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Small Farmer's Journal
PO Box 1627
Sisters, Oregon 97759
800-876-2893
541-549-2064
agrarian@smallfarmersjournal.com
Mon - Thu, 8am - 4pm PDT

Determining the Age of Farm Animals by their Teeth

Determining the Age of Farm Animals by their Teeth

U. S. Department of Agriculture
Farmers’ Bulletin No. 1721, March 1934
by George W. Pope, chief, Field Inspection Division, Bureau of Animal Industry

Importance of Determining the Age of Farm Animals

The productive life of farm animals is comparatively brief, the height of their usefulness being limited to a few years. For this reason the returns from livestock tend to decrease with advanced years. The age of animals, therefore, is a matter of utmost importance to the breeder, the seller, and the buyer.

Physical changes within the body are constant. They affect the general outward appearance and disposition and, within certain limitations, it is not difficult by mere general appearance to distinguish the young animal from one that has reached maturity, or even to determine the approximate age of an old animal. Changes which take place in the teeth, however, afford the best opportunity of determining the age.

Establishing the age of farm animals through the appearance of the teeth is no new thing. The possibility of judging in this manner apparently was well known in ancient days. The old saying, “Do not look a gift horse in the mouth,” is attributed to Saint Jerome, of the fifth century, who used this expression in one of his commentaries. Certainly for generations the appearance, development, and subsequent wear of the teeth has been recognized as a dependable means of judging approximately the age of animals.

With a knowledge of the age at which the teeth appear, the time for shedding temporary or milk teeth and their replacement with permanent teeth, and the changes in form which result from natural wear, the approximate age of farm animals can be determined. Theoretical knowledge, however, is not sufficient, and any one who would become proficient must also have practical experience. This bulletin describes briefly the normal processes of dentition and the changes which time brings about, and explains how to determine the ages of animals by examining their mouths.

Determining the Age of Farm Animals by their Teeth

Fig 1. Skull of the horse.

Horses and Mules

The ordinary observer can readily learn to tell the age of horses or mules with considerable accuracy until the animals have passed their eighth year. Beyond this time even those who are experienced may find it difficult to determine the exact age.

The mature male horse has 40 teeth (fig. 1). Twenty-four of these are molars or grinders, 12 are incisors or front teeth, and 4 are tushes or pointed teeth. The 2 central incisors are known as centrals or nippers; the next 2, 1 on each side of the nippers, are called intermediates or middles, and the last, or outer pair, the corners. The tushes are located between the incisors and the molars. They are not usually present in the mare, and accordingly she may be considered to have a total of 36 teeth rather than 40, as in the male.

The young animal, whether male or female, has 24 temporary teeth, commonly called milk teeth, as they are much whiter than the permanent teeth. These milk teeth consist of 12 incisors and 12 molars. The latter are the 3 back teeth on each side of both the upper and the lower jaw. The milk teeth are shed and replaced by permanent teeth at fairly definite periods, which serve as an index in determining the age of young colts.

Determining the Age of Farm Animals by their Teeth

Fig 2. Temporary incisor teeth of a young colt: A, immediately after the birth; B, at 6 weeks; C, from 6 to 10 months after birth.

The temporary central incisors or nippers may be present at birth (fig. 2, A); otherwise they appear before the colt is 10 days old. There are two in each jaw.

At the age of from 4 to 6 weeks the two temporary intermediates, upper and lower, appear (fig. 2, B). These teeth immediately adjoin the nippers.

When the colt is from 6 to 10 months old the corner or outer incisors, two above and two below, are cut (fig. 2, C). This gives the young animal a full set of temporary front teeth.

Determining the Age of Farm Animals by their Teeth

Fig 3. Appearance of the incisor tooth of a colt: A, at 1 year; B, at 18 months; and C, at 2 years.

By the time the colt has reached the age of 1 year the crowns of the central incisors show wear (fig. 3, A). In another 6 months the intermediates or middles become worn (fig. 3, B), and at 2 years all the teeth are worn (fig. 3, C). During the following 6 months there are no changes which will distinguish the exact age. At about 2 1/2 years, however, the shedding of the milk teeth begins and at 3 years the temporary central nipper, two above and two below, are replaced by the permanent central incisors.

Determining the Age of Farm Animals by their Teeth

Fig 4. Incisors of a horse at 4 years. The permanent incisors are the four in the center, and the temporary ones are at the corners.

At 4 years the four permanent intermediates have taken the place of the four temporary middles (fig. 4).

Determining the Age of Farm Animals by their Teeth

Fig 5. Permanent incisors of a horse at 5 years. The tushes also shown here indicate that the animal is a male.

