Effects of the reduction of dietary heat increment on the performance, carcass yield, and diet digestibility of broilers submitted to heat stress

Effects of Cyclic Thermal Stress at Later Age on Production Performance and Meat Quality of Fast-Growing, Medium-Growing and Thai Native Chickens

The present study aimed at assessing the impact of cyclic thermal stress on production performance and meat quality of commercial broilers (BRs), Thai native chickens (NT) and the hybrids between BR and NT (H75; crossbreed 25% NT). At the age of 3, 5 and 9 weeks for BR, H75 and NT, respectively, each strain was equally divided (n = 50) into control and treatment groups. The controls were raised at a constant 26 ± 1 °C, while the treatments were subjected to thermal stress (35 ± 1 °C, 6 h daily) for 3 weeks. The results indicated that final weight and average daily gain of BR and NT treated groups were significantly lower than those of their control counterparts. Reduced body weight gain of BR and H75, as well as feed intake of H75, was observed in the treatment groups (p < 0.05). The stressed BR breasts showed decreased moisture, fat and carbohydrate, accompanied by increased protein, ash, L *-value, b*-value and shear force (p < 0.05). No significant effects (p ≥ 0.05) of the thermal stress on meat quality indices were found for H75 and NT breast samples. Pectoral myopathies were observed in BR and H75 chickens, but the numbers of cases were decreased in the thermally treated groups.

Nutritional manipulation to combat heat stress in poultry - A comprehensive review

Global warming and climate change adversely affect livestock and poultry production sectors under tropical and subtropical conditions. Heat stress is amongst the most significant stressors influencing poultry productivity in hot climate regions, causing substantial economic losses in poultry industry. These economic losses are speculated to increase in the coming years with the rise of global temperature. Moreover, modern poultry strains are more susceptible to high ambient temperature. Heat stress has negative effects on physiological response, growth performance and laying performance, which appeared in the form of reducing feed consumption, body weight gain, egg production, feed efficiency, meat quality, egg quality and immune response. Numerous practical procedures were used to ameliorate the negative impacts of increased temperature; among them the dietary manipulation, which gains a great concern in different regions around the world. These nutritional manipulations are feed additives (natural antioxidants, minerals, electrolytes, phytobiotics, probiotics, fat, and protein), feed restriction, feed form, drinking cold water and others. However, in the large scale of poultry industry, only a few of these strategies are commonly used. The current review article deliberates the different practical applications of useful nutritional manipulations to mitigate the heat load in poultry. The documented information will be useful to poultry producers to improve the general health status and productivity of heat-stressed birds via enhancing stress tolerance, oxidative status and immune response, and thereby provide recommendations to minimize production losses due to heat stress in particular under the growing global warming crisis.

Broiler production challenges in the tropics: A review

Under tropical climate, broiler production is encumbered by several constraints which make it difficult for them to attain their genetic potential. The scarcity and high price of poultry feed and veterinary services and the harsh environmental conditions with respect to thermal stress are some of the challenges that hinder optimal growth of the birds. Limited availability of feedstuffs, including crucial feed ingredients like maize and oil seedcakes, is an important challenge to the sector, since feed still represents a major cost of producing broiler chickens. Additionally, the problem of climate change, which has become a global concern, is the main problem in broiler production under hot and humid climate. Under high ambient temperature, feed intake decreases, carbohydrates metabolism and protein synthesis efficiency are disturbed. Lipid utilization is lower and glucose or insulin homeostasis is altered while fat deposition and oxidative stress increases. Several strategies are used to ameliorate the effect of heat stress in poultry. The objective of this review was to summarize the challenge in broiler production under hot and humid climate and different approaches to fight heat stress in poultry.

