Intestinal microbiota of broilers submitted to feeding restriction and its relationship to hepatic metabolism and fat mass: Fast-growing strain.

The present study was conducted to verify how feed restriction affects gut microbiota and gene hepatic expression in broiler chickens and how these variables are related to body weight gain. For the experiment, 21-d-old Cobb500TM birds were distributed in a completely randomized experimental design with three treatments: T1. Control (ad libitum-3.176 Mcal/kg ME-metabolizable energy-and 19% CP-crude protein); T2. Energetic restriction (2.224 Mcal/kg ME and 19% CP) from 22 to 42 days with consumption equivalent to control; T3. Quantitative restriction (70% restriction, i.e., restricted broilers ingested only 30% of the quantity consumed by the control group-3.176 Mcal/kg ME and 19% CP) for 7 days, followed by refeeding ad libitum from 28 to 42 days. Ileum and caecum microbiota collections were made at 21, 28 and 42 days of age. Hepatic tissue was collected at 28 and 42 days old for relative gene expression analyses. At 43-d-old, body composition was quantified by DXA (Dual-energy X-ray Absorptiometry). Both feed restriction programmes decreased Lactobacillus and increased Enterococcus and Enterobacteriaceae counts. No differences were found in the refeeding period. Energetic restriction induced the expression of CPT1-A (Carnitine palmitoyltransferase 1A) gene, and decreased body fat mass. Quantitative feed restriction increased lipogenic and decreased lipolytic gene expression. In the refeeding period, CPT1-A gene expression was induced, without changing the broilers body composition. Positive associations were found between BWG (Body Weight Gain) and Lactobacillus and Clostridium cluster IV groups, and negatively associations with Enterobacteriaceae and Enterococcus bacterial groups. In conclusion, differences found in microbiota were similar between the two feed restriction programmes, however, hepatic gene expression differences were only found in quantitative restriction. Higher counts of Lactobacillus and Clostridium cluster IV groups in ileum are likely to be related to better broiler performance and low expression of lipogenic genes.

Dynamic of heat production partitioning in rooster by indirect calorimetry.

OBJECTIVE: The objective of this study was to describe a methodological procedure to quantify the heat production (HP) partitioning in basal metabolism or fasting heat production (FHP), heat production due to physical activity (HPA), and the thermic effect of feeding (TEF) in roosters. METHODS: Eighteen 54-wk-old Hy Line Brown roosters (2.916±0.15 kg) were allocated in an open-circuit chamber of respirometry for O2 consumption (VO2), CO2 production (VCO2), and physical activity (PA) measurements, under environmental comfort conditions, following the protocol: adaptation (3 d), ad libitum feeding (1 d), and fasting conditions (1 d). The Brouwer equation was used to calculate the HP from VO2 and VCO2. The plateau-FHP (parameter L) was estimated through the broken line model: HP = U×(R-t)×I+L; I = 1 if tR; Where the broken-point (R) was assigned as the time (t) that defined the difference between a short and long fasting period, I is conditional, and U is the decreasing rate after the feed was withdrawn. The HP components description was characterized by three events: ad libitum feeding and short and long fasting periods. Linear regression was adjusted between physical activity (PA) and HP to determine the HPA and to estimate the standardized FHP (st-FHP) as the intercept of PA = 0. RESULTS: The time when plateau-FHP was reached at 11.7 h after withdrawal feed, with a mean value of 386 kJ/kg0.75/d, differing in 32 kJ from st-FHP (354 kJ/kg0.75/d). The slope of HP per unit of PA was 4.52 kJ/mV. The total HP in roosters partitioned into the st-FHP, termal effect of feeding (TEF), and HPA was 56.6%, 25.7%, and 17.7%, respectively. CONCLUSION: The FHP represents the largest fraction of energy expenditure in roosters, followed by the TEF. Furthermore, the PA increased the variation of HP measurements.

Heat stress affects breathing and metabolism of chicks incubated at high temperature.

