Efeito do resfriamento evaporativo e do balanço eletrolítico sobre a lactação de porcas em condições de verão tropical / Effect of evaporative cooling and electrolyte balance on lactating sows in tropical summer conditions

O experimento foi realizado em uma granja comercial com 72 fêmeas suínas da genética DanBred(r) e objetivou avaliar os efeitos do resfriamento evaporativo e do balanço eletrolítico sobre o desempenho e os parâmetros de termorregulação de porcas lactantes no verão. O delineamento experimental foi blocos ao acaso com quatro tratamentos em disposição fatorial 2 x 2 e 18 repetições por tratamento. Os tratamentos foram dois sistemas de ventilação (ventilação natural ou resfriamento evaporativo) e duas dietas (balanço eletrolítico de 175mEqkg-1 ou balanço eletrolítico alto de 275mEqkg-1). Os valores médios encontrados para temperatura ambiente e umidade relativa do ar foram de 24,8ºC e 64,5%, respectivamente, sendo obtidos valores diários de 31,6°C para a temperatura ambiente máxima e de 19,8°C para a temperatura ambiente mínima. Não houve efeito (P>0,05) significativo do resfriamento evaporativo e do balanço eletrolítico sobre o consumo de ração, a condição corporal e o intervalo desmame-estro das porcas. O sistema de resfriamento evaporativo proporcionou redução (P<0,05) na frequência respiratória e temperatura superficial mensuradas nos períodos da manhã e da tarde e na temperatura retal à tarde e aumento (P<0,10) no peso dos leitões ao desmame. A dieta com balanço eletrolítico alto não influenciou essas variáveis. Concluiu-se que a utilização do sistema de resfriamento evaporativo contribuiu para reduzir os efeitos do calor sobre as variáveis relacionadas à termorregulação das porcas em lactação durante o verão e proporcionou aumento no peso dos leitões ao desmame. Em dieta com níveis nutricionais específicos para climas quentes, o balanço eletrolítico alto não minimizou os efeitos do estresse calórico.(AU)

The field trial was conducted in a commercial farm with 72 sows from DanBred(r) genetics and aimed to evaluate the effects of the evaporative cooling and electrolyte balance on the performance and thermoregulatory parameters of lactating sows during summer. The experimental design was randomized blocks with four treatments in a factorial arrangement 2 x 2 and 18 replicates per treatment. Treatments were two ventilation systems (natural ventilation or evaporative cooling) and two diets (electrolyte balance of 175mEqkg-1 or high electrolyte balance of 275mEqkg-1). The average values for temperature and relative humidity were 24.8°C and 64.5%, respectively, being obtained daily values of 31.6°C for the maximum temperature and of 19.8°C for the minimum temperature. There was no effect (P>0.05) of evaporative cooling and electrolyte balance on feed intake, body condition and weaning-to-estrus interval of sows. The evaporative cooling caused a significant reduction (P<0.05) in respiratory rate and surface temperature measurements in the morning and afternoon and evening rectal temperature and increase (P<0.1) in the weight of piglets at weaning. The dietary high electrolyte balance did not change these variables. It was concluded that the use of the evaporative cooling system helped to reduce the effects of heat on the variables related to body thermoregulation during the summer and provided an increase in weaning piglet weight. The utilization of a diet with specific nutrient levels for hot climates, the high electrolyte balance did not reduce the effects of heat stress in sows.(AU)

Efeito do resfriamento evaporativo e do balanço eletrolítico sobre a lactação de porcas em condições de verão tropical / Effect of evaporative cooling and electrolyte balance on lactating sows in tropical summer conditions

O experimento foi realizado em uma granja comercial com 72 fêmeas suínas da genética DanBred(r) e objetivou avaliar os efeitos do resfriamento evaporativo e do balanço eletrolítico sobre o desempenho e os parâmetros de termorregulação de porcas lactantes no verão. O delineamento experimental foi blocos ao acaso com quatro tratamentos em disposição fatorial 2 x 2 e 18 repetições por tratamento. Os tratamentos foram dois sistemas de ventilação (ventilação natural ou resfriamento evaporativo) e duas dietas (balanço eletrolítico de 175mEqkg-1 ou balanço eletrolítico alto de 275mEqkg-1). Os valores médios encontrados para temperatura ambiente e umidade relativa do ar foram de 24,8ºC e 64,5%, respectivamente, sendo obtidos valores diários de 31,6°C para a temperatura ambiente máxima e de 19,8°C para a temperatura ambiente mínima. Não houve efeito (P>0,05) significativo do resfriamento evaporativo e do balanço eletrolítico sobre o consumo de ração, a condição corporal e o intervalo desmame-estro das porcas. O sistema de resfriamento evaporativo proporcionou redução (P<0,05) na frequência respiratória e temperatura superficial mensuradas nos períodos da manhã e da tarde e na temperatura retal à tarde e aumento (P<0,10) no peso dos leitões ao desmame. A dieta com balanço eletrolítico alto não influenciou essas variáveis. Concluiu-se que a utilização do sistema de resfriamento evaporativo contribuiu para reduzir os efeitos do calor sobre as variáveis relacionadas à termorregulação das porcas em lactação durante o verão e proporcionou aumento no peso dos leitões ao desmame. Em dieta com níveis nutricionais específicos para climas quentes, o balanço eletrolítico alto não minimizou os efeitos do estresse calórico.(AU)