Short chain fatty acids may improve hepatic mitochondrial energy efficiency in heat stressed-broilers

The present study was conducted to investigate the effects of four dietary fat types and two environmental temperatures on the hepatic mitochondrial energetic in male broilers exposed to heat stress. The birds were kept in two separate rooms at 24 °C or 36 °C from 32 to 42 d of age with four experimental groups in each room. The birds fed on the diets supplemented containing rich sources of long-chain saturated fatty acids (beef tallow), middle-length-chain saturated FA (coconut oil), monounsaturated FA (olive oil), or polyunsaturated FA (soybean oil) for ten days. At 36 °C, the highest body weight and lowest feed conversion ratio were recorded in the birds fed on the diets supplemented with coconut oil or beef tallow. Temperature and fat type significantly affected the activities of the mitochondrial electron transport chain complexes (P < 0.01). There was a significant interaction between the temperature and fat type (P < 0.01). Generally, electron transport chain complexes I-V enzymatic activities were decreased at 36 °C. The coconut oil-fed birds showed the highest complex I activity at both temperatures. The beef tallow-fed broilers showed the lowest complex II activity at 24 °C. In birds exposed to 36 °C, complex II activity was higher for birds fed saturated coconut oil or beef tallow than those feeding the unsaturated olive oil or soybean oil-supplemented diets. At 24 °C, the highest and lowest complex III activities were recorded for the coconut oil- and beef tallow-supplemented diets, respectively. At 36 °C, the activity of complex III was coconut oil > beef tallow > olive oil > soybean oil. At 24 °C, complex IV activity was highest in coconut oil- or soybean oil-fed broilers; and at 36 °C, complex IV showed the lowest activity in soybean oil-fed birds. The highest complex IV activity was observed in coconut oil-fed chickens followed by olive oil-fed and beef tallow-fed birds, respectively. At 24 or 36 °C, the highest and lowest complex V activity was observed in coconut oil-fed and soybean oil-fed chickens, respectively. ATP concentration and mitochondrial membrane potential were in the order of coconut oil > beef tallow > olive oil > soybean oil at both temperatures. Temperature and fat type significantly affected the avANT mRNA concentration. Exposure of broilers to 36 °C generally decreased the mRNA expression of avANT, with beef tallow- or coconut oil-supplemented birds showing a lower avANT mRNA expression than those receiving olive oil- or soybean oil-supplemented diets. These findings provide further information on the use of fat sources in the diet of heat stressed-broilers.

Dietary Moringa oleifera improves growth performance, oxidative status, and immune related gene expression in broilers under normal and high temperature conditions

The aim of this study is to evaluate the effects of Moringa oleifera (MO) on the performance, antioxidative status, and immune related gene expression in broilers raised under normal or heat stress conditions. Broiler chickens were distributed into 4 groups and fed diets with dietary MO at 0% or 5% (MO0 or MO5) and raised under ambient temperature 22 ± 1 °C (N) or 35±1 °C (HS). HS conditions negatively affected the weight gain and FCR, while feeding MO exhibited beneficial effects especially under HS conditions. Triglycerides, total cholesterol and low-density lipoprotein cholesterol (LDL) levels were significantly (P < 0.05) higher in chickens raised in HS conditions and fed the basal diet than those in normal condition and fed with or without MO, while MO decreased triglycerides and total cholesterol levels in normal and HS conditions. Blood high-density lipoprotein cholesterol (HDL) was significantly decreased in broilers raised in HS conditions and fed diets without MO, while MO increased HDL level. Blood glutathione peroxidase (GSH-Px) was significantly (P < 0.05) decreased in broilers raised in HS conditions and fed the basal diet without MO. mRNA expression of GSH-Px was significantly (P < 0.05) downregulated in broilers raised in HS conditions and fed diets without MO. Broilers under normal or HS conditions and fed the basal diet exhibited significantly (P < 0.05) downregulated mRNA expressions of superoxide dismutase (SOD) and catalase (CAT) compared to chickens under normal conditions and fed MO. Liver and muscle thiobarbituric acid reactive substance (TBARs) were significantly (P < 0.05) increased in broilers under HS conditions and fed diet without MO. The expressions of interleukins (IL2 and IL6) were significantly (P < 0.05) downregulated in broilers under normal or HS conditions and fed diets without MO. To sum up, HS conditions depressed the performance, antioxidative status, and immune related gene expression in broilers, while MO obviously alleviated these negative effects in broilers.

