What Do Cattle Prefer in a Tropical Climate: Water Immersion or Artificial Shade?

Animal performance is affected by high air temperature and it is known that shade reduces the absorption of radiant temperature, and water for immersion facilitates heat loss. This study intends to find preferences of resources that contribute for the well-being of cattle and how they alterdaily behaviour. During summer, six Caracu and six Red Angus bulls were submitted to two different treatments: availability of artificial shade and water for immersion and availability of water for immersion. The categories observed were: positions (in the sun, under the shade, in the water), posture (standing, lying down) and activities (grazing, ruminating, leisure). The behavioural patterns were recorded using the focal sampling method every 15 minutes (from 6:00 a.m. to 6:00 p.m.). When shade and water for immersion coexists, cattle in this study prefer shade to avoid solar radiation. Both breeds had remained more time grazing, followed by ruminating in the Caracu breed, and by resting in the Red Angus breed. The Caracu breed had presented clear preference for the shade resource, but that fact was not always observed in the Red Angus breed. In hot climates, resources for defence against heat load, as shade and water for immersion improve the well-being of cattle

Reactivity of Nellore steers in two feedlot housing systems and its relationship with plasmatic cortisol

To evaluate reactivity to assess the temperament of Nellore steers in two feedlot housing systems (group pen or individual pen) and its relationship with plasmatic cortisol, 36 experimental units were observed five times at 28-day intervals of weight management during a 112-day feedlot confinement. A reactivity score scale ranging from 1 to 5 was applied when an animal was in the chute system. To the calmest animal, a reactivity score of 1 was ascribed and to the most agitated, 5. Blood samples were collected for cortisol analysis. No differences were found in reactivity and feedlot system. There was a relationship noted between reactivity and feedlot time in both housing systems (Pb0.01). There was a relation between reactivity and cortisol levels for group animals (P=0.0616) and for individual ones (Pb0.01). Cortisol levels varied among housing systems (Pb0.01). Feedlot time influenced the cortisol levels (Pb0.09 individual; Pb0.01 group) and when variable time was included, these levels changed, decreasing in the group pen and increasing in individual pens. The continuous handling reduces reactivity and plasmatic cortisol, and group pen system seems to be less stressfully than individual pens

Evaluation of reactivity of horses in the presence of unknown stimulus

The study aimed to evaluate reactivity of horses during usual brushing management against the repeated presence of an unknown sonorous stimulus. Twenty Mangalarga Marchador horses, distributed in different categories (mares and foals), were evaluated. The animals were allocated into the control treatment (N = 10) and the treatment with unknown sonorous stimulus (N = 10) from a rattle and a tambourine. Four consecutive evaluations were carried out first (day 0, 1, 2, 3). Two consecutive assessments were carried out after 30 days of the first collection (day 30 and 31), and two consecutive assessments were carried out 15 days after the second evaluation (day 45 and 46). The behavioral observations were made by assigning a score to behaviors of movement, position of ears and eyes, breathing, and vocalization during brushing management. A response variable called reactivity was attributed to each animal, ranging from score 1 (not reactive or calm animal) to reactivity score 4 (very reactive or aggressive animal). For statistical analysis, the results were adjusted to a logistic regression model using the categories, day, and treatment as covariates. The animals of the unknown stimuli showed greater reactivity. The days of the experimental period influenced the reactivity of animals between 6 and 7 months old, with a decrease in the possibilities of the animals to have a higher reactivity. The maturity of the foal with repeated exposure to the unknown sound stimulus may decrease the possibility of the animal being reactive

Behavior of Holstein milking cows exposed to different environmental conditioning systems

Objectives: The aim of the study was to evaluate the behavior of dairy cows in summer in relation to the environmental conditioning system (fans with or without misting). Materials and Methods: Twenty Holstein lactating cows were allotted in free-stall pens, divided in two groups: VN ? with fans plus misting; V ? only with fans. The behavior was estimated as time standing and eating, ruminating and idling activities. Data were registered during 4 days by scan method, from 0600h to 1800h, with 30 minutes intervals. Results: Air temperature and relative humidity were registered and indicated a heat stress situation, with maximum temperatures of 32oC and 87% of relative humidity. We observed high values of in standing posture and eating activity on 11h30, 1630h and 1700h hours of VN animals (P <0.05). High frequency for ruminating and idling activities were found at 1700h and 1630h, respectively, for the V animals (P <0.05). Conclusions: The use of fans as the only resource of thermal comfort in these experimental conditions was inefficient when compared to the combination of fans and misting, which give a better thermal comfort condition, allowing cows to feed for long periods, even during the hottest hours of the day, indicating less heat stress

Heat stress and ACTH administration on cortisol and insulin-like growth factor I (IGF-I) levels in lactating Holstein cows