Global warming poses serious implications to animal physiology and a gradual increase in ambient temperature affects all living organisms, particularly fast-growing selected species. We recorded ventilation (V̇E), body temperature (TB), oxygen consumption (V̇O2) and respiratory equivalent (V̇E/V̇O2) of 14-day-old (14d) male and female chicks at room air conditions, hypercapnia and hypoxia at heat stress (HS, 32 °C). These chicks had previously been exposed to control (CI, 37.5 °C) and high (HI, 39 °C) temperatures during the first 5 days of incubation. Under resting conditions, acute HS increased V̇E in HI females but not in HI males. Hypercapnia combined with heat promoted a potentiation of CO2-hyperventilatory response in HI females when compared with thermoneutral condition, whereas in HI incubated males a hypoventilation under hypercapnia and heat stress was observed compared to the CI group. Hypoxia associated with heat stress increased V̇E only in HI females. Our data indicates that females are more sensitive to thermal manipulation during incubation and it seems that the thermal embryonic manipulation, at least during the first days of development, does not improve the adaptive response of chicks to heat stress.

Embryonic Thermal Manipulation Affects Ventilation, Metabolism, Thermal Control and Central Dopamine in Newly Hatched and Juvenile Chicks.

The first third of incubation is critical for embryonic development, and environmental changes during this phase can affect the physiology and survival of the embryos. We evaluated the effects of low (LT), control (CT), and high (HT) temperatures during the first 5 days of incubation on ventilation ( V . E ), body temperature (Tb), oxygen consumption ( V . O2), respiratory equivalent ( V . E / V . O2), and brain monoamines on 3-days-old (3d) and 14-days-old (14d) male and female chickens. The body mass of LT animals of both ages and sexes was higher compared to HT and CT animals (except for 3d males). The heart mass of 14d HT animals was higher than that of CT animals. Thermal manipulation did not affect V . E , V . O2 or V . E / V . O2 of 3d animals in normoxia, except for 3d LT males V . E , which was lower than CT. Regarding 14d animals, the HT females showed a decrease in V . E and V . O2 compared to CT and LT groups, while the HT males displayed a lower V . O2 compared to CT males, but no changes in V . E / V . O2. Both sexes of 14d HT chickens presented a greater Tb compared to CT animals. Thermal manipulations increased the dopamine turnover in the brainstem of 3d females. No differences were observed in ventilatory and metabolic parameters in the 3d animals of either sexes, and 14d males under 7% CO2. The hypercapnic hyperventilation was attenuated in the 14d HT females due to changes in V . O2, without alterations in V . E . The 14d LT males showed a lower V . E , during hypercapnia, compared to CT, without changes in V . O2, resulting in an attenuation in V . E / V . O2. During hypoxia, 3d LT females showed an attenuated hyperventilation, modulated by a higher V . O2. In 14d LT and HT females, the increase in V . E was greater and the hypometabolic response was attenuated, compared to CT females, which resulted in no change in the V . E / V . O2. In conclusion, thermal manipulations affect hypercapnia-induced hyperventilation more so than hypoxic challenge, and at both ages, females are more affected by thermal manipulation than males.

Cardiorespiratory and thermal responses to hypercapnia in chickens exposed to CO2 during embryonic development.

The concentration of CO2 in the environment surrounding the embryo impacts development and may also influence the cardiorespiratory responses after hatching. Therefore, we aimed to evaluate the cardiorespiratory and thermal responses to hypercapnia in chicks that were exposed to CO2 during embryonic development, i.e., incubation. Embryos were incubated without and with a gradual increase in CO2 concentration up to 1 % during the first ten days of incubation. Ten-day-old chicks (males and females) were again acutely exposed to hypercapnia (7 % CO2), or to room air (normocapnia) and pulmonary ventilation, arterial pH and blood gases, arterial blood pressure and heart rate, body temperature (Tb) and oxygen consumption (V⋅O2) were measured. Compared to control animals, male chicks incubated with 1 % CO2 presented an attenuated ventilatory response to hypercapnia (P < 0.05), whereas no difference was found in the hypercapnic ventilatory response in both female chick groups (0 % vs 1 % CO2 incubation). Hypercapnia induced bradycardia in all groups (P < 0.001). The CO2 exposure during incubation did not alter the cardiovascular responses to hypercapnia in post-hatch animals. There were no significant effects of incubation treatment (0 % vs 1 % CO2) or sex in the mean arterial pressure, Tb, and V⋅O2 of animals in normocapnia and hypercapnia. As for the V⋅E/V⋅O2, hypercapnia caused an increase in both groups (P < 0.05), regardless of incubation treatment. In conclusion, among cardiorespiratory and metabolic variables, the ventilatory response to hypercapnia can be attenuated by pre-exposure to 1 % CO2 during embryonic development, especially in male chicks up to 10 days.

