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

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

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

Effect of artificial shading on performance and reproductive parameters of semi-confined young Brangus bulls

Thirty Brangus bulls were used in a 90-d study to assess the effect of artificial shading on the performance and reproductive characteristics of semi-confined cattle. Animals were kept in four one-ha paddocks in two groups of eight for shade treatment (5 m²/animal of 80% solar block shade cloth) and two groups of seven animals in no-shade treatment. Each treatment had two homogeneous groups, each divided into heavy-bulls (351-450 kg) and light-bulls (300-350 kg). Time spent under shade, time standing, average daily gain, testicular development and sperm quality were investigated. Animals spent 24% of the daylight under the shade and no-shaded bulls spent more time standing (P 0.05) and testicular development between shaded and no-shaded animals. However, scrotal perimeter was higher for shaded light animals compared to no-shaded light bulls (P < 0.10). Sperm motility increase during the experimental period for shaded animals (P < 0.05) and sperm abnormalities were higher for the shaded ones (P < 0.05). Although the results did not indicate pronounced benefits on cattle performance, this resource was an important alternative because it appears to provide an improvement in some reproductive parameters and ensure a better thermal comfort to the animals

Application of a thermolysis capacity test for dry and lactating cows

The heat stress has negative effects on animal comfort and productivity. Genetic progress in milk production is related closely to an increase in metabolic heat increment, which makes cows more affected by heat stress. Individual thermotolerance can be an important tool in genetic selection. The study aimed to validate a new proposal for assessing the ability of heat loss after sun exposure in cows and its application in dry and lactating cows kept or not on thermal comfort condition. The test consists in three days of sun exposure for one hour followed by one hour rest in the shade to determine the individual thermolysis capacity (TC) by the variables rectal temperature, body surface temperature, internal tail base temperature, respiratory rate, plasma cortisol and IGF-I. In the new proposal these physiological variables were measured before sun exposure, after 50 min in the sun and after one hour in the shade (T0, T1 and T2 consecutively). The test in which this new test was adapted lacked T1.The three day test was applied with similar meteorological variables as black globe temperature of 48.1°C (1.32), air temperature of 31.7°C (0.92) and relative humidity of 39.5% (3.38). The differences between dry and lactating cows were measured in 28 animals divided into two experimental groups housed in free-stall with and without evaporative cooling system (mist and fans). The animals remained at the facility for seven months (from spring to summer) then after they were subjected to heat stress and the TC (10-[(T1-T0)-(T2-T1)]) was determined. There was no difference between the TC of dry and lactating cows (P>0.05), but respiratory rate and IGF-I were greater and body surface was lower in dry cows during sun exposure (P0.05). The thermolysis capacity test was validated and can be used for either dry or lactating cows. Milk production did not influence the thermoregulatory responses of Holstein cows, but when lactating and kept in cooling system they showed better thermolysis capacity index

Reactivity in ewes submitted to invasive and non-invasive techniques of samples collections

The first-time experience of a procedure or with a person should be as positive as possible. If a procedure is very aversive or painful at first contact, it can be difficult to persuade the animal to return to the local where this occurred. For this reason it is important to develop a strategy in experimental and routine activities, taking into account that sheep has often reactive temperament. This study aims to evaluate the possible decreased of the reactivity in sheep across the prior presentation of invasive and non-invasive techniques for collecting saliva and blood samples for cortisol analysis and transepidermal water loss through the use of Vapometer®. Saliva was collected using Sallivetes® and blood was taken from the jugular vein in heparinized tubes, placed on ice, and then centrifuged at 4 °C and 3,000 for 15 min. The tubes containing serum were stored at −20 °C until CORT and IGF-I determination using an enzyme immunoassay kit (Diagnostic Systems Laboratory, Webster, TX). The collection of transepidermal water loss (TEWL) was performed using a Vapometer ® (Dolphin, Finland) device. In the three techniques the ewes were always contained by the same person for the time necessary to collect the variable. To take saliva samples the animals were contained during 2 minutes, for blood samples during 1 minute and for TEWL during 30 seconds. The test consists of six data collections performed with increasing intervals between days, checking the possible adaptation of the animal management factors. The first interval was 2 days and after 3 days, then after 4 days, and the next was 7 days and again 7 days, totaling 24 days of experiment. Before sampling saliva, blood or TEWL the reactivity of the ewes was analyzed by a composite score scale when animals were inside the chute. The composite score (CS) is a combination of the scores of: entrance (1 to 4), respiratory rate (1 to 4), vocalization (0 or 1), movement (1 to 4) and flight speed (1 to 4). After the chute a score of containment (1 to 4) was attributed by the same person, which had contained the animal. The experimental unit was each animal and the average of the observations in each sheep was used for the statistical analysis. The observed data of transepidermal water loss, salivary cortisol and serum cortisol were subjected to analysis of variance, with the days and the groups as fixed effect. In case of significant results (P<0.05) it was adopted Tukey-Kramer Test as the procedure for multiple comparisons. Cortisol decreased for saliva and blood groups during the experiment days (P<0.05), showing habituation of the animals to the management. In the same way, TEWL had the highest mean value on day 1, and decreased afterwards (P<0.05). The score of containment was lower for the TEWL group compared to the other two groups (P<0.05), however the higher value was observed on day 5, seven days after a sampling (P<0.05). The score of containment of saliva and blood groups decrease in day 2, but return to increase in the next sampling day (P<0.05). The CS was higher for saliva group (P<0.05). On day 5 CS increased for blood group, but decreased for TEWL (P<0.05). The invasive techniques (saliva and blood) increased the reactivity of sheep before and after retention. Sheep are reactive animals therefore need a more gentle handling during the experiment with invasive samples