The field trial was conducted in a commercial farm with 72 sows from DanBred(r) genetics and aimed to evaluate the effects of the evaporative cooling and electrolyte balance on the performance and thermoregulatory parameters of lactating sows during summer. The experimental design was randomized blocks with four treatments in a factorial arrangement 2 x 2 and 18 replicates per treatment. Treatments were two ventilation systems (natural ventilation or evaporative cooling) and two diets (electrolyte balance of 175mEqkg-1 or high electrolyte balance of 275mEqkg-1). The average values for temperature and relative humidity were 24.8°C and 64.5%, respectively, being obtained daily values of 31.6°C for the maximum temperature and of 19.8°C for the minimum temperature. There was no effect (P>0.05) of evaporative cooling and electrolyte balance on feed intake, body condition and weaning-to-estrus interval of sows. The evaporative cooling caused a significant reduction (P<0.05) in respiratory rate and surface temperature measurements in the morning and afternoon and evening rectal temperature and increase (P<0.1) in the weight of piglets at weaning. The dietary high electrolyte balance did not change these variables. It was concluded that the use of the evaporative cooling system helped to reduce the effects of heat on the variables related to body thermoregulation during the summer and provided an increase in weaning piglet weight. The utilization of a diet with specific nutrient levels for hot climates, the high electrolyte balance did not reduce the effects of heat stress in sows.(AU)

Turkey Wattle Temperature Response to Distinct Environmental Factors

Rearing environmental conditions are important for turkey production, because this bird is particularly sensitive to heat stress. This study aimed at measuring the wattle temperature response of turkeys of three different ages (61, 96, and 131 days old) exposed to different combinations of dry bulb temperature, relative humidity, and wind speed ranges, as an indication of their physiological responses. The experiment was conducted with 42 male birds housed in a controlled environment chamber and exposed to different combinations of two air speed (WS) ranges (WS1 = 0.3-0.6 ms-1, considered low, and WS2 = 1.2-1.6 ms-1, considered high), dry bulb temperature (DBT) between 22 and 34 °C, and relative humidity (RH) between 40 to 90 %. The statistical analysis showed that WS, DBT, and RH significantly influenced wattle temperature of 61-d-old turkeys, while only WS and DBT influenced this response when turkeys were 96 days old. Furthermore, DBT was highly correlated with both low and high WS. In 131-day-old turkeys, WT response was virtually the same at both wind speed ranges when high DBT was applied. Turkey wattle temperature was influenced by wind speed, and was dependent on both environmental dry bulb temperature and relative humidity, as well as bird age.

Turkey Wattle Temperature Response to Distinct Environmental Factors

Rearing environmental conditions are important for turkey production, because this bird is particularly sensitive to heat stress. This study aimed at measuring the wattle temperature response of turkeys of three different ages (61, 96, and 131 days old) exposed to different combinations of dry bulb temperature, relative humidity, and wind speed ranges, as an indication of their physiological responses. The experiment was conducted with 42 male birds housed in a controlled environment chamber and exposed to different combinations of two air speed (WS) ranges (WS1 = 0.3-0.6 ms-1, considered low, and WS2 = 1.2-1.6 ms-1, considered high), dry bulb temperature (DBT) between 22 and 34 °C, and relative humidity (RH) between 40 to 90 %. The statistical analysis showed that WS, DBT, and RH significantly influenced wattle temperature of 61-d-old turkeys, while only WS and DBT influenced this response when turkeys were 96 days old. Furthermore, DBT was highly correlated with both low and high WS. In 131-day-old turkeys, WT response was virtually the same at both wind speed ranges when high DBT was applied. Turkey wattle temperature was influenced by wind speed, and was dependent on both environmental dry bulb temperature and relative humidity, as well as bird age.(AU)

Minimum ventilation systems and their effects on the initial stage of turkey production

