Feeding and Behaviour Flashcards
What is starch?
Starch is a very available storage carbohydrate found in horse feeds and forages.
More starch = more glucose, which means more sugar.
What are the names of the horse’s ancestors?
The earliest is hyracotherium who lived about 55 million years ago
Mesohippus came next - 35 million years ago
Merychippus was after - 15 million years ago
Pliohippus - 8 million years ago
Then came the modern horse, Equus, which dates back to about 1 million years ago
What was the original diet of the horse’s earliest ancestor?
The original diet of hyracotherium was soft shoots and berries. This was because they lived in the rainforest. They were able to consume a lot of sugar and readily available carbohydrates. They were meal feeders, often found alone due to predators.
Has brachyodont teeth, in which the enamel does not extend past the tooth root. This is the same as modern day humans.
What is the significance of a changing climate on the horse?
As the earth cooled, rainforests shrunk and gave way to open grassland and the horse evolved to survive on silica rich, fibrous grass. Their teeth evolved into hypsodont teeth, with enamel covering right down to the root, which needed grinding down by continually eating fibre. They became herd animals, grazing on open grassland for up to 18 hours a day (due to the low nutritional content of grass).
Define FERAL
Feral horses are horses descended from a domestic ancestor. They are not truly wild, but not domesticated either. An example would be the TBs released and still living in the Namibian desert.
How is a feral horse’s time divided? How does this differ from a domesticated horse?
Feral horse:
60% eating, 20% standing, 10% lying down, 10% other
Domesticated horse:
15% eating, 65% standing, 15% lying down, 5% other
What is amylase? Where is it produced in the horse?
Amylase is an enzyme that breaks down starch in the small intestine. In the horse, it is produced in the pancreas
How much amylase is produced by the horse in comparison to other animals, such as a pig or a rat? What does this indicate?
Horse produces 2.3mg Pig produces 107mg Rat produces 56mg This indicates that both the pig and the rat can cope with, and are designed to, eating lots of starchy, sugar rich foods. The horse is not - fibre should be the main component of the horse's diet. REFERENCE: Lorenzo-Figueraz et al, 2007
What happens if a horse ingests a lot of starch?
If a lot of starch is consumed, the majority is dumped in the large intestine, because the small intestine cannot handle it all - this is a major cause of colic, laminitis and EMS
Define the GLYCAEMIC RESPONSE
The glycaemic response is the effect that a meal has on blood sugar levels after consumption. It will elevate the blood sugar levels, but the amount will depend on the feed. It usually occurs about 2 hours after feeding. The glucosal peak is associated with abnormal behaviour
What parts of the brain are linked to the glycaemic response?
- the amygdala
- the hippocampus
Define the AMYGDALA
The amygdala is an almond shaped set of neurons located deep in the temporal lobe. It controls fear, anxiety and aggression. It is part of the limbic system and is the fight or flight centre.
Define the HIPPOCAMPUS
The hippocampus is one of the brain’s pleasure centres. It has the opposite function to the amygdala - one of the primary neurotransmitters in the hippocampus is serotonin
How is glucose linked with hippocampul serotonin?
- as glucose reached the blood stream, huge amounts of serotonin were released from the hippocampus
- an experiment in rats, where a glass tube was inserted into the brain to test hippocampul response to glucose, shows this
- this experiment can be used as a base for evidence in horses, due to the ethical restrictions on conducting a similar experiment on horses themselves.
REFERENCE: Bequet et al, 2001
How is serotonin synthesised in the brain?
Key components are:
Tryptophan, an amino acid in the general circulation
—————————————————————
– tryptophan hydroxylase
5 - hydroxytryptophan (5HTP)
– amino acid decarboxylase
Serotonin (5-HT)
– hydroxyindole methyltransferase
Melatonin (from the pineal gland)
Draw out the diagram don’t be lazy!
What is the blood/brain barrier?
The BBB is a barrier that separates the brain from the general circulation. It only lets certain blood products into the brain. It is bathed in cerebrospinal fluid.
What is serotonin synthesised from?
It is synthesised from tryptophan, an amino acid.