Influence of rearing temperature and feed format in the development of the pendulous crop in broilers.

The pendulous crop is characterized by excessive distension of the crop musculature, compromising the bird's productivity and welfare. The etiology is still unknown, but it is believed that factors related to the birds' handling might be related to its incidence. The study was conducted in 2 environmental chambers. One was maintained at a comfortable temperature, while the other was set at a much lower temperature. In each chamber, animals were divided into 16 experimental pens (8 received mash feed and the others received pelletized feed) with a density of 12 birds/m2 (an expected stocking density of 32-36 kg/m2 after 42 d). The effects of rearing temperatures were evaluated in terms of broiler performance, specifically weight gain (kg), feed intake (kg), weekly feed intake (kg/wk), and feed conversion (kgfeed/kggrowth). The occurrences of pendulous crop were quantified every 2 d after the 14th day of rearing. Birds grown in thermal comfort and fed a pelletized ration were most susceptible (12%) to pendulous crop, followed by birds fed pelletized feed and reared in cold conditions (6.8%), and birds given mashed feed and reared at either temperature (about 3%). We concluded that feeding pelleted feed combined with warmer rearing temperatures may have caused some alteration of the gastrointestinal system of birds, which caused pendulous crop to be more prevalent.

Poultry rearing on perforated plastic floors and the effect on air quality, growth performance, and carcass injuries-Experiment 1: Thermal Comfort.

The present study investigated the use of perforated plastic floors in the rearing of male and female poultry under thermal comfort conditions. The study was conducted in 2 climate chambers, in one was conventional poultry litter (wood shavings) and in the other was a perforated plastic floor. The experimental design was a completely randomized design with the factors wood shavings and plastic floor. In each chamber, the animals were divided into 16 experimental pens (8 with males and 8 with females) with a density of 12 birds/m2. The poultry rearing effect was evaluated in terms of air quality (% concentration of ammonia [NH3] and carbon dioxide [CO2]); broiler performance, e.g., weight gain (kg), feed intake (kg), feed conversion, carcass yield and parts (%), meat production (kg/m2), and viability (% of live birds at d 42); scores of hygiene and mobility; and injuries in the chest, hocks, and footpads. Treatments affected air quality, with higher concentrations of NH3 on d 42 (25 ppm vs. 2 ppm) and CO2 (1,400 ppm vs. 1,000 ppm) for wood shavings than for perforated plastic floor, respectively. Males showed a better performance (weight gain, feed intake and feed conversion) than females on d 42 in both floor types (wood shavings and plastic floor). Males reared on wood shavings showed a higher meet production (35.992 kg/m2) than females (32.257 kg/m2). On the plastic floor, males showed a better viability (100%) than females (94.05%), as well better meet production for males (38.55 kg·m-2) than females (31.64 kg/m2). There was no incidence of breast lesions in any of the studied systems. The birds reared on the plastic floor had better hygiene scores and lower hock injury rates than birds reared in the wood shavings chambers. The results of the present study show that the use of perforated plastic floors in chicken farming is an efficient method, which promotes a better-quality environment, superior production rates, and reduced incidence of injuries.

Analysis of metabolic pools in broilers chicks.

