Grazing problems with cows’ teeth

By Dr Clive Dalton

Looking at a cow’s teeth

When buying or selling sheep, farmers and stock agents always inspect the animals’ front teeth (incisors) to make sure they can eat pasture effectively.  It’s called ‘mouthing’ and standard practice is that sale ewes are ‘guaranteed in mouth and udder’ before the hammer falls.

Why don’t we take the same approach with cattle, as their teeth are equally as important?  The answer is simple; it’s too difficult, as wrestling with a cow to open her mouth to inspect teeth needs strong arms, and can be dangerous, even with her head locked in a headbail. 

You need to get her nose in a half-Nelson wrestling hold, while leaning back against the headbail gate with feet well planted, and even then her head can still move quickly and hit you in the ribs.  Horns are an added hazard.

You then have to force the cow to open her mouth, which is best done by grabbing the side of her lip with your closed fingers, on the opposite side from where you are standing. 

There’s a small gap between a cow’s front incisors and her back molars where there is only gum.  You can poke your fingers in there for leverage to open her mouth while pulling her whole head upwards, but care is needed!  If she opens her mouth quickly and your fingers slip back between her molars, they’ll be neatly guillotined off, and you won’t see them again to get them sewn on again!

To get a good front view of a cow’s incisors, you need to hold their lips open (which they don’t like) to check for teeth numbers, missing teeth, gaps, to check the gums around the teeth, the state of wear and especially to see how well the incisors meet the gum.  To do all of this at once, you need three hands or a strong assistant.

Harvesting pasture

 
 The cow has a long ‘prehensile’ (gripping) tongue which is designed to sweep the grass into its mouth, where it’s immediately grabbed by the front incisors and held against the top hard dental pad before being ripped off by movement of the head.  A dairy cow can easily make up to 36,000 bites per day when in full lactation and being fully fed. So the state of her front incisors is critical to doing all this work.

Digestion

Reticulum or honey-comb bag

 After biting off the pasture, it is mixed with saliva (100L/day for a dairy cow) and masticated (chewed) by the back molars before being swallowed into the rumen (the largest of the four stomach compartments) for the first time. 

After bacterial fermentation in the rumen, the grass is regurgitated back into the mouth in round boluses to be chewed for a second time by the molars and swallowed back via the reticulum (honey comb bag used for tripe) into the omasum with many leaves for finer grinding (called the Bible). Then it passes in finely ground form into the abomasum or fourth stomach for final acid digestion before it’s voyage down the digestive tract into the small and then large intestine.

  

Eating short pasture
 So the first harvesting stage by the incisors is easiest when pasture is long – at least 2500kg DM/ha. So for a cow to eat say 13kg of DM/day for its maintenance and production needs, it has to harvest 90-100kg of wet herbage from the paddock.

It cannot do this effectively when grass is short (below 1100kg DM/ha), and when forced to nibble like a horse.  Horses have both upper and lower incisors so can easily graze down to soil level.  If cattle are forced to eat down to soil level, it’s a major challenge and results in severe damage to their incisors.

Teeth damage in winter

How much soil and teeth wear in this mob?

This incisor damage happens too often during winter when cows are held at very high stocking rates to build up pasture for spring.  These conditions also force cows to eat large amounts of soil, which is not good for their digestion.  On pumice soils, the risk of incisor damage is even greater due to the extra abrasion of the teeth dentine from the pumice.

Teeth damage in drought

Incisor damage also increases in extended summer dry spells and severe droughts when there is little green feed available, and most of what is on offer is very short, dry and wiry dead stems which are tough to tear off even when they can be held by the incisors.

Damage when changing teeth

Cattle are born with 8 temporary milk incisors which are then replaced in pairs from the middle pair outwards at an average of 1.5, 2.5, 3.5 and 4.5 years of age. After about 5 years of age (called full mouth), you cannot tell the age of a beast by its incisors and can only guess based on wear.  Very old cows will have very worn teeth and may have none (called gummies) – but this is prone to great variation and error.

Note that these ages are general averages, and there’s enormous variation between individuals.  As the new teeth push the old ones out and this can pose problems when aging, so beware of this when mouthing a cow.

Gaps between teeth

A good set of incisors has no gaps between the teeth, as when gaps develop, grass gets down between the teeth and the biting action causes it to act as an abrasive – eventually making the gap wider and the teeth forced further apart.

 As the teeth get more spaced out, they are then more prone to becoming loose and being pulled out completely.

Eating supplements

Cows with worn, damaged or missing teeth usually have no problems eating roughages like hay or silage, as there is little initial biting to be done. Similarly they can eat dry concentrates with ease.

