewing), and mixing of feed with saliva as preparatory steps for subsequent digestion in the remaining parts of the alimentary canal. The lips, tongue, and teeth are used to pick and hold feed while it is in the mouth. The teeth grind the feed, and the tongue mixes it with saliva. The lips of sheep, goats, and horses are flexible, while those of cattle and buffaloes are relatively stiff and immobile. In horses, the upper lip is very sensitive and mobile and is used to feel the feed and direct it towards the moouth. Horses also have both upper and lower incisors which cut herbage like scissors and help in prehension. The mastication of feed with grinding molars is also very efficient in horses. In cattle, buffaloes, and sheep, the upper incisors are absent. Instead, they have a hard pad called the dental pad. During grazing, the tongue is used to guide feed into the mouth, and plants are grasped between the dental pad and lower incisors and torn away.

Saliva is a watery solution containing small amounts of mucin, inorganic salts and enzymes. It is secreted into the mouth from three pairs of salivary glands (paratoid, sub-maxillary, and sub-lingual). Secretion of saliva increases during mastication of feed. Cattle and buffaloes produce 130 - 200 litres, sheep and goats 2 - 3 litres, and horses 10 - 12 litres of saliva per day. Saliva lubricates the ingested feed and thus facilitates swallowing. It also helps in maintaining optimum pH in the rumen and provides a mechanism for recycling urea in ruminants.

Oesophagus:

This is a muscular tube extending from the back of the mouth (pharynx) to the stomach. Ingested feed is forced through the oesophagus by its wavelike muscular contractions.

(Note: In next Post, find about Function of stomach in digestive system of farm animals)

Parts of digestive tract

The digestive tract, also known as the alimentary canal, is a tube like structure extending from the mouth to anus. The different parts of the digestive tracts of ruminants and non-ruminants are illustrated in figures. The alimentary canal is comprised of the following parts,

1. Mouth (lips, tongue, gums and teeth) and pharynx
2. Oesophagus
3. Stomach (In ruminants, the stomach includes the rumen, reticulum, omasum, and abomasum)
4. Small intestine (duodenum, jejunum, and ileum)
5. Large intestine (caecum, colon, and rectum)
6. Anus

In addition to the above, the following accessory organs/glands also take part in the process of digestion: salivary glands, liver, gall bladder, and pancreas.

Among domestic animals, the proportion of the digestive tract to total body weight is higher in ruminants than in non-ruminants, as shown in table. Horses, for example, have a large caecum (15.6% of the total alimentary tract) where extensive microbial fermentation of plant materials takes place. Similarly, rabbits also have a well developed caecum. In ruminants, the stomach compartments (rumen, reticulum, omasum, and abomasum) occupy the major part (62%) of the digestive tract. Large variations in the proportion of different parts of the digestive tract in farm animals reflect differences in their feeding habits. These variations have evolved over time, and the animals have gradually adapted to various feed resources.

	Cattle	Buffaloes	Sheep/Goats	Horses	Dogs
Body Weight (Kg)	450	600	50	450	20
	Volume in liters, and proportion of body weight (percent)
Stomach
Reticulo-rumen	97.6 (48)	130.3 (48)	10.7 (56.7)	-	-
Omasum	15.8 (7.6)	20.9 (7.6)	0.6 (3.3)	-	-
Abomasum	11.8 (5.8)	15.7 (5.8)	1.3 (6.7)	8.0 (8.9)	1.0 (63)
Small Intestine	50.9 (25)	67.7 (25)	3.8 (20)	27.0 (30.0)	0.37 (23.0)
Caecum	7.7 (3.8)	10.3 (3.8)	0.6 (3.3)	14.0 (15.6)	0.02 (1.0)
Large Intestine	19.7 (9.5)	26.0 (9.5)	1.9 (10.0)	41.0 (45.6)	0.21 (13.0)
Total	203.5	270.9	18.9	90.0	1.6

Reproductive Hormones

Hormones are organic substances secreted by certain specialized cells (glands) in the body, which are diffused or transported to some other part of the body and bring about certain changes. A number of hormones are directly or indirectly involved in vaarious aspects of reproduction. The secretion of these hormones is essential for the maintenance of a proper internal environment to ensure successful reproduction. The hormones involved in reproduction may be divided into two groups: 

