The medullation characteristic of the hair coat as a factor in heat tolerance of cattle

1959 ◽  
Vol 10 (5) ◽  
pp. 736 ◽  
Author(s):  
DF Dowling
Keyword(s):  
Seasonal Variation ◽  
Thermal Effect ◽  
Heat Tolerance ◽  
Rectal Temperature ◽  
Structural Component ◽  
Heat Dissipation ◽  
Unit Area ◽  
Hair Coat ◽  
Critical Characteristic ◽  
Hair Fibre

Measurements of the hair fibres of the cattle coat show, besides considerable seasonal variation in the length, diameter, and weight of hair per unit area, marked changes in the incidence and degree of medullation, which may account for the required variation in the thermal effect of piliary development associated with seasonal conditions. The medulla, a structural component of the hair fibre, may be a critical characteristic of the coat in the regulation of heat dissipation by the animal. The correlation between the incidence of medullation and the animal's ability to regulate the rectal temperature was 0.95.

scholarly journals Breed and seasonal variation in thermoregulatory paramters of some selected Nigerian indigenous cattle

2021 ◽  
Vol 47 (6) ◽  
pp. 18-31
Author(s):  
H. Y. Abbaya ◽  
I. I. Adedibu ◽  
M. Kabir ◽  
A. O. Iyiola-Tunji
Keyword(s):  
Heat Stress ◽  
Seasonal Variation ◽  
Respiratory Rate ◽  
Pulse Rate ◽  
Heat Tolerance ◽  
Rectal Temperature ◽  
Indigenous Cattle ◽  
Fréquence Cardiaque ◽  
Stress Thermique ◽  
Breed Differences

The study was conducted to evaluate breed differences in thermoregulatory parameters of four Nigerian indigenous breeds of cattle over two seasons (late rainy and late dry). Data on thermoregulatory parameters (rectal temperature, respiratory rate, pulse rate and Heat Tolerance Coefficient) of eighty (80) cattle, comprising 20 each of Bunaji, Rahaji, Bokoloji and Adamawa Gudali were obtained and subjected to analysis of variance of SAS software. In the pooled breed variation, breed influenced (p<0.05) all the parameters measured. Bunaji recorded the highest rectal temperature (37.92oC) in all the seasons of measurement. Respiratory rate and Heat tolerance coefficient were highest in Bokoloji while the least were in Bunaji and Adamawa Gudali. Season significantly (p<0.05) affected thermoregulatory parameters measured except (p>0.05) rectal temperature. The highest recorded values of respiratory rate (27.85 beat/min), Pulse rate (27.62breaths/min) and HTC (2.19) were in the late dry season. The effect of interaction between breed and season on thermoregulatory parameters significantly affected (p<0.05) all the thermoregulatory parameters measured. It was concluded that Bokoloji and Bunaji breeds of indigenous cattle are more reactive to Heat stress than Rahaji and Adamawa Gudali even though this could vary with seasons of the year as seen in the interaction between breed and season in this study.   L'étude a été menée pour évaluer les différences entre les races dans les paramètres thermorégulateurs de quatre races indigènes de bétail nigérianes sur deux saisons (pluvieuse tardive et sèche tardive). Des données sur les paramètres thermorégulateurs (température rectale, fréquence respiratoire, fréquence du pouls et coefficient de tolérance à la chaleur) de quatre-vingts (80) bovins, comprenant 20 de chacun de Bunaji, Rahaji, Bokoloji et Adamawa Gudali ont été obtenues et soumises à l'analyse de variance du logiciel 'SAS'. Dans la variation de race combinée, la race a influencé (p <0,05) tous les paramètres mesurés. Bunaji a enregistré la température rectale la plus élevée (37,920 ° C) de toutes les saisons de mesure. La fréquence respiratoire et le coefficient de tolérance à la chaleur étaient les plus élevés à Bokoloji tandis que les plus faibles étaient à Bunaji et à Adamawa Gudali. La saison a affecté significativement (p <0,05) les paramètres thermorégulateurs mesurés sauf (p> 0,05) la température rectale. Les valeurs les plus élevées enregistrées de la fréquence respiratoire étaient (27,85 battements / min), la fréquence cardiaque (27,62 respirations / min) et le 'HTC' (2,19) étaient à la fin de la saison sèche.L'effet de l'interaction entre la race et la saison sur les paramètres thermorégulateurs était significativement affecté (p <0,05) tous les paramètres thermorégulateurs mesurés. Il a été conclu que les races Bokoloji et Bunaji de bovins indigènes sont plus réactives au stress thermique que Rahaji et Adamawa Gudali, même si cela peut varier avec les saisons de l'année, comme le montre l'interaction entre la race et la saison dans cette étude.