Physiological and productive responses were studied in five Holstein cows in thermal comfort (T1), stress by exogenous adrenocorticotropic hormone (ACTH) administration (T2) and heat stress (T3) to compare acute and punctual stress (ACTH) and prolonged stress (heat stress). During T1 and T2, cows were housed in a climatic-free stall barn. In T3, the animals were kept in a climatic room (air temperature of 37°C from 08:00 to 13:00 h, and of 26°C from 14:00 to 07:00 h) for 7 days. Milk yield, rectal temperature (RT), respiratory rate (RR) and blood samples were obtained before, during and after all treatments. In T1 at 08:00 h, RT and RR were below the upper critical limit. Simultaneously, cortisol and insulin growth-factor I (IGF-I) were within the normal limits. After ACTH administration (T2), cortisol significantly increased, reaching maximum levels at 60 min and returning to basal levels at 300 min. However, IGF-I was not affected. During T3, Holstein cows did not effectively dissipate their body temperature and RT, RR and cortisol significantly increased. There was a 26.6% reduction in milk production after heat stress (P < .05). Prolonged heat stress was more stressful and cows had higher levels of CORT in T3 than in T2 even before the increase in body temperature. Although the total amount of cortisol and IGF-I presented a negative and significant Pearson correlation (r = −0.79), IGF-I was not significantly influenced by heat stress or ACTH administration, and the relationship between IGF-I and heat stress remains controversial

Assessing heat tolerance of Alentejana and Mertolenga portuguese cattle breeds under influence of solar radiation

Abstract Objectives: During summer in Mediterranean regions, well adapted native cattle breeds present differences in environmental tolerance. The objective of this study was to compare heat tolerance of Alentejana and Mertolenga heifers under direct solar radiation, by quantifying the pathways of evaporative thermolysis and thermostability. Materials and Methods: The experiment was carried out in 5 days. 6 Alentejana and 6 Mertolenga heifers were kept under direct solar radiation, in individual stalls (3.0 —1.1 m) and restrained by head halted. Food, water and mineral mixture were available ad libitum. Respiratory frequencies (RF) were measured by observing costal movements, rectal temperatures (RT ) were measured using a digital thermometer (Digitron, with an 8-cm flexible probe) and thermal balance was calculated according to procedures described by Silva et al., (2010). These measurements were carried out every day at 06:00, 10:00, 13:00 16:00 and 20:00h. Heat storage (HS) was calculated as described by McGovern and Bruce (2000). Sweat rate was measured at 15:00 hours using methodology described by Pereira et. al. (2010). Variables were analyzed according to a general linear model procedure with 2 fixed factors (breed and hour) and 1 nested factor (animal within breed). Results: Except for the cases of RT and HS, in the other variables no significant differences between the breeds were found. Despite the absence of significant differences in the thermal balance between breeds, there was a slightly tendency for a bigger acquisition of heat in Alentejana and a faster recovery in the Mertolenga after 16:00h. The sweating rates were not significantly different, with mean values of 271.5 and 286.3 (g.m-2.h-1) respectively for the Alentejana and Mertolenga. Respiratory frequencies were virtually equal between breeds. In RT there were significant differences between breeds. The Mertolenga has shown significantly lower RT at 16:00h and 20:00h, with 38,9ºC and 38,7ºC compared to 39,3ºC and 39,1ºC in Alentejana. The same trend was found in the HS at 16:00h and 20:00h with 0,018 and 0,016 W.m2 in Alentejana compared to 0,014 and 0,009 W.m2 in Mertolenga. Conclusions: The results show that both breeds present good heat tolerance. The sweating rate values of both breeds are very high and are quite similar to those found in tropical cattle breeds. However, Mertolenga shows slightly better thermal balance and evaporative heat loss (SR ans RF), which eventually may have contributed to the enhanced thermostability comparatively to Alentejana. The superior stability of the RT and particularly the lower HS suggest a higher heat tolerance of Mertolenga breed

Reactivity of Nelore cows during reproductive management

The Nelore breed is recognized as rustic and well adapted to parasites and high temperatures, and these features composes a good part of the Zebu genetic group. However, they are considered more reactive than other breeds and for this reason they require more time to be managed, putting at risk the safety of employees, the animals themselves and also compromise installations. In order to solve problems such as short duration and high nocturnal occurrence of oestrus many properties choose to perform artificial insemination during the breeding season. At this time, there is an intensification of human-animal interaction in short periods and at different times. When animals are more reactive on handling and are exposed to an uncomfortable thermal environment the stress rises causing impacts on reproduction and production. Stress is comprehended by a set of behavioral and physiological changes when in threatening or uncomfortable situations caused by stressors (physical environment, social or management practices). Some farms have already made the selection for temperament, using different methods of evaluation in accordance with the conditions of creation and infrastructure available at the property. Thus, the aim of this research was to evaluate the reactivity of Nelore cows in different managements that occur in the breeding season. Was evaluated 20 multiparous Nelore cows from October 2013 to March 2014, during the spring and summer seasons with air temperature averages ranging from 22.7 ± 4.9°C to 25.2 ± 4.7°C, in the Campus’ beef cattle sector of the Universidade de São Paulo in Pirassununga. Reactivity was evaluated using scores of escape velocity or output speed using subjective scores: 1 - does not leave the chute, needs to be touched; 2 - walking out the chute; 3 - exits the chute at average speed; 4 – exists the chute quickly. So, as higher is the score as higher is the stress. The scores were given immediately after the animals exists the chute from the managements of sync (M1), artificial insemination (M2), pregnancy diagnosis at 30 days (M3), pregnancy diagnosis at 60 days (M4), pregnancy diagnosis at 90 days (M5). The data of the escape score was analyzed using analysis of variance, using the GLM procedure of SAS and means were compared using the Tukey test at 5%. It was noted that, there was no differences on the average of escape score (2.34) at the managements M1, M2, M3 and M4. However, in management M5 the average was 1.79 differing from the other managements (P<0.05). In this way, at the last management, there was a reduction of 23.50% in escape score. So, we conclude that with the increase in frequency of human-animal interactions during the reproductive managements, there is a decrease in the escape score and consequently the stress, contributing to the agility on each management, security of employees, lower physical trauma on animals and damages to facilities