(a) Primary hormones of reproduction

(b) Secondary hormones of reproduction

(a) Primary hormones of reproduction:

Gland	Hormone	Important Function
Anterior Pituitary	Follicle stimulating hormone (FSH)	Spermatogenesis; ovarian follicular growth.
	Lutenizing hormone (LH) (ICSH)	Androgen release; ovulation.
Posterior Pituitary	Oxytocin	Parturition; uterine contractions; milk letdown.
Testis	Testosterone	Maintenance of male reproductive duct system and secondary sexual characteristics; male sexual behavior; spermatogenesis
Ovary	Estradiol	Maintenance of female reproductive duct system and secondary sexual behavior; mammary gland stimulation.
	Progestrone	Implantation; pregnancy maintenance; mammary gland stimulation.
	Relaxin	Relaxation of uterine cervix and pubic symphysis; inhibition of uterine contractions.
Placenta	Human chorionicgonadotrophin (HCG [primate])	LH-Like
	Pregnant mare's serum (PMS [horse])	FSH-Like

(b) Secondary hormones of reproduction:

Gland	Hormone	Important Function
Anterior Pituitary	Somatotropin releasing hormone (STH)	Body growth; protein synthesis.
	Thyroid stimulating hormone (TSH)	Stimulation of thyroid gland; thyroxine release and iodine uptake by thyroid.
	Adrenocorticotropic hormone (ACTH)	Stimulation of adrenal cortex; release of adrenal corticoids
Posterior Pituitary	Vasopressin (antidiuretic horomne) (ADR)	Water balance.
Thyroid	Thyroxine	Body growth; development of maturation; oxidation of feeds.
Adrenal Cortex	Aldosterone	Electrolyte and water metabolism.
	17-OH corticoids (cortisone) (cortisol) (corticosterone)	Carbohydrate, protein, and fat metabolism.
Pancreas	Insulin	Carbohydrate, fat, and protein metabolism.
Parathyroid	Parathormone	Calcium and Phosphorus metabolism.

 

The primary hormones are directly involved in various aspects of reproduction, such as spermatogenesis, oogenesis, and ovulation. The secondary hormones are needed for the normal functioning of the organisms which makes it possible for reproduction to occur.

Casting animals: Horses

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The following methods are employed for casting horses: 

(a) the use of side lines (single as well as double)

(b) the use of hobbles

Single side lines: Cotton web is ideal for a good side line. A slipping knot is made at the pastern. The side line is then passed between the forelegs, and the free end taken round the neck, brought up over the shoulder to the near side, and a knot applied near the elbow drawing the hind leg a little bit forward.

Double side lines: A slipping knot is made at the near hind pastern, the knot being on the outside. The side line is then passed between the forelegs and given a turn. The free end is then passed under the previous turn of the side line and passed over the shoulder onto the off side. The side line is then wound round the off forelimb in a similar fashion as was done on the near side, and then it is passed around the pastern and a knot tied on the outside. Both the hind legs are brought slightly forward during the operations.

Hobbles: Hobbles are used for heavy draught horses. A set of four hobbles with a chain about 3 m long is used. Attached to this is an approximately 5 m long rope with a spring "D"-catch. One of the hobbles, the "master hobble", has an arrangement by which the chain is screwed on to it.

Hobbles (Courtesy: chestofbooks.com)

The hobbles should first be laid out, each in its right position, and then placed on the horse. If the horse is to be east on the right side, the master hobble is attached to the left fore-pastern. A rope is slipped round the upper arm of the foreleg which is to be uppermost, and passed over the withers to the assistant standing on the other side whose task is to pull the animal on to the required side. As soon as the hobbles are adjusted, the person at the head backs the horse quickly. At the same time, the hobbles are pulled together, and the person holding the rope over the withers pulls the horse over. As soon as the operation is finished, the hobbles must be taken off with the horse still lying down. 