Saturated fatty acids may ameliorate environmental heat stress in broiler birds by affecting mitochondrial energetics and related genes

Heat stress decreases performance of poultry. The novel strategies to maintain production level, or at least minimizing the decrease in productivity during hot days need to be elucidated. This study was conducted to determine the effect of four fat types on mitochondrial energetics in heat-stressed broilers. In experiment 1, nitrogen-corrected apparent metabolizable energy (AMEn) content of four supplemental fat sources, including olive oil, soybean oil, coconut oil and beef tallow, all supplemented at 3%, 6%, and 9% in the basal diet, was evaluated. The AMEn values of fats were determined as 9738.0 ± 137.9, 8949.0 ± 159.9, 7844.0 ± 91.7, and 7368.0 ± 190.3 kcal/kg for olive oil, soybean oil, coconut oil and beef tallow, respectively. In experiment 2, birds were kept in two separated rooms under 24 °C or 36 °C from 32 to 42 d of age. Each room consisted of four experimental groups. Birds in the experimental groups were fed on beef tallow-, coconut oil-, olive oil- or soybean oil-supplemented diets (factorial arrangement with two factors of fat types and environmental temperatures). The birds reared under 24 °C had higher final body weight (P < 0.01), weight gain (P < 0.01), feed intake (P < 0.05) and lower feed conversion ratio (P < 0.01) than the birds grown under 36 °C. There was a temperature by fat type interaction effect on mitochondrial attributes. At 36 °C, in birds fed on coconut oil- or beef tallow-supplemented diets, the expression levels of avUCP and avANT mRNA were lower (P < 0.05) but that of HSP70 mRNA was higher (P < 0.01) in comparison with the birds feeding on the olive oil- or soy oil-supplemented diets. An interaction effect was recorded between the temperature and fat type for ATP concentration and mitochondrial membrane potential (P < 0.01); with significant differences between birds receiving the coconut oil- or beef tallow-supplemented diets and the birds feeding on the soy oil- or olive oil-supplemented diets. It was also found that unsaturated fatty acids had a more significant effect on avUCP and avANT mRNA expression. It can be concluded that when using fat in the diet of heat stressed-broilers, it is advisable to choose a type, which has a lower effect on the expression of avUCP and avANT, and hence reduces the metabolic heat load in the bird.

Response of two broiler strains to four feeding regimens under hot climate

In total, 392 male broilers were randomly distributed in a factorial arrangement of 2 × 4, with two commercial broiler strains (Arbor Acres (AA) and Hubbard (Hub)) and four (NRC, Degussa, CVB, and strain guides) different feeding regimens (FR), totaling eight treatments and seven replicates, with seven broilers in each one. The following parameters were evaluated: bodyweight gain (BWG), feed intake (FI), feed conversion ratio (FCR), carcass yield, meat quality, nutrient intake, and its correlation with BWG. Interaction strain type × FR was significant for BWG, FI, and FCR, with the AA broilers showing higher BWG and FI and lower FCR than the Hub broilers. There was no difference in BWG, FI, and FCR of the AA broilers regardless of FR they were on, but the Hub broilers had lower BWG when they were fed according to the Degussa and CVB regimens; BWG and FCR were negatively affected. During the starter phase, BWG of the AA broilers was significantly correlated with feed, metabolisable energy (ME), lysine, and sulfur amino acids (SAA) intake. However, BWG was correlated with feed and ME intake and feed intake from 1 to 31 and from 1 to 42 days of age, respectively. In the Hub chicks, ME and crude protein intake and lysine and SAA intake were inversely correlated with BWG from 1 to 31 days and from 1 to 42 days of age, respectively. There was no significant effect of FR on dressed carcass weight or relative gizzard, pancreas, and liver weights and on intestinal weight; however, abdominal fat and spleen differed significantly with FR. Strain type significantly affected the relative weight of the intestines. There was no significant effect of FR and/or strain type on meat moisture, crude protein, lipid and ash content, or pH, colour, meat juiciness and tenderness (meat softness). In conclusion, AA strain of broiler performed better than the Hub strain under the different FR in all the evaluated production phases, but neither FR nor strain type affected carcass characteristics.

