Avaliação das respostas fisiológicas de bezerros zebuínos puros e cruzados nascidos em clima subtropical
01 Jun 2006-Revista Brasileira De Zootecnia (Sociedade Brasileira de Zootecnia)-Vol. 35, Iss: 3, pp 1146-1153
TL;DR: The influence of environmental parameters on the physiological responses of purebred and crossbred Nellore calves born in a subtropical region was studied and PT level was significantly higher in NR calves than in NI ones.
Abstract: Estudou-se a influencia de fatores climaticos sobre as respostas fisiologicas de bezerros, puros e cruzados, filhos de vacas da raca Nelore ou de alta mesticagem de Nelore acasaladas com touros das racas Aberdeen Angus (AN), Simental (SN), Canchim (CN) e Nelore (NI e NR). Os bezerros AN, SN, CN e NI foram mantidos em sistema rotacionado intensivo, enquanto o grupo NR foi mantido em sistema extensivo. Os bezerros foram observados de forma direta desde o nascimento ate a primeira mamada, medindo-se a latencia para a primeira mamada (LM). Aproximadamente 24 horas apos o parto, coletaram-se amostras de sangue do bezerro para as dosagens de proteina total (PT), glicose (Gli), triiodotironina (T3), tiroxina (T4), relacao T4:T3, cortisol (Cort) e imunoglobulina G (IgGb), alem das medidas de temperatura retal do bezerro (TR) e dos pesos de vacas e bezerros. Para analise dos efeitos de clima, foram tomadas no dia do nascimento as medidas de temperatura do ar (Temp), umidade do ar (UR) e precipitacao (PRE). Os parâmetros fisiologicos foram estudados pelo metodo dos quadrados minimos com modelos que incluiram os efeitos de ano e mes de nascimento, grupo e sexo do bezerro, categoria da vaca e hora do parto e das interacoes ano × grupo e ano × mes de nascimento, alem das covariaveis peso do bezerro, PRE, Temp, UR e LM. Temp mostrou efeito significativo para as concentracoes de T3, T4, T4:T3 e de Cort. Quanto maior Temp, menores as concentracoes de T3 e de Cort e maiores as de T4 e de T4:T3. LM influenciou os niveis de Cort, PT e IgGb, de modo que, quanto maior LM, maior a concentracao de Cort e menor as de IgGb e PT. Tambem houve efeito significativo de grupo do bezerro sobre PT, que foi maior nos bezerros NR que nos bezerros NI.
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23 Sep 2019
TL;DR: For instance, Boff et al. as mentioned in this paper investigated the conforto térmico in ambiente externo at the University of Cachoeira do Sul, Brazil.
Abstract: ANÁLISE BIOCLIMÁTICA E INVESTIGAÇÃO DO CONFORTO TÉRMICO EM AMBIENTE EXTERNO NA REGIÃO CENTRAL DO RS
ZANANDRA BOFF DE OLIVEIRA1, ALBERTO EDUARDO KNIES2
Professora adjunta, Coordenadoria Acadêmica, Universidade Federal de Santa Maria Campus em Cachoeira do Sul, Rua Ernesto Barros, nº 1345, Bairro Santo Antônio, cep: 96506-322, Cachoeira do Sul – RS, Brasil. E-mail: zanandraboff@gmail.com
Professor adjunto, Universidade Estadual do Rio Grande do Sul Unidade em Cachoeira do Sul, Rua Sete de Setembro, nº 1040, Bairro Santo Centro, cep: 96508-010, Cachoeira do Sul – RS, Brasil. E-mail: albertoek@gmail.com
RESUMO: o presente trabalho teve como objetivo realizar a análise bioclimática e a investigação do conforto térmico em ambiente externo na região central do RS. Para isso, utilizaram-se os seguintes índices de conforto térmico: índice de temperatura e umidade (ITU) e índice de desconforto humano (IDH). Os dados meteorológicos de temperatura do ar máxima (Tmax) e mínima (Tmin) e umidade relativa do ar máxima (URmax) e mínima (URmin) foram obtidos de uma série de 10 anos (2005-2015) de dados de uma estação meteorológica automática instalada em Santa Maria (RS). A temperatura do ponto de orvalho foi estimada a partir da Tmax e Tmin e da URmin e URmax, respectivamente. Os índices de conforto térmico foram calculados a partir das médias diárias do período (10 anos) para a situação de