Use of Tranquilizers before casting: 

Very vicious and highly nervous large animals can be calmed before casting by administering tranquilizers such as "Largactal" (tm) or other chlorpromazine compounds, or depressants such as chloral hydrate or barbiturates. The drugs minimize struggling and make application of ropes and appliances easier. The narcosis or sub-narcosis attained should not be so great as to leave the animal weary for a long time.

For cattle and buffalo, chloral hydrate is most common drug used since it is cheap, efficient and can be easily administered orally as a drench or electuary in drinking water. The dose varies from 15 - 45 g for cattle and 2 - 4 g for sheep, depending upon the size of animal. The animal should be fasted for 18 - 24 hours before administering the drug, which is done about one hour before the actual handling of the animal.

A presentation about casting horses for different purposes can be viewed here.

Restraining animals: Devices - 1

Halters: Halters are one of the simplest controlling devices for horses, cattle and buffalo. To make a halter, lay about 3 m of rope on the floor. At about 1 , from the left hand end, untwist the strands sufficiently to enable the right hand end to be passed through it to make a loop of about 2.5 cm in diameter. Lay the rope down as before. Close to the loop, untwist some strands again on the right hand side, and pass the left end through it. Pull up tight and bind the splice thus made with a few turns of string. To form a poll-piece, untwist the strands of the right hand length, about 25 cm from the loof already made, and pass the left hand end through it.

Make an overhand knot to fix. Bind on either side with string. Now pass the long right hand end through the spliced loop first made. This forms the nose-band. The halter is now complete. The knot in the poll-piece can be adjusted to fit the head of different animals.

To halter a horse, first slip the rope or shank of the halter around its neck by holding the forelock or resting the right hand on the neck just behind the ears. Then slip it over the horse's ears. The halter should be prevented from becoming too tight by putting a hitch or cinch in the shank as it leaves the nose-band. Placing the halter on the animals correctly should be practised until it becomes second nature. An incorrectly placed halter may be too loose to hold the horse, or may irritate it to the point where it becomes unmanageable.

Head Collars: Effective devices for controlling animals, head collars are used mostly with horses, but may also be used with cattle and buffalo. The head collar consists of a poll-piece, two cheek pieces, a nose band, a throat-piece, and a jowl-piece. Today, nylon head collars are increasingly being used because they are cheap, easy to clean, and durable.

A head collar is a very effective means for securing a horse in a stable or stall. A neck strap or neck rope is often used in the stable, but whether it is a halter or a neck tie, the shank in each case is put through a ring or hole in the manger, with the end attached to a metal or wooden "sinker" to prevent the horse from putting his foot on the head rope, yet allowing the maximum length of movement.

Fig 1 (Click to enlarge) - Courtesy: ryancoaxum.com

Horses may be tied to the rings that are often found in stalls or on the heel post. When tying a horse in a stable, it is best to use a knot that can be released quickly. A method of tying such knot is shown in Fig 1. The knot is made by doubling the head rope or the shank of the halter with one short end. This doubled piece of rope is put under the ring, and then another loop in the long end nearest the horse is inserted through the double end. The short end is pulled tight. A second loop is made in the short end, and this is put through the firsst loop and tightened by a pull on the long end. A quick tug on the short end releases the horse.

Twitches - Courtesy: fao.org

Twitches: A twitch is a tightening device used to restrain an animal. The different types of twitches are the stick twitch, halter twitch, loop twitch, and leg twitch. Twitches should be applied immediately before the necessary restraint is used. Since the device inflicts pain, repeated use should be avoided.

a. Stick Twitches:The stick twitch consists of a piece of stout wood about 1 m long with a 1.5 cm hole about three cm from the end. A piece of rope is inserted through this hole. While applying a twitch, the animal should be haltered and backed into a corner of the stable yard. Take the twitch stick under the right arm and stand on the near side opposite the left shoulder. Put the thumb and last three fingers of left hand trough the loop of the twitch, but leave the index finger out to prevent the loop slipping over wrist. Take the animal in confidence and get a good hold of the upper lip, leaving the nostrils free. With the right hand, rapidly twist up the stick. Take as tight a hold as necessary, but do not be unduly severe. The twitch helps restrain the animal by causing a harmless pressure upon a sensitive area of the upper lip. It also diverts the animal's attention from the part being manipulated and affords a strong hold upon the head of animal. If it is not possible t apply a twitch on the upper lip, then the lower lip or an ear may be used.

b. Loop Twitches: The loop twitch consists of a pliable rope with a running noose on one end. The noose is passed over the poll, into the mouth, and pulled tight. It should be used very carefully since it is liable to cut the commissures of the lips.

c. Leg Twitches: The leg twitch is an ordinary tourniquet applied about 10 cm above the knee or hock to immobilize the leg.

