Technical Terms for Animal Nutrition PDF

TECHNICAL TERMS In the Textbooks of Animal Nutrition, we will meet some of the technical terms and definitions which are important for the proper understanding of the subject and in the discussion of the practical animal feeding and feeds.  Nutrition: It's the sum of all processes by which an...

TECHNICAL TERMS In the Textbooks of Animal Nutrition, we will meet some of the technical terms and definitions which are important for the proper understanding of the subject and in the discussion of the practical animal feeding and feeds.  Nutrition: It's the sum of all processes by which an animal or plant utilizes a food substance. 1- Nutrient:  It's a term applied to any feed constituent or a group of feed constituents which have the same general chemical composition that supports the life.  It's the unit structure of a feedstuff that supports the life.  It's the simplest feed constituent of a feedstuff that supports the life.  Nutrients such as: carbohydrates, lipids, proteins, water, vitamins and minerals. Also air and water might be so termed. A- Macronutrients Nutrients: required in high dietary amount (Kg or %). Those that make up the greatest fraction of foods are carbohydrates, lipids and proteins and are called the macronutrients. B- Micronutrients Nutrients: required in low dietary concentrations (ng, _g or mg kg_1). Nutrients that fall into this category are vitamins and minerals. 2- Digestible Nutrient (DN):  It's the portion of a nutrient which is digested and absorbed in the body. 10   It's the portion of a nutrient which is not excreted in the faeces and assumed to be absorbed by the animal.  The term is generally applied to proteins, carbohydrates and fats, and it is commonly expressed in terms of dry matter and as a percentage of the nutrient content.  Digestible nutrient = Nutrient intake – Nutrient excreted. 3- Digestion coefficient (DC):  It's the percentage of each nutrient which is digested in a feeding stuff or in a ration.  Digestion coefficient = Digestible nutrient X 100 Nutrient intake Example: If an animal given 50 g protein and excrete 5 g in the fecal matter. Calculate the digestion coefficient. 4- The Total Digestible Nutrients (TDN):  It's the sum of the percentages of digestible organic nutrients.  It's the sum of the percentages of digestible carbohydrates (crude fibre + nitrogen-free extract), digestible proteins and digestible fat X 2.25.  Digestible fat being multiplied by 2.25 because its energy value for animals equals to 2.25 times as that of proteins and carbohydrates.  TDN = D.CP + D.CHO + D.Fat X 2.25  Although TDN represents the approximate energy value of the feed, the digestible protein is included in this total, due to excess protein used for energy production. 11  The TDN value of a feed or a ration can be determined only through a digestion trials where the feed under investigation is given to the animal in known amounts and the output of faeces measured, and by difference the digested amount of each nutrient can be determined. Example: The following data gives an example of a digestibility trial in which steers were fed 10 kg hay per day; they excrete an average of 25 kg of faeces / day. The nutrient contents in hay & faeces are Moisture CP EE CF NFE Ash Hay 1 1.5 0.2 3.0 3.6 0.7 Faeces 21.25 0.5 0.1 1.25 1.4 0.5 Amount digested - 1.0 0.1 1.75 2.2 0.2 TDN = 1.0 + 1.75 + 2.20 + 0.1 x 2.25 = 5.175 TDN % of hay in this experiment = 5.175 x 100 = 57.5 9  Cereal grains are rich in TDN. Leguminous hay and grass hay have much smaller amounts of TDN than the grains and other concentrates, and straws have especially too low values.  A few feeds, such as flax seeds, which are unusually rich in fat, supply more than 100 lbs of TDN per 100 lbs of dry feed.  The high TDN (108.3 %) for flax seeds means that 100 lbs of flax seed furnish as much heat or energy as would be supplied by 108.3 lbs of digestible starch. 5- Feeding stuff:  It's any product that when properly used in the diet has a nutritional value. 