Climate change is seen as a significant threat to the sustainability of livestock production systems in many parts of the world, particularly in tropical regions. Extreme meteorological events can result in catastrophic production and death of livestock. Heat waves in particular can push vulnerable animals beyond their survival threshold limits. However, there is little information about buffalo responses to sudden changes in the thermal environment, specifically the heat waves. This study aimed to quantify the thermoregulatory and blood biochemical responses of heat-acclimatized buffaloes to a simulated heat wave. The experiment was designed in a climatic chamber with two periods of 4 days each. Twelve heat acclimated buffalo heifers aged 18 months were used. The climatic chamber environment was set as follows: 4-day period (P1) simulating the same weather conditions of a summer in humid tropical climate used as a baseline, with daily cycle with Ta and RH at 27 ± 1 °C and 76% from 0600 h to 1900 h and 24 ± 1 °C and 80% from 1900 h to 0600 h, and 4-day period (P2), simulating a daily heat wave cycle, from 0600 h to 1900 h with Ta and RH kept at 36 °C and 78% and from 1900 h to 0600 h, 27 °C and 74%. All animals were subject to both treatments and data were analyzed by a repeated measure analysis of variance, with post-hoc pooling comparison performed by Tukey’s test. In P2, there was observed a significant increase in respiratory frequency (p < 0.01), found four times in P1. The sweating rates were quite high in both periods; still, there were significant increases in P2 compared to P1 (p < 0.01) (4931 and 3201 g/m2/h, respectively). A slight but significant increase in rectal temperature was observed during the day (p < 0.01), with a rising until 1900 h. The simulated heat wave in P2 did not affect the values of the erythrogram or leukogram, excluding the significant reduction in K+ (p < 0.05). The low heat storage and the subsequent fast and full recovery of the thermal balance late afternoon appear to be related to the high sweating rate values. The massive sweating rate emphasizes its relevance in the maintenance of buffalo homeothermy. The absence of changes in hematological parameters has revealed the considerable physiological resilience of buffaloes toward simulated heat waves.
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. ARTICLE HISTORY
a b s t r a c tThis study aimed to identify the parameters related to the expression of the reactivity in horses during handling and based on that proposed and validated a scale of composite measure reactivity score to characterize horse's reactivity. To this end, the first stage (S1) proposed the scale and the second (S2) validated it. In S1, 364 Lusitano horses were evaluated, 188 were adult breeding mares (4-12 years old), and 176 were foals (males/ females, aged from 2 months to 2 years). During hooves trimming, vermifuge application, palpation scores were assigned to behaviors of movement, ears and eyes position, breathing, vocalization, and urination. A response parameter called reactivity was attributed to each animal, ranging from score 1 (nonreactive/calm) to score 4 (very reactive/ aggressive). The verification of the possible parameters (age, behavior), which explains the response parameter (reactivity), was taken using ordinal proportional odds model. Movement, breathing, ears and eyes position, vocalization, and age appear to explain the reactivity of horses during handling (P < .01). Therefore, based on these parameters, it was possible to propose two scales of composite measure reactivity score: one to characterize the mares and another the foals. On S2, the proposed scale was validated by the simultaneous application of Forced Human Approach Test, another commonly used test to evaluate the reactivity in horses, with a correlation of 0.97 (P < .05). The assessment of the reactivity of horses during handling by a composite measure reactivity score scale is valid, and easy to apply, without disrupting daily routine and override the impact of individual differences.
ResumoO objetivo do presente estudo foi avaliar a reatividade de equinos durante o manejo habitual de escovação, frente à exposição repetida a um estímulo sonoro desconhecido. Para isto, foram utilizados 20 equinos da raça Mangalarga Marchador, de diferentes categorias (éguas e potros), os quais foram alocados aos tratamentos: controle (N = 10) e com estímulo sonoro desconhecido (N = 10), que consistia em confrontar os animais com o estímulo sonoro de um chocalho e um tamborim. Primeiramente, foram realizadas quatro avaliações consecutivas (dia 0, 1, 2, 3). Após 30 dias da primeira coleta, foram realizadas duas avaliações consecutivas (dia 30 e 31), e passados 15 dias desta, foram realizadas mais duas avaliações consecutivas (dia 45 e 46). As observações comportamentais foram feitas por meio da atribuição de escores aos comportamentos de movimentação, posição das orelhas e dos olhos, respiração e vocalização durante o manejo de escovação. Também foi conferida a variável resposta de reatividade com valores variando de 1 a 4 (animal não reativo ou calmo a animal muito reativo ou agressivo). Foi ajustado o modelo de regressão logística ordinal usando como covariáveis as categorias, dia e tratamento. A reatividade dos animais com estímulo sonoro desconhecido foi maior. Os dias do período experimental influenciaram a reatividade dos animais entre 6 e 7 meses de idade, com diminuição das chances dos animais desta idade apresentarem maior reatividade no decorrer dos dias. O amadurecimento do potro junto com a exposição repetida ao estímulo sonoro desconhecido podem diminuir a possibilidade de o animal ser reativo.Palavras-chave: Cavalo. Comportamento. Temperamento. AbstractThe 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 a...
CALVIELLO, R.F. The influence of relationship between the mare and foal in social behavior and temperament of the foals Mangalarga Marchador. 2016. 122f. Thesis (Doctoral)
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