Concepts of Growth of Farm Animals PDF

CONCEPTS OF GROWTH OF FARM ANIMALS  CONTENTS I. Phases of Growth II. Growth Targets III. Changes in Proportion to Growth IV. Hormonal Influence on Growth V. Genetic Influence on Growth Introduction ❑ Dynamic changes occur in size, shape and proportions ❑ The problem of animal scie...

CONCEPTS OF GROWTH OF FARM ANIMALS  CONTENTS I. Phases of Growth II. Growth Targets III. Changes in Proportion to Growth IV. Hormonal Influence on Growth V. Genetic Influence on Growth Introduction ❑ Dynamic changes occur in size, shape and proportions ❑ The problem of animal scientist and biologist is sensible comparison between animals. Simple Concept About Growth ❑ In relation to time Biochemical process requires time Acquisition of food Transcription Building of new tissue The phases of growth Accelerating phase (exponential growth) Unicellular Organisms. Cells doubling at regular interval Day 1 1gm and doubles every 12 hr; then? Day 2 to day 3; Day 7 to 8? True for ideal situation and unicellular organism Multi-cellular organism 1) Organization (there is complexity) 2) Transport of nutrients and waste products Concept of Percentage Growth = proportionate and relative growth Conflicting factors, i.e. increase in number of replicating units versus limitation due to complexity of structure and availability of the food supply for growth. Epiphyseal Growth Plate Growth Targets * The functional needs of the animal changes as it develops and matures. * Growth is not a uniform process but an adaptation to the current and future needs of the animal kt Samuel Brody (1945) = W = Ae Exponential phase (embryonic phase) Linear phase (growing phase) Logarithmic phase (peripubertal phase)  3. Final phase (self-decelerating phase) maturity and there is inbuilt restraint for further growth 2. Linear phase 1. Exponential phase Changes in Proportion During Growth N B M F VFI 100% 75% 50% 25% Sequential Growth Targets Maturity or adult form is the growth target in mammals 1. Embryo as an effective parasite the developing embryo has command of a sufficient area of uterine space for the supply of nutrients 2. Fetus as a competitor 16 fetuses in sows uterine horns develop and establishe not only the placenta but also the priority for a circulatory system and liver 3. Fetus as the template for growth (complete parts) brain, limb, bones and digestive tract and lungs have little function in utero 4. Semi-independent at birth (colostrum, nutrition) at birth almost instantly in place are functioning lungs, a redirected circulatory system, fully operative suckling reflexes, limited communication skills and limbs fully functional for locomotion within minutes 5. Newly weaned juvenile from nutritional dependence on the dam to the ability to forage and digest food obtained from the pasture (abomasal digestion to ruminal fermentation of roughages); also dentition in some species 6. Growth Phase each species must attain a certain optimal size before embarking on the responsibilities and challenges of reproduction (weaning to puberty is the period of greatest absolute growth rate) 7. Puberty and the onset of reproductive capability modify growth to produce the secondary sex characteristics and symbolic changes 8. Reproductive phase mammalian female is characterize by storage in adipose tissue before and during pregnancy and the progressive release of this energy during lactation in the form of lipids dairy cows and sows gradually loose body condition with lactation period 9. Senescence and death death is a genetic program…. the conclusion of reproductive phase brings about the onset of senescence There is a season for everything, and a time for every event under heaven: ❖ a time to be born, and a time to die; a time to plant, and a time to uproot what was planted; ❖ a time to kill, and a time to heal; a time to tear down, and a time to build up; ❖ a time to weep, and a time to laugh; a time to mourn, and a time to dance; ❖ a time to scatter stones, and a time to gather stones; a time to embrace, and a time to refrain from embracing; ❖ a time to search, and a time to give up searching; a time to keep, and a time to discard; ❖ a time to tear, and a time to mend; a time to be silent, and a time to speak; ❖ a time to love, and a time to hate; a time for war, and a time for peace. Ecclesiastes 3:1-8