When the animal is about 4 1/2 years old the shedding of the four corners begins, and at 5 years the permanent teeth which replace them are well up but not in contact (fig. 5).

Determining the Age of Farm Animals by their Teeth

Fig 6. Incisors of a horse at 6 years.

In a 6-year-old horse the corner incisors are on a level with the adjoining teeth, with a well-marked dental cavity or “cup” showing practically no wear (fig. 6). The nippers show wear over the entire surface; the “cup” though visible shows indications of gradual disappearance and at this stage is without a hollow.

Determining the Age of Farm Animals by their Teeth

Fig 7. Incisors of a 7 year old horse.

Determining the Age of Farm Animals by their Teeth

Fig 8. Side view of incisors of a 7 year old horse. Note, in upper corner incisors, the notch which appears at this age.

When the animal is 7 years old, not only the nippers but also the middles show wear (fig. 7). Each upper corner tooth has an indentation caused by wear from the corresponding lower tooth, resulting in a downward triangular projection of the posterior edge. This projection is commonly termed “dovetail” (fig. 8).

Determining the Age of Farm Animals by their Teeth

Fig 9. Incisors of 8 year old horse. Dark line in front of cup is the dental star.

In the 8-year-old horse all the incisors are worn, the cup has entirely disappeared from the nippers, but shows to a slight extent in the middles, and is still well marked in the corners. At this stage what is termed the “dental star” makes its appearance as a yellow transverse line just back of the front edge of the table, or flat surface, of the nippers and middles (fig. 9).

Determining the Age of Farm Animals by their Teeth

Fig 10. Incisors of a male horse 9 years old.

Determining the Age of Farm Animals by their Teeth

Fig 11. Incisors of a horse at 10 years.

Determining the Age of Farm Animals by their Teeth

Fig 12. Incisors of a horse at 11 or 12 years.

Determining the Age of Farm Animals by their Teeth

Fig 13. Incisors of a horse at 13 years.

Between the ages of 9 and 13 years there is a gradual change in the contour of the tables of the incisors. In a 9-year-old animal the nippers take on a more or less rounded contour; the dental cavity or cup has disappeared from all but the corners; the dental star is found in both the nippers and middles and in the former is near the center of the table (fig.10). At 10 years the middles become rounded, and the dental star, now seen on all the incisors, is near the center of both the nippers and middles (fig. 11). At 11 or 12 years the corners have a somewhat rounded form, and the dental star approaches the center of the table (fig. 12). As the horse reaches 13 years of age all the lower incisors are unmistakably rounded, the dental star is found in the center of all the tables, and the enamel rings which formerly surrounded the cups have entirely disappeared (fig. 13).

Determining the Age of Farm Animals by their Teeth

Fig 14. Incisors of a 14 year old horse.

Determining the Age of Farm Animals by their Teeth

Fig 15. Incisors and tushes of a male horse at 17 years. The mouth of the female has the same appearance except for the absence of tushes.

In a horse about 14 years of age the tables of the incisors begin to change from a rounded to a triangular contour. This change occurs in the nippers at 14 years (fig. 14), in the middles at 15 years, and in the corners at 16 or 17 years (fig. 15).

Determining the Age of Farm Animals by their Teeth

Fig 16. Characteristic shape of an old horse’s lower incisors at 18 years.

Determining the Age of Farm Animals by their Teeth

Fig 17. Comparison of incisors and tushes of horses at different ages: A, at 6 years, and B, at 20 years.

During the following 4 years after the appearance of the triangle, there is a gradual approach of the tables to the form of a rectangle, as shown in figure 16. The teeth during this period are usually elongated and directed obliquely. The dental arch also becomes contracted and pointed and the under edges of the lower jaw are thin and sharp as compared with their appearance in a young horse (fig. 17). Should the animal live more than 20 years, these conditions become more marked and are accompanied by excessive wear and loosening or loss of molars.

Determining the Age of Farm Animals by their Teeth

Fig 18. Skull of an ox.

Cattle

Cattle at maturity have 32 teeth, of which 8 are incisors. All incisors are in the lower jaw (fig. 18). The two central incisors are called pinchers; the next two, first intermediates; the third pair, second intermediates or laterals; and the outer pair is known as the corners. In place of the upper incisor teeth there is a thick layer of the hard palate called the dental pad (fig. 19).

Determining the Age of Farm Animals by their Teeth

Fig 19. Hard palate of an ox showing dental pad.

Determining the Age of Farm Animals by their Teeth

Fig 20. Internal face of incisors of the calf at 1 month.

