Academic Research on cattle’s acclimatisation process

2005

The objective of this study was to evaluate the heat resistance in different breeds of naturalised cattle, at two different times of day with different temperatures and humidity. The experiment took place at Sucupira farm of Embrapa/ Cenargen in Brasília-DF. A total of 52 animals were used, 11 Curraleiro, 11 Crioulo Lageano, eight Nelore, eight Pantaneiro, six Junqueira, four Holstein and four Mocho Nacional including both males and females. The measurements were taken at 08:00 and 14:00 after the animals had been exposed to the sun for 6 hours. The procedure was repeated 3 times. The data collected included heart rate (HR), rectal temperature (RT) and respiratory rate (RR). Blood was also collected as well as sweating rate and the length and number of hairs per cm2. Breed influenced (p<0.001) the heat response. The Nelore breed had the best response (HR= 66.06, RR= 32.71, RT= 39.36 and sweating= 215.22), followed by the Junqueira (HR= 76.71 RR= 33.05 RT= 38.75 Sweating= 247.14), which although had high heart rate maintained the other parameters at a low level. The Pantaneira

Journal of Animal Behaviour and Biometeorology, 2017

This review aimed to detail the main information pertinent to the physiological and behavioral mechanisms evidenced in cattle under heat stress conditions. Brazilian cattle-breeding represents the second largest herd in the world, promoting great impact on the country's exports. Throughout their adaptability, these animals were submitted to different environments, which directly influence productive and reproductive performance, seeking compensatory mechanisms to maintain body homeostasis. Therefore, we can consider that heat stress directly affects the physiological and behavioral responses of cattle subjected to high temperatures. Adaptability of breeds to tropics should be considered of extreme importance in the choice of a productive activity for cattle-breeding and, particularly, in hot environments.

Livestock Science, 2009

Research carried out at the Sucupira Farm of Embrapa Recursos Genéticos e Biotecnologia, in Brasilia-DF, aimed to evaluate heat tolerance in five naturalized and two exotic breeds of cattle, at different temperatures and humidity, based upon physiological and blood parameters. The data collected included heart rate (HR), rectal temperature (RT), respiratory rate (RR), and sweating rate (SR). Blood was also collected for hemogram analysis and cortisol level. The measurements were taken at 7 am and at 2 pm after the animals were exposed to the sun, with water ad libitum. This procedure was repeated for six days, three in the middle of the dry season when temperatures and humidity were lower and three at the start of the rainy season when temperatures and humidity were higher. Significant statistical differences were observed in RR and HR for day, breed and animal within breed. The analysis indicated that the Junqueira and Nellore breeds are most adapted to climatic conditions in Brasilia; while Mocho Nacional and Holstein breeds were the least adapted. Although sample size is limited, these results are important to identify which breeds are most resistant towards climatic variations observed in the Brasilia region, as well as which physiological parameters are the most indicated for use in animal breeding programs intended to select animals and breeds adapted to thermal stress conditions.

Tropical Animal Health and Production, 2011

Adaptability can be evaluated by the ability of an animal to adjust to environmental conditions and is especially important in extreme weather conditions such as that found in tropical Brazil. A multivariate analysis using physical and physiological traits in exotic (Nellore and Holstein) and naturalized (Junqueira, Curraleira, Mocho Nacional, Crioula Lageana, and Pantaneira) cattle breeds was carried out in the Federal District of Brazil to test and determine which traits are important in the adaptation of animal to heat stress as well as the ability of these traits and statistical techniques to separate the breeds studied. Both physical and physiological traits were measured on three occasions and included body measurements, skin and hair thickness, hair number and length, pigmentation, sweat gland area as well as heart and breathing rates, rectal temperature, sweating rate, and blood parameters. The data underwent multivariate statistical analyses, including cluster, discriminate, and canonical procedures. The tree diagram showed clear distances between the groups studied, and canonical analysis was able to separate individuals in groups. Coat traits explained little variation in physiological parameters. The traits which had higher discriminatory power included packed cell volume, shoulder height, mean corpuscular volume, body length, and heart girth. Morphological and physiological traits were able to discriminate between the breeds tested, with blood and size traits being the most important. More than 80% of animals of all breeds were correctly classified in their genetic group.