12   Natural: plant or animal products and their by-products.  Chemical: synthesized pure nutrients used as supplements to natural feeds. 6- Supplements:  They are concentrated sources of protein, some mineral elements or vitamin content.  Protein supplement: Single feeds that contain 20 % or more of protein.  Mineral and vitamin supplements: Any mineral or vitamin carriers added to the ration are normally referred to as supplements. 7- Ration:  It's the amount of feed allowed for a given animal during 24 hours. It may be fed at one time or in portions at different times during 24 hours. 8- Balanced ration:  It's the ration which meets or covers the nutrient requirements of the animal within 24 hours.  It's the ration which furnishes the proper amounts nutrients (proteins, carbohydrates, fats, mineral and vitamins) in the needed amounts which properly nourish a given animal for 24 hours. 9- Maintenance ration:  It's the minimum amount of feed which maintain and keep the animal life without gain or loss during 24 hours, it is given for idle animal or animals having no work or yielding no production. 13 10- Nutritive ratio (NR):  It's the ratio between the digestible crude protein (DCP) and the digestible carbohydrates and fats multiplied by 2.25.  It's the ratio between the digestible nitrogenous nutrients to the digestible non-nitrogenous nutrients as it serves special uses in the body.  Nutritive ratio is calculated as follows: NR = DCP : DC + (DF x 2.25) = DCP : DC + DF x 2.25 DCP DCP = 1: DCP + DF x 2.25 = 1: second factor DCP  Relationship between TDN and NR: NR = DCP: Non-nitrogenous nutrient = DCP: TDN – DCP divided on DCP = 1 : TDN _ 1 DCP  The nutritive ratio is divided into 3 groups: (1) Narrow NR: 1: 5 or less, high in protein content (LSC 1:2.4 & tankage 1: 0.5). (2) Medium NR: 1: 6 - 1: 7, middle in protein content as rice bran. (3) Wide NR: 1: 8 or more, low in protein content (Corn 1: 10.4, wheat straw 1:51 & molasses 1:58.5). 14 Example: In the Corn, DCP 7.5 %, D. Carbohydrate 67.8 % and D. fat 4.6 %. DCP DC + OF x 2.25 NR = : DCP DCP 7.5 67.8 + 4.6 x 2.25 = : 7.5 7.5 = 1:10.4  What is the meaning of NR of corn is 1: 10.4? This means that each pound of digestible protein in corn there are 10.4 lbs of digestible carbohydrate and digestible fat x 2.25. 11- Biological value (BV):  It's the proportion of the digested and absorbed protein that is not excreted in the urine (retained N relative to N intake).  Percentage of the nitrogen absorbed which is retained by the animal which can be utilized by the animal for synthesizing body tissues and compounds.  It's a direct measure of the proportion of the feed protein which can be utilized by the animal for synthesizing body tissues and compounds N intake - [fecal N + urinary N]  Apparent BV% = X 100 N intake - fecal N  N intake - (faecal N - MFN) - (urinary - N - EUN) True BV% = X 100 N intake - (faecal N - MFN) Where MFN =Metabolic faecal nitrogen, and EUN = Endogenous urinary nitrogen. 15  The following data show an example for calculation of a biological value from a nitrogen balance data for maintenance and growth of the rat.  Feed consumed daily (g) 6.00  Nitrogen in feed (%) 1.043  Daily nitrogen intake (mg) 62.60  Total nitrogen excreted daily in urine (mg) 32.80  Endogenous nitrogen excreted daily in urine (mg.) 22.00  Total nitrogen excreted daily in faeces (mg) 20.90  Metabolic faecal nitrogen excreted daily (mg) 10.70 62.6 - (20.9 - 10.7) - (32.8 - 22.0) BV% = X 100 = 79 % 62.6 - (20.9 - 10.7)  Animal proteins generally have higher biological values than plant proteins, although there are exceptions such as gelatin, which is deficient in several essential amino acids, also soybean protein has a BV which may reach that of some of the animal proteins.  This term is not one that can be recorded in tables of feed description because feed proteins don't have fixed biological values as it depend upon the level of protein intake, the species of animal and the type of product produced. 16