In the calf at birth two or more of the temporary or first set of incisor teeth are present. Within the first month the entire eight incisors have appeared (fig. 20).

Determining the Age of Farm Animals by their Teeth

Fig 21. Internal face of incisors at 2 years.

As the animal approaches 2 years of age the central pair of temporary incisor teeth or pinchers is replaced by the permanent pinchers. At 2 years these teeth attain full development (fig. 21).

Determining the Age of Farm Animals by their Teeth

Fig 22. Internal face of incisors at 3 years.

At about 2 1/2 years the permanent first intermediates, one on each side of the pinchers, are cut and are usually fully developed at 3 years (fig. 22).

Determining the Age of Farm Animals by their Teeth

Fig 23. Internal face of incisors at 4 years.

At 3 1/2 years the second intermediates or laterals are cut. They are on a level with the first intermediates and begin to wear at 4 years (fig. 23).

Determining the Age of Farm Animals by their Teeth

Fig 24. Internal face of incisors at 5 years.

At about 4 1/2 years the corner teeth are replaced. At 5 years the animal usually has the full complement of incisors with the corners fully developed (fig. 24).

At 5 or 6 years there is a leveling of the permanent pinchers, the pinchers usually being leveled at 6 years and both pairs of intermediates partially leveled and the corner incisors showing wear.

At 7 or 8 years there is a noticeable wearing of the pinchers; at 8 or 9 years, of the middle pairs; and at 10 years, of the corner teeth.

Determining the Age of Farm Animals by their Teeth

Fig 25. Internal face of incisors at 12 years.

After the animal has passed its sixth year, the arch gradually loses its rounded contour and becomes nearly straight by the twelfth year (fig. 25). In the meantime the teeth have gradually become triangular in shape, distinctly separated, and show progressive wearing to stubs. This condition becomes more marked with increasing age.

Determining the Age of Farm Animals by their Teeth

Fig 26. Skull of a sheep.

Sheep and Goats

Mature sheep and goats have 32 teeth, of which 24 are molars and 8 are incisors (fig. 26). There are no tusks and, like those of cattle, all the incisors are in the lower jaw. As in the case of cattle, also, the two central incisor teeth are called pinchers; the adjoining ones, first intermediates, the third pair, second intermediates; and the outer ones, corners. The temporary incisors are readily distinguished from the permanent ones by their smaller size and milky whiteness.

In the new-born animal none of the teeth may have made their appearance though sometimes the two pinchers and also the two first intermediates are pressing through the gums or even have cut through. In a few days these teeth and the second intermediate incisors will appear, followed somewhat later by the corners, thus giving the animal, by the time it is 3 months old, a full set of completely developed temporary incisor teeth, as shown in figure 27, A.

Determining the Age of Farm Animals by their Teeth

Fig 27. Incisors of sheep at different ages: A, at 3 months; B, at 12 to 15 months; C, at nearly 2 years; D, at 3 years; and E, at 4 years.

When the animal is between 12 and 15 months of age the temporary pinchers are replaced by the two permanent ones (fig. 27, B).

The shedding of the first temporary intermediates and their replacement by permanent teeth indicate that the animal is approaching its second year (fig. 27, C).

The replacement of the second temporary intermediates by the permanent ones takes place when the animal is about 3 years old (fig. 27, D).

The two temporary corner incisors are replaced by permanent teeth as the sheep reaches the age of 4 years. All the permanent teeth are then present, and the animal has what is termed a “full mouth” (fig. 27, E.)

After this time there is a distinct and progressive increase in size of the spaces between the teeth, which gradually become worn to stubs and frequently attain an unnatural and uneven length. In old sheep some teeth may be broken or loose; in such cases the animal is said to have a broken mouth.

Determining the Age of Farm Animals by their Teeth

Fig 28. Skull of a hog.

Swine

A mature hog has 44 teeth (fig. 28). Of these, 12 are front teeth or incisors, and 6 are in the upper and 6 in the lower jaw. Four others lie in the open spaces back of the incisors and are known as tusks, or tushes. They are usually more prominent in the male than in the female. Back of each tush is a tooth commonly called the premolar, and immediately back of this on each side of the upper and lower jaws there are 6 molars, the first 3 in each row sometimes being termed premolars. As in the horse, the incisors are grouped in three pairs in each jaw and are termed centrals, intermediates, and corners in accordance with their relative positions.

Determining the Age of Farm Animals by their Teeth

Fig 29. Teeth in the lower jaw of the hog: A, at birth; B, at about 5 weeks; C, at 3 months; and D, at 12 months.