This paper shows the possibility of obtaining new parameters for the mathematical modelling of data on stable isotopes in biological systems and its application in obtaining data on metabolic pools of blood plasma, blood serum, liver and muscle of broilers. This theory states that the modelling of turnover used for studies of isotopic incorporation when the metabolism has a single metabolic pool is feasible by the technique of setting an exponential. However, when the metabolism has more than one metabolic pool, it is necessary to apply the linearization technique, linear regression adjustment and evaluation of the assumptions of regression to obtain the kinetic parameters such as half-life (T1/2) and isotope exchange rate (k). The application of this technique on carbon-13 data from 100 one-day-old chicks, with the change of diet composed of grains of the photosynthetic cycle of plants from C4 to C3, in broilers has enabled the discovery that the liver, blood plasma and blood serum have a single metabolic pool; however, the pectoral muscle has two metabolic pools. For the liver, blood plasma and blood serum, the half-life values were found by the exponential fit being T1/2 = 1.4 days with the rate of exchange of k = 0.502, T1/2 = 2.4 days with k = 0.293 and T1/2 = 2.0 days with k = 0.348, respectively. For the pectoral muscle, after linearization, the half-life values were found for T1/2(1) = 1.7 and T1/2(2) = 3 days, with exchange rates of k1 = 0.405 and k2 = 0.235, representing approximately 66 and 34%, respectively.

Effect of moderate and severe heat stress on avian embryonic hsp70 gene expression.

Stress response is a universal mechanism developed by all organisms to deal with adverse changes in the environment, which lead to the synthesis of heat shock proteins (Hsps). In this study, the effect of moderate (41 degrees C) and severe (44 degrees C) heat stress on Hsp70 transcript expression pattern was investigated during chicken embryogenesis. Acute exposure to severe heat stress for one hour resulted in a fifteen-fold increase in Hsp70 mRNA levels. The return of stressed embryos to normal incubation temperature resulted in Hsp70 mRNA levels five-fold higher than control after three hours and normal levels after six hours. Moderate heat stress did not induce enhancements on Hsp70 mRNA levels. The spatial expression of Hsp70 transcripts was detected in embryos under normal incubation conditions. Whole-mount in situ hybridization analysis showed that Hsp70 transcripts were constitutively present in somite and in distinct encephalic domains (predominantly in prosencephalon and mesencephalon areas) of the chicken embryo. These results showed that Hsp70 induction is dependent on incubation temperature conditions, suggesting that early chicken embryos may induce a quick emergence response to cope with severe heat stress by increasing Hsp70 mRNA levels.

Age and gender influence the cardiorespiratory function and metabolic rate of broiler chicks during normocapnia and hypercapnia.

Pulmonary ventilation (V˙(E)), body temperature (Tb), mean arterial pressure (MAP), heart rate (f(H)) and metabolic rate (V˙(O2)) were measured in 10 (d10)- and 21 (d21)-day-old male and female chicks exposed to 7% CO2. Under normocapnia, V˙(E) was higher in d10 chicks than in d21 due to a higher tidal volume; in females a higher respiratory frequency (f(R)) was also observed. The d10 birds presented higher f(H) and V˙(O2). The d21 females showed the highest CO2 ventilatory response due to increased f(R). MAP did not change during hypercapnia while a hypercapnic bradycardia occurred, except in d21 females. Hypercapnia induced a drop in Tb in all groups and an increase in V˙(O2) in d21 males. Overall, no gender effect is observed in cardiorespiratory and metabolic variables in d10 and d21 chicks under normocapnia, the differences in V˙(E) and f(H) between ages may be related to distinct metabolic demands of these phases. The d21 female chicks seem to be more sensitive to hypercapnia.

Expression of heat shock protein in broiler embryo tissues after acute cold or heat stress.

This study evaluated the expression of heat shock protein 70 kD (hsp70) in broiler chicken embryos subjected to cold (Experiment I) or high incubation temperature (Experiment II). In each experiment, fertile eggs were distributed in three incubators kept at 37.8 degrees C. At day 13 (D13), D16, and D19 of incubation, the embryos were subjected to acute cold (32 degrees C) or heat (40 degrees C) for 4-6 hr. Immediately after cold or heat exposure, samples from the liver, heart, breast muscle, brain, and lungs of 40 embryos were taken per age and treatment (control or stressed embryos). A tissue pool from 10 embryos was used as 1 replication. The levels of hsp70 in each tissue sample was quantified by Western blot analysis. The data were analyzed in a 3 x 2 factorial arrangement of treatments with four replications. hsp70 was detected in all embryo tissues, and the brain contained 2- to 5-times more hsp70 protein compared to the other tissues in either cold or heat stressed embryos. hsp70 increases were observed in the heart and breast muscle of cold stressed embryos at D16 and D19, respectively. Heat stressed embryos showed an increase of hsp70 in the heart at D13 and D19, and in the lung at D19 of incubation. Younger embryos had higher hsp70 synthesis than older embryos, irrespective of the type of thermal stressor. The results indicate that the expression of hsp70 in broiler chicken embryos is affected by cold and heat distress, and is tissue- and age-dependent.

