Effect of low incubation temperature and low ambient temperature until 21 days of age on performance and body temperature in fast-growing chickens

Use of in ovo transponder telemetry to determine the effects of a reduction in temperature initiated on day twelve of incubation on the subsequent body temperature and somatic characteristics of Ross 708 broiler chicks

The effects of a reduction in incubation temperature, made to accommodate higher levels of embryonic heat production, on the post hatch body temperature and somatic characteristics of Ross 708 broilers were determined. Incubation temperature treatments (TRT) were a standard (STRT, 37.5 °C) and a lower (LTRT, 35.6°C) TRT provided between 12 and 21 d of incubation (DOI). All eggs were incubated at 37.5 °C between 0 and 12 DOI. Temperature transponders implanted in the air cell of each egg at 12 DOI were extracted and inserted subcutaneously into the neck of the corresponding hatchling to record chick body temperature (CBT) through 21 d of grow out (DOG). After placement, multiple CBT and litter temperature (LT) readings were recorded daily between 1 and 21 DOG, and BW was determined at placement (0 DOG), and BW, body length (BL), and BW to length ratio (BWTLR) were determined on 7, 14, and 21 DOG. Thirteen daily mean CBT readings in the STRT were significantly higher than those in the LTRT between 1 and 21 DOG. Nevertheless, there was no significant correlation between LT and CBT, and when hatch time (HT) and BW were accounted for, embryo temperature (ET) and CBT were not significantly correlated. At 0 and 7 DOG, no significant differences in BW were observed between the STRT and LTRT within either sex; however, BW was greatest in males belonging to the STRT at 14 (x̄ = 483.1 g) and 21 (x̄ = 1,033.8 g) DOG. Across DOG and sex, BL was significantly longer in the STRT than in the LTRT, and at 14 and 21 DOG, BWTLR was greater in the STRT than in the LTRT. The LTRT subsequently lowered CBT and negatively affected chick BW, BL, and BWTLR. In conclusion, CBT is not directly associated with ET, but the reductions in CBT and various performance variables in Ross 708 broilers in response to the LTRT is a result of its adverse effects on chick HT and BW.

Management factors associated with the survival and market weight of broiler chickens among small-scale farmers in the Dodoma City of Tanzania

Broiler chickens have the genetic potential for significant weight gain over a very short period of time. As a result, they account for over 92 % of the world's poultry meat production in different parts of the world. Yet, to fully realise their growth potential, effective management practices are crucial, encompassing aspects like nutritious feeds, disease control, optimal temperature, and adequate housing. The purpose of the study was to determine the management practices associated with the survival and market weight of broiler chickens in small-scale production. Small-scale poultry production plays a significant role in poverty reduction and household nutrition in developing countries. One hundred and forty small-scale broiler farmers were visited for interviews in the Dodoma City. Employing a structured questionnaire, data on management practices was gathered, while past production records determined market weight and survival rates. Most chickens weighed 1.8-2.3 kg at the end of the production cycle, with a mean live weight of 2.0 kg. Heat provision to chick housing in the early growth stages increased both survival and market weight. Conversely, chicken vaccination and the farmer's experiences were correlated with an increased survival rate. Furthermore, higher feed quantities offered to growers and finishers were linked to greater market weight. It was concluded that enhancing knowledge among small-scale farmers through training and extension services has the potential to increase broiler productivity.

Embryonic thermal manipulation: a potential strategy to mitigate heat stress in broiler chickens for sustainable poultry production

Due to high environmental temperatures and climate change, heat stress is a severe concern for poultry health and production, increasing the propensity for food insecurity. With climate change causing higher temperatures and erratic weather patterns in recent years, poultry are increasingly vulnerable to this environmental stressor. To mitigate heat stress, nutritional, genetic, and managerial strategies have been implemented with some success. However, these strategies did not adequately and sustainably reduce the heat stress. Therefore, it is crucial to take proactive measures to mitigate the effects of heat stress on poultry, ensuring optimal production and promoting poultry well-being. Embryonic thermal manipulation (TM) involves manipulating the embryonic environment's temperature to enhance broilers' thermotolerance and growth performance. One of the most significant benefits of this approach is its cost-effectiveness and saving time associated with traditional management practices. Given its numerous advantages, embryonic TM  is a promising strategy for enhancing broiler production and profitability in the poultry industry. TM increases the standard incubation temperature in the mid or late embryonic stage to induce epigenetic thermal adaption and embryonic metabolism. Therefore, this review aims to summarize the available literature and scientific evidence of the beneficial effect of pre-hatch thermal manipulation on broiler health and performance.