máximo desconforto térmico que ocorre nos extremos: 1) quando a temperatura do ar é máxima e a umidade relativa do ar é mínima - denominados de ITUmax e IDHmax; 2) quando a temperatura do ar é mínima e a umidade relativa do ar é máxima - denominados de ITUmin e IDHmin. Em função da elevada amplitude térmica mensal (>10ºC<18ºC) e diária (>5ºC<10ºC), os valores dos índices de conforto térmico (ITU e IDH) variam entre 51,5 e 80,4, indicando que a situação de conforto térmico do ambiente externo na região central do RS vai nos extremos de estresse térmico devido ao frio (julho) a estresse térmico devido ao calor (janeiro). No período de maio a outubro o conforto térmico ocorre na Tmax, mas na Tmin a situação é de desconforto a estresse por frio. No período de novembro a fevereiro, o conforto térmico ocorre na Tmin, mas na Tmax ocorre desconforto a estresse térmico por calor. Nos meses de março e abril, o desconforto ocorre tanto por frio quanto por calor. Dessa forma, para a produção zootécnica e para o conforto térmico humano na região central do RS, são necessárias práticas de acondicionamento ambiental que visem a minimização do estresse térmico.
Palavra-chaves: índices de conforto térmico; análise bioclimática; amplitude térmica.
BIOCLIMATIC ANALYSIS AND RESEARCH OF THERMAL COMFORT IN EXTERNAL ENVIRONMENT IN THE CENTRAL REGION OF RS
ABSTRACT: The present work had the aim of performing the bioclimatic analysis and the investigation of the thermal comfort in an external environment in the Central region of RS. For this, the following thermal comfort indexes were used: temperature and humidity index (THI) and human discomfort index (HDI). The maximum air temperature (Tmax) and minimum air temperature (Tmin) and maximum relative humidity (URmax) and minimum air humidity (URmin) were obtained from a series of 10 years (2005 to 2015) of data of an automatic meteorological station installed in Santa Maria - RS. The temperature of the dew point was estimated from the Tmax and Tmin and the URmin and URmax, respectively. The thermal comfort indexes were calculated from the daily average of the period (10 years) for the situation of maximum thermal discomfort that occurs in the extremes: (i) when the air temperature is maximum and the relative humidity of the air is minimal - denominated of THImax and HDImax; (ii) when the air temperature is minimal and the relative humidity of the air is maximum - denominated THImin and HDImin. In function to the high temperature amplitude, monthly (> 10ºC <18ºC) and daily (> 5ºC <10ºC), the values of thermal comfort indexes (THI and HDI) vary from 51.5 to 80.4, indicating that thermal comfort of the external environment in the Central region of RS goes in the extremes of thermal stress due to the cold (July) to the heat stress due to the heat (January). In the period from May to October the thermal comfort occurs in Tmax, but in Tmin the situation is of cold stress discomfort. In the period from November to February, thermal comfort occurs in Tmin, but in Tmax, heat stress discomfort occurs. In the months of March and April the discomfort occurs as much by cold as by heat. Thus, for a zootechnical production and human thermal comfort in the central region of RS, it is necessary to practice environmental conditioning to minimize thermal stress.
Keywords: thermal comfort index; bioclimatic analysis; thermal amplitude.
3 citations
21 Feb 2007
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References
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TL;DR: By standardizing the technical conditions of the experiment it is possible to use this principle for the immunochemical determination of antigens, and the lower limit of the method was found to correspond to 0·0025 μg of antigen, and to an antigen concentrations of 1·25 μg per ml.
