Temperatura de superfície corporal em vacas leiteiras mestiças em condições climáticas do Triângulo Mineiro/Brasil

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Reatividade e níveis de cortisol, glicose e insulina em cordeiros confinados suplementados com cromo

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Rectal temperature and conception of inseminated crossbred dairy cows

In tropical and subtropical regions animals suffer pronounced heat stress effect on reproductive function, being one of the most noticeable effects the reduction of conception rate. When evaluating animals heat stress, rectal temperature measurement is important tool because indicates heat release mechanisms became insufficient to maintain homeothermy. This study aimed to evaluate body temperature at fixed time artificial insemination of crossbred dairy cows and their conception at 30 days pregnacy. Experiment was performed from April 26, 2010 to January 28, 2012 at Estação Experimental Glória of Universidade Federal de Uberlândia, at Triângulo Mineiro, Brazil. One hundred-twelve crossbred dairy cows and heifers were used. At the moment of insemination, animals were housed in shaded pen and body temperature was collect using clinical thermometer introduced in rectal mucosa. Environmental variables collect were air temperature, maximum temperature, minimum temperature and relative humidity. Data were analyzed in two different periods: from April to September (mild weather-MW) and from October to March (hot weather-HW). The statistical model included the effect of category, period, pregnancy diagnosis and their interactions, comparing means by Tukey’s test, with a significance level of 5%. Means and standard deviations of air temperature, maximum temperature, minimum temperature and relative humidity for MW and HW, were respectively, 23.85 ± 3.44°C and 23.15 ± 2.07°C; 29.16 ± 1.79°C and 29.84 ± 3.40°C; 16.20 ± 3.00°C and 21.06 ± 2.28°C; 82.72 ± 8.49% and 94.54 ± 4.66%. Rectal temperatures are presented on Table 1. Thermal environment of both weathers set up thermal comfort condition. Rectal temperature detected was within normal limits and it did not vary with pregnancy stage or weather condition, but was higher on heifers on mild weather probably because more reactivity behavior

Transepidermal water loss in ewes submitted to sun exposure

The work aims to determine thermolysis capacity by losses by sweating using trans epidermal water loss values (TEWL) and by tachypnea. Fifty six Santa Ines ewes were divided in facilities having covered area with a cement floor and ï¬ber cement roof panels (4 m high, 8 x 10 m) and uncovered area with hard dirt floor (15 x 15 m). Thermolysis capacity was evaluated using heat stress challenge in three consecutive days, in which animals stayed under the shade, from 08:00 to 13:00 h, when the ï¬rst sample was taken (T0: 08:00 h). From 13:00 to 14:00 h, they stayed in sunny place for 1 h, and the second sample was taken (T1: 14:00h). Then, animals went back to the shade, where they stayed for more 45 minutes (14:00–14:45 h), and the third sample was taken (T2: 14:45h). TEWL with a VapoMeter (Delfin, Finland), respiratory rate (RR) by count of movements per minute and rectal temperature (RT) with a digital thermometer were collected in all sampling times. During the heat challenge, air temperature and relative humidity were measured under the shade and in the sun (Table 1). Variance analysis with multiple comparisons of means by Tukey test at 5% was performed. The study was approved by Ethics Committee of USP (12.1.755.74.9). The highest values of TEWL, RR and RT were found shortly after 1 hour of sunshine (P<0.05, Table 2). Despite TEWL and RR decreased after 45 minutes under the shade, RT did not decrease significantly during this period. This can be explained by the lower thermal inertia for body heat loss, with 17.4% decrease in RR and 0.21% in RT. TEWL can be used to evaluate thermolysis capacity of ewes in addition to RR

Use of lipopolysaccharide (E. coli) as stress inducing in sheep in intermediate stage of pregnancy