Embryo thermal manipulation modifies development and hepatic lipid metabolism in post-hatch layer-type chicks

Incubation temperature is a crucial environmental factor affecting embryonic development and chick quality. Metabolism during the embryonic stage, particularly liver lipid metabolism, is essential for the growth and development of poultry. This study aimed to investigate the effects of embryo thermal manipulation with high (TMH, 39.5 °C, 65% RH, 8 h/d) and low (TML, 20 °C, 65% RH, 1 h/d) temperatures during 8th to 15th embryonic age on hatching performance and liver lipid metabolism in layer chicks. Additionally, the duration of TM effects was evaluated through a short-term feeding trial. The results indicated that TMH accelerated the hatching process without significantly affecting hatchability and growth performance. In contrast, TML delayed hatching time and significantly reduced hatchability and chick quality. After hatching, TML also increased residual yolk weight and reduced the relative liver weight in relation to body weight and yolk-free body mass. Moreover, lipid droplets in the liver were stained with Oil Red O, and the lipid content in the liver and serum was further detected. TMH had no significant impact on triglyceride (TG) and total-cholesterol (TCHO) content in the liver and serum but upregulated the expression of lipogenesis-related genes ACC, Fas, and Fatp1 compared to the TML group. Conversely, TML significantly reduced liver TG content, enhanced lipoprotein lipase (LPL) activity, and promoted the expression of lipid oxidation-related genes CPT-1, PGC-1α, and PPARα. At 7 d of age, liver LPL activity was significantly increased in the TMH group. However, there were no significant changes in the content of TG and TCHO in the liver and the expression of lipid metabolism-related genes in the TML group. Overall, these results indicate that embryonic TM alters hatching performance and liver lipid metabolism in layer chicks. TML reduces TG content by increasing liver lipid oxidation capacity. However, this effect is not long-lasting, as the influence of TM diminishes as the chicks develop.

Early-age thermal manipulation and supplemental antioxidants on physiological, biochemical and productive performance of broiler chickens in hot-tropical environments

Heat stress has been ranked as a critical environmental issue confronting chicken farmers worldwide because of its detrimental effect on the growth, performance and health of the birds. This study evaluated the effects of early-age thermal manipulation (EATC) and supplemental antioxidants on the physiological responses of broilers in a hot tropical environment. A total of 300 day-old Ross broiler chicks were allocated to five thermal and dietary treatments, having 5 replicates of twelve birds each. The treatments were: chicks reared using the conventional method (CC), chicks exposed to early thermal manipulation with a temperature of 38 °C at day 5 with no antioxidant supplementation (TC), TC plus vitamin E at 250 mg/kg of feed (TV), TC plus selenium at 0.5 mg/kg of feed (TS) and the combination of TS and TV(TVS). The experiment was laid out in a Completely Randomized Design and data collected were analyzed using SAS (2008). The results showed that TVS broilers had significantly higher (P < 0.05) body weights at the finisher phase than the other treatment groups. The feed conversion ratio of TVS broilers was comparable to the TV group but lower (P < 0.05) than the other treatments. Reduced levels (P < 0.05) of heterophil, lymphocytes and hetrophil and lymphocyte ratio were recorded in the TVS compared to TV, TS and TC broilers. On day 42, the rectal temperature was significantly higher in CC than those in other treatment groups, which were comparable. TVS birds had higher (P < 0.05) weights of spleen, liver and lower abdominal fat than other treatments. The lowest concentration of plasma malondialdehyde and the highest activity of superoxide dismutase and glutathione peroxidase were recorded in TV and TVS birds. The study concluded that the growth performance and oxidative status in broilers were improved by the combination of EATC with supplemental Se and vitamin E (TVS).

