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

Use of Barkhausen Noise in Fatigue

Barkhausen noise is generated by abrupt changes in the magnetization of materials under applied AC magnetizing field /1/. These changes are known to be affected by residual and/or applied stresses /2, 3/. Monitoring the Barkhausen noise under controlled conditions then provides a means of evaluating the stress state of the material /4/. The relation between stress and Barkhausen noise level is illustrated in Figure 1: the lower the compressive stress or the higher the tensile stress, the higher the Barkhausen noise level

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

Correlation between methods of temperament evaluation on confined Angus x Nellore crossbreed steers

The aim of this study was to understand the correlations between the three methods of temperament evaluation on confined beef cattle. The experiment was conducted at the Laboratory of Biometeorology and Ethology of the Faculty of Animal Science and Food Engineering of the University of São Paulo, FZEA/USP, in Pirassununga Campus, State of São Paulo (21°57'12'' South, 47°27'06'' West, 606 meters). One hundred and twenty Angus and Nellore crossbreed male steers with an average of 17 (±2) months of age and 365.4 (±29.97) kg of initial body weight, were finished in a feedlot during 130 days, housed in four pens, with 20 m 2 of free area, 6 m 2 of artificial shade, and 70 cm of linear feeder per animal. Every 28 days the animals were weighed, and at the same time the temperament was assessment by the Crush Score Tests in squeeze chute (CS) assigning a 1-4 score (ranging from non-reactive to very reactive). After, the exit velocity of the animal from the chute was measured, named Flight Speed (FS). The Qualitative Behavior Assessment (QBA) was recorded by the individual observation of the animal in a corral, after exit from the chute, and then describe its body language using a list of six adjectives/indicator categories (motor activity, relaxed, agitated, fearful, attentive and calm), quantified along a 125 mm visual analog scale, which indicates the intensity of each behavioral expression. Specific and trained person made these entire tests. Spearman’s correlations were used to examine the relationship between CS, FS and QBA. The means observed for FS and for CS were 3.28 ±0.083 m.s -1 and 1.96 ±0.058, respectively. There was a negative correlation (p<0.05) between FS and CS (-0.37) and between FS and the QBA categories of motor activity, agitated and fearful with values of -0.48, -0.41 and -0.39, respectively. The correlation results allow us to conclude that animals, which were more reactive to containment during weighing, showed lower flight speed afterwards, but were then more active, agitated and fearful in a corral as evaluated by the QBA

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

Cortisol fecal em ovinos: curva de excreção e estabilidade

Objetivou-se determinar a curva de excreção do cortisol fecal perante exposição a uma situação de estresse, correlacionando com concentrações de cortisol sanguíneo. Foram colhidas as fezes de seis fêmeas mestiças (Dorper x Santa Inês) durante 24 horas após a aplicação do hormônio adrenocorticotrófico (ACTH), além de colheitas de sangue realizadas antes da aplicação do ACTH (0,6 UI por kg PV, Porcine ACTH 1-24, Sigma, St. Louis, MO, USA), 60, 120 e 300 minutos depois. Os dados da curva de excreção foram analisados por ANOVA, bem como pela correlação entre os valores de cortisol sanguíneo, fecal e reatividade. Para avaliação das variáveis comportamentais foi realizada a transformação de escala dos dados para “arco-seno raiz de porcentagem”, procedendo-se à análise de variância com efeitos de dia (1, 2 e 3) com análise individual por animal. Os parâmetros de cortisol sanguíneo, frequência respiratória e temperatura retal foram analisados pelo teste t e correlação de Pearson. Todas as comparações de médias foram realizadas por teste F e teste t (PDIFF). A reatividade durante a colheita não exerceu efeito significativo sobre os valores de cortisol sanguíneo. Os valores de cortisol sanguíneo apresentaram médias maiores aos 60 minutos após a aplicação do ACTH e, após 300 minutos as ovelhas apresentaram níveis de cortisol considerados normais para ovinos sem estresse. Por outro lado, o pico de cortisol nas fezes foi verificado aproximadamente 10 a 12 horas após o pico de cortisol no sangue, não sendo verificadas diminuições significativas nas concentrações que indicassem o retorno aos níveis basais durante o período de 24 horas (P>0,05)

Heat loss efficiency and thermoregulation responses of Nellore cows

Abstract: Nellore cattle is well adapted to tropical environmental conditions with good thermoregulatory characteristics. However, knowledge related to body temperature regulation and acclimatization mechanisms are still scarce. This investigation aimed to understand the heat loss efficiency and thermoregulation responses of Nellore cows in tropical climate conditions. In this study was used 16 healthy purebred Nellore cows classified by heat loss in efficient and non-efficient using the vaginal temperature continuously monitored by data-loggers. The rectal, tail and ocular temperatures, sweating rate and respiratory frequency were also measured to understand the thermoregulatory responses and correlate to previous classification. In our findings, were noticed that according to heat loss classification the nonefficient cows showed greater amplitude of temperature variation. The body temperature increased from 12:00 PM to 19:00 PM with gradual decreased from 19:00 PM to 07:00 AM, reaching the peak in both groups at around 16:00 PM. In addition, the efficient cows presented higher sweating rate than non-efficient that presented higher rectal temperature, therefore the reduction of body temperature by improving evaporative mechanisms is a good trait of acclimatization to heat. No statistical difference was observed for the other physiological variables between groups. In conclusion, the methodology to classify the cows by heat loss using vaginal data loggers allowed us to distinguish Nellore cows according to their body temperature regulation, being feasible and reproducible. Furthermore, the efficiency to heat loss of this bred was mainly associated with sweating capacity

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