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Learn about the essential nutrients and feeding requirements for successful broiler production, focusing on skeletal development, immune health, and meat yield potential.
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ANIMALNUTRITION &FEEDINGFEED REQUIREMENT NANUNG DANAR DONO, Ph.D. BagianNutrisidanMakananTernak, FakultasPeternakan UGM
INTRODUCTION It is quite common to process straight-run broilers at 2.5-3.2 kg while some companies are exceeding 3.6 kg live weight. Producing these heavy broilers requires adequate nutrition to promote early skeletal development, optimize live bird performance, and allow the bird to express its meat yield potential. The dietary density needed for optimum performance has increased as the amount of feed per unit gain (FCR) has decreased. This requires a balance of aminoacids, minerals, vitamins, and energy. Proper management programs such as temperature control, ventilation and lighting are also very important, as well as bird health.
For successful broiler production a chick requires good bodyweight, with excellent nutritional reserves at day old. It needs to be in excellent health with a fully functioning immune system. From this starting point, providing the broiler with suitable environment and nutrition will enable optimal performance to be achieved. The developing embryo and the hatched chick are completely dependent for their growth and development on nutrients deposited in the egg. Consequently the physiological status of the chick at hatching is greatly influenced by the nutrition of the breeder hen.
NUTRIENT LEVELS IN BROILER BREEDER FEEDS When considering nutrient levels in breeder feeds, the nutritionist must focus on the daily supply of individual nutrients to the bird. Starting with protein, studies have shown that the protein levels fed to breeders in production can affect chick bodyweight and final broiler performance. The relationship between protein content of breeder feed and chick weight seems well defined.
Using this information, a breeder diet with an energy density of approximately 2750 Kcal/Kg should have a protein content of 15%. This optimum protein level has been supported by other work, and it is important to remember this is an optimum level, not a minimum, as excess protein can be as detrimental as insufficient protein. In particular, it has been shown that excess protein reduces fertility. When considering energy, attention must also be given to fat composition and in particular to the requirement for unsaturatedfats such as linoleic acid. This essential fatty acid is required for cellmembraneintegrity, immune competence, and embryonicdevelopment, therefore directly affecting chick quality.
The minimum protein levels listed are those that have been successfully used with synthetic lysine, methionine, and threonine to obtain optimumperformance under a wide range of field conditions. The levels of amino acids shown in all the diets are designed to promote good growth, FCR, and optimum yield. If the dietary energy levels are much different from those shown, then the amino acid levels should be adjusted accordingly to maintain similar amino add to energyratios. If the amino acid density is lowered, particularly lysine, by as much as four or five percent (0.05-0.06% total lysine), the white meat yield may drop by at least one percent with an increase in FCR.
The broiler is quite adaptable to a wide range of energy levels and within reason the bird is able to adjust feed intake accordingly. The adjustment is not perfect and the broiler tends to consume less energy on the lower energy diets. The optimum protein : energylevel in broiler are approximately 1 : 150 It is important to build a good skeletal "foundation" early to support the heavy muscle development in the yield-type broilers. The recommended levels of calcium (Ca) and phosphorus (P) are shown above. Lower levels, especially in the starter and grower diets, have been associated with higher incidences of leg problems which often occur after 3-4 weeks of age. The available Ca : P levels in the diet should be 2 : 1.
HUNGER – SATISFIED REGULATION Mechanism in ‘Starting Feed’ and ‘Stopping Feed’ is controlled by following factors: • Crop Condition : • When the crop is empty, the broiler will feel hungry, and he will start to consuming diet. • At the opposite, when the crop is full of diet, he will stop consuming the diet spontaneously. • Blood Condition : • When the glucose level in the blood is decrease under minimum level, the broiler will feel hungry, and he will start to consuming diet. • At the opposite, when he consume diet, the glucose level will raise up. When the glucose level is reach maximum level, he will stop consuming the diet.
FUNCTIONS OF WATER • Poultry producers need water for many thing, such as : • to drink birds, • to reduce air temperature (includes evaporative cooling pad and fogging systems), and • to clean and sanitize the facility. Broilers consume approximately 1.6 to 2.0 times as much water on a weight basis as feed. Water is a critical nutrient in bird metabolism and nutrition. From a physiology perspective, water consumed by the bird is used for nutrienttransportation, enzymatic, and chemicalreactions in the body, bodytemperature regulation, and lubrication of joints and organs.
There is a strong relationship between feed and water consumption, so water can be used to monitor flock performance. Many of the electronic controllers in poultry houses have the ability to monitor daily water consumption. A potential problem may exist if there is a sudden change in water intake. Bird uniformity between the front and back of the house can be monitored using water consumption. Water consumption will be greater in the area of the house that has more birds. When birds are not distributed evenly between the front and back of the house, increased competition for feed and water space and can reduce bird performance.
