ANSC20002 Assignment 2022

Due date: Fri 23/9/2022

Submission via LMS.

500 words max (excluding references, figures and tables).

Please answer ONE of the following questions (short answer style, not essay). As there is a low word limit the use of dot points is encouraged. Tables and figures must be appropriately introduced, referenced and have appropriate titles if used. The assignment must be appropriately referenced (minimum 2 references) using primary sources where possible (citing lecture materials is not appropriate, textbooks are acceptable) as required. Please use the Harvard or APA style for reference list formatting.

Marks are allocated per sub-question as shown. A total of 50 marks are available, and 5 marks are allocated to referencing and formatting per question.

1. It is well established that responses in milk production to incremental increases in energy intake above maintenance are not constant and there is a curve of diminishing returns. This is illustrated by the curve shown in the below diagram (Figure 1).

a. When ME intake is below maintenance requirements, what is occurring in relation to body tissues and milk production? (5 marks)

b. Metabolic bodyweight and metabolic rate determine energy requirements. Discuss and compare each of these components and briefly describe: what impacts them (think physiology), assumptions these calculations make and how these values will change as animal increase in size (20 marks)

c. When ME intake is in excess of maintenance requirements incremental increases in consumed energy do not result in continued increases in milk production (i.e. there is a maximum production level reached). List 3 factors (physiological or metabolic) that contribute to this phenomenon. (20 marks)

Figure 1. Relationship between net energy consumed above maintenance and energy secreted in milk.

2. Digestive tracts are specialised to suit the food/feed selection and dietary strategies of the animal and the animals’ ability to obtain nutrients from this diet.

a. Why is the giant panda referred to as a ‘vegetarian carnivore’? (10 marks) b. Describe one other specialist feeder species (can be from anywhere in the world, both

terrestrial and aquatic) and briefly describe the key physiology and metabolism that allows the animal to obtain nutrients from this diet. (10 marks)

c. You are a ’mad scientist’ that has found a way to breed an entirely new species of animal from scratch. Describe the basics of a digestive system (including teeth, tract type such as key stomach structure, other accessory organs where relevant, and any metabolic adjustments) for a new species that you have designed that feeds upon one of the following foods (select one only): (25 marks)

i. Meat from seals or other aquatic mammals ii. Grape plants (including fruit, leaves and stems)

iii. Sugarcane iv. Insects v. Another food/feed of your choice (be creative / strange!)

*note – there is no ‘correct’ answer to part c, be creative but use your knowledge (and some more research) on digestive physiology to make these decisions. Use dot points to justify the choices you have made.

3. Digestive physiology is determined by the food/feed selection and dietary strategies of the animal and the animals’ ability to obtain nutrients from this diet. For a species of your choice (please name them) describe:

a. The type of digestive tract, briefly describing the key organs and physiological structures (15 marks)

b. Describe the types of feed ingested and discuss how the digestive system has evolved to efficiently obtain nutrients from the available feeds (10 marks)

c. If it is a production animal, describe the influences of production systems on the animal. I.e. how is the animal fed? (10 marks)

d. Describe any limitations to the digestive system (for example can only digest a specific feed type, limited volume, inefficiency etc.) (10 marks)

4. Diet selection and feed choices are important in all animals a. What are associative effects of feeds? (10 marks) b. Define ‘post-ingestive feedback’ giving an example. (15 marks) c. While we make assumptions about feed selection based on the digestive system of

the animal, species differences within animal types also influence diet selection. Compare a grazing small ruminant animal (e.g. sheep) with a large ruminant (e.g. cow) and comment on key differences each species would make in terms of diet preferences and the physiology/anatomy underpinning such choices. (20 marks)

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