This study aimed at evaluating the live performance of turkeys during the initial stage of production (1-26 days of age) and to map the environmental variables inside turkey houses, such as temperature, relative humidity, CO2 concentration, at two distinct minimum ventilation systems. House 1 (H1) was equipped with a negative-pressure ventilation system and House 2 (H2) was equipped with a positive-pressure ventilation system. This study was performed in commercial poultry houses, located in Francisco Beltrão, Paraná, Brazil, in June, 2008. A number of 14,000 turkeys toms at the same age, provided by the same local hatchery and were housed at a stocking density of 23 birds m-2. Three 13 m² boxes with 300 turkeys each were placed inside the poultry houses. All treatments were assigned for the birds inside each of the three boxes. The poultry barns were virtually divided in eight equally distributed in areas where the environmental variables were recorded. The performance parameters measured were weight gain, feed conversion and mortality rate, recorded weekly. Analysis of variance and F-tests were performed to compare results within different environmental conditions, using MINITAB 14 statistical software. The ventilation systems did not significantly influence CO2 concentrations (p = 0.489), whereas temperature (p = 0.016) and relative humidity (p = 0.0001) and feed conversion (p = 0.001) were significantly affected by ventilation system. Temperature and relative humidity in H2 (positive pressure ventilation system) was found to be less aversive than those in H1 (negative pressure system). Also, bids in H2 presented lower feed conversions than those in H1.

Minimum ventilation systems and their effects on the initial stage of turkey production

This study aimed at evaluating the live performance of turkeys during the initial stage of production (1-26 days of age) and to map the environmental variables inside turkey houses, such as temperature, relative humidity, CO2 concentration, at two distinct minimum ventilation systems. House 1 (H1) was equipped with a negative-pressure ventilation system and House 2 (H2) was equipped with a positive-pressure ventilation system. This study was performed in commercial poultry houses, located in Francisco Beltrão, Paraná, Brazil, in June, 2008. A number of 14,000 turkeys toms at the same age, provided by the same local hatchery and were housed at a stocking density of 23 birds m-2. Three 13 m² boxes with 300 turkeys each were placed inside the poultry houses. All treatments were assigned for the birds inside each of the three boxes. The poultry barns were virtually divided in eight equally distributed in areas where the environmental variables were recorded. The performance parameters measured were weight gain, feed conversion and mortality rate, recorded weekly. Analysis of variance and F-tests were performed to compare results within different environmental conditions, using MINITAB 14 statistical software. The ventilation systems did not significantly influence CO2 concentrations (p = 0.489), whereas temperature (p = 0.016) and relative humidity (p = 0.0001) and feed conversion (p = 0.001) were significantly affected by ventilation system. Temperature and relative humidity in H2 (positive pressure ventilation system) was found to be less aversive than those in H1 (negative pressure system). Also, bids in H2 presented lower feed conversions than those in H1.(AU)

Effects of initial body weight and litter material on broiler production

his experiment was carried out in a 104 m2 poultry house located between the geographical coordinates 25°45'00" south latitude and 53°03'25" west longitude and an average altitude of 550 m, from September to November, 2008. The chickens were placed in 12 pens measuring 2 m2 each at a stocking density of 12 chickens m-2. This study aimed at evaluating the effect of two different initial weights (chick weight on first day of experiment) and two types of litter material on broiler production parameters, litter humidity, as well as on breast and footpad lesions. A total of 240 female Cobb® chickens, derived from the same flock of breeders, was distributed in a completely randomized experimental design with a 2 (initial weight) by 2 (litter material) factorial arrangement with three replicates per treatment. Initial weights were classified as light (34.40 - 35.22 g) or heavy (39.29 - 41.30 g), whereas wood shavings and sawdust were used as litter material. Data were analyzed by ANOVA and means were compared by Tukey's test at 95% confidence level. Initial weight significantly influenced bird performance, as chickens with heavy initial weight presented higher feed intake and body weight. Type of litter did not have any effect on breast injuries and litter humidity. However, the wood shavings litter significantly influenced footpad lesions.

Effects of initial body weight and litter material on broiler production

his experiment was carried out in a 104 m2 poultry house located between the geographical coordinates 25°45'00" south latitude and 53°03'25" west longitude and an average altitude of 550 m, from September to November, 2008. The chickens were placed in 12 pens measuring 2 m2 each at a stocking density of 12 chickens m-2. This study aimed at evaluating the effect of two different initial weights (chick weight on first day of experiment) and two types of litter material on broiler production parameters, litter humidity, as well as on breast and footpad lesions. A total of 240 female Cobb® chickens, derived from the same flock of breeders, was distributed in a completely randomized experimental design with a 2 (initial weight) by 2 (litter material) factorial arrangement with three replicates per treatment. Initial weights were classified as light (34.40 - 35.22 g) or heavy (39.29 - 41.30 g), whereas wood shavings and sawdust were used as litter material. Data were analyzed by ANOVA and means were compared by Tukey's test at 95% confidence level. Initial weight significantly influenced bird performance, as chickens with heavy initial weight presented higher feed intake and body weight. Type of litter did not have any effect on breast injuries and litter humidity. However, the wood shavings litter significantly influenced footpad lesions.(AU)