Bird Age • Water consumption increases with age but decreases as a percentage of bodyweight. FACTORS AFFECTING WATER CONSUMPTION Several factors affect water consumption: • Bird Age • Environmental Temperature / Heat Stress • Water Temperature • The Use of Electrolyte
Environmental Temperature/Heat Stress: • Birds consume more water as temperature increases. One of the main ways birds regulate body temperature is to removeheat from the body by evaporating water through the respiratory system during panting. As birds pant, water is lost and needs to be replaced in order to maintain body water balance. • Water consumption can double and even triple during periods of heatstress. Water consumption in broilers increases approximately 7 percent for each degree Fahrenheit increase in temperature. • A study at the University of Georgia examined : • As temperatures increased, the water consumed per pound of feed consumed also increased.
Water Temperature: • Several studies have examined the effects of providing cool water to birds during hot weather. In most of these studies, water temperature has improved the performance of broilers and layers. • Any water temperature below the body temperature of the bird will be beneficial. The water consumed will help dissipate body heat temperature. In commercial operations, however, air speed is the most effective way to keep birds cool.
Electrolytes: • During periods of potential heat stress, many producers supplement drinking water with electrolytes. Electrolytes are certain minerals that can be found in the blood and are important for normal cell function and growth. • Electrolytes, as the name implies, help regulatenerve and musclefunction by conducting electrical signals from nerves to muscles. • Electrolytes are also important for the acid-base balance of the blood and fluid retention. Some of the electrolytes found in blood plasma include : sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), chlorine (Cl), bicarbonate (HCO3) and sulfate (SO4). The addition of the electrolytes not only replenishes those depleted during heatstress, it also stimulates water consumption. When the results of these are added together (electrolytes and increased water consumption), the mortality due to heat stress canbereduced.
In broiler chickens, it may not be possible to increase feed intake as broilers have reached the upper limit of their capacity. Optimization of feed quality will only be effective during the growth phases. Therefore, a good management of feeding practice is needed to support broilers’ fast growth.
FACTORS AFFECTING FEED INTAKE Numerous factors to influence birds’ feed intake: Feed quality 9. Stress Feed form 10. Prior ingredients exposure Feed flavor 11. Energy density of the diets Age and body size 12. Diet phase transition Ambient temperature 13. Palatability Lighting regimen (intensity) 14. Water quality Stocking density 15. Hygiene Physiological state 16. etc. In broiler chickens, it may not be possible to increase feed intake as broilers have reached the upper limit of their capacity.
FEED QUALITY Some aspects in feed quality that influence birds’ feed intake: Feed with low level of protein will be needed more. Feed with low content of energy will be required less. Feed with low content of water will be consumed more. Some feed ingredients such as raw soybeans contain a number of unknown factors (anti-nutritional factors) which inhibit pancreatic trypsin activity and inhibit digestion of the dietary proteins. Therefore, chickens fed raw soybeans often exhibit low intake and reduced feed efficiency. In one study, average feed intake by broiler chickens has been reduced from 2,955 to 2,400 grams, and feed efficiency from 1.97 to 2.45 when raw soybeans have been used as a sole source of protein in the diet in place of heated soybeans over the first six weeks of age
FEED PHYSICAL FORM PELLETING feeds usually results in increased density and intake of the ration, and also improves growth and feed efficiency (as compared to those of ground rations). These particular comparisons were conducted on the same breed of chickens under similar management conditions. The differences in feed conversion observed within the pelleting treatment could have been linked with differences in pellet quality. It has been estimated that 0.01 in feed conversion is lost with each 10% increase in ‘fines’ in pelleted feeds. On the other hands, through pelletizing, the birds can not choose the ingredients. Therefore, the positive thing is, ‘unpleasant’ materials will still be consumed by the birds.
FEED FLAVOR Certain natural feedstuffs are relatively unsuitable for chickens because they are not palatable. For example, chickens tend to avoid diets high in barley, rye, or oat in comparison with similar diets containing yellow corn. They also tend to avoid diets containing unusual ingredients such as single-cell proteins, fruit processing wastes, marine flora, etc. in comparison with respective diets providing the basic nutrients from natural feed materials. Even with natural feeds known to be highly palatable, there may still be spoilage factors that adversely affect palatability due to rancidity of fats, moulding of sugars and putrefaction of proteins, particularly when the feed is used after a long storage period. Deterioration of these important nutrients will produce flavours and odours that are not acceptable by the birds, representing a key factor in poor feed performance.
AGE & BODY SIZE The amount of food a chicken or turkey requires changes with age. In general, young birds require food for growth and mature birds require food to maintain their adult weight. Poultry of all ages require the energy from food to keep their immune system functional and adults require energy to reproduce. Adult chickens or turkeys that are kept for commercial purposes require diets that have been specially designed to produce either additional body weight or larger and more eggs.
