ANFS251 Notes Week of 03/14/16
ANFS251 Notes Week of 03/14/16 ANFS251
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This 9 page Class Notes was uploaded by Rachel Schmuckler on Friday March 18, 2016. The Class Notes belongs to ANFS251 at University of Delaware taught by Dr. Lesa Griffiths in Spring 2016. Since its upload, it has received 18 views. For similar materials see Animal Nutrition in Animal Science and Zoology at University of Delaware.
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Date Created: 03/18/16
Dietary Energy Feeding standards based on some measure of energy Additional requirements for protein/amino acids, essential fatty acids, vitamins, minerals Energy derived from the dietary organic components Carbohydrates provide the bulk of energy Low cost per unit of energy Energy Amount of heat produced when a compound is complexly oxidized in the body The loss of energy from the body Different units o Calories Amount of heat required to raise the temperature of 1 gram of water by 1C calorie (cal) Kilocalorie (kcal) = 1000cal Megacalorie (Mcal) = 1000kcal or 1000000cal o British Thermal Units (BTUs) o Joules Work: anything above maintenance that uses energy (i.e. lactation, gestation, running, growing, pulling) Gross Energy (GE): amount of heat produced when a feed is completely oxidized (burnt) Digestible Energy (DE): measure of the amount of energy apparently absorbed from a feed after it has been consumed and digested Metabolizable Energy (ME): determined by subtracting energy losses in urine and combustible gases from the DE value Net Energy (NE): determined by subtracting energy losses resulting from rumen fermentation and tissue metabolism from ME Total Digestible Nutrients (TDN) Method to estimate energy content of a feed Sums up all fractions of a feed that are digestible TDN = Digestible CP + Digestible CF = Digestible NFE (starch and sugars) + 2.25xDigestible Ether Extract (fat) Tends to overvalue roughages – not accounting for indigestible fiber Widely used because values to plug into the equation are easily accessible Factors Affecting Energy Metabolism Greatest energy loss in feces o Feces Dietary components that are not digested Diet components greatly influence the amount of feces produced o Level of feed consumption also influences digestibility Diarrhea, presence of toxins, and parasite infections reduce digestibility Monogastric diets are more digestible than herbivorous/ruminant diets Losses associated with metabolism Losses after absorption vary greatly o Level of intake o Quality of diet Fermentation Heat o Produced as a result of microbial fermentation in the GIT o As nutrients are oxidized o Referred to as heat increment Largest heat associated with metabolism of proteins/amino acids>carbs>fats o Microbes are generating heat just by living in the gut of ruminants Barrels of hay that are sitting in barns can spontaneously combust from the heat that the microbes sitting in that hay are giving off Energy requirements are affected by: o Age o Species o Activity level o Production level o Environmental conditions o Nutrient deficiencies Requirements directly related to body surface area (metabolic body weight) o Management practices influence the surface area of the animal and change the rate of heat loss i.e. factors that affect heat/cold stress Blanket on the horse to keep in metabolic heat – requires less food Comfort zone: range of temperatures in which an animal does not need to use energy to cool/heat itself o Feeds that have high feed increments are harder to digest (versus low feed increments) Straw = high feed increment o If the body is super hot, appetite decreases – produces less metabolic heat Solution: concentrate the diet to insure the animal gets the correct amount of nutrients in the small amount of food it’s eating Energy Deficiencies Wild species may go through alternating periods of energy surplus, adequacy, and deficiency o Trend follows seasonal availability of feed Free-range domestic animals may also experience fluctuations in energy surplus and adequacy o Fluctuations occur because of unregulated pastures Deficiency extremes are less severe Owners feed them supplements o Animals in confinement should not experience such extremes Periods of energy deficiency can negatively impact the animal o Fat reserves are metabolized for energy weight loss Very common in lactating animals After all the fat is metabolized, muscle starts getting broken down – malnutrition! Life Cycle Nutrition Continuous development and growth from birth of one generation to the birth of the next generation Match nutrients to true needs for current stage