Factor affecting growth.ppt
- 1. FACTORS AFFECTING THE GROWTH AND DEVELOPMENT OF MEAT ANIMALS
- 2. Genetic Makeup/Breed • The genetic makeup of animals influences the growth in earlier embryonic life as differences exist in the rate of cell division of their embryo • The breed of animals has significant impact on different parameters of commercial importance and one main among them is degree of fatness • The fatness level in carcasses varies greatly in animals having same weight or age but different breed • e.g. sheep breed Suffolk and Southdown slaughter at same weight (20 kg) have 32.9 and 38.5% fat respectively in their carcass
- 3. • The physiological age at birth depends upon how a great part of growth is spent in uterus • The birth weight of young ones is influence by age, size and nutritional status of mother • The length of gestation period (5 months for sheep and 9 months for cattle), sex and number of young one born also have impact on the birth weight • The young mothers generally have low birth weight offspring compared to mature females and similarly the birth weight of offspring is greater from larger animal compared to smaller mothers • The recessive genes in cattle control certain growth features like dwarfism
- 4. • The responsible gene controls the longitudinal bone growth and vertebral development in lumbar region • A major gene having significant role in meat animal growth and quality of their flesh is the “Barooroola gene (F)” • The selection of animals for improved performance can be done based on the heritable characters like birth weight, growth from birth to weaning, post-weaning growth and feed conversion efficiency (Table 1.4) • The differences in requirement of essential nutrients like vitamin D and pantothenic acid by domestic animal are genetically controlled • One of the important aspects of gene variability is the determination of the endocrine control balance of growth and development
- 5. • The genetic compatibility with environment affects the apparent variation in growth • The lambs with higher rate of thyroid secretion have rapid growth compared to those with intrinsically low rate of thyroid secretion • The advances in genetics and breeding have made it possible to alter the specific features of muscles Environmental conditions • The regulation of heat in farm animals is the subject of wide economic importance • The body temperature is maintained at constant level by cattle and sheep required for optimum biological activity
- 6. • The living organism can tolerate normally an environmental temperature lying in the range of 0-40oC but some animal are habitual to extreme conditions like below freezing or above 50oC • The short periods of even more sever conditions are compatible with polar animal survival as they can tolerate - 80oC by maintaining their body temperatures • The development of animals is extended in the environment of low temperature while high temperatures retard the development of un-adapted livestock • The uniform low or high temperature has lesser impact on the metabolism of animals but variable temperatures have greater influence
- 7. • An animal can tolerate prolong exposure to heat or cold waves by hormonal changes to these two stress conditions • The animals having large bodies can better withstand the low temperature of cold environment because of low surface to volume ratio while small animals due to high surface to volume ratio can efficiently dissipate heat in warm environment • The yak among cattle has heavy and compact body with short neck and legs covered with thick long hair inhabitant to the regions of cold environment and rarefied atmosphere • The temperate regions cattle have somewhat less compact body than cold environment cattle
- 8. • The cattle of tropical regions have angular frame, long legs and neck, large dewlap to increase surface to volume ratio and have coat of short hair • Furthermore, the tropical cattle have lightly colored coat as dark coloration absorb more radiant energy • The temperate region animals will have higher body temperature than tropical animals under conditions of heat stress • The heat disposal mechanisms are less efficient in temperate region animals and they maintain their body temperature through behavioral changes like voluntary restriction of feed intake, seeking shade and inactivity
- 9. • Feed and Nutrition • The development, dominance and survival of all living organism are determined by the most important factor of finding enough foods of right kinds • The major proportion of life time of all cold blooded animals and most of warm blooded animals is spent doing nothing • They spent greater part of their life in eating when they start doing • The feed and nutrition factors affecting the growth and development of animals are plan and quality of nutrition, interspecies interaction, plant nutrition and micronutrients
- 10. • Feeding plan and nutritional quality • The feeding plan and nutritional quality of feed at any stage of animal life alter the growth of animal in general and also affect the development of different regions, tissues and organs differentially • The animal of same breed and weight will vary in form and composition if they have different feeding plans and nutrients quality • The brain and nervous system have priority over bone, muscles and fat in development order in relation to plan of nutrition • The tissues and body regions are utilized in reverse order of their maturity for energy and protein supply to body under conditions of low nutrients diets
