AGR2AN Prac Exam Revision
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Is vitamin C a water soluble or a fat soluble vitamin?
When foods are boiled, what happens to vitamin C in the food?
Vitamin C can leach out of food when cell walls are broken during boiling.
What happens to other water soluble vitamins in food when they are boiled?
Vitamin B can leach out and dissolve in water
Why were the feed samples in the Vitamin C prac mixed and ground with trichloroacetic acid (TCA)?
To extract the vitamin C present in the feed samples.
Why must you wear gloves and safety glasses when grinding feed samples with TCA?
It is an acid, therefore it can cause burns if contacted with bare skin
What does MSDS stand for?
Material Safety Data Sheets
When you draw a standard curve, on which axis is the concentration?
the X axis
Why is it important to provide vitamin C in fish food and guinea pig food?
Some fishes and guinea pigs cannot synthesis vitamin C in their bodies because they lack the enzyme gulonolactone oxidase. Therefore, they need a dietary source of vitamin C
Why is it not essential to include vitamin C in dog and cat food?
Because they can synthesis the enzyme gulonolactone oxidase which is essential for the concersion of L-gulonolactone to L-ascorbate.
In order of highest to lowest, list the phytate contents of the grains or seeds listed in Selle et al. 2003.
- Rice pollard 14.9g phytate-P/kg
- Canola meal 5.6g phytate-P/kg
- Soybean meal 4.1g phytate-P/kg
- Wheat 1.7g phytate-P/kg
Why is it necessary to add rock phosphate to the intermediate and high phytate diets?
To increase the available phosphorus content of the diets
Which diet in experiment 1 by Selle et al had the highest total phosphorus content?
High phytate (7.8 g/kg)
Which diet in experiment 1 by Selle et al. had the highest available phosphorus content?
Low phytate (4.7 g/kg)
What effect did the high-phytate diet unsupplemented with phytase have on the growth rates of weaner pigs when compared with the growth rates of the pigs on the low-phytate diet with or without supplementation?
Lower growth rate (330g/day compared with 392 or 387 g/day)
Did the level of phytate-P cause a statistically significant effect on growth rate of the pigs??
Did phytase supplementation to the diets cause a significant increase in growth rate?
What effect did addition of phytase to the high-phytate diet have on the growth rate of pigs?
Increased rate of growth from 330g/day to 370g/day
What reasons to Golovan et al. givefor thehigh levels of phosphorus in pigs and poultry faeces?
- Inability to monogastric animals to digest phytate (up to 80% of phosphorus in grains, oil seed and their by-products is phytate P
- Supplement of feed with bioavailable mineral P
What effects does excess phosphorus have on rivers and streams?
Eutrophication causes algal blooms oxygen depletion and food webs are disrupted causing death of dish and increase greenhouse gas production.
What reason is given by Golovan et al. for the change in the ingrediants of pig diets from mean and bone meals with more available phosphorus to plant feeds in which phosphorus is not as readily available?
Concern over spread of animal diseases
What disease of cattle can be transmitted to cattle and humans by feeding infected meat and bone meals?
Bovine spongiform encephalopathy (BSE) aka mad cow disease
Besides the addition of phytase genes into transgenic pigs, what other genetic modification could be or has been used to try to reduce environmental pollution by phosphorus from animal feeds?
Increase phytase content of feeds/plants
Why do phytates in feeds not affect the availability of phosphorus in cattle and sheep?
Because phytate is degraded by microbes in the rumen
What is the structure and chemical name of phytate?
- Myo-inositol 1,2,3,4,5,6-hexaki dihydrogen phosphate
How are metabolic rates related to body weight?
The higher the body weight the higher the metabolic rate
What is the relationship between metabolic rate per kg of body weight and size?
The smaller the animal, the higher the rate. This is because heat loss is proportional to the animal's free body surface ('free' means exposed to the environment). If the body temperature is to remain constant, as it does in homeotherms, then heat loss from the animal must be equalled by its heat production. Therefore, heat production is proportional to the animal's free body surface, which in turn is proportional to the square of the linear dimensions of the animal.
How is speed of walking of the cattle affected when walking on unploughed, course, gritty soil compared with the unploughed, dry, fine sandy soil and why does this occur?
Speed decreases 0.1m/s because hooves sink into soft sandy soil and it takes longer to lift feet (like walking on beach sand)
How is energy expended by the cattle affected when walking on unploughed, course, gritty soil compared with the unploughed, dry, fine sandy soil and why does this occur?
Energy expended increases as hooves sink into soft sandy soil (like walking on beach sand) so it takes longer to lift feet out and requires more energy.
Energy expended when walking on dry, ploughed land is almost double that when walking on dry, unploughed land but walking speed does not seem to be halved. Explain why.
More energy is expended to maintain speed as well as walk in the softer soil that has been turned over by ploughing
What effect does walking on wet sand have on walking speed and energy requirements compared to walking on dry sand?
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