White hair coat color does not influence heat tolerance of sheep grazing under a hot arid environment

2021 ◽  
pp. 106410
Author(s):  
Ahmed Abrahim Al-Haidary ◽  
Yusuf Al-Dosari ◽  
Abd-Elatif Abd-Elwahab ◽  
Emad Mohamed Samara ◽  
Mohammed Abdo Al-Badwi ◽  
...  
Keyword(s):  
Heat Tolerance ◽  
Coat Color ◽  
Arid Environment ◽  
White Hair ◽  
Sheep Grazing ◽  
Hair Coat

Genetic variation of rectal temperature and its relationship to milk production in Holstein dairy cows

2009 ◽  
Vol 2009 ◽  
pp. 63-63
Author(s):  
S Khalajzade ◽  
N Emam Jomeh ◽  
A Salehi ◽  
A Moghimi Esfandabadi
Keyword(s):  
Heat Stress ◽  
Dairy Cows ◽  
Milk Production ◽  
Heat Tolerance ◽  
Rectal Temperature ◽  
Weather Factors ◽  
And Performance ◽  
Very High ◽  
Selection Of ◽  
Holstein Dairy Cows

Milk production is significantly decreased by thermal stress. The survival and performance of an animal during heat stress periods depend on several weather factors, especially temperature and humidity. Researchers reported dramatic decreases in milk production as temperature rose above 30 degree of centigrade. Very high environmental temperature is common during the summer months in Iran. Rectal temperature is as indicator of heat tolerance and has been the most frequently used physiological variable for estimating heat tolerance in cattle. Some dairy cows are more heat tolerant and productive when subjected to heat stress. Identification and selection of heat stress resistant cattle offers the potential to increase milk yield in tropical environment. The aim of the present study was to estimate genetic parameters of heat tolerance and its relationship to milk production in Holstein Dairy Cows in Iran.

scholarly journals The Physiology of Heat Tolerance in Small Endotherms

Physiology ◽  
2019 ◽  
Vol 34 (5) ◽  
pp. 302-313 ◽  
Author(s):  
Andrew E. McKechnie ◽  
Blair O. Wolf
Keyword(s):  
Climate Change ◽  
Body Temperature ◽  
Small Mammals ◽  
Heat Tolerance ◽  
Heat Dissipation ◽  
Heat Exposure ◽  
Tolerance Limits

Understanding the heat tolerances of small mammals and birds has taken on new urgency with the advent of climate change. Here, we review heat tolerance limits, pathways of evaporative heat dissipation that permit the defense of body temperature during heat exposure, and mechanisms operating at tissue, cellular, and molecular levels.

Prediction of heat tolerance from heart rate and rectal temperature in a temperate environment

1977 ◽  
Vol 43 (4) ◽  
pp. 684-688 ◽  
Author(s):  
E. Shvartz ◽  
S. Shibolet ◽  
A. Meroz ◽  
A. Magazanik ◽  
Y. Shapiro
Keyword(s):  
Heart Rate ◽  
Heat Tolerance ◽  
Rectal Temperature ◽  
Room Temperature ◽  
Heat Stroke ◽  
Work Load ◽  
Average Work ◽  
Single Score ◽  
Temperate Environment ◽  
Best Responses

To determine if heat tolerance could be predicted from responses to exercise in temperature conditions, 51 young men performed 15 min of bench stepping at an average work load of 80 W at 23 degrees C. On the following day they attempted to perform 3 h of bench stepping at 40 W in heat (39.3 degrees C dry bulb, 30.3 degrees C wet bulb). Of these subjects, 4 were heat intolerant, judged by previous heat stroke episodes during field marches, 12 were heat acclimated, and 35 were unacclimated. The heat-intolerant subjects showed the highest heart rates (HR) and rectal temperatures (Tre) at 23 degrees C and in heat, and the acclimated subjects showed the lowest corresponding values. HR and Tre in each environment were combined into a single score, from 10, indicating the poorest responses, to 100, indicating the best responses. These scores at 23 degrees C when correlated with the corresponding scores in heat resulted in a linear correlation coefficient of r = 0.94 with a standard error of estimate of 8.6%. Scores of the heat-intolerant subjects were below 35, and those of the acclimated subjects were between 70 and 100. Thus heat tolerance can accurately be predicted for HR and Tre responses to exercise at room temperature.

Heat tolerance of exercising lean and obese prepubertal boys

1975 ◽  
Vol 39 (3) ◽  
pp. 457-461 ◽  
Author(s):  
E. M. Haymes ◽  
R. J. McCormick ◽  
E. R. Buskirk
Keyword(s):  
Heart Rate ◽  
Oxygen Uptake ◽  
Heat Tolerance ◽  
Rectal Temperature ◽  
Sweat Rate ◽  
Rest Periods ◽  
Lower Oxygen ◽  
Prepubertal Boys ◽  
Submaximal Work ◽  
Prepubertal Girls

Seven lean and five obese boys, aged 9–12 yr, exercised in four environments: 21.1, 26.7, 29.4, and 32.2 degrees C Teff. Subjects walked on a treadmill at 4.8 km/h, 5% grade for three 20-min exercise bouts separated by 5-min rest periods. Rectal temperature (Tre), skin temperature (Tsk), heart rate (HR), sweat rate, and oxygen uptake (VO2) were measured periodically throughout the session. Lean boys had lower Tre and HR than obese boys in each of the environments. Increases in Tre were significantly greater for the obese at 26.7 and 29.4 degrees C Teff. No significant differences in Tsk and sweat rate (g-m-2-h-1) were observed between lean and obese boys. Obese boys had significantly lower oxygen consumptions per kg but worked at a significantly higher percentage of VO2max than lean boys when performing submaximal work. Responses of the obese boys to exercise in the heat were similar to those of heavy prepubertal girls studied previously, except that the boys were more tolerant of exercise at 32.2 degrees C Teff than the girls. Lean boys had lower HR than lean girls in each environment, but lower Tre only at 32.2 degrees C Teff.