Abstract: When an unknown amount of antigen is allowed to diffuse radially from a well in a uniformly thin layer of antibody-containing agar for a sufficient time to allow all antigen to combine, the final area reached by the precipitate is directly proportional to the amount of antigen employed, and inversely proportional to the concentration of antibody. It is also shown that the temperature at which the plates are incubated has no perceptible influence upon the results. By standardizing the technical conditions of the experiment it is possible to use this principle for the immunochemical determination of antigens. In the experimental albumin-antialbumin system here described, the lower limit of the method was found to correspond to 0·0025 μg of antigen, and to an antigen concentrations of 1·25 μg per ml. The standard deviation of the antigen determinations was less than 2 per cent of the mean.
8,937 citations
TL;DR: In this article, a comprehensive knowledge of piglet thermoregulation is now available and may be helpful to increase our understanding of the biology of neonatal losses, and the effects of key factors such as birth weight, genotype, colostrum intake, hypothermia and hypoxia on the maturation of skeletal muscle energy metabolism after birth are described.
Abstract: Neonatal mortality is still a source of serious loss to the swine industry. We know that optimal development of thermoregulation is a prerequisite of utmost importance for successful adaptation to extra-uterine life. Indeed, a comprehensive knowledge of piglet thermoregulation is now available and may be helpful to increase our understanding of the biology of neonatal losses. The newborn pig is poorly insulated and maintenance of its homeothermic balance depends essentially on its capacity to produce heat. However, unlike most newborn mammals, piglets do not possess brown adipose tissue and rely almost exclusively on shivering thermogenesis for thermoregulatory purposes. Therefore, skeletal muscle plays an essential role in preserving homeothermy. Key factors involved in the limited cold tolerance of the new-born and enhancement of thermoregulatory abilities early after birth have been identified. Most of them, and especially the maturation of skeletal muscle metabolism and function are suggestive of the relative physiological and metabolic immaturity of piglets at the time of birth. Therefore, physiological, biochemical, molecular and ultrastructural adjustments involved in the maturation of skeletal muscle energy metabolism after birth are presented. Finally, effects of key factors such as birth weight, genotype, colostrum intake, hypothermia and hypoxia on thermoregulatory abilities are described.
282 citations
"Avaliação das respostas fisiológica..." refers background in this paper
...…experimental dos anos de 1998 e 1999 positivo desencadeados pelo baixo nível de T3, que levaria a tireóide a secretar mais T3 e T4, sendo a concentração de T4 bem maior que a de T3 (Anderson et al., 1988).. Resultados semelhantes foram citados por Collin et al. (2002) e Herpin et al. (2002)....
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TL;DR: Major science-based improvements in the management of pregnancy and birth have markedly reduced the overall amount of welfare compromise experienced by newborn farm animals and further improvements may be expected as knowledge is refined and extended in the future.
Abstract: Much has been learnt during the last 50 years about the causes of neonatal mortality and morbidity and about practical means for minimising them in newborn lambs, kids, bovine calves, deer calves, foals and piglets. The major causes of problems in these newborns are outlined briefly and include hypothermia due to excessive heat loss or to hypoxia-induced, starvation-induced or other forms of inhibited heat production. They also include maternal undernutrition, mismothering, infection and injury. The published literature reveals that the scientific investigations which clarified these causes and led to practical means for minimising the problems, involved iterative successions of self-reinforcing laboratory and field or clinical investigations conducted over many years. These studies focused largely on solutions to the problems, not on the suffering that the newborn might experience, so that an analysis of the associated welfare insults had not apparently been conducted until now. The present assessment focuses on potentially noxious subjective experiences the newborn may have. The account of the causes of neonatal mortality and morbidity outlined early in this review indicates that the key subjective experiences which require analysis in animal welfare terms are breathlessness, hypothermia, hunger, sickness and pain. Reference to documented responses of farm animals and, where appropriate, to human experience, suggests that breathlessness and hypothermia usually represent less severe neonatal welfare insults than do hunger, sickness and pain. Major science-based improvements in the management of pregnancy and birth have markedly reduced the overall amount of welfare compromise experienced by newborn farm animals and further improvements may be expected as knowledge is refined and extended in the future.
