Animal Nutrition Training Manual Atnesa
Animal nutrition training manual. Dr. Alimuddin Naseri National Animal Husbandry Advisor AKF Kabul - Afghanistan Mobile: +93 (0)79 211 047 Animal nutrition, with emphasis on dairy cows.
Submitted by Alimuddin Naseri, Afghanistan: Page 1 CHAPTER 1 COMPOSITION AND FUNCTION OF FEEDSTUFFS Introduction: the Animal and its Food Food consists of water and Dry Matter (DM). If the water content in food is 75%, the DM content is 25%. Although water is very important, the DM is crucial to the composition of a ration. More food is needed when it contains more water.
The main components of a foods are: Water Food Dry Matter (DM) True Proteins Organic Matter (OM) Vit. B,C Inorganic Matter (IOM) minerals/ash N Compounds (CP) Undesirable Substances N Free compounds Energy Non Proteins (NPN) Degradable Lipids (EE) + Vit. A,D,E,K Carbohydrate Degradable Undegradable SugarsStarches (NFE) Cellulose Lignin (CF) Major Elements (Na,Ca,P,CL,K,S,Mg) Undesirable substances Trace Elements (I,Mn,F,Co,B,Zn,Fe,Cu,M) 1.1 Water Water is vital to any animal. The bodies of young animals may consist up to 80% of their live weight.
Older, and especially fat animals, have less water in their bodies (down to 50%). Feeds can contain both high and low water percentages. Examples of feeds with high water contents are young grass (± 15% DM) and cabbage (7) may be caused by urea toxicity (alkalosis) and possibly be followed by death. Note: monogastrics have a stomach pH 2. Rumen Fermentation Rumen fermentation consists of two processes: Animal nutrition, with emphasis on dairy cows.
Submitted by Alimuddin Naseri, Afghanistan: Page 12 A. Microbial degradation of food components, mainly carbohydrates and proteins. Food enters the rumen partly in a degradable form, and partly in an undegradable form. If the undegradable food particles are sufficiently reduced in size, the particles move to the abomasum and small intestines for digestion and absorption.
Synthesis of organic macromolecules into microbial biomass, mainly proteins, nucleic acids and lipids. (Tropical) forages in a late stage of maturity (hay, straw) usually have a high fibre contents and can be highly lignified and usually have a low protein contents. Utilization of energy from such roughage increases heat production, lowering the feed intake, which was probably already low due to the slow rates of degradation and slow rate of passage of food (full stomach, thus feeling less hungry). 2.1.3 Abomasum and Small Intestines In the abomasum and small intestines the 'normal' chemical digestion (enzymes) takes place of the food as in monogastric animals. This digestion does not affect the management of ruminant nutrition and is consequently not further discussed in this paper. 2.2 Digestion of Food Components in Rumen 2.2.1 Fermentation of Carbohydrates All carbohydrates entering the rumen are 'attacked' by RMO's, except lignin. Generally, 90% of the carbohydrates are broken-down (degraded, fermented, digested) into three types of Volatile Fatty Acids (VFA's).
In a ration with mainly roughage, VFA's are normally proportioned as follows: - Acetic acid (acetate) Propionic acid (propionate) Butyric acid (butyrate) 65-70% 20-25% 10% Also carbondioxide (CO2) and methane (CH4) are released in the process. Quite some body heat is produced from energy required to break-down carbohydrates.
Poorer quality roughage require more time and energy from RMO's. This slows down digestion of roughage and increases body heat production. Ensuing, this leads to a lower food intake due to lower turnover rates (passage rates of food in the rumen). Increase in heat production by the body may also depress appetite, especially in warm climates/seasons and/or during hotter parts of the day. The production of body heat and gas is at its peak immediately after a meal.
Gas production can reach over 30 litres of gas per hour. Regular feeding or continuous access to food will reduce the gas- and heat production peaks, while night feeding of roughage will increase appetite (DMI). The latter should especially be considered for the warmer climates and seasons. Animal nutrition, with emphasis on dairy cows. Submitted by Alimuddin Naseri, Afghanistan: Page 13 The amount of VFA's produced can be as high as 4 kg/cow/day. Most of the acids are directly absorbed into the bloodstream through the walls of the pre-stomachs (mainly rumen).
Some VFA's enter into the abomasum and small intestines and some VFA's are used by the RMO's for the development of their own microbial tissues. In rations with substantial amounts of roughage, acetic acid will exceed the amount of propionic acid. Acetic acid is formed mainly from cellulose and has a very positive effect on the butterfat contents of milk. A sufficient amount of cellulose (fibre) in a ration is also essential for a proper functioning of the rumen and to keep the desired optimum range of the rumen pH level between 6-7. However, propionic acid production may exceed acetic acid production in diets containing high levels (over 70% of the total ration DM) of energy rich concentrates. Starches and sugars are very quickly fermented into propionic acid. This results in lowering the rumen pH level.
