Aquatic Animal Nutrition FAS 2240C Lecture 1: Introduction

1. Aquatic Animal NutritionFAS 2240CLecture 1: Introduction

2. Course Syllabus Study of aquatic animal nutrition: • bioenergetics • digestion/digestive anatomy/metabolism • nutrient classes/sources/requirements • formulation/feedstuffs • manufacturing processes • practical pond feed management

3. Syllabus • Animals covered: variety of finfish and crustacean species • textbook: none are current or adequate • also, various reprints of peer review journal articles • on reserve: • De Silva, S.S., and T.A. Anderson, 1995. Fish nutrition in aquaculture • Lovell, T., 1989. Nutrition and feeding of fish • D’Abramo, Conklin and Akiyama, 1992. Crustacean Nutrition • Halver, J., 1988. Fish Nutrition • Maynard and Loosli, 1969. Animal Nutrition

4. Today’s Lecture: 8/25/05 • Part 1: Introduction (Maynard et al.; Lovell) • What is nutrition??? • History of nutrition • Nutrition today • Nutrient essentiality • Part 2: The animal body and its food (Maynard, et al.; Lovell) • Aquatics vs. terrestrials

5. What is Nutrition? • Nutrition: the provision of all indispensable nutrients in adequate amounts to insure proper growth and maintenance of body functions • involves various chemical reactions and physiological transformations which convert foods into body tissues and activities • involves ingestion, digestion and absorption of various nutrients • transport into cells • removal of unusable elements and waste products of metabolism

6. History of Nutrition I. • Lavoisier is generally credited as being the “father” of nutrition • until the first quarter of 19th Century, we thought the nutritive value of food resided only in one component • near the end of the 19th Century research started to focus primarily on the need for protein, lipids and carbohydrates • minerals were considered important, but their essentiality was unknown

7. History of Nutrition II. • Tremendous expansion in the 20th Century with the discovery of vitamins, role of amino acids, more minerals • the body is now known to need more than 40 nutrients for normal growth and maintenance • what have been the reasons for these advances??? • Human nutritional/health problems • also, basic studies of the functioning of the animal organism supplemented research

8. History of Nutrition III. • Example of historical nutritional research: • heifers fed wheat-based diets produced calves at lower rates than those fed corn diets • assumption: something toxic in wheat • analysis: nothing toxic in tissues • reality: vitamin deficiency • scientific methods for formulating feeds were inadequate • research diets eventually simplified/purified

9. History of Nutrition IV. • First vitamin discovered in 1913 • pioneer nutritional work achieved primarily through the use of animal subjects • same today, but with restrictions • rats  vitamins, amino acids, minerals • dogs  insulin, nicotinic acid • guinea pigs  prevention of scurvy • chicks  thiamin and other vitamins • bacteria  growth factors, nutrient function in metabolism • final answers must be derived from speciesstudied

10. Nutrition Today Animal nutrition today is multidisciplinary: • metabolism: physiologists, biochemists • vitamins: organic chemists • isotopes/chromatography: physicists • protein structure: molecular biochemists • breed variation: geneticists • vitamins/amino acids: microbiologists • additives/improved digestibility: food technologists

11. Issue: Overexpansion • Everyone now-a-days appears to be an expert in nutrition • infomercials, algae, diet fads • claims of superiority without scientific evidence (science vs. pseudoscience) • example: massive doses of vitamins are useless, often toxic • nutrition industry might need to become more conservative • it’s no wonder why the average consumer is puzzled!!

12. Nutrient Essentiality • essential nutrient: one that must be provided in the diet in order to insure adequate growth and maintenance, indispensable • Nutrient categories: macro and micro • macronutrients: protein, lipid, carbohydrate, etc. • micronutrients: trace metals, vitamins • important: molecular weight is not the basis, requirement level is • proteins: g/kg vitamins: µg/kg • large requirement doesn’t imply greater importance (example: B12 in some fish 0.4 µg/day)

13. Basic Nutritional Concepts • Animal nutrition is tied back to food crops and ultimately to the nutritive value of soil • strong interrelationship between human and animal nutrition • foods/feeds of both contain similar nutrients • metabolic processes are basically similar • nutritional niche of animals: animals concentrate nutrients of food crops into more nutritious and palatable forms for humans • point:animals take sources unsuitable for humans and improve their quality for us!

14. Animals as Primary Consumers • Animals produce meat, milk, etc. on land that is often unsuitable for production of food crops • problem: overall land availability vs. protein demand • fisheries flat, agriculture barely keeping up • nutrition has greatly improved production capacity, however it is not going to be enough

15. What Does it All Mean? • We already know that agriculture is barely keeping up with world food demand and... • Fisheries are being improperly managed to the point of steady state • Either we must quickly apply Iowa corn field technology to all arable land on Earth or food must be found from other sources • One possible option is aquaculture.

16. Current Challenges/Problems • For aquaculture to contribute more to the world’s food supply, production must be intensified • higher yields must be achieved in ponds • better and more predictable natural sources of nutrition (natural productivity) must be available (too unpredictable) • more crude feed materials used as supplements or • compounded feeds must provide all nutrients • retention vs. digestibility: Which is best metric?

17. Part 2: The Animal Body and Its Food From: Lovell and Maynard, et al.

18. Learning Objectives • Aquatics, compared to terrestrials, are typically better converters of nutrients into body tissue. • This does not apply in all cases to all nutrients.

19. Aquatics vs. Terrestrials: feeding issues • Aquatics are what they are: submerged in water • Guess what?? The water itself can serve as a source of nutrition (natural productivity). Examples? • Overfeeding of land animals does not necessarily imply ruining of their environment • In water, nutrients are quickly “lost” if feed is not immediately consumed • Waste is not readily observable, thus, attraction and palatability of aquatic feeds is important.

20. Aquatics vs. Terrestrials: nutrient requirements • Overall qualitative (which nutrients) requirement is generally similar between land and aquatic animals. • Energy requirements are lower for fish than most terrestrials  higher protein: energy ratio. • Marine species require some fatty acids and sterols that terrestrials don’t. • Aquatics have reduced dietary mineral requirement (environment is nutrient source) • Some fish/most crustaceans have limited ability to synthesize ascorbic acid • Shrimp cannot synthesize cholestrol.

21. Aquatics vs. Terrestrials:nutrient requirements • Nutrient requirements for one group of finfish or crustaceans can only serve as a starting point for other species • Lysine example. • Nutrient requirements will ultimately become more and more refined • Problem: apparent vs. true requirement

30. Percent Composition of Aquatics

39. For Next Time… • Quiz 2: Environmental Factors • Topic 3: Digestive Physiology, Nutrient Digestability (What happens to the food fish eat?) • Handouts, Lovell (1989).