The young pig at birth usually has 8 teeth. These consist of the 2 tusks and 2 corner incisors on each jaw. They are all sharply pointed and are sometimes known as needle teeth (fig. 29, A). It is a common practice to cut them off, about halfway between the gum and point of the tooth, in the new-born pig, in order to avoid discomfort and injury to the nursing sow.

When the pig reaches the age of 4 or 5 weeks the central temporary incisors appear, two in the upper and two in the lower jaw (fig. 29, B).

As the animal approaches the age of 6 to 8 weeks the two intermediate incisors will have cut through the gums of the lower jaw between the corners and the centrals and will be fully grown at 3 months (fig. 29. C).

As the pig passes 6 months of age the temporary corner incisors are shed, and the permanent corners appear. Shortly after 9 months the permanent tusks take the place of the temporary tusks. At approximately 12 months the central permanent incisors replace the temporary centrals, and the lower teeth appear as shown in figure 29, D.

During the next 3 months the first 3 temporary molars, on each side of upper and lower jaw, will be shed. These are immediately back of the premolars, which in turn are back of the tusks. When these temporary molars, 12 in all, have been replaced by permanent molars, the pig has attained the age of at least 15 months.

Determining the Age of Farm Animals by their Teeth

Fig 30. Lower front teeth of a hog approximately 20 months old. The prominent tusks indicate that the animal is a boar.

As a rule the shedding of the temporary intermediate incisors and the appearance in their places of the permanent ones are indications that the hog is approximately 18 months of age. By the time the animal has reached the age of 20 months these intermediate incisors will be in line with the centrals (fig. 30).

As there is no further shedding or eruption of teeth, the age of hogs beyond 20 months of age cannot be so easily estimated. At 2 years, however, the incisors, including the intermediates, will show wear, and the sixth or last molars (one upper and one lower on each side) will be fully up and about to come in contact.

After 2 years it is difficult to judge the age of swine by the teeth. However, except in the case of breeding and exhibition animals, it is not often important to know the exact age of mature hogs. It is possible, however, to associate progressive wear of the teeth with the advance in age. Aged swine show considerable wear of the teeth, especially of the molars (fig. 31).

Determining the Age of Farm Animals by their Teeth

Fig 31. Typical appearance of teeth of an 8 year old sow.

Spotlight On: Crops & Soil

Farm Manure

Farm Manure

Naturally there is great variation in manure according to the animals it is made by, the feeding and bedding material, and the manner in which it is kept. Different analyses naturally shows different results and the tables here given serve only as a guide or index to the various kinds. The manure heap, by the way, is no place for old tin cans, bottles, glass, and other similar waste material.

Fjordworks Horse Powered Potatoes Part 2

Fjordworks: Horse Powered Potatoes Part Two

These types of team implements for digging potatoes were the first big innovation in horse powered potato harvesting in the mid-19th century. Prior to the horse drawn digger the limitation on how many potatoes a farmer could plant was how many the farm crew could dig by hand. The basic design of these early diggers works so well that new models of this type of digger are once again being manufactured by contemporary horse drawn equipment suppliers.

Carrots and Beets The Roots of Our Garden

Carrots & Beets – The Roots of Our Garden

by:
from issue:

Carrots and beets are some of the vegetables that are easy to kill with kindness. They’re little gluttons for space and nutrients, and must be handled with an iron fist to make them grow straight and strong. Give the buggers no slack at all! Your motto should be – “If in doubt, yank it out!” I pinch out a finger full (maybe 3/4” wide) and skip a finger width. Pinch and skip, pinch and skip, working with existing gaps and rooting out particularly thick clumps.

Onion Culture

Onion Culture

The essential requirements of a soil upon which to grow onions profitably are a high state of fertility, good mechanical condition, properties – that is, if it contains sufficient sand and humus to be easily worked, is retentive of moisture and fertilizers, and is capable of drainage – all other requirements can be met.

An Introduction To Farm Woodlands

The farm woodland is that portion of the farm which either never was cleared for tillage or pasture, or was later given back to woods growth. Thus it occupies land that never was considered suitable, or later proved unsuitable, for farm enterprises.

Cabbage

Cabbage

by:
from issue:

Cabbage is the most important vegetable commercially of the cole crops, which include cabbage, cauliflower, Brussels sprouts, kale, kohlrabi, collard, broccoli, and many others. It also ranks as one of the most important of all vegetable crops and is universally cultivated as a garden, truck and general farm crop. The market for cabbage, like that for potatoes, is continuous throughout the year, and this tends to make it one of the staple vegetables.