Also less saliva will be produced and consequently less base-minerals, with an acid buffering capacity, will enter the rumen. The consequences depend on how much the rumen pH will be lowered: - At pH 5, the appetite will decrease as the first RMO's get killed. The lower amount of acetic acid and higher amount of propionic acid will results in a lower butterfat content in the milk: the so called low butterfat-syndrome - At pH levels below 4½, the animal may suffer from acidosis. This can lead to laminitis (hoof problems) and ketosis (fat cow syndrome).
The normal RMO's in the rumen are getting destroyed, as the more acid loving lacto-bacilli (lacto-acid) will start to prevail. Symptoms indicating acidosis are: panting, distress, diarrhoea and anorexia. In prolonged cases, the rumen wall lining may be affected, destroyed and shed. At pH level below 3½, the cow may experience shock and die of toxaemia. In order to prevent the diseases and to keep the rumen functioning at an optimum, with a sufficient level of butterfat in the milk, it is advised to feed a maximum of 70% DM concentrates, and a minimum of 30% DM roughage. Note: Monogastric animals that can eat large quantities of roughage, such as horses, donkeys, rabbits and pigs to a certain extend, have bacterial protozoal fermentation of carbohydrates (fibre, cellulose etc.) in specific parts of the hindgut (intestines after the stomach), like the caecum and/or colon.
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These are generally less efficient than the rumen. 2.2.2 Digestion of Lipids/Fats (Ether Extract) Ruminants have evolved as plant-eaters and the rumen is not adapted to diets that contain a high amount of lipids/fats. The capacity of RMO's to digest lipids/fats is strictly limited. Fat/lipid contents of ruminant diets is normally low ( 2NH3 + CO2 ammonia However, one has to be careful with urea as a supplement. High amounts of ammonia in the rumen and in the blood may lead to toxicity and possibly death (urea toxicity). In practice urea is only supplemented to rations with a rather low energy and protein value (poor roughage quality).
The supplementation of urea to dairy with a high production potential is not recommended, as results have been disappointing. This training course supports management of intensive/high dairy production systems with feeding rather high amounts of concentrates. These concentrates should contain sufficient amounts of proteins to meet the need of degradable proteins.
Therefore, the subject is not further elaborated upon, as urea does not play a role in these systems. Treatment of straw with urea may offer some scope for certain production systems. 2.3 Practical Implications for Ruminant Management The rumen plays a very important and specific role in the digestion of food by dairy.
In order to exploit the high (genetic) potential of a cow to an economic maximum, a manager has to consider some important aspects in the feeding. In fact, one must know exactly how to manage and manipulate the RMO's in the rumen. The farm manager thus has to be a Rumen Management Officer. Some aspects to consider in feeding management are: A. Composition of the ration.
It is seen, that the RMO's play a very important role in the digestion of food. RMO's have to adopt themselves to certain rumen climates as created by the different types of food given to them. Changes in the diet and in the composition of the ration will disturb and/or change the rumen climate to which the RMO's have adopted themselves. Therefore such changes should be as much as possible limited and only introduced very gradually. Frequent feeding will reduce the peaks in heat-and gas production.
This peaks may result in lower food intake. For a high milk production a high food intake is essential and it is therefore advisable to allow the dairy cattle to have continuous access (24 hours per day) to food and water. During warmer seasons roughage should be offered during the cooler nights. If outside feeding is practised (in yards) during the hotter parts of the day (between 10 am and 4.30 pm) it is advised to provide shade over the feeding place and feed-trough. Shade protects animals from direct sunlight and also may create some extra natural ventilation, reducing the heat load.
Sufficient (ad lib) amounts of water should be available to support food intake. Water plays an important role in the digestion of food (saliva). Sufficient minerals P, Ca and Na have to be offered. Those are the most important minerals excreted in the saliva to regulate the pH level of the rumen (acid-buffering capacity) to create an optimum environment for the RMO's.
Animal nutrition, with emphasis on dairy cows. Submitted by Alimuddin Naseri, Afghanistan: Page 17 E. A minimum amount of (good quality) roughage has to be offered. A minimum 30% of the total DM allows the rumen to function properly. This will avoid rumen and metabolic disorders due to a lowered rumen pH and guarantees a high butterfat content in the milk. If the available roughage is ground finely or chopped less than 1 cm, arising problems may be similar to lack of fibre structure. One has to keep in mind that the rumen (ruminant) evolved in order to digest large amounts of roughage (nature!).
Poor quality roughage with low digestibility, such as straw, stover, chaff and mature stalky hay takes a longer time to be digested in the rumen and increase the heat-load in the animal (body-heat). This reduces the capacity to eat large amounts of roughage and either results in a higher demand for concentrates. This is probably more expensive, or reduces production. The total diet may not contain more than 10% fats/lipids (EE).
