Flashcards in 4b Nutrient Requirements of Horses 1 Deck (45):
What is the definition of a mature horse?
- considered mature at 86% of body weight (36 months)
- dependent on breed/use (2-6)
What are 4 factors that influence the energy requirements of horses?
- Activity level
Define maintenance energy requirement (MER)
- amount of dietary energy needed to prevent change in total energy contained in the body of a horse
- does not include energy needed to support additional activity (gestation, lactation, growth, performance)
How is MER established in mature horses?
- metabolic body weight (surface area vs body weight)
Explain the need for metabolic body weight.
- not all tissues require energy to be maintained
- MBW ensures that these tissues are not accounted for
Which 3 parts of daily heat production form together the heat increment?
- heat of product formation
- heat of digestion and absorption
- heat of waste formation and excretion
- heat of fermentation
Why does gut size matter in heat production?
- in animals that ferment a lot of feed, cells proliferate much more and gut is bigger and heavier
How can body condition score affect requirements?
- low muscle tissue = low energy requirement
What is the average DEm of horses?
Do you think the minimum maintenance requirement calculated is high, low or correct?
- low because animals were confined
What were the calculated average and elevated energy requirements?
- average 10% increase
- elevated 20% increase
What are the 5 climatic variables that have effects on energy?
- ambient temperature
- wind velocity
- global solar radiation
- relative humidity
(horses must maintain constant core body temperature)
What effects can extreme cold cause?
- increased eating
- increased hair coat
- decreased rectal temperature
- decreased respiratory rate
What effects can extreme heat cause?
- increased sweating rate
- increased respiratory rate
- decreased feel intake
- increased water intake
What is a thermoneutral zone?
- when metabolic heat production does not need to increase to maintain thermostability
What is the general lower and upper critical temperature?
How much should DE intake increase for each degree below LCT?
How can feed management help animals cope with hot or cold temperatures?
feeding a more forage based diet in winter increases fermentation which helps them maintain heat
What is the total body water in adult horses?
- water balance achieved if water loss = water intake
How long can water restriction be tolerated?
- extended periods but more so tolerated with lack of feed as well
What are the 4 main types of water loss?
- fecal losses (3-3.8L/100kg)
- urinary losses (0.5L/100kg)
- respiratory losses (0.8-2.1L)
- cutaneous losses (1.7-3.3L/100kg)
Why is there more water loss with hay diets
- hay higher in soluble fibre so more water in poop
What are the 3 main types of water intake?
- drinking (5-9.6L/100kg)
- food (hay less moisture than pasture)
- metabolic water (0.68L/100kg)
What is the main determinant of total water intake?
- body weight
What is the only amino acid requirement that has been established in horses?
Why can you feed ruminants non protein nitrogen but not horses?
- horse cannot absorb amino acids after small intestine
Protein digestibility is correlated to ______
dietary CP content
How do you calculate the lysine requirement?
lysine (g/d) = CP requirement x 4/3%
What is an ideal protein?
- 100% biological value
- ability for a specific dietary protein to supply amino acids in the relative amounts required for protein synthesis by body tissues
How can the ideal protein be estimated in horses?
- by using muscle tissue
- use these ratios to estimate requirements for EAA
What are the effects of protein deficiency?
- weight loss in adult horses
- fetal loss in pregnant mares
- decrease milk production in lactating mares
- loss of muscle in exercising horses
What are the effects of protein excess?
- increases urea which is excreted in urine
- increases water loss
- increases water requirements
- decrease growth in younger horses
- increases Ca and P loss in weanling horses
What are some examples of carb containing feeds?
- grain by products
Do all carbs contain the same amount of gross energy?
- yes, but different digestible, metabolizable and net energies
What fractions are currently used?
- NDF neutral detergent fibre (cellulose, hemi cellulose nd lignin)
- NFC non-fibre carbohydrates (mono, di, oligosaccharides and starch)
What is the new proposed system of fractions?
- hydrolyzable CHO
- rapidly fermented
- slowly fermented
Cecal VFA production can meet up to what percentage of MER?
What are fats used for in the diet?
- improve energetic efficiency
- enhance body condition
- diminish excitability
- help increase fat oxidation
- facilitate absorption of ADEK vitamins
What are the 2 essential fatty acids and what are their requirements?
- linoleic acid
- alpha-linolenic acid
- no requirements
Do added fats have increased or decreased fat digestibility?
What is calcium important for and what is the requirement?
0.04g Ca/kg BW per day
- muscle contraction, cell membranes, enzymes, blood homeostasis
What is phosphorous important for and what is the requirement?
0.28g/kg BW per day
- important for energy reactions and synthesis of nucleic acids
What is the Ca:P ratio?
What are potassium and sodium requirements, and how are they met?
25g K/day 10g Na/day
- salt block and forages