LESSON 3. Physiological Reactions of Farm Animals


Since the major purpose of environmental control in buildings for housing livestock is for  comfort of the animals, it should be fairly obvious that the physiological reactions of the animals are of extreme importance in determining design conditions.  Warm-blooded animals, such as cattle, swine, sheep, and poultry, give off heat and moisture during normal living processes.  The rate at which these are expelled will vary with environmental conditions.  Unfortunately, complete information is not available on the reactions of all animals under all conditions.  Research is under way at various stations in the United States to determine this information  where such information are based on practical experience.

Dairy Cattle:  The first approach to presenting information on the heat and moisture production of dairy cows was made in 1921 by Armsby, who presented a method of computing the heat production of dairy cows.  Based on Armsby’s method, together with research information on steers presented by various works, Strahan suggested basic information to be used in design of insulation and ventilation for dairy barns. 1 This information is shown in Figure 14.4.  Curve A shows the effect of environmental temperature on the percentage of total heat in latent form.  Latent heat is that heat contained in the vaporized moisture expelled by the animal.  As the temperature increases, more moisture is given off by the animal,  carrying with it moreheat in latent form to regulate the body temperature of the animal.  Curves  B and C show the reduction in sensible-heat production with increasing temperature;  Fig.  14.4.  Effect of temperature on heat and moisture production of dairy cattle. (From J. L. Strahan,  A method for Designing Insulation and ventilation for Animal Shelter Buildings, Agr.  Engg.)

1Samuel Brody, Physiological Backgrounds, Ho. Agr. Fept. Sta. Research Bull, 423, September, 1948.

One of the first important considerations is the effect of temperature on milk production.  Data from the Missouri study on the influence of ambient temperatures from 4 to 95°F   on the milk production of Jersey and Holstein cows indicate the following:1

1. Lowering the temperature from 50 to  4°F depressed the milk production.  Effects of sudden lowering of temperature from 50 to 4°F were much more striking on unacclimatized cows than on acclimatized cows.

2. The optimal temperature zone for milk production appeared to be not far from 50°F.  Critical high temperature was apparently 80°F, whereas no critical low temperature was evident.

3. Rising temperatures were more detrimental to the Holsteins, and declining temperatures more detrimental to the Jerseys.  The effect of lowering temperatures below 50°F was much less for both breeds than rising temperatures above 50°F.

Date on the influence of ambient temperature on moisture given off by Jersey and Holstein cattle indicate the following:2

At 0°F, about 8 percent of the total heat given off by the animals was dissipated by evaporative losses; at about 102°F all of the heat produced was dissipated by moisture vaporization.

  1. Between 90 and 100°F, the cows vaporized about 2 pounds of moisture per hour.

  2. At other temperatures, data presented showed the following ranges of moisture vaporization per 1000-pound animal unit.

0-20°F        0.3-0.4 pound per hour

20-40°F     0.4-0.6 pound per hour

40-60°F     0.6-0.8 pound per hour

60-80°F     0.8-1.7 pounds per hour

When computed to a comparable basis, these figures are higher than those proposed by Strahan.

Data on the effect of ambient temperature on heat production of Holstein and Jersey cows indicated the following:2           

1A.G.Ragsdale, D.M. Worstell, H.J. Thompson, and Samuel Brody, Influence of Temperature, 50° to 0°F and 50° to 95°F, on Milk Production, Feed and Water Consumption and Body Weight in Jersey and Holstein Cows, Mo. Agr. Expl. Sta. Research Bull. 449, September, 1949.

2H. J.  Ragsdale, D.M. Worstell, H.J. Thompson, and Samuel Brody, Influence of Ambient Temperature, 0° to 105°F,  on Insensible Weight Loss and Moisture Vaporization in Hostein and Jersey Cattle, Mo. Agr. Expt. Sta. Research Bul, 451, October, 1949.

3H. H. Kibler and Samuel Brody, Influence of Temperature, 50° to 5°F and 50° to 95°F, on Heat Production and Cardiorespiratory  Activities of Dairy Cattle, Mo. Agr. Expt. Sta. Research Bull, 450, October, 1949.

