Nutrition affects fat-free body composition in broiler chickens.
The relationship of body composition, feed intake, and metabolic hormones for broiler breeder Animal Feed/analysis; Animals; Body Composition/physiology* . The efficiency of nutrient use for growth of individual animals is affected. ) ., Current feeding systems do not allow body composition to be Only one, SCA (), attempts to do so by providing empirical relationships between rate of. The independence of fat-free body composition from nutrition is assumed in most We studied the allometric relationships between water and ash with protein in Animal Feed; Animal Nutritional Physiological Phenomena*; Animals; Body.
Feed intake is regulated as a balance between energy intake, expenditure, and environmental losses and inputs. All the above interact. In this system, growth and efficiency of nutrient use arise from interactions between structural inherited and environmental energy and amino acid supply elements, rather than implicit mechanisms.
Several novel representations are incorporated. Rate of protein deposition behaves as if it is first order with respect to protein mass in unperturbed normal or continuously grown animals. In perturbed systems, the future trajectory of potential protein deposition is altered to target a potential protein mass which may differ from the original depending on timing and extent of deviation. Differences in feed composition alter efficiency of energy retention in ruminants through the effect of the feed on visceral mass and energy expenditure.
Through this approach, the need to invoke variation in efficiency of energy use for maintenance and growth due to differences in substrate use is not required. Both the short term variation and long term stability seen in ad libitum feed intake of individual animals arises from the time scale of the dynamics of the interactions, rather than specific causes. The work is unfiiished, and is presented in this early form to promote discussion.
Introduction Important challenges that confront applied animal scientists are: Quantitative understanding of the factors which affect efficiency either in terms of monetary or nutrient use, and improvement in achieving market goals, is a prerequisite to meeting these challenges. The efficiency of nutrient use for growth of individual animals is affected.
Ferrell, so animals with proportionately less visceral mass are more efficient, - turnover of protein and ion transport processes-lower turnover relative to mass should be associated with reduced energy expenditure Webster, ; Milligan and McBride, ; Knapp and Schrama, ; and l pattern and amount of nutrients supplied by a feed Webster, These are influenced by both genetic and environmental factors e.
Our challenge is to draw these aspects together at the individual animal level to predict growth of body components in response to feed and environmental factors in animals of diverse genotype.
This paper describes our thinking about how growth and body composition, and in turn the efficiency of individual animals, can be predicted from simple assumptions using non-linear mathematical techniques. Our thinking is not complete, and this paper should be viewed as a statement of progress rather than a definitive document.
The nature of the problem Previous growth rate usually arising from nutritional treatment affects finishing growth rate, retail meat yield, fat depth and intrainuscular fat content of beef cattle Carstens, ; Oddy et al. Low growth rate of weaned ruminants pre-finishing may be accompanied by enhanced growth during finishing, and a greater proportion of lean and less fat in the finished carcass.
On the other hand, low growth rate before weaning, or early in life may reduce subsequent growth, and increase fat deposition Carstens, ; Oddy et al. Thus, prior nutrient restriction may affect body composition either by increasing or decreasing fat content at a given weight, depending on the age of the animal at the time of feed restriction and the extent of feed restriction at that time.
The practical implication of these observations is that previous nutrition can alter subsequent body composition, but the magnitude and direction of change is dependent on the stage of growth at which alteration of nutritional input occurs. This is not predictable by our present feeding systems. There is a need for a feeding system for ruminants which predicts not only the weight gain of an animal, but also describes outputs of marketable body components and some meat quality attributes.
Immediate inputs to such a system ideally should remain much the same as in present feeding systems and represent animal genotype, gender, feed quality and amount, and some elements of the thermal and disease environment. An additional input will be some description of the nature of prior growth, both with respect to time relative to developmental pattern, and extent relative to potential for more details, see the companion paper, Ball et al.