Energy and oil levels in broiler starter diets / Níveis de energia e de óleo vegetal em dietas iniciais de frangos de corte

The feed intake and performance of the broilers fed with different levels of dietary energy in the starter diet to 21 days of age were evaluated. In Experiment 1 it was evaluated the performance of birds fed to 2,900 and 3,200kcal ME kg-1 diets, and the results show that ME intake was highest for birds 3,200kcal ME kg-1 on the 7th day of age. Feed intake (FI), weight gain (WG), and feed conversion (FC) were not affected by dietary energy level on the 7th and 14th day of age, but on the 21st day of age, WG and FC were better for 3,200kcal ME kg-1 diets. In the experiment 2, isocaloric diets (2,900kcal ME kg-1) were formulated with four different oil levels (0, 1, 2, and 3 percent), in order to observe diet preference. Between 6 and 10 days of age, a quadratic response in FI for oil level was observed (Y=47.6+49.8x-13.4x², R²=0.98). Between 11 to 15, and 16 to 20 days of age, birds preferred to eat the diet with the highest level of oil (Y=16.6+52.85x, R²=0.97 and Y=19.30+59.05x, R²=0.98, respectively). Experiment 3 evaluated the performance and the pancreatic Lipase and Amylase activities of birds. On the 11th day of age, a linear response to WG and FC dietary oil level occurred. No differences were found in pancreatic lipase and amylase enzyme levels at 5 days of age. The diets with higher levels of energy and/or oil, during the first days of age, did not influence dietary preference, pancreatic lipase and amylase level or the performance of broilers. The results of this study show that diets with high levels of energy derived from lipids may not be interesting for young broilers, as they do not result in better performance (FI, WG, and FC).

Foram avaliados o comportamento ingestivo e o desempenho de frangos de corte alimentados com diferentes níveis de energia e inclusões de óleo vegetal na dieta inicial. No Experimento 1, foi comparado o desempenho de frangos alimentados com dietas contendo 2.900 ou 3.200kcal EM kg-1 de ração, e a ingestão de EM foi maior nas aves alimentadas com 3.200Kcal EM kg-1 na primeira semana de idade. O consumo de ração (CR), o ganho de peso (GP) e a conversão alimentar (CA) não foram influenciados pelo nível de energia aos sete e aos 14 dias, entretanto, aos 21 dias de idade, GP e CA foram melhores paras aves alimentadas com dietas com 3.200Kcal de EM kg-1. No Experimento 2, foram formuladas dietas isocalóricas (2.900 Kcal EM kg-1) com diferentes níveis de óleo (0, 1, 2 e 3 por cento). Entre o sexto e o décimo dia de idade houve aumento no CR, concomitantemente à inclusão de óleo (Y=47,6+49,8x-13,4x², R²=0,98). Entre o décimo e o décimo quinto dia e também entre o décimo quinto e vigésimo dia de idade, houve preferência pela ingestão de rações com maior nível de óleo (Y=16,6+52,85x, R²=0,97 e Y= 9,3+59,05x, R²=0,98 respectivamente). No experimento 3, foi avaliado o desempenho e a atividade da lipase e amilase pancreáticas. No décimo primeiro dia de idade, houve aumento linear em GP e CR com o aumento no nível de óleo. Não houve alteração nos níveis de enzimas estudados. Dietas com altos níveis de energia e/ou óleo não alteram o desempenho ou a produção de lipase e amilase em frangos nos primeiros dias de idade. Os resultados deste estudo mostram que altos níveis de energia proveniente de lipídios não são interessantes para frangos de corte, por não alterarem o seu desempenho (consumo de ração, ganho de peso ou conversão alimentar).