1. An increase in heat production of 30 to  3 percent in lactating Jerseys and of 20 to 30  per cent  in lactating Folsteins for gradually decreasing temperatures from 50 to 5°F.

2. A decrease in heat production by both breads of 20 to 30 per cent  above 70 to 80°F with gradually increasing temperatures from 50 to 100°F.

Actual values of heat production in the data around the 50°F range did not differ greatly from the figures proposed by Strahan.

Poultry.  Studies of the physiological reation of poultry to environmental conditions are under way at Beltsville, Mayland, by the Division of Farm Bujildings and Rural Housing, Bureau of Plant Industry, Soils, and Agricultural Engineering, USDA.  Although these studies have not been completed, some information has been reported which  can be used as tentative considerations for design procedure.1  Results of this study to date are shown graphically in Figure 14.5.  All data re converted to a single basis of 5-pound Rhode Island Red hens.  Results shown on the lower chart would indicate that the optimal temperature range for egg production lies in the neighborhood of 50 to 55°F.  Temperatures as low as 45° and as high as 65° do not seem seriously affect egg production.

The upper chart shows a reduction in total heat and sensible heat and an increase in latent heat with increasing temperature.  The amount of moisture produced can be estimated from the latent-heat production.  It takes approximately 1070 But to change I pound of water to vapor at 40°F and about 1040 at 90°F.  Considering that the latent-heat production is about 22 But per hour at 50°F and 1065 But are required to evaporate water at this temperature, then the equivalent moisture vapor produced could be computed as follows:

M2 Lesson 3 eq.1 pound of moisture produced per day by a 5 lb hen at 50°F

This value is higher than estimates made by previous workers.  The authors of the report emphasize that the work must be considered as preliminary since it was based on a limited number of hens.  Further work should produce valuable design information for poultry laying houses.

When baby chicks are first hatched, they do not have the facility to produce heat.  Hence the beat must be supplied artificially.  It has long been accepted practice to start day-old chicks at a temperature of 95°F and drop the temperature 5°F each week until 70 is reached.

Considerable interest is being shown in the broading of chicks at lower.     

1Hajime Ota, H. L. Garver, and Wallace Ashby, Heat and Moisture Production of Laying Hens, Agr. Eng. 34:163-167, March, 1953.

FrG. 14.5.  Effect of temperature on heat and egg production of poultry.  (From Hajime Ola, h.L. Garver, and Wallace Ashby, Heat and Moisture Production of laying Hens, Agr. Engg. 34:163-167, march 1953.)

Temperatures under infrared lamps.  Experimental work on this method has been reported by Baker and Bywaters.1  More information is needed than is available at the time of this writing before specific recommendations can be made.

1vernon Baker and James Bywaters, Boording Poultry with Infrared Energy, Agr. Eng., part, 32:316-320, June, 1951, and part II, 33:15-18, January, 1952.

Swine, Studeis of the effects of environmental conditions on the Physiological reactions of swine are being made at the University of California at Davis jointly with the U.S. Dep[artment of Agriculture.  A report on heat and moisture production based on preliminary studies has been made by Bond et al.1

FIG. 14.6 Effect of environmental temperature on heat and moisture production of hogs. (from T.E. Bond, C.G. Kelly, and Hubert Heitman, Jr., Heat and Moisture Losses from swine, Agr. Eng., 33:148-154, march, 1952.)

Some of the data collected by these workers are shown in Figure 14.6. Based on these data, the reactions of a 100-pound hog could be determined as follows.  In Figure 14.6b, such a hog would produce about 350 Btu per hour sensible heat and about 410 Btu per hour total heat at 60°.  This means that 60 But per hour is produced in moisture.  It 1060 Btu is required to evaporate a pound of moisture, the hog would be roducing approximately 0.06 pound of water vapor per hour.

1T.E. bond, C.G. Kelly, and Hubert Heitman, Jr., Heat and Moisture Loss from Swine, Agr. Eng., 33:148-154, March, 1952.      

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