Cães pastores - notáveis companheiros e muito úteis em sistemas de produção eficientes.

Criadores de bovinos, um pouco por todo o mundo, têm vindo a perceber que o aumento do nível tecnológico dos seus sistemas de produção beneficia bastante com a introdução de um bom cão pastor. Um cão pastor tem um marcado instinto de pastoreio, uma grande inteligência e uma profunda ligação ao seu dono, com quem quer trabalhar e a quem quer agradar.A relação inicial predador–presa deve alterar-se através de boas práticas de maneio e de reforço positivo. As vacas devem aprender a confiar e a obedecer ao cão, da mesma forma que acontece com o Homem. Esta mudança de atitude também facilitará o maneio do efectivo, melhorando a segurança dos operadores e reduzindo os riscos de acidentes. Esta modelação do comportamento, baseada na confiança recíproca fará toda a diferença, pois possibilitará maior economia e eficiência na utilização da mão-de-obra, maior rapidez na execução dos trabalhos com o efectivo, maior docilidade dos animais com menores riscos de acidentes, níveis satisfatórios de bem-estar e um aumento da rendibilidade do efectivo devido aos menores gastos energéticos. Um cão pastor bem treinado é um óptimo companheiro e é uma mais-valia no quotidiano de explorações com elevados índices tecnológico

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

Estimação da zona de conforto térmico de ovinos deslanados

Conduziu-se um experimento na câmara bioclimática do Centro de Estudos Bioclimáticos da Universidade Estadual do Sudoeste da Bahia – Brasil, cujo objetivo foi estabelecer a zona de conforto térmico para ovinos deslanados. Em um experimento completamente casualizado, sete fêmeas da raça Santa Inês (repetições) foram expostas durante três dias consecutivos a cada um dos sete tratamentos (temperaturas de 10, 15, 20, 25, 30, 35 e 40oC na umidade do ar fixa de 65%), Entre cada tratamento, os animais ficavam ao ar livre por cinco dias para eliminar o efeito residual. Foram coletadas as temperaturas de bulbo seco e úmido e de globo negro e calculados o THI e BGHI. Também, se mediu as variáveis fisiológicas freqüência respiratória, freqüência cardíaca e temperatura retal.Os testes de adaptabilidade utilizados foram os de Ibéria, Benezra e Benezra modificado. Concluiu-se que a zona de conforto térmico para ovinos deslanados está entre 15 e 25oC sob 65% de UR

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

Influence of availability of shade on testicular characteristics of Santa Ines rams

The purpose of this study was to evaluate the effects of availability of artificial shading on testicular and seminal characteristics of Santa Ines crossbred rams. Twelve 8 month old rams at 38.1 ± 5.2 kg average weight, were used in a total random design with two treatments: areas with and without available artificial shading (black polyethylene mesh screen for a 50% reduction of solar radiation). The scrotal circumference, scrotal length, scrotal volume, rectal temperature and scrotal temperature were measured twice a week. Also a biweekly analysis of the semen was carried out, measuring the volume and spermatic concentration as well as the percentage of normal spermatozoa. The results show that available shading provided for lower scrotal temperatures and higher sperm concentration, without influencing the scrotal volume and the percentage of normal spermatozoa. The testicular measures, such as the scrotal circumference and length were higher in the rams that were subjected to the no available shading treatment. The absence of differences, in some of the analyzed variables, between the two treatments, with and without available shading, could be due to high adaptability of the animals

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

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

Características físicas dos ovos da perdiz vermelha (Alectoris rufa) criada em cativeiro

The objective of the present study was to evaluate the effects of female age (1, 2 and 3-year-old) and month of laying (March, April and May) on the physical characteristics of the red-legged partridge eggs reared in captivity. O objetivo do presente estudo foi avaliar os efeitos da idade das fêmeas (um, dois e três anos) e do mês de postura (março, abril e maio) sobre as características físicas dos ovos da perdiz vermelha (Alectoris rufa) criada em cativeiro. O peso (W), o comprimento máximo (L) e a largura máxima (B) de 2878 ovos foram determinados diretamente, enquanto o índice de forma (B/L), o volume (V) e a superfície (S) foram calculados com base nos parâmetros determinados diretamente. A análise mostrou diferenças significativas (P0,05). Observaram-se diferenças significativas (P<0,01) na largura máxima e no índice de forma do ovo entre as diferentes classes de idades, com valores mais elevados nas fêmeas mais velhas e no período de postura mais tardio. O volume dos ovos estimados por meio de V1 = 0,51LB2 e V2=0,913W foi afetado significativamente (P<0,01) pela idade e pelo mês de postura, bem como as áreas, S1=4.835W0,662, S2=4,951V10,666 e S3=4,951V20,666, as quais apresentaram os mesmos efeitos. Palavras-chave: perdiz vermelha, Alectoris rufa, características dos ovo

Kidney histological alterations and metallothionein and heat shock protein expression in Wistar rats after fungicide thiram exposure

The histological alterations and the expression of metallothionein (MTs) and heat shock protein (Hsp70) in the kidney of Wistar rats after thiram fungicide exposure were evaluated. Animals were distributed into three groups: standard diet group, standard diet + corn oil group and thiram group. Significant differences were found (P<0,05) in the evolution of body weight between rats in the thiram group and those in the control and corn oil groups, and no histological lesions were evident in the animals’ kidneys. Differences were found among animals in the group exposed to thiram and the control and oil groups regarding histomorphometric characteristics of the renal corpuscle – except for the proportion in the area of Bowman’s capsule: glomerulus area – and regarding the height of the epitelium in the distal tubules. In rats exposed to thiram, a positive moderate to strong immunoexpression was observed for MTs, in the cortical convulated tubules decreasing the cortex towards the medulla, and a strong immunoexpression for Hsp70 in the cortex and medulla areas, in the glomerulus and convulated tubules. The results suggest that thiram may have chronic toxicity in mammals affecting their growth, and that the expression of MTs and Hsp70, a probable cellular adaptive response to the oxidative stress caused by thiram, may be used as a biomarker of exposure to this chemical. Keywords: rat, kidney, thiram, histology, metallothioneins, heat shock proteins (Hsp70