257 citations
"Avaliação das respostas fisiológica..." refers background in this paper
...Entre as maiores causas dessa mortalidade, destacam-se a hipotermia, como resultado da excessiva perda de calor, a hipoxia, a fome e outros fatores que inibem a produção de calor, além da desnutrição materna, da baixa habilidade materna, das infecções e das lesões (Mellor & Stafford, 2004)....
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TL;DR: Overall severity and duration of scours were less for calves fed colostrum with high compared to low immunoglobulin and a positive relationship developed between serum protein and immunoglOBulin at 12 h to 24 h, 4 and 11 days.
Abstract: Holstein calves (159) were assigned alternately to one of seven regimens through, day 45: nurse dam for 12 to 24 h, dam's milk to 96 h, milk replacer with all milk protein; low (less than or equal to 45 mg/ml) immunoglobulin colostrum to 96 h, then either colostrum, replacer with all milk, or soy protein; high (less than 60 mg/ml) immunoglobulin colostrum to 96 h, then replacer all milk; replacer all milk protein from birth; or saleable milk from birth. Colostrum immunoglobulin was estimated by colostrometer and colostrum was frozen. Starter and water were offered free choice on day 5. Calves deprived of colostrum gained poorly and suffered severe and long scour episodes and high mortality. No differences of body weight gains were observed between calves that nursed compared with those hand fed. Calves fed colostrum with high immunoglobulin gained weight from birth to day 4 while those fed low lost weight. Overall severity and duration of scours were less for calves fed colostrum with high compared to low immunoglobulin. Calves fed undiluted colostrum (5 to 45 days) had more severe scours longer than those fed milk replacer. Serum protein and immunoglobulin were higher for calves hand fed high immunoglobulin compared to low immunoglobulin colostrum or nursing at 12 to 24 h and 4 days after birth. A positive relationship developed between serum protein and immunoglobulin at 12 h to 24 h, 4 and 11 days. Mortality was low for all calves receiving colostrum.
168 citations
"Avaliação das respostas fisiológica..." refers background in this paper
...…a correlação entre as concentrações de proteína total plasmática e de imunoglobulinas em bezerros é baixa antes da ingestão do primeiro colostro, aumentando significativamente após a ingestão (Machado Neto, 1985) e mantendo-se alta (em torno de 0,8) nos primeiros dias de vida, (Nocek et al., 1984)....
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TL;DR: Calving records from 1969 to 1989 were used to investigate how climatic conditions, in addition to dystocia, age of dam, size of calf, and sex affect calf survival from birth to 1 wk of age.
Abstract: Calving records from 1969 to 1989 from the Roman L. Hruska U.S. Meat Animal Research Center were used to investigate how climatic conditions, in addition to dystocia, age of dam, size of calf, and sex affect calf survival from birth to 1 wk of age. Data were analyzed separately for cows calving with (n = 11,094) or without (n = 72,187) dystocia. Neonatal mortality was described by a logit model and parameters were estimated by maximum-likelihood procedures. Calves born to cows with dystocia were five times as likely to die neonatally than calves born without assistance. Of all calves that died, 43.6% were born with difficulty. Of these calves, survival was lowest for those that were small relative to their genetic group, sex, and age of dam. Large calves had markedly increased mortality only when born to 2-yr-old dams. Average ambient temperature and precipitation on day of calving affected survival nonlinearly and the magnitude of the effect depended on age of dam, sex and size of calf, and dystocia incidence. Calves born to 2-yr-old cows were more susceptible to severe weather conditions than calves born to older cows. The negative effect of precipitation on survival increased with decreasing temperature.
99 citations