Buying beef cattle

Beef cattle are not the problem that dairy cattle are, as beef animals are not kept at high stocking rates and hence forced to graze down so low to the ground.  Even in droughts’ beef cattle can usually find enough long roughage so don’t have to eat down to ground level.

Buying dairy cattle

The big concern is with dairy cows when people may have to pay up to $3000 for top genetics.  At these prices, you don’t want a cow with broken or missing teeth, especially if you are a sharemilker depending on money from the bank to buy the herd.

So the message is if you have to buy a good cow (beef or dairy) to be a foundation cow for the future of the herd, it would be a very good idea to insist that she is guaranteed to have a ‘correct mouth’. 

If you cannot get this guarantee or don’t trust the vendor, then insist that you have permission to mouth all the animals on offer before purchase, as a beast that cannot harvest pasture effectively will have her production compromised.  A sound mouth on a cow is as important as a sound udder and teats, and cows are always sold with these guarantees by all reputable stock companies.

Buying cattle on line

When buying stock on line, especially older animals, it’s equally important to check teeth before purchase, as there is no guarantee, as when buying through a stock firm, that your money and the stock will be protected during the transaction.

Dairy industry changes

Dairy herds have increased rapidly in size over the last decade, and so has the change from herringbone milking sheds to large rotaries with in-line medication systems, so farm staff don’t see the condition of cows’ teeth each day as when orally drenching in the herringbone.

So the chances of cows in the herd with defective incisors will be much less likely to be noted.

Genetics

In sheep it’s well recognised that the shape and closing (occlusion) of the incisors against the dental pad has a genetic component, and rams are regularly inspected and culled for any defects, or with undershot or overshot jaws which are considered to be very serious inherited traits.

It’s highly likely that a similar situation occurs in cattle but it has never been investigated.  When bulls can now have thousands of daughters in herds all over the country, it would seem to be a good idea to give some attention to their teeth, especially when modern dairy husbandry systems at times of the year force cows to eat hard dry herbage very close to the ground.

Examples of teeth

Cows  using their tongues to sweep grass into their mouths

Full mouth of fairly good set of teeth

Cow in serous trouble for grazing.  Missing teeth and remainder worn away

Another cow in serious trouble with critical middle teeth missing

All teeth present but large gaps between teeth for grass to get stuck and increase wear

Full mouth but large gap showing

Four tooth cow with gaps starting to develop

Four tooth cow showing grass stuck between teeth

Good full mouth but top of teeth unevenly worn

Full mouth with grass stuck between teeth

Six tooth mouth with temporary tooth still in gum on right

Full mouth of badly worn teeth

Full mouth of evenly worn teeth

Full mouth of evenly worn teeth

Angora (Mohair) Goat Basics: Aging goats by teeth

Agriculture, farming, animal husbandry, goats, Angora, Mohair, aging goats, teeth.




By Dr Clive Dalton

Aging goats by teeth

• Goats have no top teeth and instead have a hard dental pad that their bottom incisors bite against.
• You can estimate the age of goats by the age at which the milk teeth are replaced by permanent incisors. They get new ones in pairs working from the middle outwards.
• But be warned about average ages of eruption – there is enormous variation between animals. Here are some values:
  

• Kid - starts with 8 temporary incisor milk teeth
• Hogget - the centre pair of permanent teeth start to erupt at 12 months of age.
• Two-tooth - first central pair of permanent teeth present at 13-15 months old.
• Four-tooth - second pair present at 18-21 months old.
• Six-tooth - third pair present at 22-24 months old.
• Full mouth - complete set of 8 permanent teeth present at 27-32 months old.
  

Looking in a goat’s mouth
Goats don’t like dental examinations, so you’ll have to firmly restrain each animal. Here are some tips:

• Sit the goat upright in the shearing position and use both hands to open its mouth.
• Cup your left hand around its jaw and use your left thumb to lift its top lip and then use your thumb on the other hand to pull the bottom lip down.
• You’ll be able to see if the teeth are meeting the gum correctly and are not “undershot” or “overshot”.
• When undershot the teeth meet the gum back from the edge (called parrot mouth), and when overshot the teeth stick out beyond the gum edge and can be very sharp as they have not been worn down with biting off grass.
• If you want another view, slide your left thumb into the space behind the incisors where there is a gap before the molars start and this will open the mouth so you can see the top of the teeth.
• If you are not able to tip the goat up, then hold it up against a fence or in the corner of a pen and pull its lips down as described above. You don’t get such a good view.
  

Be prepared for surprises

• You can often get a shock when you see the state of a goat’s teeth. Teeth do an enormous amount of tearing and pulling of fibrous herbage and are subject to great mechanical stresses.
• Here are some things regularly seen:
• Overshot and undershot jaws as mentioned above. The overshot teeth may be only partly overshot where the back half contacts the gum and the front half has a lance-like edge that can lacerate your fingers.
  
