Document dODKodY6LX6XagbKmBdbM71q

i i I i I 116 CHAPTER 7 reactions aftadividualworkers to high effective temperatures (ASHVE Transactions, VoL 45, 1939, p. 59).' F.,C.Houghterv A..A. Rosenberg, and- M. B. Feideroer:-.ASHVE Research Repobt No.- 1153--Rwuw>*t variations in reaction-to hot at-' njospherea.(ASHVE Transactions, Voi. 46,.l&40,.p.-l85).- ;: F. C: Hougbteh, .W.-W. Teague, and W. E. Miller: ASHVE Research Report-No. 755--Elective temperature for persona lightly dothed and working instillair (ASHVE Tbansacotons,- VoL &,.1936, p. 315). : - : ,i - * F. C.' Hnn^itwi;: W: W. Teague, .W. EL: Miller, and :W. P. Yant: Heat and moisture losses from men at work and applica tions to air conditioning problems (ASHVE Transactions, VoL 37, 1931, p. 541).t : '` 1965 Guide And DataiBook ** L. W. Eichrui, W. F. Ashe, W; B. Bean, and ,W. B. Shelley- The upper limits of environmental,heat and humidity:tolerated by acclimatized men working in holt environments (The Journal of Industrial Hygiene and Toxicology, VoL 27, March-1945, p 59).. . ...... . t . . ** A..P. Gagge; A. C. Burtoiy and H. C. G&zett: A practical system of units for the descripuonof the heat-exchange of man with hia environment (Science,-Voi. 94,,1941,-p.' 428). C. P. Yagiou: Thermal-/insulation of dpthing (ASHVE Transactions; VoL 54* 1945, p.'291). ** C- P. Yaglou, Philip Diinker,;and K. P. .Blackfao: Appli cation of-air. conditioning, toipreaoture auioeriea in hospitals (ASHVE Transactions,. VqL'36,. 1930, p?353). ..... ' -T n; - ff CHAPTER 8 ENVIROMENTAL ; CONTROL FOR ANIMALS AND PLANTS--PHYSIOLOGICAL CONSIDERATIONS ANIMALS: Cottle, Sheep. Swine, Poo/fry,- PLANTS: Environment and'fLonf Growth. THE control of environment for,animals and plaits is is shifted to insensible,-or evaporative, heat loss.'Thus,- at lining studied more closely as.efforts are made to attain higher-ambient temperatures, high'humidity may limit pro greater efficiency and better quality in linstock.production.duction. The interrelation of temperature and humidity-have Thi3 information is being compiled through the joint efforts been studied to some extent for some species,- but the results of scientific research projects. This chapter is a product of are far from complete. some of the published ,results of the various studies in this field. It provides a concept of.the physiological factors in Animals confined in a closed environment tend to alter the composition of the air by reducing the oxygen content,' in volved in controlling environments. creasing the carbon dioxide and vapor content, and by adding ruminant gases, ammonia from,feces and urine, and micro PART I: ANIMALS. Important domestic animal* are. homeothermic, and it is reasonably assumed that for each species; there exists, one environment at which maximum productivity is associated with maximum production efficiency. If the temperature is increased above that of the ideal environment, the animal must decrease its fuel intake to maintain a constant .body temperature, consequently reducing its productivity. If the temperature is decreased below that of the ideal environment, the animal must increase its fuel intake to maintain homeo- thermy.and this reduces its efficiency of production. Y> When genetic engineering becomes a practiced ait, an ideal environment could be established for each species,.according to age, weight, sex, kind of fuel, or any other variable. At present, data define broad environmental limits within which production may be said to be maximum, and production effi ciency more or less uniform. j i^ These limits are largely defined in terms of temperature and humidity. Future research, no doubt, will fully describe the effects of air movement, barometric pressure, air composition, etc., but, until most livestock are housed in controlled en vironments, the accumulation of such information will tfe rather slow. Air temperature must be considered the major variable de scopic particles of dust from feed, bedding, etc: Experience has shown that, when operating at an environment designed to . elicit maximum productivity, the addition of sufficient fresh air'to remove water vapor and ammonia will prevent, any detectable effects of carbon dioxide build-up, lung respiratory irritation due to dust particles; or harmful effects from methane. _; The study of air movement has been insufficient to clearly define its effect in terms of temperature or humidity equiva-' lents. Studies tend to show that air movement in excess of that required to remove stationary layers accumulated about - animals is of doubtful benefit. - Heat production data;. under conditions of normal meta bolic activity have been'accumulated for'domestic"animals customarily confined in housing, Le., dairy cattle,.poultry and swine, but generally have not been accumulated for range animals, Le., beef cattle and sheep."' ~ . Unlike heat production, animal productivity is only in directly related to environment. Maximum productivity is a genetically inherited characteristic, but realisation-of the full-^ potential is controlled by other factors. Some of these are: 1. Environmental, such as temperature or light. 2. Nutritional, such as feed composition ox enzyme activity. 3. Pathological, such as microorganisms. 4. Psychological, such as fright or sexual stimulation. scribing environment, since the'animal's sensible beat dissi pation is a function of -.temperature difference. Second in importance is humidity. All homeotherms are Alika to the extent that a portion of, the heat.dissipated is in the form of In general, the physiological control systems.will-react to unfavorable conditions in such:a manner as to insure survival, of the, animal at the expense of productivity. ( .,. vapor. .When increasing ambient temperature approaches the animal's surface temperature, the burden of heat dissipation cattle '.nTS*,**1***!. rxstJOimbiKty for thH chapter to teaigaod ,to th* ASHRAB-r r* i**r>ciety Ceauaitw* oo Pfeat ad Animal PhyxioJocr- Thto later- tertx Comsat*** wrote ol'ASHRAE^TC 'LfiAad Committee C-18 erf tb* Soctoty d Actoeoltani Bo&xaocte. Because\of .their ecohoqnc mport&nw^dwy^cattl^Have been the "subject of'mu^'research.reading"their physio logical responses tb environment. Fig. 1 illustrates the effect 117