2 research outputs found
Correlação entre variáveis ambientais e fisiológicas de novilhas leiteiras mestiças
<p>Devido
às perdas produtivas e reprodutivas, têm sido propostos estudos para avaliar
indivíduos mais adaptados ao estresse pelo calor<b>.</b> Assim, objetivou-se
correlacionar medidas fisiológicas de termorregulação de novilhas
leiteiras mestiças e variáveis do ambiente térmico em Uberlândia-MG,
Brasil. Oito novilhas mestiças foram expostas ao sol das 09h às 13h. Após, os
animais foram conduzidos para o tronco para quantificar frequência respiratória
(FR), temperatura retal (TR) e temperatura corporal superficial (TCS). Simultaneamente, foram obtidas a temperatura de
bulbo seco (T<sub>A</sub>), a temperatura de bulbo úmido (T<sub>U</sub>), a
temperatura do globo negro (T<sub>G</sub>) e a velocidade do vento (V).
Realizou-se a estatística descritiva dos dados e a correlação simples de
Pearson entre as variáveis fisiológicas e ambientais. As variáveis fisiológicas
apresentaram média de FR 41,97 mov.min<sup>-1</sup>, TR de 38,8ºC e TCS no
flanco preto e no flanco branco foram, respectivamente de 35,82°C e 35,04°C. Referente
às variáveis ambientais, a T<sub>A</sub> média foi 29,96ºC, a T<sub>G</sub>
média, 41,73ºC, a V teve uma variação de 0 a 1,2 m.s<sup>-1 </sup>e a umidade
relativa do ar (UR) variou de 39% a 80%. A TR não correlacionou com nenhuma das
variáveis ambientais avaliadas. A FR teve as maiores correlações com a T<sub>G</sub>
e a V. Por fim, a TCS, seja no flanco branco ou no preto, teve as correlações
mais expressivas com a T<sub>A</sub> e com a T<sub>G</sub>. A temperatura
ambiente e do globo e velocidade do vento influenciam diretamente na frequência
respiratória de novilhas leiteiras mestiças criadas em Uberlândia MG e estas
são adaptadas às condições meteorológicas da região.</p
Ingestive behaviour of Nelore bulls fed with a GrowSafe system and its relation to the thermal environment
<p>The demand for food,
especially of animal origin, is increasing every year. On the other hand, it is
believed that climate changes will have impacts on livestock production,
especially in tropical regions. Therefore, the development and improvement of
livestock production systems is crucial. Thus, the objective of this study was
to relate the ingestive behavior of Nellore cattle reared in confinement and
fed with a GrowSafe System with measures of the thermal environment. Fifty
Nelore bulls, with an average age of 21 months were distributed into two
paddocks. The behavioural categories (resting while standing, resting while
lying, ruminating while standing, ruminating while lying, eating at feedbunk
and feedbunk intention) and meteorological variables (dry and wet bulb
temperatures, wind speed [v] and black globe temperature [Tg] were evaluated.
The Temperature and Humidity Index (THI), Equivalent Temperature Index (ETI),
Black Globe humidity Index (BGHI) and Heat Load Index (HLI) were calculated. Observations
were divided into two periods (morning and afternoon) and the study was divided
into the following schedules: 1 = 07 hours to 08 hours; 2 = 08 hours: 30
minutes to 09 hours 30 minutes; 3 = 13 hours: 45 minutes to 14 hours: 45
minutes; 4 = 15 hours: 30 minutes to 16 hours: 30 minutes and 5 = 17 hours: 15
minutes to 18 hours: 15 minutes. Pearson's simple correlation between ingestive
behavior and thermal environment measurements was performed. There was a
positive and moderate correlation between animals eating at feedbunk and air
temperature (Ta). Ruminating while standing showed moderate and negative
correlation with Ta and Tg, being moderate and positive with relative humidity
(Ur). Ruminating while lying correlated moderately and positively with HLI.
There was a moderate and negative correlation between the resting while
standing activity and the variables Tg, v, BGHI and HLI, while resting while
lying had a moderate and positive correlation with Tg and HLI. It is concluded
that the thermal environment can affect the ingestive behavior of confined
Nellore bulls fed through a GrowSafe System during winter time at Uberlândia,
MG.</p