• Goats with undershot parrot-mouths have great difficulty in eating short pasture.
• Gum cavities that still have both the old tooth present and the new one pushing it out, and the gum looking very inflamed.
• Missing permanent teeth – especially the central pair which are critical for grazing.
• Very long wobbly teeth that are loose in the gum. This may be “periodontal disease” which has many causes and there’s not much you can do about it.
• Most permanent teeth missing and only an odd single very long loose tooth left. It’s better to pull this out to even up the sheep’s bite.
• No permanent teeth at all – the goat is described as being “broken mouthed” or called a “gummy”. They have all worn off by the gum. In pumice country this can be a special problem with the very abrasive nature of the soil.
• If all the teeth are worn right down to the gum but are still there, it’s very difficult to age the goat as you cannot tell which stumps are temporary and which are permanent teeth.
• Long permanent teeth where grass has been getting in between them and wearing away great holes.
  

Goats with no teeth can still manage to eat if there is plenty of pasture available, as the front teeth only bite off the grass and the back incisors do the grinding.

When fed root crops like turnips, they really need good teeth to break the skin of the bulb and eat it down to ground level once the leafy top has been eaten. Also good teeth are important if goats are to browse hard woody shrubs.

Sheep breeders have shown that the solution to teeth problems is through an effective selection and culling programme.

Cattle farm husbandry – aging cattle by their teeth

By Dr Clive Dalton

Aging cattle by their teeth

Four permanent teeth

• You may need to determine a cow’s age and like sheep; this can be done by the age at which their permanent teeth erupt. Cattle are big, so this can be a hazardous exercise.
• Never attempt to look in a cattle beast’s mouth unless you have its head firmly held in a good solid headbail. Moving heads are dangerous missiles.
• Even then, you’ll need a fair bit of brute strength. Stand on the right side of the beast’s head with your back against the headbail and your feet (wearing good safety boots) firmly planted.
• Put your left arm around the beast’s muzzle and pull it over towards you.
• Use your left thumb to pull down the beast’s lower lip to expose the teeth, making sure your finger doesn’t catch the edge of the teeth as they are very sharp and may make a nice cut.
• You can’t see a beast’s front teeth with its head down so heave the cow’s head up to make inspection easier. She won’t like this much.
• The best idea is to get someone else to do all the physical holding and you just pull the lip down and inspect the teeth from the front.
• The beast won’t put up with this indignity for long so make it short and sharp.
• If you have strong fingers you can insert a couple of fingers in one nostril and your thumb in the other to hold the beast and then pull its head up. You have to nip fairly hard to hang on as the mucous from the nostrils makes things rather slippery. The beast does not like this either.
• You can also use nose grip pliers with a short rope attached to do this. No beast likes this so expect a battle with the risk that it’s shaking head may hit you – and it’s hard!

Teeth eruption
This is what the text book says about the age of teeth eruption although in practice there is enormous variation around these ages:

• A calf is born with 8 temporary milk incisors in the bottom jaw. These teeth grow in size and last until the animal is yearling, as in the teeth below.
  

• At 22-34 months – 2 permanent incisors erupt.
• At 27-40 months – 4 permanent incisors erupt.

• At 33-42 months – 6 permanent incisors erupt.
• At 40+months – 8 permanent incisors (full mouth).
  
• Above this you can’t tell.
  

Complete set of teeth - but what age is she?

You don't mouth cattle!
Nobody buying cattle ever looks in their mouths like sheep farmer do – for obvious reasons. If they did they’d get some surprises as some of the defects you find make it very difficult for a beast to harvest grass efficiently and some defects must even be painful:

• Some old cows have worn all their teeth right off by the gum. Biting herbage contaminated by coarse soil like pumice makes teeth wear worse.

• Some cows will have 2 or 4 middle teeth permanently missing.

• Some will have grass packed in the enlarged gaps between teeth making them sore, wearing them away and loosening them.
• Where teeth are changing the beast may have both the old and new tooth still present in the same cavity and the gum looking very red and sore.

• Some undershot teeth will have made big depressions in the top dental pad.
• Some teeth are overshot and miss the dental pad making biting difficult or impossible.
• There is a toothless gap in a cow’s mouth just behind where the front teeth end and before the back teeth (molars) start.
  