To analyze stress during the intermediate stage of gestation, 43 multiparous, crossbred Santa Inês, pregnant ewes, with a average age of 5 and average body weight (BW) of 60kg, were challenged with a intravenous administration of 0.8µg.kg-1 of LPS (lipopolysaccharide E. coli - outer membrane cell of gram-negative bacteria), diluted in physiological saline solution - simulating an immune stressor. The females were placed in individual cages at feedlot, with adaptation period of 5 days before the begin of sampling, with free access to good water quality, shade and food in the trough (corn silage and mineral supplementation). The ewes were divided into three groups, with a completely randomized design (CRD): CG - control group, with 15 animals that were not subjected to stress; IG - intermediate group stage, with 14 animals undergoing stress at 70 days of gestation; FG – final group, made up of 14 animals undergoing stress at 120 days of gestation. The variables used to investigate stress were measured during the intermediate stages of pregnancy in a 24 hour sampling, with this was possible to observe the change in rectal temperature (RT) and blood levels of cortisol by its circadian rhythm. Shortly after the baseline sampling, the treatment corresponding to the intermediate stage of gestation was submitted to stress, with the sampling interval of one hour each, from the first to the third samplings and after it the samplings was taken from two to two hours till the end of 24h sampling. At the same time, a dose of placebo was administered in the animals that didn’t receive LPS, equalizing the effect of the invasive needle. The study was approved by Ethics Committee of FZEA/USP (13.1.2109.74.8). Variance analysis was performed with multiple comparisons of means by Tukey test with 5%. Significant difference in RT between IG and the other treatments at 07:00 h, 09:00 h, 11:00 h, 23:00 h, 01:00 h, 03:00 h and 05:00 h were observed, with no difference (P>0.05) between CG and FG in those times. As cortisol levels during the circadian rhythm, the figures for IG were higher than the CG and FG to 06:00 h, 07:00 h, 09:00 h, 11:00 h, 13:00 h, 15:00 h, 01:00 h and 03:00 h. No significant differences (P>0.05) were observed between CG and FG in any of the crops of cortisol. The highest RT for IG was observed at 21:00 h, with a range of 1.26°C basal RT, but there was no significant difference within treatments at 9:00, a time that had the highest the amount of cortisol. As the values of RT the three treatments differed at 9:00 h, where it was found the highest value of serum cortisol in time for IG, with a difference of basal crop of 12.4225 µg d/L (P<0.05). The use of LPS to induce stress in sheep at the intermediate stage of pregnancy promotes interference in the values of rectal temperature and blood cortisol levels when measured during the circadian rhythm

Thermal regulation in horses submitted to exercise at different times of the day

It is evident the necessity of a better understanding regarding the influence of warmth on the performance of horses in training, establishing that an efficient thermoregulation is essential to provide the physiological demands resulting from effort required and the climatic variables which the animal is exposed. This study aimed to evaluate thermoregulation in horses subjected to 30 minutes of exercise during three periods of the day with different air temperatures and to compare two techniques for measuring the sweating rate (SR) and trans epidermal water loss (TEWL). Three castrated crossbred horses were submitted to a series of half an hour of exercise at different moments (07:00, 13:00, 16:00 hours), carried out as follows: 3 minutes walking, 3 minutes of canter, 10 minutes of trot, 10 minutes of canter, 2 minutes of trot and 2 minutes of canter. Relative humidity, black globe and air temperature were 50%, 34Cº and 20.8ºC; 62%, 35ºC and 28.8Cº; 48%, 34.5Cº and 27.4Cº; respectively for the three periods. Rectal temperature (RT), respiratory rate (RR), body surface temperature (BST), SR through the methodology of Schleger and Turner (1965) and TEWL measured by VapoMeter (Delfin, Finland) were taken before and after exercise. Model for analysis of variance included fixed effects of time and moments, and the means were compared by Tukey test or T at 5% of significance. Significant differences were observed between all variables at all time of samplings, except for the values of BST and TEWL at 13:00 hours. Regarding time of the day, significant differences were observed after exercise in variables RR, RT and BST, and also differences in the BST between the three periods before exercise. In this context, the time of day and weather can influence the thermoregulation. The use of VapoMeter was easier because it was faster and did not have external influences of relative humidity, however, it is necessary to carry out more researches to validate this equipment to horses

Estresse gestacional em ovelhas e cordeiros no momento do parto

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Efeito de um tratamento aversivo no comportamento de leitões em lactação

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