Only one, SCAattempts to do so by providing empirical relationships between rate of gain, current and potential weight, and composition. NRC use body condition score to adjust for previous nutrition. However, it is acknowledged that this does not adequately describe potential changes in body composition. The basic premise of current feeding systems for ruminants is to use a single term for efficiency of feed for weight gain which encompasses deposition of energy in both fat and protein.
In the California net energy NE system and its derivatives NRC, variation in efficiency of feed utilisation is seen as a property of the feed which is given an estimate of feed value for maintenance and another value for growth or yet another for lactation. In both, there is no adjustment in efficiency of feed use for age, or composition of body gain.
Present systems assume the current state of the animal is the major determinant of the animal component which responds to feed intake. Accordingly they cannot satisfactorily incorporate previous nutritional effects. Although SCA and NRC attempt to account for prior nutrition, they do so by linear adjustments to intake, rather than account for the changes in body composition which emerge in response to variation in feed regime.
Inclusion of genotype, Understanding body compostion and efficiency in ruminants gender and growth promotant induced differences between animals in feeding systems are confounded within a size term used as a proxy for both mature size and hence body composition and are reflected in estimates of maintenance requirements, rather than in a description of body composition and hence as a contributor to variation in efficiency of gain.
These and other shortcomings of current ruminant feeding systems are described by Ferrell To be fair to the current feeding systems, they are limited by the realities of data collection and analysis, and the corresponding error structures which are implicit in the data, and the linear methods used for analysis. Moreover, they evolved fiom a time when feeding for liveweight and liveweight gain and milk production were the required production goals.
Product description and meat quality was less well accepted as an important attribute of output from ruminants. With the success of the products of the intensive livestock industries in the marketplace, which arose predominantly from consistency of supply of relatively cheap high quality meat products, the technical needs of the ruminant production industries have to change to compete. They operate far from equilibrium conditions.
The mathematics required for dealing with such systems is that of non-linear rather than linear systems. This requires quite a different approach to that traditionally used in development of feeding systems. With this view, we see variation in body composition as a result of interactions between internal information genotype and external inputs the dissipative system which arise from the environment, of which matter and energy nutrition are the major components.
Those variations in growth and efficiency which are essentially expressed in the open domain arise, we believe, from the dynamics of the interaction between feed energy and amino acid intake, deposition of protein and fat which give rise to changes in body composition and heat production Figure 1.
Section 1 - Module 7: Animal nutrition
Combining components of both internal and external control directly confronts the research paradigm of the experimental animal scientist.
In our experiments we generally observe states at a point in time, and not the evolution of the states through time. We experiment by attempting to hold factors other than the experimental variable constant, but in animal studies we know this is rarely true.
Although the experimental and statistical techniques available to remove unwanted influences have become increasingly sophisticated i. Non-linear models do not obey superposition rules, so extracting effects assuming additivity is questionable.
New mathematical techniques which can simultaneously consider non-linear interactions are emerging. This mathematics of nonlinear dynamic systems requires us to think differently about the biology, but at the same time offers opportunities to deal with the complex problems of animal growth and efficiency in, perhaps, a more realistic way.
We outline here an initial attempt to develop the guidelines for a non-linear dynamic system to interpret and analyse factors which influence efficiency and body composition in animals.
Although it is intended only to outline our ideas in a general sense, we have attempted to draw together the key components to illustrate the implications in the special case of compensatory gain.
The ideas presented here comprise the major components that will be integrated in a framework which uses non-linear dynamics to predict body composition and efficiency of gain of sheep and cattle. We believe that a high degree of simplification is sufficient to capture most of the observed behaviour of animal growth, body composition and efficiency. Figure 1 Schema for a minimal model describing the interactions between body protein and fat energy and hence weight and body composition and feed intake.
Note that this is not meant to represent a compartmental model. The important elements are the arrows denoting matter and energy flow and interactions, and the boxes represent both capacity for pattern emergence and mass storage.
Past representations of the problem Growth is a change in weight of the organism. It is a summation of a number of components which are developing at different rates, and which interact within themselves and externally with the environment. Current models of animal growth work from either one of two premises. Growth is either pulled through time by some notion of maturity e.