AMBIENT TEMPERATURE Probably the most important non-dietary factor influencing feed conversion is the ambient temperature of the poultry house. Chickens are homeotherms (warm-blooded) meaning they maintain a relatively constant body temperature regardless of the environmental temperature. Broilers perform best when there is minimal variation in house temperature over a 24 hour period of time. In a cool environment, broilers will eat more feed but many of the calories they obtain from this feed will be used to sustain normal body temperature. When the calories are used for warmth, they are not converted to meat.
AMBIENT TEMPERATURE Optimum temperatures allow the broilers to convert nutrients into growth rather than using the calories for temperature regulation. The ideal environmental temperatures for promoting feed conversion will be provided by your service personnel. At high environmental temperatures, broilers consume less feed, and convert this feed less efficiently. The biological cooling mechanisms that birds use during hot weather (panting, etc.) require energy, just as the warming mechanisms do during cool weather.
AMBIENT TEMPERATURE The efficiency of feed utilisation for gain is reduced under heat stress. It has been reported that body weight gain from 4-8 weeks of age was 1,225 grams at 21ºC, and was reduced linearly to only 1,087 grams at 26ºC. Such a problem comes not so much from temporary exposure to heat as from continuous exposure, as the chickens will have no opportunity to move to more comfortable temperatures. Heat stress does not only affect feed intake and utilisation, but also has negative impacts on the carcass quality. This is due primarily to the unfavourable partitioning of ME consumed, with the greater part of it being deposited as fat and the lesser part as protein.
LIGHTING REGIMEN A maximum performance can be attained when an excellent lighting program is given to the birds. Improper lighting management affects several things that connected with poultry production. Instead of optimizing the potential genetics, incorrect lighting program interrupts body-immune and reproductive system. Peak performance will be achieved when 17-20 hours daylight per day. Maximum feed intake might be reached when 20 hours of daylight is utilized. Transition from a 23:1 (light:dark) or 24:0 (light:dark) has different consequence on feed intake as to when during the first week the transition happened and whether a sudden or gradual reduction in daylight length happened..
LIGHTING REGIMEN The colour of lighting also affects feed utilisation and growth performance. Generally, birds prefer to consume feed under WHITE light because it helps them identify texture differences they cannot see under different colours. In some cases, however, poultry producers may be prompted to use other light colours in order to alleviate a variety of production problems. RED light, for example, may be used for control of cannibalism, because birds cannot see the blood stimulant under red light. In other cases, BLUE or GREEN lights may be used to keep birds calm by reducing hypothalamic gonadotropin production, and hence alleviate much of the losses caused by hyperactivity.
STOCKING DENSITY • Feed intake and efficiency in broiler chickens were adversely affected by high stocking rate (30-40 kg/m2) compared to moderate stocking (24 kg/m2), even under conditions of sufficient feeder space. • The effect of stocking rate and feed utilisation could be attributed mainly to: • the restricted access to the feed, • increased heat stress, • increased ammonia level, and • occurrence of pathologies. • Much of these effects could, however, be alleviated with proper ventilation and other management and feeding practices.
PHYSIOLOGICAL STATE Energy that is required for growth is used to fight infection and other disease conditions in poultry and ill birds therefore do not grow optimally. Those strains of poultry which are kept for eggs production, do not supply eggs of the required size or quantity, if they are in poor condition. Poultry must be fed a nutritionally balanced diet to ensure optimal health and the diet of birds which have become ill, must be amended to assist the bird to recover its health. In some cases, ill poultry may need to be tube fed to ensure that they receive the correct daily food intake.
STRESS Heat stress is one of the most important environmental stressors challenging poultry production worldwide. The detrimental effects of heat stress on broilers and laying hens range from reduced growth and egg production to decreased poultry and egg quality and safety. This imbalance may be caused by variations of a combination of environmental factors (e.g., sunlight, thermal irradiation, and air temperature, humidity and movement), and characteristics of the animal (e.g., species, metabolism rate, and thermoregulatory mechanisms).
FEED PALATABILITY In a study using whole or grain barley, wheat, milet, or rice, feed intake was not affected by the grain source. However, chickens (6-8 weeks of age) consumed much more whole grain than ground grain. The percentage of whole grain in left-over diets was much less than in the original diets, indicating that finishing broiler chickens prefer whole grain. Feed palatability is also affect behaviour of the birds. When offered pellet or mash feed, broiler chickens on mash spent more time eating than those of pelleted feed. It seems that pelleted feed was converted more efficiently than mash, mainly because the digestibility of feed was improved by pelleting. The chicks spent time on feed intake and therefore expended less energy.