of life of the animal you are feeding Transitional, gradual Body weight = primary driving force Maturity, aging, maintenance + work Broken into discreet stages – each stage has nutritional priorities Neonate Growing animal Young adult Adult Reproduction Senescent (aged) Neonate Energy thermogenesis o Shivering to generate body heat o As animals grow, they gain the ability to control their body heat Brown fat = rapidly metabolizable form of fat that can be burned for energy Some born with glycogen stores that can be burned for energy Glucose = required energy source for the brain Lactose = glucose + galactose, milk sugar Suckling phase o Easily digestible and high quality nutrients (found in milk) o Requirements of energy, amino acids, vitamins, minerals per unit body mass are higher for younger or smaller animals Weaning Adaption to change in diet Wet, highly digestible drier, highly variable nutrients, poorer quality, less moisture Adaption o Enzymes – proteins! o Changes in gene regulation is a gradual process (times time) Begin feeding food before removing milk source o Nutritional stress Digestive upset, disease/inflection Diarrhea, gas, constipation, gastroenteritis Diarrhea = #1 killer of baby animals Can damage digestive tract o Psychological Stress Distrupted eating, digestion, heart rate, liver metabolism Consider process, provide system Plan weaning Feeding transition Growth Building muscle and organs o Need for protein/amino acids, energy for synthesis Muscle internal organs bone fat (adipose tissue) o The fat that gets inside the muscle (marbling) is what gives meat its juice and flavor o Where the fat is stored depends on the animal Under the skin vs in the muscle Environmental or genetic factors Growth curves and maturity o As maturity is reached Muscle growth slows Most growth is body fat Reproductive systems Nutrient requirements for maintenance o Puberty: physiological maturity Mechanisms o Hyperplasia Increase in a number of cells Those born with more fat cells or faster rates of hyperplasia early in life = more prone to obesity Genetic disorder Hyperplasia, “a” = more DNA o Hypertrophy Increases in the size of cells Does not result in obesity At birth, animals are born with a total number of muscle cells. Any growth in muscle is by increase in cell diameter, not number. Genetics to improve The smaller the mature size, the sooner they reach maturity o Toy dogs quicker than a Great Dane o True in livestock as well Adulthood and Maintenance Maintaining body weight o Slow gain slow loss degeneration (aging) o More energy needed if larger in size Feed intake per unit body weight decreases o Metabolic rate slowly decreases Counter with exercise for pets to prevent obesity Additional requirements for pregnancy, gestation, and lactation Affected by disease Turnover Needs become a function of weight o Tissues constantly recycling o Basic functions Keeping energetic processes going at the same rate Tougher for heavier animals Can be hard to notice Affected by activity, environmental temperature, disease Rate of new tissue = rate of old tissue Adult Females Breeding season – no special nutrients needed Pregnancy (gestation) o Balance and amount of nutrients critical o Metabolic system of mother adapts Provide a balanced ration early Premade rations made for livestock Recommendation to increase normal ration in small amounts for companion animals Avoid fattening during first and second trimester Last trimester Actual weight gain of fetus Increase in appetite – change in diet to supplement the weight gain of the fetus Increase nutrients Lactation o Most nutritionally demanding o Synthesis and secretion of milk o Mother has to maintain weight o Nutrients needed above can increase 2-5x above maintenance Increase intake Uses body components o Early lactation = mother’s appetite does not equal nutrient demands, decrease in weight Recovery and Rebreeding o Delay rebreeding to recover Lost body fat and protein o Feed normal ration Amount depends on need Return to estrus depends highly on nutrition o To return to estrus, they must have enough fat Too fat = lazy = loss of sex drive Adult Males Keep at maintenance No extra for breeding Aging Metabolic rate decreases o Reduced total nutrient requirements Consumed less feed or diet containing less energy Ability to digest food changes – lessened ability to adapt to diet changes o Higher digestible diet necessary Muscle protein/mineral turnover slows down o Good balance of amino acids/mineral supplements necessary Monitor animal for changes in weight o Companion animals are tougher to monitor
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