Browsing by Subject "Heat stress"

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Effect of sodium and potassium chloride supplementation in drinking water on performance of laying hens and broilers under high ambient temperature
(2008) Nguyen Van, Dai; Bessei, Werner
It is well known that water intake and maintenance of electrolyte balance play a vital role in the resistance of chicken to high temperature. It was hypothesis that voluntary water intake in response to heat stress may not be sufficient to prevent the reduction of performance in laying hens and broilers, and that stimulation of water intake through supplementation of electrolytes in drinking water may assist the birds to maintain high productivity under heat stress. The present study includes three experiments. Two experiments were carried out with laying hens in controlled ambient temperature conditions to study the effects of sodium chloride (NaCl) and potassium chloride (KCl) supplementation in the drinking water on water intake, feed intake, egg quality, body temperature, body weight and productivity of laying hens under high temperature. The third experiment with broilers was conducted in tropical summer conditions of Viet Nam to find out whether supply NaCl and KCl in drinking water would improve productivity and carcass quality of broilers under tropical summer conditions and which concentration of both minerals should be used. The first experiment was conducted for three weeks (from 26 March to 16 April 2007) at the research station of Hohenheim University, Germany. A total of 48 Hisex hens (76 weeks old) were kept in individual laying cages in climatic chambers and were randomly allocated to three experimental groups of 16 hens each. These groups were given 0; 0.2 and 0.4 % KCl in the drinking water for seven consecutive days of heat stress. Before and after heat stress, birds were given normal drinking water. Water and feed were provided ad libitum. The birds were fed a layer diet containing 11.45 MJ/kg Metabolizable Energy, 16.97 % Crude Protein, 3.73% calcium, 0.62% phosphorus, 0.22% sodium and 0.33% chloride. The room temperature was constant at 21±1°C for 7 days, afterwards, it was cycled from 21±1°C to 34±1°C (from 9 to 22 o?clock) for 7 days, and then constant at 21±1°C for 7 days. Humidity was not controlled. 14-hours lighting schedule was maintained during the experiment. Water and feed intake, water: feed ratio, body weight, body temperature, egg production, egg weight, egg shell thickness, egg deformation, egg shell strength, yolk colour and Haugh Unit (HU) were recorded. In the second experiment, effect of NaCl supplementation (0.2 and 0.4%) in drinking water on laying hens was tested under the same temperature program as in the first experiment. A total of 48 Hisex hens (80 weeks old) were used. The third experiment was carried out on the commercial chicken farm from 26 June to 14 August 2007 (49 days). A total of 240 21-day-old broiler chicks (Lohmann meat) were randomly allocated to 5 treatment groups in a randomized block design. Each treatment consisted of three replicates of 16 chickens each. Both, NaCl and KCl, were supplemented from the beginning of the 4th to 7th weeks of age at 0.2% and 0.4% to drinking town water, and unsupplemented water was used as control. The birds were kept in an open sided poultry house on the rice hull litter. Temperature and humidity of the house were not controlled. Water and feed intake were measured weekly. Body temperature of 15 birds per treatment was measured at 23, 33 and 40 day of age. All birds was individually weighed on day of hatching and afterwards at weekly intervals up to 7 weeks of age. At 49 days of age, one male and one female bird from each replicate (a total of 30 birds) were slaughtered to determine carcass characteristics. The results showed that in laying hens, heat stress increased water intake, water to feed ratio, body temperature and eggshell defects. Feed intake, egg production and egg weight decreased tendentiously during heat stress. Body weight, eggshell thickness, eggshell strength, egg deformation, yolk color and HU were not significantly affected by heat stress. Supplementation of KCl or NaCl in drinking water increased water intake and water: feed ratio. Only KCl supplementation maintained body weight, egg weight and egg production, and decreased eggshell defects. Feed intake, eggshell deformation, yolk color and HU were not significantly affected by either KCl or NaCl supplementation. The results showed that KCl supplementation through drinking water may be a means to maintain egg production and egg quality which are usually deteriorated when the temperature in the layer house increases while NaCl was less effective under these conditions. Supplementation of KCl or NaCl in drinking water enhanced water intake and water: feed ratio of broilers under tropical summer conditions. 0.4% NaCl supplementation in drinking water reduced body temperature, increased body weight, improved feed conversion ratio (FCR) and decreased abdominal fat while feed intake was not affected by both NaCl and KCl supplementation. Therefore, 0.4% NaCl added in drinking water may be a means to improve productivity of broiler under high temperature. 0.4% KCl supplementation increased thigh meat, and improved FCR. However, carcass percentage was reduced by KCl supplementation. Therefore, in the tropical summer conditions, higher levels of KCl concentration and economic aspect should be further studied. It was not clear whether the beneficial effects of KCl and NaCl supplementation in drinking water was caused by the cooling effect of the increased water intake and/or the maintenance of electrolytes balance.
Is heat stress a growing problem for dairy cattle husbandry in the temperate regions? A case study of Baden-Württemberg in Germany
(2024) Leandro, Miguel António; Stock, Joana; Bennewitz, Jörn; Chagunda, Mizeck G. G.
Heat stress with measurable effects in dairy cattle is a growing concern in temperate regions. Heat stress in temperate regions differs between environments with different geophysical characteristics. Microclimates specific to each environment were found to greatly impact at what level heat stress occurs and will occur in the future. The landlocked state of Baden-Württemberg, Germany, provides several different environments, hence, a good case-study. Temperature–Humidity Index (THI) from 17 weather stations for the years 2003 to 2022 was calculated and milking yields from 22 farms for the years 2017 to 2022 were collected. The occurrences and evolving patterns of heat stress were analyzed with the use of a THI, and the effect of heat stress on milk yield was analyzed based on milking records from Automated Milking Systems. Daily average THI was calculated using hourly readings of relative humidity and ambient temperature, disregarding solar radiation and wind, as all animals were permanently stabled. Based on studies conducted in Baden-Württemberg and neighboring regions, cited ahead in the section of THI, THI = 60 was the threshold for heat stress occurrence. Findings show that the heat stress period varied between stations from 64 to 120 d with THI ≥ 60 in a year. This aligns with yearly and summer averages, also steadily increasing from May to September. The length of the heat stress period was found to increase 1 extra day every year. Extreme weather events such as heat waves did not increase the heat stress period of that year in length but increased the average THI. Milk yield was found to be significantly (α = 0.05) different between counties grouped into different zones according to heat stress severity and rate of increase in daily average THI. Future attempts at managing heat stress on dairy cattle farms in the temperate regions should account for microclimate, as geographical proximity does not mean that the increase in heat stress severity will be the same in the 2 neighboring areas.