- 11. • Fats are utilized first under these conditions followed by proteins and bones and these are first depleted from those regions latest to maturity • The high plan of nutrition lead to faster growth rate causing earlier onset of growth’s fattening phase • The fastest growing animals may become leaner by increasing the protein/energy ratios and at very high ratio the growth rate can be diminished • Male animals require diets having high protein/energy ratio than female and this requirement can causes the difference in carcass composition between two sexes fed on same protein/energy ratio diet
- 12. • The rumen microflora substantially determined the intake to ruminant tissues so they have quite different relationship with quality of diet • Ammonia derived from deamination of soluble protein entering the rumen is the major nitrogen source for microbial synthesis and activity of the micro-flora and is determined by amount of energy available to animals • The ingested protein through high protein diet may be excreted as non-incorporated ammonia • The non-protein nitrogen of low protein fed diets can be converted to proteins and ruminant may vary in their protein requirements depending upon their rumen microflora and these amino acids can be supplemented in the feed of ruminants
- 13. Plane and quality of nutrition • Differences in the plane of nutrition at any age from the late foetal stage of maturity not only alter growth generally but also affect the different regions, the different tissues and the various organs differentially • Thus animals on different planes of nutrition, even if they are of the same breed and weight, will differ greatly in form and composition • The relationship of the ruminant to the quality of the diet is different since the intake into the tissues is substantially determined by the rumen microflora Interaction with other species • In general, there are definite upper and lower limits to the size of animal which a carnivore can utilize
- 15. • The most serious effects of other animal species on domestic stock, however, arise indirectly when the rate of natural increase of small species • The rabbit, when introduced into Australia, increased at a phenomenal rate and denuded vast areas of the vegetation upon which stock had previously subsisted • Some species, of course, are beneficial to domestic stock • Ruminants largely depend on the micro-organisms in their digestive tract to break down the cellulose of plant foods • They are thus equipped to make use of poor-quality diets
- 16. Soils and plant growth • Although some animals are carnivores they are ultimately as dependent on plant life for their sustenance as the herbivores • Food represents stored energy utilizable by animals and it can be released at a rate determined by metabolic needs • The major ultimate source of energy is sunlight; and it is only in the Plant Kingdom that a mechanism exists for its conversion into a stored form • The fertility of soils depends not only on the chemical nature of the rocks from which they have been formed but also on particle size
- 17. • The latter determines how much moisture soils will hold and for how long, and the availability of its nutrients to plants • Soils and climate affect plant growth qualitatively as well as quantitatively • The grasses of low nitrogen content develop on acid soils • The nitrogen content of grasses and legumes diminishes on prolonged exposure to high temperatures • The digestibility of plants may be altered artificially • The increasing use of plant growth substances, such as gibberellic acid, which increases the internode distance in grasses, tends to lower the nitrogen content of grasses and to decrease digestibility
- 18. Trace materials in soils and pastures • It is being increasingly recognized that many animal ailments can be explained on the basis of dietary deficiencies or excesses of biologically potent materials which are present only in minute quantities in soils and pastures • A deficiency of cobalt in the soils of certain areas was the cause of various wasting and nervous diseases in cattle and sheep which had been known for many years by settlers • Animals, after grazing for several months, would lose their appetite and finally die in the midst of rich pasture • Copper deficiency inhibits the action of various amine oxidases, and, thereby, the structural integrity of elastin and collagen in connective tissues
- 19. • An excess of molybdenum in the soil is said to enhance copper deficiency in animals • An excess of selenium interferes with metabolism by displacing sulphur from the essential –SH groups of dehydrogenase enzymes • An excess of potassium, by interfering with the accumulation of sodium, alters the ionic balance of body fluids and may cause hypersensitivity to histamine • Conditions such as grass tetany and milk fever, wherein the magnesium or calcium content of blood serum is especially low
- 20. • Toxicity in stock may also arise by the excess ingestion of trace organic substances • Some pastures, may contain sufficient isoflavones or flavones of oestrogenic potency to affect the reproductive activity of grazing ewes