The approach which we believe has come closest to prediction of body composition and through that carcass yield is that of Keele et al. These workers have constructed a model of cattle growth and body composition based on the assumption that faster rates of growth contain more fat, and that the allometric relationship between body components holds.
Using these simple assumptions the model they have developed is able to predict the direction of changes in body composition associated with changes in growth rate, but not where the composition of the diet induces changes in body composition.
Unfortunately, it does not adequately predict where previous nutritional effects are substantial, such as seem to occur with nutrient restriction in pastoral conditions in Australia. In these circumstances, we have found that faster growth during compensatory growth is associated with higher rates of protein and water deposition, but that rate of fat deposition may not increase Oddy et al.
The nutritional inputs used in the model of Keele et al. In particular the form, and number, of the equations chosen constrains the dynamics of the system, yet there is little recognition of this mathematical impasse. The first task is to construct a minimal model that can describe the behaviour of the system. Our current attempt is shown in Figure 1. The choice of level of abstraction to represent the system as simply and as completely as possible is not arbitrary. The rigorous process of system development will both require and provide fundamental information about the constructs incorporated.
The minimal components we wish to describe are temporal development of I mass of protein in the carcass, and non-carcass viscera ; II mass of fat; and III their summation to body weight and liveweight. The units used for the model are energy MJ. The assumptions included in our simple model are: The problem we are trying to resolve is how to represent an animal, as a simplified or model system, realistically in terms of growth of the major components of the body given genetic and nutritional inputs and II heat production is a function of feed intake and protein mass of the animal; III the animal is homeothermic, i.
The key elements of our approach are to bring together relationships between feed intake and heat production through protein mass and gain in viscera viscera being a high turnover, low mass component and in the carcass low turnover, high mass.
Little et al described a method for obtaining accurate estimates of blood inorganic P concentrations, but the difficulties of interpretation of such data were noted by Gartner et al Basically, only low blood inorganic P values have any diagnostic value. Because of the problems just described, tests using bone samples have been developed to test for phosphorus deficiency in livestock.
Samples of rib bone can be obtained by simple surgery. For FSR diagnostic work, simple measurements that can be made on certain long bones at slaughter can provide results which are generally more reliable than those obtained from blood samples.
These methods have been described by Little Liver samples have been used to diagnose for copper, cobalt and vitamin A deficiencies in African livestock Tartour, ; van Niekerk, ILCA has used samples of milk to diagnose mineral deficiencies in cattle in Ethiopia.
However, since milk composition is influenced by such factors as cow age, stage of lactation and genetic potential, milk sampling tends to be unreliable. The 'let-down' problem associated with zebu cattle Module 5 also means that it is cliff cut to obtain representative samples in field studies.
Large variations in butterfat content between successive milkings of the same cow reflect this problem Lambourne et al, However, milk samples are very useful in the diagnosis of iodine deficiency Committee on Mineral Nutrition, Apart from their use in digestibility and intake studies, faecal samples have been used to diagnose for phosphorus and sodium deficiencies Little, Sodium problems are diagnosed more accurately, but with more difficulty, from saliva samples.
However, the analysis of mineral deficiencies is probably best done by feed analysis at the diagnostic phase of farming systems research. The methods described above are more applicable to specific problems requiring more sensitive analysis Little, A knowledge of the symptoms involved will provide further confirmatory evidence e. The opinions of traditional herders will also be useful in identifying mineral deficiencies particularly the need for saltas will be the movement of stock over large distances to natural sources of minerals.
Fibre analysis The crude-fibre Weende method is described in most texts on animal nutrition. The method has been widely used to determine the fibre content of feed, but it has two serious shortcomings, particularly with respect to highly fibrous feeds such as crop residues, straws etc.
Ruminants can, however, utilise some cellulose and hemicelluose though lignin is essentially indigestible. The digestibility of a feed therefore tends to be underestimated. As a result, a portion of these components is included in the nitrogen-tree extract sugars and starches and is, therefore, assumed to be highly digestible.