Acta Scientiarum. Animal Sciences, 2013

This work was carried out to evaluate the physiological thermoregulation responses of Girolandobreed dairy cows kept in feedlot during summertime. A total of 15 animals were used, belonging to three genetic groups: 1/2, 5/8 and 3/4 Holstein-Gir (HG), with five cows from each genetic group, distributed in a completely randomized design, in subplots. The physiological parameters were sweat rate (SR), respiratory rate (RR), epidermis temperature (ET) and coat surface temperature (CST), and were evaluated once a week, during nine weeks, from December 2009 to February 2010, totaling 135 observations. Throughout the experimental period, climatic data were recorded using an automated weather station, and later used to calculate the different thermal comfort indexes: THI (temperature-humidity index), BGHI (black globe temperature and humidity index) and RTL (radiant thermal load). 1/2 HG animals showed the highest SR and lowest RR, ET and CST of all three genetic groups, while 3/4 HG cows had the lowest mean SR and highest ET and CST. 5/8 HG cows had intermediate values for SR, ET and CST. Mean RR values did not differ between 5/8 and 3/4 HG cows. It was concluded that animals from genetic groups 3/4 and 5/8 HG showed greater sensibility to heat stress than 1/2 HG cows.

Journal of Animal Behaviour and Biometeorology, 2018

Climate change associated heat stress was established to be the crucial factor, which negatively influences animal production. The animals possess several adaptive mechanisms which are helpful for their survival in harsh environmental conditions, but while doing so their productive performances are compromised. Among the various mechanisms, which helps to maintain homeostasis in animals, Physiological adaptability was considered one of the primary response mechanisms by which the heat stressed animals survive the heat stress. This review is therefore an attempt to provide the audience an updated review on the subject to signify the importance of physiological responses in animals and their role in surviving the stressful environment. Respiration rate (RR), pulse rate (PR), rectal temperature (RT), sweating rate (SR) and skin temperature (ST) are the cardinal physiological variables which helps to maintain the heat balance and homeostasis in the stressed animals. Among the various physiological variables, RR, RT and ST were established to be ideal indicators for quantifying heat stress in several farm animals. Therefore, these variables can be effectively used to assess the severity of heat stress in livestock. Although these variables are considered significant in establishing the heat stress impact in animals, a wide genetic variation was also established in these response mechanisms. Further, variations in physiological adaptability were also established between indigenous, cross bred and pure bred animals. The indigenous livestock breeds were tipped to be exhibiting less physiological variability as compared to their counterparts. These discussions vividly indicate the importance of studying in detail the physiological adaptive mechanisms in different farm animals and these efforts can help the farming community to identify the suitable agroclimatic zone specific livestock breeds which can go in long way to help to ensure climate resilient livestock production.

Journal of Animal Science

A Model of Thermal Acclimation in Cattle 1985, 61:297-306. J ANIM SCI http://jas.fass.org/content/61/2/297 services, is located on the World Wide Web at:

Black Sea Journal of Agriculture

Herd management and nutrition strategies against increasing negative effects of global warming on farm animals have been the subject of significant debates in recent years. The fact that the changes in the environmental conditions are directly related to the habitats of the animals and the conditions inside the barn can affect the farm animals negatively. Although effects of heat stress differ according to species, especially high-yielding dairy cattle exposed to heat stress, respond with various interactive mechanism such as physiological, biochemical, immunological, anatomical and behavioral. Therefore, with the selection practices that have been going on for many years to improve the yield characteristics of the animals significantly increased. In this respect, the increased heat load in the body of dairy cattle due to the high productivity decreases their tolerance to environmental conditions. This situation adversely affects the productivity of cows with high breeding value. Yi...