Effects of embryonic thermal manipulation on the immune response to post-hatch Escherichia coli challenge in broiler chicken

Background and Aim

Thermal manipulation (TM), exposure to mild heat shock during embryogenesis, which is a critical developmental period of broiler chickens, improves tissue stability, oxidative stress response, and immune response during heat stress. Thermal manipulation could be more cost-effective than other methods to boost the immune response. This study aimed to evaluate the impact of TM during embryogenesis, concomitant with an Escherichia coli challenge, on body weight (BW), body temperature (Tb), and splenic mRNA expression of cytokines (Interleukin [IL]-1β, IL-2, IL-6, IL-8, IL-12, IL-15, IL-16, IL-18, and interferon [IFN]-γ) in poultry.

Materials and Methods

A total of 740 fertile eggs were procured from a certified Ross broiler breeder. The eggs were divided into two incubation groups: the control and TM groups. The eggs in the control group were kept at 37.8°C air temperature and 56% relative humidity (RH) during incubation; eggs of the TM group were incubated under standard conditions, except for embryonic days 10-18, during which they were incubated at 39°C and 65% RH for 18 h daily. On the 7th day of incubation, eggs with dead embryos were excluded. After hatching was complete, each group was further subdivided into saline-treated or E. coli-challenged groups. The E. coli (serotype 078 with the dose of 1.5 × 105 colony-forming unit/mL) challenge was performed when the birds were 20 days old. Body weight and Tb measurements were taken on post-hatch days 20, 21, 23, and 25. Splenic mRNA expression of cytokines (IL-1β, IL-2, IL-6, IL-8, IL-12, IL-15, IL-16, IL-18, and IFN-γ) was analyzed by real-time quantitative polymerase chain reaction.

Results

Following the E. coli challenge, the TM-treated group's body performance parameters (BW and Tb) were significantly increased compared with the control group. Body weight was higher in the TM group than in the control group (p < 0.05); Tb was lower in the TM group than in the control group (p < 0.05). The mRNA levels of IL and IFN-γ were more stable and moderately induced in the TM group compared with the control group. Thermal manipulation altered the basal mRNA levels of ILs and IFN-γ and changed their expression dynamics after the E. coli challenge.

Conclusion

Thermal manipulation during embryogenesis could boost the immune system response to E. coli.

Utilizing in ovo telemetry to examine the effects of reduced incubation temperature on broiler embryo temperature and subsequent hatchability

The current commercial broiler embryo experiences a rapid metabolism and growth rate and may produce more heat than those of the past. Consequently, it may be beneficial to lower standard incubation temperature for commercial broiler hatching eggs. The purpose of this experiment was to determine if lowering incubation temperature at 12 d of incubation (DOI) would affect embryo temperature (ET) in embryonated Ross 708 broiler hatching eggs. From 0 to 12 DOI, eggs were incubated under standard conditions (37.50°C dry bulb, 29.76°C wet bulb). At 12 DOI, temperature transponders were aseptically placed on the inner air cell membrane to measure air cell temperature (ACT) as an estimate of ET in 120 eggs. The eggs were then randomly assigned to 4 separate still-air incubators, each containing 30 eggs. Two replicate incubators were maintained at a standard (STRT; 37.5°C) or low (LTRT; 35.6°C) temperature treatment between 12 and 21 DOI. A significant positive correlation existed between incubator air temperature (IAT) and ACT across temperature treatment and in the STRT. However, IAT was not significantly correlated with ACT in the LTRT. A significantly higher ACT was observed in the STRT than in the LTRT for 88% of the readings taken between 12 and 21 DOI. Percent egg weight loss (PEWL) between 13 and 17 DOI did not significantly differ between temperature treatments. From 13 to 17 DOI, there was a significant positive correlation between PEWL and ACT in the STRT, however, no significant correlation occurred between PEWL and ACT in the LTRT. Percent hatch of fertile eggs containing live embryos at 12 DOI was 93.3% in the STRT and 100% in the LTRT. However, time of hatch occurred 14 to 19 h later and hatchling BW was lower in the LTRT than in the STRT. Although lowering IAT at 12 DOI may improve hatchability, an associated delay in hatch and a decrease in hatchling BW may not be commercially acceptable.