Continue... (Read about more restraining devices as gags, bull rings, muzzles, cradles, crushes and ropes in next post)

Transporting horses by train and vehicle

When horses are to be taken to a distant area, the train is considered to be the most effective mode of transportation. In Pakistan trains have special boxes or wagons reserved for horses. They can accommodate three to five horses and contain separate feeding and watering devices for each animal. There is a layer of bedding material on the floor for the animals' comfort.
The horse, wearing a head collar, should be led into the wagon from a platform. If the horse is overly excited, wait until it calms down, do not try to drag it. The horse can be tied to a ring attached to the manger. Talk to the horse and pet it. When the horse is tied, close the door or snap a chain across it quietly. Care must be taken with yearlings that have never been on a train. They can be a problem unless they have been handled constantly. If they have not yet learned to accept discipline readily, they can do a lot of damage. When it is time to release the horse, make sure that it has been untied before opening the door to the wagon. Unsnap the chain or open the door, walk away and let the horse come out at will.
It is best to start getting a horse used to a truck or trailer early in life and especially before a journey is planned. If a mare is an easy loader, the foal can be allowed to follow her on and off the vehicle, and young animals may be fed in and around it. Never allow the horse to come off the trailer or truck as soon as the ramp is down. Make it a habit to insist that the horse stand still for a few minutes. This will prevent it from rushing backwards to get off. This is a frequent cause of injury to horses and people, and can also damage equipment.
There are a number of useful techniques for loading difficult horses. The best method is to park the truck or trailer in an alleyway or up against a wall, so that there is no escape around one or both sides. One person should hold the head with the animal wearing a bridle. Place a new market loader, purchased or improvised, on the horse's quarters and have two reliable helpers each hold the handle of the loader. The two helpers should pull forward as evenly as possible and not give up. The person at the head should guide the animal in, but not pull too hard or the horse may be inclined to throw its head up. The pressure on the loins and buttocks appears to prevent the horse from both rearing and kicking, although it may produce a small buck on the first occasion it is used.

Moving animals: Horses

Even though horses are social animals, strange horses should not be allowed to get too close to the others. When leading or riding in a line, keep at least one horse's length between animals to avoid kicking. Horses being introduced nose-to-nose for the first time will often squeal and strike out with a front foot or even try to turn quickly and kick. When crossing a road, it is extremely important that all the horses cross together. One person should take charge and check that all are ready to cross simultaneously or in larger groups. It is better to hold the traffic and let the whole line cross. If one horse is left behind, it could get out of control and cause an accident.
Similar precautions should be taken when turning a group of horses out into a field. All the horses should be taken into the field and held well apart and clear of the gateway. The gate should then be closed. They should all be turned to face the gate and, when all are ready, released together. Turning the horses to face the gate means that the horses have to turn before they charge off and the handlers have time to step clear.
In a situation where the person riding or leading the horse loses control of the animal, the others should try to remain calm and stand still. Trying heroically to rescue a bolting horse at a gallop will only make matters worse.

Handling animals: Horses and ponies

Anticipation is the key to safe handling of horses and ponies. Developing an awareness of the animal's natural behaviour and thus avoiding certain situations can enable handlers to prevent accidents. Most horses and ponies will behave better if handled with confidence, firmness, and kindness. Thrashing an animal will only produce fear and panic, and the horse or pony invariable stronger than the handler, will react instinctively and be less likely to perform the required activity. Wearing stout footwear is essential to give confidence to the handler. Boots or shoes with steel toe-caps are well worth considering as they protect the foot from trampling and enable the handler to stay close to the horse without fear of injury.
There are a number of tricks for catching difficult horses or ponies which are worth trying, depending on the circumstances.