The digestibility of a feed therefore tends to be overestimated. Because of these shortcomings, Van Soest devised a method which separates feed dry matter into two fractions - one of high or uniform digestibility and the other of low or non-uniform digestibility. Feed samples are boiled in a neutral-detergent solution and components are separated as follows: This fraction more closely corresponds to the true fibre fraction than the estimate of the Weende crude-fibre analysis.
However, NDF is not a uniform chemical entity, its overall nutritive value is considerably influenced by the amount of lignin present. To determine this amount, the feed is treated by acid detergent, and the procedure is known as the acid-detergent fibre ADF analysis. By heating the NDF in acid detergent, the presence of tannins can also be detected. The detergent analysis and its different procedures are discussed in greater detail by Van Soest and Reed and Van Soest Because of the high costs of reagents and apparatus used in detergent analysis, developing countries have been slow to adopt the method.
ILCA's Animal Nutrition Section has recently developed a low-cost micro-fibre apparatus which uses one tenth of the amount of reagent used in conventional detergent analysis experiments. Feed sampling for laboratory analysis The types of feed usually sampled for laboratory analysis are crop residues and hays, grains and fresh forage or silage.
Crop residues and hays. Most African farmers store crop residues and hays in stacks, and the nutritive value of the feed tends to be highly variable both within and between stacks. This increases sampling requirements and complicates the procedures involved. Because of the variability in the nutritive value of crop residues and hay commonly encountered, it is useful to make a visual estimate of the variation in a selected stack before sampling begins, and to interview the farmer about the time of harvesting, the methods of stacking used and the composition of the stack i.
Sampling may be done with a coring device or by hand. Samples should always be taken from a cross-section of each chosen stack. When large stacks are encountered, dismantling may be necessary to ensure that samples from the less accessible parts are obtained.
When the coring device is used, at least 10 samples should be taken per stack. The material gathered should be properly mixed, weighed and stored in a dry place before dispatching it to the laboratory. The combined dry weight of corings taken per stack should not be less than 2 kg. The samples should be clean and stored in a porous paper or a piece of cloth to avoid moisture contamination.
Relevant information date, feed type, sample weight, identification should be recorded in duplicate. When samples are taken by hand, several visits are normally required to ensure that the nutritive value of the stack is properly assessed. At each visit, grab samples should be taken from the face of the stack and mixed. They should be taken at every an, as the farmer makes use of the stack. If the farmer finishes one stack and starts another, or alternates between different stacks, new samples should be taken following the same procedure.
Although hand-sampling is tedious, changes in feed quality over time e. With coring, several return trips would be required if specific information on quality change over time was needed. Grain samples are usually taken with a grain probe. Between cores should be taken at random from the storage bin. The samples should then be mixed and separated into subsamples of about g.
Each sub-sample should be placed in a porous paper or cloth sack and properly labelled before dispatch or storage.
These are usually fresh forage or silage. If it is not possible to weigh the sample when it is taken, one half should be placed in a sealed plastic bag to retain moisture and then weighed after returning from the field. This fresh weight is needed to calculate dry-matter content after drying.
Understanding body composition and efficiency in ruminants : a non-linear approach.
The other half of the sample should be kept in a porous paper or cloth sack for other analyses than dry-matter content. In the event that samples cannot be transported to the laboratory the same day, they should be dried either by hanging under cover or by spreading them out on paper in a dry and protected place.
Alternatively, samples can be hung in sacks above the coil of a kerosene refrigerator. If drying is delayed, samples should be kept in plastic bags out of direct sunlight to avoid spoilage, or they should be stored frozen. Cored samples should be taken from the pit using the procedure outlined above for stacked hay and crop residues.
If sampling is done by hand, about 20 grab samples should be taken from the freshly cut face and mixed thoroughly. A subsample of 2 kg is required for analysis. The procedure should be repeated every third or fourth face cut to account for within-pit variability. If oven-drying is not possible, one of the drying methods given for fresh forage will suffice.Feeding ALL Of My Pets! 40+ Animals
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