Incubation variables, performance, and morphometry of the duodenal mucosa of Japanese quails (Coturnixcoturnix japonica) submitted to different incubation temperatures and thermally challenged after hatching

ABSTRACT This study aimed to evaluate the effects of different temperatures on incubation variables, performance, and morphometry of the duodenal mucosa of Japanese quails (Coturnix coturnix japonica) submitted to chronic heat stress after hatching. We distributed 540 eggs in three incubators with a temperature of 37.8°C and 60% of humidity. From the 6th day of incubation until hatching, the temperatures were adjusted to (37.8°C, 38.5°C and 39.5°C). After hatching, quails were evaluated for the quality score, weighed, and distributed in a completely randomized design with three incubation temperatures (37.8, 38.5, and 39.5°C) and two ambient temperatures (stress and thermoneutral). At 10, 20, 30, and 40 days they were weighed to determine the live weight (g) and weight gain(g). To collect the duodenum and determine morphometric parameters, we euthanized four quails of each treatment. The data were analyzed, and the differences between the means determined by the Tukey test at 5%. The incubation temperature of 39.5°C provided lower hatching rate and the live weight at birth; however, from the 10th day of age, increased live weight, weight gain, and positively influenced the morphological parameters of the duodenal mucosa in situations of chronic stress.

Short cold exposures during incubation and postnatal cold temperature affect performance, breast meat quality, and welfare parameters in broiler chickens

Cold stimulations during egg incubation were reported to limit the occurrence of ascites in broilers subjected to cold temperature after 14 d of age. However, data are lacking on the impacts of such strategy in case of cold temperature conditions at start. This study aimed to evaluate the effects of incubation and posthatch cold challenge on performance, breast muscle integrity, and meat processing quality in broiler chickens. Ross 308 eggs were incubated under control temperature (I₀, 37.6°C) or subjected to 15°C during 30 min on day 18 and 19 of incubation (I₁). Chicks from each group were reared in floor pens either at standard rearing temperature (T₀), from 32°C at 0 d to 21°C at 21 d of age, or exposed to colder rearing temperature (T₁), from 29°C at 0 to 21°C at 21 d of age. All birds were then kept at 21°C until slaughter (day 40), when body weights (BW), feed conversion ratio (FCR), breast muscle yield, meat processing quality, and the occurrences of meat defects, hock burns, and pododermatitis were recorded. No significant impact of incubation conditions on hatchability was observed. At day 40, BW was more under T₁ than under T₀ conditions, with T₀ females (but not males) presenting more BW after I₁ than after I₀ conditions. In the whole period, T₁ chickens presented lower FCR than T₀ chickens and higher breast meat yields at day 40. The occurrence of white striping was more in I₁T₁ males than in all other groups, except for the I₀T₁ males. Hock burns were more frequent in I₁T₁ males than in all females and I₀T₀ males, whereas the occurrence of pododermatitis was lower in T₀ males than in other groups. Despite some positive effects of I₁ incubation on growth after starting under low ambient temperature, this study reveals the limits of such strategy concerning chicken health and welfare, demonstrating that early thermal environment is a major component of the quality and sustainability of chicken meat production.

Embryonic thermal manipulation has short and long-term effects on the development and the physiology of the Japanese quail

In vertebrates, the embryonic environment is known to affect the development and the health of individuals. In broiler chickens, the thermal-manipulation (TM) of eggs during the incubation period was shown to improve heat tolerance at slaughter age (35 days of age) in association with several modifications at the molecular, metabolic and physiological levels. However, little is known about the Japanese quail (Coturnix japonica), a closely related avian species widely used as a laboratory animal model and farmed for its meat and eggs. Here we developed and characterized a TM procedure (39.5°C and 65% relative humidity, 12 h/d, from days 0 to 13 of incubation) in quails by analyzing its short and long-term effects on zootechnical, physiological and metabolic parameters. Heat-tolerance was tested by a heat challenge (36°C for 7h) at 35 days of age. TM significantly reduced the hatching rate of the animals and increased mortality during the first four weeks of life. At hatching, TM animals were heavier than controls, but lighter at 25 days of age for both sexes. Thirty-five days after hatching, TM decreased the surface temperature of the shank in females, suggesting a modulation of the blood flow to maintain the internal temperature. TM also increased blood partial pressure and oxygen saturation percentage at 35 days of age in females, suggesting a long-term modulation of the respiration physiology. Quails physiologically responded to the heat challenge, with a modification of several hematologic and metabolic parameters, including an increase in plasma corticosterone concentration. Several physiological parameters such as beak surface temperature and blood sodium concentration revealed that TM birds responded differently to the heat challenge compared to controls. Altogether, this first comprehensive characterization of TM in Japanese quail showed durable effects that may affect the response of TM quails to heat.