Acta Amazonica, 2018

The relationship between the indices of thermal comfort and internal temperature in lactating cows was evaluated inRondônia, western Amazonia in a 2 × 2 crossover trial carried out with eight Girolando cows, ½ Holstein × ½ Gyr (n=4) and ¾ Holstein × ¼ Gyr (n=4), grazing palisade grass supplemented with or without soybean oil concentrates. Data logger thermometers adapted to intravaginal devices (hormone free) were used to measure internal temperatures (IT) every 10 min over 48 h. Concomitantly, environmental parameters (air temperature, relative humidity, wind speed, and solar radiation) were collected for the estimation of the temperature-humidity index (THI), equivalent temperature index (ETI), and predicted respiratory rate (PRR). Supplementation with soybean oil did not affect the internal temperature of the cows. IT varied significantly between the genetic groups, with the highest mean observed at night in the ¾ Holstein × ¼ Gyr cows, compared with that in the ½ Holstein × ½ Gyr cows (39.54 °C vs 39.06 °C, respectively). THI, ETI, and PRR were significantly and positively correlated with the IT of the Girolando cows; however, the PRR was not found to be adequate in indicating the night-time heat stress in cows. Relação entre índices de estresse térmico e a temperatura interna de vacas Holandês x Gir lactantes em pastejo na Amazônia Ocidental RESUMO A relação entre índices de conforto térmico com a temperatura interna de vacas lactantes foi avaliada em Rondônia, na Amazônia Ocidental, em um ensaio crossover 2x2 utilizando oito vacas Girolando, ½ Holandês x ½ Gir (n=4) e ¾ Holandês x ¼ Gir (n=4) pastejando capim-marandu suplementadas com concentrados contendo ou não óleo de soja. A temperatura interna (TI) dos animais foi aferida com termômetros eletrônicos adaptados em dispositivos intravaginais (livres de hormônio) a cada 10 minutos durante 48h. Concomitantemente, dados climáticos (temperatura do ar, umidade relativa do ar, velocidade do vento e radiação solar) foram coletados para cálculo dos índices de temperatura e umidade (ITU), índice de temperatura equivalente (ITE) e o índice de frequência respiratória predita (PFR). A suplementação com óleo de soja não afetou a temperatura interna das vacas. A TI variou significativamente entre os grupos genéticos, com a maior média observada à noite nas vacas ¾ Holandês × ¼ Gir em relação às ½ Holandês × ½ Gir (39,54 °C vs 39,06 °C, respectivamente). ITU, ITE e PFR tiveram correlação significativa e positiva com a TI de vacas Girolando, mas o PFR não foi adequado para indicar estresse térmico em vacas no período da noite. PALAVRAS-CHAVE: estresse por calor, Holandês x Zebu, gado leiteiro, índice de estresse ambiental CITE AS: Carvalho, G. A.; Salman, A. K. D.; Cruz, P. G.; Silva, F. R. F.; Halfen, J.; Schmitt, E. 2018. Relationship between thermal comfort indices and internal temperature of grazing lactating Holstein × Gyr cows in the western Amazonia. Acta Amazonica 48: 191-196.

International Journal of Biometeorology, 2015

This study compared the two breed groups of Girolando (½ Holstein ½ Gyr vs. ¾ Holstein ¼ Gyr) through analysis of the percentages (stressed or non-stressed cows) of rectal temperature (RT), respiratory rate (RR) and pregnancy rate (PR), and means of production and reproduction parameters to determine the group best suited to rearing in semiarid tropical climate. The experiment was conducted at the farm, in the municipality of Umirim, State of Ceará, Brazil. Two hundred and forty cows were used in a 2×2 factorial study; 120 of each group were kept under an intensive system during wet and dry seasons. The environmental parameters obtained were relative humidity (RH), air temperature (AT), and the temperature and humidity index (THI). Pregnancy diagnosis (PD) was determined by ultrasonography 30 days after artificial insemination (AI). The milk production of each cow was recorded with automated milkings in the farm. The variables were expressed as mean and standard error, evaluated by ANOVA at 5 % probability using the GLM procedure of SAS. Chi-square test at 5 % probability was applied to data of RT, RR, pregnancy rate (PR), and the number of AIs to obtain pregnancy. The majority of ½ Holstein cows showed mean values of RT and RR within the normal range in both periods and shifts. Most animals of the ¾ Holstein group exhibited the RR means above normal during the afternoon in the rainy and dry periods and RT means above normal during the afternoon in the dry period. After analyses, ½ Holstein crossbred cows are more capable of thermoregulating than ¾ Holstein cows under conditions of thermal stress, and the dry period was more impacting for bovine physiology with significant changes in physiological parameters, even for the first breed group. Knowledge of breed groups adapted to climatic conditions of northeastern Brazil can directly assist cattle farmers in selecting animals best adapted for forming herds.