1. Always approach the horse or pony from the front and slightly to one side where it can see you. The animal's vision behind and directly in front is good. Speak as you approach in order to give it a warning. Handle the horse or pony first on the lower neck or shoulder as this a safe area. 
2. Offer food over the fence. Some animals will then consider you to be a visitor rather than a catcher. This works best if the animal is wearing a head collar. It will usually submit once you have hold of the head.
3. Try sending someone to catch the animal who does not normally ride the pony or who is dressed in clothing not usually worn when handling or riding.
4. When an animal comes close but snatches its head away when you try to catch it, try crouching on the ground with some food close by. The unsuspecting animal may allow you to touch a front leg which you can then pick up. It then assumes that it is caught. Leaving a short length of rope or leather on the head collar may also help with a head-shy animal.
5. Cornering a horse or pony with the help of two or more people some times works, provided it does not usually gallop off when you are still a long way from it. Try to avoid exciting the animal, and if possible let it move forward a little. Many animals will give up once they are cornered and allow themselves to be caught.
6. Sometimes an animal can be difficult to catch even in a confined space because it is frightened or has been injured. In this case it may be necessary to use a lasso. If the animal cannot be caught with a lasso, a lariat can be tried. A lariat is a rope constructed with an extremely tight or hard twist and is used for holding and catching an animal. Knots are difficult to tie in a lariat because of the stiffness of the rope.

Many of the above techniques will be more effective if other animals are removed from the vicinity. Try not to chase the animal around the field. It will only make matters worse. Horses and ponies that have been handled well from birth are seldom difficult to catch. The handling they receive in the first few hours of life is particularly important in this respect.

Approaching animals for handling and restraining

General Precautions:

1. When approaching an animal in a shed, stall, or paddock, always speak to it before touching it.
2. Approach the anoimal from the left side and handle from the head or near the head (beware of the horns of cattle and buffalo).
3. It is not advisable to carry a stick, but if one is needed it should be kept out of sight of the animal.
4. Get some information about the animal from its attendant or owner, e.g. whether the animal is calm or aggressive.
5. Treat strange animals with suspicion, but try not to let the animal know that you are afraid of it.
6. The animal should wear a head collar or a halter. If required, use two ropes on the head collar and tie one to each pillar ring. (Two ropes are especially needed when working with stallions or bulls).
7. Never handle the hind quarters or hind legs without having the animal's head held and a foreleg lifted or restrained.
8. Take hold of the forelock (in the horse), ear, or nose until a halter has been put on. Do not grasp the nose too tightly, otherwise breathing may be obstructed.
9. It is important never to make a sudden snatch at the animal's head collar. This alarms the animal and may make it suspcious on future occasions. 
10. Keep in mind that some animals kick backwards, some forwards, and other laterally with their hind legs. some cattle can kick all three ways.
11. Bulls, especially over a year old, are often treacherous and should be properly secured before being approached by a stranger. They are usually rung before they are one year old. It is wise not to trust a bull.
12. When haltering horned animals, it is best to slip the poll-piece of the halter over the horns and ears before adjusting the loop around the nose, so that the animal cannot take the halter off and break loose.
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Handling and restraining of farm animals

Handling, controlling, restraining, transporting, and casting farm animals sometimes causes them distress even when they are being well managed. Three principles should be kept in mind when conducting these procedures to avoid harming the animals or affecting their productivity.
- The stock man should try to minimize any stress experienced by the animals or the workers handling them.
- These procedures should be carried out in such a manner that the animal are not injured.
- These procedures should be carried out in such a way that the workers are not injured.
In order to meet these objectives, the stock man should ensure before starting that proper equipment is available for the procedure and that the equipment is clean and in good working order. He should know how to use the equipment properly, efficiently and quietly. People assisting a procedure should also know the procedure and feel comfortable while performing it. Fear is perhaps the most dangerous emotion when working with livestock, since a frightened person seldom considers the consequences of his actions. His fear may also be communicated to the animals and upset them, thus making handling more difficult.