• You can safely feel for this gap and insert your fingers. Then with an upward action pull the cow’s head up and open her mouth. You can grab a bit of her lip too when you get experienced and that encourages her to open her mouth.
• This is the technique used to open a cow’s mouth when drenching or if you don’t open her mouth, it’s the spot you insert the spout of the drench gun.
• But don’t try this until some experienced person has shown you the spot and you’ve had a bit of practice, because if your fingers slip back into the back molars and the cow’s mouth closes, your fingers will be guillotined off- and you won’t find them to take to the hospital A&E department as they’ll be in the cow’s rumen and will be few days before they come through!
  

Disclaimer This material is provided in good faith for information purposes only, and the author does not accept any liability to any person for actions taken as a result of the information or advice (or the use of such information or advice) provided in these pages.

Sheep Farm Husbandry - Teeth

Sheep’s teeth, telling age by teeth, normal and abnormal mouth, teeth defects

By Dr Clive Dalton

Ageing sheep by their teeth

Sheep have no top teeth. Instead they have a hard dental pad that their bottom incisors bite against. You can estimate the age of sheep by when the front temporary milk teeth are replaced by permanent incisors. They get new ones in pairs working from the middle outwards. But be warned – it can only be an estimate as there is enormous individual variation between animals.

This is what is supposed to happen:

• Lamb - starts with 8 temporary incisor (front) milk teeth
• Hogget - the centre pair of permanent teeth start to erupt at 12 months of age.
• 2-tooth - first central pair of permanent teeth present at 12-18 months old.
• 4-tooth - second pair present at 21-24 months old.
• 6-tooth - third pair present at 30-36 months old.
• Full mouth - complete set of 8 permanent teeth present at 42-48 months old.
  

Looking in a sheep’s mouth
This is a much simpler job than with cattle but you still need to fully restrain the sheep.

• The easiest way is to sit the sheep upright in the shearing position and use both hands to open its mouth.

Inspecting a sheep's mouth. This picture shows a two-tooth with the next pair have nearly completed their eruption. The lips are being held open by just one hand

• Cup your left hand around its jaw and use your left thumb to lift its top lip and then use your thumb on the other hand to pull the bottom lip down.
• You’ll be able to see if the teeth are meeting the gum correctly and are not “undershot” or “overshot”.
• When undershot the teeth meet the gum back from the edge (called parrot mouth), and when overshot the teeth stick out beyond the gum edge and can be very sharp as they have not been worn down with biting off grass.
• If you want another view, slide your left thumb into the space behind the incisors where there is a gap before the molars start and this will open the mouth so you can see the top of the teeth.
• The sheep won’t like this, so get yourself in a good solid position for when the sheep fights your restraint.
• If you are not able to tip the sheep up, then hold it up against a fence or in the corner of a pen and pull its lips down as described above. You don’t get such a good view.
• You can also do a quick inspection (e.g. secretly in a sale yard) by just sliding you fingers along the front of the teeth to make sure the sheep has teeth, and if they fit the gum. Any that don’t feel normal you can then look at more carefully. You can do a quick udder check with your other hand at the same time!
  

Be prepared for surprises
You can often get a shock when you open a sheep’s mouth and see the state of its teeth. Teeth do an enormous amount of tearing and pulling of fibrous herbage and are subject to great mechanical stresses.

Here are some things regularly seen:

• Overshot and undershot jaws as mentioned above. The overshot teeth may be only partly overshot where the back half contacts the gum and the front half has a lance-like edge that can lacerate your fingers. Sheep with undershot parrot-mouths have great difficulty in eating short pasture.

Undershot jaw in lamb- incisors meet well back from gum

• Gum cavities that still have both the old tooth present and the new one pushing it out, and the gum looking very inflamed.
• Missing permanent teeth – especially the central pair which are critical for grazing.
• Very long wobbly teeth that are loose in the gum. This may be “periodontal disease” which has many causes and there’s not much you can do about it.
• Most permanent teeth missing and only an odd single very long loose tooth left. It’s better to pull this out to even up the sheep’s bite.
• No permanent teeth at all – the sheep is described as being “broken mouthed” or called a “gummy”. They have all worn off by the gum. In pumice country this can be a special problem with the very abrasive nature of the soil.
• If all the teeth are worn right down to the gum but are still there, it’s very difficult to age the sheep as you cannot tell which stumps are temporary and which are permanent teeth.
• Long permanent teeth where grass has been getting in between them and wearing away great holes.
  

Sheep with no teeth can still manage to eat if there is plenty of pasture available, as the front teeth only bite off the grass and the back incisors do the grinding. When sheep are fed root crops like turnips, they really need good teeth to break the skin of the bulb and eat it down to ground level once the leafy top has been eaten.

Many breeders have shown that the solution to teeth problems is through an effective selection and culling programme.

Disclaimer
This material is provided in good faith for information purposes only, and the author does not accept any liability to any person for actions taken as a result of the information or advice (or the use of such information or advice) provided in these pages.