An Introduction Into Plant Polyculture

An excerpt from What’s Wrong With My Fruit Garden
Companion Planting for Beginners

Cultivating Questions: Alternative Tillage & Inter-Seeding Techniques

Our intention is not to advocate the oddball living mulches we use with this single row inter-seeding system, but just to show how it is possible to utilize the between-row areas to improve insect habitat, reduce erosion, conserve moisture, fix some nitrogen, and grow a good bit of extra organic matter. If nothing else, experimenting with these alternative practices continues to keep farming exciting as we begin our twentieth season of bio-extensive market gardening.

Cultivating Questions Ridge-Till Revisited

Cultivating Questions: Ridge-Till Revisited

Delay ridge building until early fall so that the cover crop on the ridge does not grow more than 12” tall before winter. The residues from a short cover crop will be much less challenging to cultivate than a tall stand of oats, especially if tangly field peas are mixed in. Waiting for the winterkilled cover crop residues to breakdown as long as possible before ridge-tilling in the spring will also make cultivation much easier until you gain familiarity with the system.

Asparagus in Holland

Asparagus in Holland

by:
from issue:

The asparagus culture in Holland is for the majority white asparagus, grown in ridges. This piece of land used to be the headland of the field. The soil was therefore compact, and a big tractor came with a spader, loosening the soil. After that I used the horse for the lighter harrowing and scuffle work to prevent soil compaction. This land lies high for Dutch standards and has a low ground water level, that is why asparagus can grow there, which can root 3 foot deep over the years.

Purslane, Portahoopies and Plow Planted Peas

Purslane, Portahoopies and Plow Planted Peas

For those not familiar with this tasty, nutritious weed, purslane can be a real challenge to manage in vegetable crops for a number of reasons. The seeds of this weed remain viable for many years in the garden, and generally do not germinate until hot weather — that is, after many of the market garden crops have already been planted. To make matters worse, this succulent plant often reroots after cultivation. Purslane also grows so close to the ground that it is impossible to control by mowing.

Beautiful Grasses

What follow are a series of magnificent hundred-year old botanist’s watercolors depicting several useful grass varieties. Artworks such as this are found on the pages of Small Farmer’s Journal quite regularly and may be part of the reason that the small farm world considers this unusual magazine to be one of the world’s periodical gold standards.

What We've Learned From Compost

What We’ve Learned From Compost

by:
from issue:

Our compost piles will age for at least a year before being added to the garden. We have learned that the slow aging is more beneficial to the decomposition process as well as not losing nearly as much nitrogen to off-gassing as happens with the hot and fast methods. Another benefit is the decomposition is much more thorough, destroying weed seeds, pathogens and any unwanted chemicals much better in a slower composting setup.

Fjordworks: Horse Powered Potatoes

Fjordworks: Horse Powered Potatoes

This is the account of how one farm put more horse power into the planting, cultivation, and harvesting of its potato crop. Ever since we began farming on our own in 1994 one of our principle aims has been the conversion of our farm operation to live horse power wherever feasible. This has meant replacing mechanized tools such as tractors and rototillers and figuring out how to reduce human labor as we expanded upon the labor capacity of our work horses.

Cultivating Questions Winterkilled Cover Crops for a Mild Climate

Cultivating Questions: Winterkilled Cover Crops For A Mild Climate Part 1

Our mild climate makes it too easy to overwinter cover crops. Then the typically wet springs (and, on our farm, wet soils) let the cover put on loads of topgrowth before getting on the soil. Buckwheat is the only crop that I can be certain will winterkill. Field peas, oats, annual rye and crimson clover have all overwintered here. Any suggestions?

Peach

Peach

by:
from issue:

The Peach is a showy tree when in bloom. There are double-flowered varieties, which are as handsome as the dwarf flowering almond, and they are more showy because of the greater size of the tree. The flowers of the Peach are naturally variable in both size and color. Peach-growers are aware that there are small-flowered and large-flowered varieties. The character of the flower is as characteristic of the variety as size or color of fruit is.

Planting Calendar and Other Diagrams

From Dusty Shelves: A 1943 calendar for seeding your vegetable garden.

Ginseng Culture

Ginseng Culture

U.S. Department of Agriculture Farmer’s Bulletin No. 1184 Issued 1921, Revised 1941 — The evident preference of the Chinese for the wild root and the unsatisfactory state of the general market for cultivated ginseng have caused grave doubts as to the future prospects of the industry. These doubts will probably be realized unless growers should strive for quality of product and not for quantity of production, as has been the all too common practice in the past.

Small Farmer's Journal

Small Farmer's Journal
PO Box 1627
Sisters, Oregon 97759
800-876-2893
541-549-2064
agrarian@smallfarmersjournal.com
Mon - Thu, 8am - 4pm PDT