For the proper functioning of the RMO's, a minimum CP content of 7% is required in the diet (survival diet). The degradable part of the CP can be utilized up to a maximum level of 13% CP. Protein requirements over 13% CP (protein requirements) are to be fed as undegradable protein. The degradable proteins with a CP contents of over 13% will be excreted as urea in the urine, and therefore lost. NPN supplement (urea) for (high yielding) dairy is usually not suitable as the NPN will be quickly degraded and probably excreted (see previous point). Signs of health are: - a good appetite - a rumination of 40-50 times per bolus, and - rumen contractions of 10-12 times per 5 minutes K.
High standards of feeding are required for calves and young stock. The rumen need a good development to ensure maximum intake of DM in order to reach a high production level (a cow only converts!). Animal nutrition, with emphasis on dairy cows. Submitted by Alimuddin Naseri, Afghanistan: Page 18 CHAPTER 3 FEED EVALUATION AND EXPRESSION OF VALUE Introduction Expression of values are used to show the nutrient requirements and nutrient values in feedstuffs. The total value of a feedstuff in practical nutrition depends on the following factors: Energy content → carbohydrates, fats, proteins & digestibility Protein content → including NPN and aspects of degradability Nutrient density (digestibility) and structure value Digestibility Vitamin/mineral contents Special aspects → like keeping quality, taste, toxins, influence on milk colour/taste, availability, handling etc. Physical aspects 8.
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The expression of feed value for dairy cattle strictly speaking, however, is a measurement for energy content unit and the amount of protein, in Poland respectively in the values FUM units and gram DCP per kg (or kg DM) product. Note: Recently, the Polish system for animal nutrition has been adjusted. The so-called 'Jednostka Paszowa Produkcji Mleka' (JPM) is used for defining energy requirements and energy availabilities. JPM is based on the Nett Energy system and as such comparable with the FUM unit utilized in this course book. For more information, it is referred to the book on animal nutrition (Polish edition) 'ywienie Przeuwaczy', published by Omnitech Press - Warsaw. As mentioned in Chapter 1, the feed value (nutritive value) of food is contained in DM, the remainder of food being water.
The DM is expressed as a percentage (%) or as gram per kg of food. For instance, the DM of grass is 15% equals 150 gram DM/kg grass. DM is very important to an animal as it is used to measure hunger or appetite (the amount of food an animal can eat per day). The daily amount of DM eaten per day is called Dry Matter Intake (DMI). The total composition of the daily ration should include all nutrients required necessary for maintenance and production purposes within the quantity of DM. Throughout this paper, calculations will use expression of feed values per kg DM of a feedstuff. If one feedstuff is compared with another the same system should be applied, otherwise the results will be distorted!
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Animal nutrition, with emphasis on dairy cows. Submitted by Alimuddin Naseri, Afghanistan: Page 19 3.1 Energy Content One of the main functions of a dairy ration is to provide energy to an animal. The total energy of food coming free during combustion is called Gross Energy. Only a fraction is used for maintenance (including some milk production) and production. Utilization is reduced by losses of defecation, urination, methane gasses in the rumen and heat. The term 'energy' includes the actual physical energy an animal needs, the heat to maintain its body temperature, the energy required for production and the nutrients for laying down its own energy reserve. The constituents that provide energy are the carbohydrates, fats and possible proteins!
If there is not enough energy from carbohydrates and fats in the food to meet its daily requirements, part of the available proteins is converted into energy-use. Not all energy value fed can be utilized for production and maintenance. The portion available for maintenance and production is called Nett Energy (NE), usually expressed in Joules (KJ = 1,000 J, MJ = 1,000,000 J). Figure 3.1 shows that the energy value is most accurate with Nett Energy. This is the energy effectively used by an animal and defined for its utilization purpose. In order to compare energy values amongst different foodstuffs, it is desirable to express the energy value in one kg (or 1,000 gram) DM (of kg) of one of the foodstuffs involved. The NE system requires precise knowledge of bodyweight, quality and quantity of feedstuffs fed and eaten by the animals.
Values are expressed both on wet basis and DM basis. Care should be taken. For the purpose of calculation we use the values based on DM. In Poland, energy requirements are expressed in FUM (Feed Units Milk). per day: FUM for cows is a figure indicating the amount of barley in grams which gives as much Nett Energy for milk production as 1 kg foodstuff. See note on JPM As a rough rule A 600 kg cow producing 15 litre milk per day (4% fat) requires 11,913 FUM, for - maintenance → 5013 FUM - production of every 1 kg milk 460 FUM → 15. 460 = 6900 FUM Animal nutrition, with emphasis on dairy cows.
Submitted by Alimuddin Naseri, Afghanistan: Page 20 3.1.1 Major Energy Systems The major energy systems in practical use for dairy production are: 1.