Early age thermal manipulation on the performance and physiological response of broiler chickens under hot humid tropical climate

Initial brooding temperature is critical for post-hatch growth of broiler chickens. A study was conducted to investigate the early age thermal manipulation (EATM) on the performance and physiological responses broiler chickens under hot humid tropical climate. A total of 260 unsexed day-old Arbor-acre broiler chicks were assigned to five thermal treatments of brooding temperature regimens having 4 replicates of thirteen birds each. The heat treatments were: initial brooding temperature of 35 °C for the first 2 days, and then decreased subsequently, gradually to 22 °C at 21 d of age (CT), initial temperature of 35 °C, sustained for the first 4 days and then decreased gradually (conventionally) (FD), initial temperature of 35 °C for the first 7 days (SD), the birds in CT, but the brooding temperature was raised to 35 °C again for another 3 days from day 7 (SD3), initial brooding temperature of 35 °C for the first 10 days (TD). Data were collected on daily feed intake and weekly body weights. Blood samples were collected from 8 birds per treatment weekly for the determination of plasma uric acid, triglycerides, triiodothyronine (T₃) and creatinine kinase. Data obtained were laid out in a Completely Randomized Design (CRD). Results showed that the final weights of the birds in FD were higher (P < 0.05) than those of the other treatments at the finisher phase. Feed intake of the birds in FD was higher than those of SD3 and TD. FCR of broiler chickens in CT, SD, SD3 and TD was higher than that of FD. The rectal temperature, plasma MDA and blood glucose of the thermally challenged birds in FD was generally better (P < 0.05) than those of the other treatments. It was concluded that EATM can be used to improve performance and also protect broiler chickens from acute heat stress at market age.

Effects of choice feeding and lower ambient temperature on feed intake, growth, foot health, and panting of fast- and slow-growing broiler strains

Effects of lowering ambient temperature in the second half of the growth period were studied in 2 broiler strains with different genetic potential for growth (Ross from 1972 and 2004) when given ad libitum access or pre-mixed increasing proportion of whole wheat in their diet. A total of 48 groups of day-old broilers (n = 64) from the 2 strains were housed as hatched in 48 pens in 4 houses and slaughtered at 6 wk of age. Half of the groups had access to pelleted feed pre-mixed with increasing proportion of whole wheat, the other half had access to pelleted feed and whole wheat in separate troughs. Ambient temperature from 28 d of age was either 21 or 15°C. The fast-growing strain had greater (P < 0.001) live weight throughout (mean slaughter weights 2.6 (±0.014) kg and 1.0 (±0.006) kg). When given a choice, the fast-growing strain consumed a lower (P ≤ 0.004) proportion of whole wheat in their diet in weeks 5 and 6 (20 and 26 (±0.9) % whole wheat), and the slow-growing strain chose a higher (P < 0.001) wheat proportion (45 and 56 (±1.7) %) than the pre-mixed inclusion of 25 and 30%, respectively. The slow-growing strain grew slightly faster in the colder ambient temperature, and slower when given a free choice of whole wheat. Both strains drank more water per feed consumed in the warmer ambient temperature treatment. Foot pad dermatitis, only seen in the fast-growing birds, had a higher occurrence in the colder and in the choice feeding treatments. Gait scoring on day 34 showed perfect gait in more than 85% of the slow-growing and less than 1% of the fast-growing birds. Activity was higher and panting levels were lower in the slow-growing strain (P < 0.001) toward the end of the growth period, with no effect of the temperature treatment on panting. Slow-growing strains increase their energy intake, and fast-growing strains increase their protein intake when given a choice.