Physiological and behavioral responses of Holstein cows housed under cooling system

Este estudo teve como objetivo avaliar a influência de recursos de climatização, ventilação e nebulização, sobre a fisiologia e o comportamento de vacas Holandesas alojadas em free-stall, durante o verão do sudeste brasileiro. Foram utilizadas 20 vacas Holandesas submetidas a dois tratamentos com e sem climatização. Os parâmetros ambientais registrados foram temperatura de bulbo seco, umidade relativa do ar e temperatura de globo negro. As variáveis fisiológicas avaliadas foram temperatura retal e frequência respiratória. As variáveis comportamentais registradas foram postura e suas atividades dentro da instalação. Para análise estatística utilizou-se a metodologia de quadrados mínimos por meio do procedimento PROC MIXED e PROC GLM. Apesar das diferenças estatísticas obtidas para as variáveis fisiológicas, as mesmas não foram biologicamente efetivas e indicaram que os animais se encontravam em conforto térmico. Os animais que dispunham de ventilação e nebulização alimentaram-se mesmo nas horas mais quentes do dia. A climatização é uma estratégia que permite maior conforto térmico aos animais e por consequência pode aperfeiçoar a produção leiteira através do aumento no consumo alimentar

In vivo and in vitro heat shock proteins gene expression in cattle.

The main purpose for this study was the quantification of the heat shock proteins HSPA1A and HSP90AA1, in cow lymphocytes, when subjected to heat stress directly - in vivo, or indirectly - in vitro. The aim was to identify differences between HSP expression in vitro and in vivo. The experiment was conducted in the Biometeorology and Ethology Laboratory of FZEA-USP. Were used three female Holstein Frisian, which were subjected to heat stress, by sun exposure. The blood samples were collected after sun exposure, with a temperature of 40 ± 2 º C, during three days. For in vitro tests, blood of the same animals was collected and placed for a period of 4 hours in a water bath at 40 º C, thus simulating the thermal stress. Total RNA of lymphocytes was extracted, treated with DNase I and submitted to cDNA synthesis for gene expression quantification of HSPA1A and HSP90AA1, by real time PCR (qRT-PCR). The data were tested for normality by Kolmogorov-Smirnov test and for homocedasticity by Levene test. Data were analyzed according to a general linear model procedure with 2 fixed factors treatment and genes expression. Significantly different means were submitted to post-hoc comparisons of means (LSD test) and regarded as significantly different when P<0.05. The results showed that there are no significant differences between the in vitro and the in vivo treatments

Influence of season on plasmatic cortisol and IGF -I in dairy cows under thermal comfort.

Objectives: Access to evaporative cooling system can increase production in dairy cows due to improve thermal comfort. The aim of this study was to evaluate the impact of ambient temperature on thermoregulation, cortisol and IGF-I, and determine the efficiency of evaporative cooling system on the physiological responses in different weather patterns. Materials and Methods: 24 Holstein cows were housed in two groups with or without access to cooling system with fans and mist in the free-stall. The parameters analyzed were: rectal temperature (TR ), body surface (TS ), internal base of tail (TC ), respiratory rate (FR), cortisol and IGF-I during the morning milking (700h) and afternoon (1430h) in five different weather patterns throughout the year (fall, winter, spring, dry summer and rainy summer). Results: TR , TS , TC and FR were lower in the morning (P<0.01). Cooling system did not affect rectal temperature, with both groups had values below 38.56 over the year (P=0.11). We observed an upward trend (P<0.05) in plasma cortisol concentrations between autumn and winter, starting the decline until the dry summer and a further increase during the rainy summer. A gradual increase of IGF-I happened between autumn until the dry summer, and decreased during the rainy summer (P<0.05). Cortisol and IGF-I may have been influenced by light hours. TR showed a moderate and positive correlation (P <0.001) with the TS (0.46) and FR (0.35). The air temperature and THI showed positive moderate to high correlations with TR , TC , TS and FR (P <0.001). Conclusions: The ambient temperature influences positively on the physiological variables, independent of the cooling system, but cooled animals kept milk production even during the summer. The plasma concentrations of cortisol and IGF-I may have been influenced by the seasons and the milk production