An experimental study of heat tolerance of cattle

1956 ◽  
Vol 7 (5) ◽  
pp. 469 ◽  
Author(s):  
DF Dowling
Keyword(s):  
Experimental Study ◽  
Heat Stress ◽  
Heat Tolerance ◽  
Rectal Temperature ◽  
Tolerance Test ◽  
The Body ◽  
Normal Body Temperature ◽  
Factors Influencing ◽  
Major Factors ◽  
Temperature Responses

The ability of cattle to maintain a normal body temperature in a dry, hot, inland Australian environment is associated with their ability to dissipate excess heat from the body. A heat tolerance test, based on rectal temperature responses after exercise, is reported. This test indicates the animal's capacity to lose heat. Forty animals, classified on their coat covering, were included in the experiments described. The differences in coat covering are described and associated with differences in rectal temperature under various forms of heat stress. The results serve to illustrate the basic weaknesses of any field test (or hot-room test) which cannot be carried out under conditions where major factors influencing the "adaptability" and type of coat can be kept uniform for all animals tested.

Effect of drinking-water temperature on heat balance and thermoregulatory responses in dairy heifers

1996 ◽  
Vol 47 (4) ◽  
pp. 505 ◽  
Author(s):  
BP Purwanto ◽  
M Harada ◽  
S Yamamoto
Keyword(s):  
Drinking Water ◽  
Water Temperature ◽  
Respiration Rate ◽  
Rectal Temperature ◽  
Heat Balance ◽  
Heat Dissipation ◽  
Environmental Temperature ◽  
Night Time ◽  
Dairy Heifers ◽  
Thermoregulatory Responses

A study was made to determine the effect of heat dissipation from drinking water (8 kg at 10, 20, or 30�C) on the heat balance and thermoregulatory responses of 4 dairy heifers housed at 24, 29, and 34�C. No effect of drinking-water temperature on heat production or heart rate was found. Respiration rate, mean skin-surface temperature, and rectal temperature all decreased with decreasing drinking-water temperature. Rectal temperature reached a minimum 20 min after watering. The respiration rate, skin temperature, and rectal temperature returned to prior-to-watering values 120-180 min after watering. The cooling efficiency of drinking water was about 40%, and decreased at high environmental temperature, because the cooling potential was used initially in depressing heat loss responses. It is suggested that in order to eliminate excessive heat load, chilled drinking water could be effective during the night time when the environmental temperature is lowest.

Studies of the environmental physiology of tropical merinos

1978 ◽  
Vol 29 (1) ◽  
pp. 161 ◽  
Author(s):  
PS Hopkins ◽  
GI Knights ◽  
AS Le Feuvre
Keyword(s):  
Low Temperature ◽  
Rectal Temperature ◽  
Water Loss ◽  
Heat Dissipation ◽  
Evaporative Water Loss ◽  
Compensatory Mechanisms ◽  
Evaporative Water ◽  
Ambient Temperatures ◽  
Diurnal Patterns ◽  
Made In

Rectal temperature measurements of tropical Merino sheep taken in the sun during summer indicated that there were high and low temperature groups. Animals of low temperature status (e.g. 39.4°C) also exhibited a low respiration rate (e.g. 110/min) in comparison with their less adapted counterparts (40.0° and 190/min). These differences were greatest when ambient temperatures were high. The repeatability of temperature status was 0.46 (P < 0.01). Animals of folds (+) phenotype had significantly higher rectal temperatures than folds (–) animals (P < 0.05). Shearing caused a marked but transient increase in rectal temperature. Compensatory mechanisms apparently involved an increase in cutaneous heat dissipation and/or a decrease in exogenous heat load. Evaporative water loss (80–115 ml/kg/day) greatly exceeded the non-evaporative water loss (40–65 ml/kg/day) of sheep in metabolism cages. Respiratory water loss could account for only 8–10% of the total daily evaporative water loss. Non-respiratory evaporative water loss (as measured by difference) was c. 75–100 ml/kg/day. There were no striking differences between high and low temperature status sheep in this regard. Measurements of respiratory (2 ml/kg/hr) and non-respiratory (5.5 ml/kg/hr) evaporative water loss made in hygrometric tents suggested that the greater non-respiratory water loss was partly due to a higher rate of loss and partly to a longer period of loss per day. This suggestion was supported by the diurnal patterns of rectal temperatures and respiration rates reported here, though no firm conclusions could be made as to the thermotaxic effect of non-respiratory water loss and thermoregulation of tropical Merinos with varying amounts of wool cover.

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