Effects of dietary electrolyte balance and addition of electrolyte-betaine supplements in feed or water on performance, acid-base balance and water retention in heat-stressed broilers

The effects of dietary electrolyte balance (DEB) and electrolyte-betaine (El-Be) supplements on heat-stressed broiler performance, acid-base balance and water retention were evaluated during the period 31-40 d of age in a 2 × 3 factorial arrangement of treatments. A total of 240 broilers were assigned to 6 treatment groups each with 8 replicates of 5 birds per cage and were exposed to cyclic high temperature (32 - 24 ± 1°C). Birds were provided with diets having DEB of either 180 or 220 mEq/kg. El-Be supplements were either added to the diet, water or not added to either of them to complete the array of 6 treatment groups. An additional 80 birds were kept at thermoneutral temperature (20 ± 1°C) and were provided with tap water and diets with DEB of either 180 or 220 mEq/kg to serve as negative controls. Exposure to high temperature depressed growth performance, increased rectal temperature and decreased potassium (K(+)) retention. In high-temperature room, birds fed on diets with DEB of 220 mEq/kg tended to increase BW from 35-40 d of age. However, at thermoneutral temperature, broilers fed on diets with DEB of 220 mEq/kg increased K(+) retention. Adding El-Be supplements in feed or water improved feed conversion ratio (FCR), enhanced water consumption and increased K(+) and sodium (Na(+)) retention. Interactions between DEB and El-Be supplements tended to affect body weight gain and FCR during the periods 35-40 and 31-40 d of age, respectively. It is suggested that when using a diet with DEB of 180 mEq/kg, adding the El-Be supplements in drinking water was more beneficial than in feed. Adding the supplements in feed or water was equally useful when using DEB of 220 mEq/kg.

Nutritional and physiological responses of finishing pigs exposed to a permanent heat exposure during three weeks

The aim of the current study was to investigate the effect of a permanent heat exposure during 21 days on pig performance, nutrient digestibility, physiological response and key enzyme of skeletal muscle energy metabolism. Twenty-four male finishing pigs (crossbreed castrates, 79.0 ± 1.50 kg body weight) were allocated to three groups (n = 8): (1) Control (ambient temperature (AT) 22°C, ad libitum feeding), (2) Group HE (AT 30°C, ad libitum feeding) and (3) Group PF (AT 22°C, pair-fed to Group HE). The permanent heat exposure decreased feed intake (p < 0.01), daily body weight gain (p < 0.05) and the digestibility of gross energy, dry matter, crude protein and ash (p < 0.05); rectal temperature and respiration rate were significantly increased (p < 0.01). The levels of plasma cortisol, creatine kinase and lactate dehydrogenase were also significantly increased in Group HE (p < 0.05). Furthermore, the heat exposure changed intracellular energy metabolism, where the AMP-activated protein kinase was activated (p = 0.02). This was combined with changes in parameters of glycolysis such as an accumulation of lactic acid (p = 0.02) and a drop of pH24 h (p = 0.02), an increase of hexokinase and pyruvate kinase activity (p < 0.01) and, finally, the maturation process of post mortem muscle was influenced. Due to pair-feeding it was possible to evaluate the effects of heat exposure, which were not dependent on reduced feed intake. Such effects were, e.g., reduced nutrient digestibility and changed activities of several enzymes in muscle and blood serum.

Dietas com diferentes densidades nutricionais para frangos de corte mantidos em ambientes com e sem nebulização

Esta pesquisa foi desenvolvida para avaliar o efeito da densidade nutricional da dieta, sobre as variáveis de desempenho de frangos de corte, mantidos em ambientes com ventilação, associado ou não a nebulização, nos períodos de oito a 21 e de oito a 41 dias de idade, bem como, avaliar o rendimento de carcaça, cortes e gordura abdominal aos 41 dias de idade das aves. O delineamento utilizado foi inteiramente ao acaso, em esquema fatorial, com três tratamentos e seis repetições, em dois ambientes, sendo 20 aves por unidade experimental. Os tratamentos consistiram de três dietas com diferentes densidades nutricionais: controle; média e alta densidade. O sistema de resfriamento evaporativo com ventilação associado à nebulização, em condição de temperatura e umidade relativa do ar elevadas, proporciona aumento no consumo de ração, mas piora a conversão alimentar dos frangos de corte na fase inicial. Para o período de oito a 41 dias, o ambiente com ventilação associada à nebulização proporciona às aves aumento no consumo de ração e no ganho de peso, sem afetar a conversão alimentar. A dieta de alta de densidade nutricional, na fase de oito a 21 dias, reduz o consumo de ração e melhora conversão alimentar em relação à dieta controle. Para o período de oito a 41 dias, a dieta de média densidade proporciona maior ganho de peso e melhor conversão alimentar em relação ao controle. As diferentes densidades nutricionais não afetam o rendimento de carcaça, dos principais cortes e gordura abdominal aos 41 dias de idade.