Estudos hematológicos e hormonal de frangos de corte tratados com contaminantes do milho: Crotalaria spectabilis e Senna occidentalis / Hematological and hormonal studies from broiler chickens fed with corn contaminants: Crotalaria spectabilis e Senna occidentalis

Crotalaria spectabilis (crotalária) e a Senna occidentalis (fedegoso) podem crescer em plantaçöes de milho e, durante a colheita, este cereal pode ser contaminado com as sementes dessas plantas, que apresenta toxicidade para os animais. O objetivo deste estudo foi investigar os parâmetros morfométricos dos eritrócitos, as variáveis hematológicas e a concentraçäo plasmática hormonal dos frangos de corte tratados com raçäo de dois níveis de energia, que foi adicionada de 0,1 por cento e 0,5 por cento de sementes de Crotalaria spectabilis e Senna occidentalis, respectivamente. Cento e oitenta frangos de corte foram divididos em seis grupos, de acordo com uma análise fatorial 3 x 2 (controle, crotalária e fedegoso como tratamentos principais e dois níveis de energia, 2.900 e 3.200 kcal ME/kg de raçäo). Os resultados deste experimento mostraram que o efeito tóxico da crotalária determinou uma reduçäo no número de hemácias, no valor do hematócrito e do VCM, nao influenciando os parâmetros morfométricos avaliados. A semente de crotalária induziu, também, aumento na incidência de ascite, em funçäo de sua toxicidade hepática. Já a semente de fedegoso näo mostrou toxicidade suficiente para induzir ascite nos frangos

Polymorphism analysis of the hsp70 stress gene in Broiler chickens (Gallus gallus) of different breeds

The promoter region and the beginning of the coding region of the hsp70 stress gene were analysed in broiler chickens of a commercial breed (Hubbard-Pettersen), a breed selected for weight gain (PP1) and a non-selected breed (naked-neck Label Rouge). The naked neck gene (Naked neck, Na), which reduces feathering in birds and is thus related to heat resistance, was present in both PP1 and Label Rouge breeds. Genomic DNA was restricted with PstI and Southern blotting analysis of the samples revealed the absence of polymorphic sites for that enzyme in the promoter region and beginning of the coding region of the hsp70 gene of studied birds. PCR-SSCP analysis of these regions, however, indicated the presence of polymorphisms in the beginning of the coding region and the sequencing of the PCR products confirmed and identified two polymorphic sites in this region: a transition A ® G in position +258 and a transversion C ® G in position +276. Both mutations were considered to be silent, since they did not modify the aminoacid sequence of the protein Hsp70. The promoter region of the hsp70 gene was identical in all studied birds, indicating that the regulation pattern of this gene must be the same in all birds at the promoter region. Three different alleles (hsp70-1, hsp70-2 and hsp70-3) were identified for the hsp70 gene from the observed mutations. The allele hsp70-3 was detected in only two breeds, Hubbard-Pettersen and PP1, but at a low frequency (0,016 and 0,006, respectively)

Hepatic mRNA expression and plasma levels of insulin-like growth factor-I (IGF-I) in broiler chickens selected for different growth rates

The hepatic expression and plasma concentrations of IGF-I were investigated in three broiler chicken strains selected for different growth rates (HP-Hubbard-Pettersen, a fast growing strain; NN-Naked-neck, a strain with an intermediate growth rate and a heterozygous genotype, and C-Caipira, a slow growing crossbred strain). The chickens were studied at 1, 21 and 42 days of age and had free access to food throughout the study. Hepatic IGF-I mRNA expression was assessed by dot blot analysis using a randomly labeled chicken IGF-I cDNA as the probe and plasma IGF-I concentrations were assayed by radioimmunoassay. The hepatic levels of IGF-I mRNA increased from 1 to 21 days of age in all strains, with NN chickens showing a higher (p < 0.05) IGF-I expression than the other strains. Plasma IGF-I concentrations increased (p < 0.05) with broiler chicken age, but there were no significant differences among the strains. These results indicate that despite differences in the growth rates among the strains, the changes in the expression of IGF-I mRNA in liver and in the plasma levels of IGF-I were independent of broiler chicken strain, but varied with chicken age.