[Music] Thank You dr. Keitel for the nice introduction and I would like also to thank the organizers of this adventure event to invite me to give me the opportunity to present this work so my talk is entitled chicken response to heat exposure and early acclimation strategies and I work at Sinha in the unit named boa for avian biology and poultry science so as you know the fast growing broiler chickens have really good performance at thermal neutrality but they are they have poor thermal tolerance when they are not acclimated and why so it's because the selection for growth and physical feed efficiency in standard conditions I've made them very performant for breast muscle mass growth but they are heat sensitive and in fact the relative mass of the cardiovascular and respiratory systems has not followed the same evolution and the morphology of the bird has much changed during the past decade and these birds have difficulties to lose the heat they produce so heat exposure heat waves and chronic exposure will have negative consequences on welfare through mobility mortality of the birds there will be also economic class and that can be interactions with other factors relative humidity we have talked about this pathogens the diet or water quality genetics Tran the age the physiological state so when you expose a bird for the first time to hit a chicken in fact there is an hyperthermia as you can see on this graph in fact at 32 degrees it is an exposure of two hours and a half in fact you have a huge increase in body temperature at 30 degrees as compared to 22 degrees for the first exposure and this hyperthermia is lower when you re expose the bird to heat to high temperature and that can be an acclamation but as you know the body temperature is the result of the balance of the heat projection from the bird and its capacity to lose heat and dissipation of the heat produced by fast growing rollers is limited by the pro capacity for sensible heat loss that is mainly due to the the phaser in fact the heat can hardly hardly be dissipated from the skin because of the feather there are only some tissues from which it can be easily dissipated that are without feather so the head and the leg below the wings and if a relative humidity is not too high in fact the birds relate on hyperventilation for evaporating water so that they can lose heat by this way so they at 32 degrees they increase the time painting and the inspiration number is a multiplied by 3 as compared to 22 degrees but this as an energy cost and also there are consequences on blood parameters they can be blood alkalosis with less protons into the blood and also there are consequences in some ions like calcium carbonate and there is a lower partial pressure in co2 in the blood rapidly also when you expose a bird to heat during a heat challenge that are results from his tune and coasters youm you have a chance you observe a change in the plasma t3 concentration the sermon is a thyroid hormone that is a major stimulator of heat production and as you can see on this table this plasma t3 concentration will be a lower in the birds that are exposed to heat as compared to thermal neutrality and there is also an increase genetic increase in plasma cortical stearin concentration during heat exposure due acute x8 exposure and this cortical stearin is a Norman a metabolic hormone that is involved in the stress response of the bird a major consequence of the heat exposure in the long term is the decrease in feed intake and in light weight gain as was already said in previous talks and there is a dramatic effect on life weight again when you go up in temperature above 26 degrees approximately and after above this temperature also you can also observe an increase in the feed conversion ratio during chronic exposure to heat the the consequences on feed feed intake and growth are important are important and that was shown in 1996 by pure hungry and closers they compared Birds at 32 degrees at libitum fed and 22 degrees and they showed that there was a 25% decrease in feeding tech but a 40% decrease in body weight gain in these conditions but there were also changes in body composition with an increased fatness of the bird reduced protein deposition changes in plasma hormone and metabolite concentrations and the lower heat production of the bird at 32 degrees mainly by decreasing metabolic rate basal metabolic rate so one strategy that we studied at the ladder to increase the adaptive capacities of the of the birds to increase their heat tolerance while maintaining performance is to try to acclimate the bird as soon as possible in their life and to get effects on the long term so there were several strategies one was to try to acclimate chick to hit very early so these are results from you have a knack mercury and also from in ha Baidu Basilio and cursors and this groups worked on very early hit stimulation of the birds and they got quite interesting results in the long term on mortality for example during your heat challenge but the problem is here is a to heat at a very high temperature the poultry house in an emoji nose way in order to condition the the chicks so the other strategy was to acclimate the birds in the incubator because it's really easier to do and to control properly the idea in fact is to act on the thermal regulation pathways so as you know this is there is a central control of body temperature at the level of the hypothalamus and there are also under crying signals through the pituitary thyroid gland password and also adrenal pathways the there are and in fact this will regulate heat exchanges heat production hit lost the behavior of the bird and the idea here in acclimating the bird very early before the end of the first week of of age so here during incubation is to modify the the threshold temperature to which the system refers to in order to regulate temperature so before in fact all of the loop is is closed so it took much time to to to optimize the temperature at which the stimulation the heat stimulation had to be done during incubation the duration of the stimulation etc and the temperature so this was also dependent on the ontogeny of the endocrine axis so the that regulate hit projection and hitless and in fact for example there were trials on mid only mid embryogenesis here that were not efficient in the long term there were also trials in the late embryogenesis and here there is an interesting results from a tuna and cutters tuna worked in a level at the university a Catholic University of Leuven and he showed that the taman manipulation of eggs induced a lower heat production of the eggs by at the end of embryogenesis so this suggested that the heat production the metabolic rate of the of the bird could be affected by this stimulation but unfortunately this program had nice well induced nights nice results in the short-term but not in the long-term so there were other experiments that were that targeted more at the middle until the end of embryogenesis so here i will give you more details about these programs it was 12 hours a day or 24 hours a day at 39 point five degrees and here the relative humidity was also quite high at 65 big percent instead of 56 in order not to dehydrate the eggs and this from day 7 to 16 of incubation and in this case in fact if you do it 12 hours a day there is a recovery by the umbria between stimulations then the hatch ability of the eggs are not different from the controls anyway if you do it continuously it gives really a really bad results because there is an REO mortality so from the work of many studies on these programs and during embryogenesis we drew this this graph on which you can see the effect of the terminal emulation on the reduction of body temperature of the bird in fact when you make this program the the men resulted that the body temperature of the chick is reduced from the hatching and in some experiments until here 50 days of age and the most efficient programs were the last one I told you about from day 7 to 16 of embryogenesis here with 0.7 to 0.4 approximately degrees less in these birds so with this program as I show you the archability was maintained the growth and fit combination ratio were also are not different and the thermal reruns of the birds were was improved in males because females were not affected it was here an acute heat exposure to 35 degrees during 5 hours and so the a little mess was reduced by half during the heat challenge it had also interesting results on abdominal fatness that was reduced with this program in the world and also bred shield was increased both male and female hair at in thermo natural conditions when they are real anomaly so on this model with cyclic elevations of a term of incubation temperature and we tried to go further into the comprehension of the mechanisms that were involved in the better thermal tolerance of these birds so we studied the birds until 34 days of age and at the end of the trial we divided the group in in two so we had the one part of the the bird that were either control or thermal manipulated that were kept at 21 degrees and we add half of the group that were submitted to a heat challenge of five hours this time at 32 degrees in order not to kill the birds but to have them just in physiological conditions but heat stress and so we tried to study what were the physiological and metabolic mechanisms that were involved in the acquisition of embryo acclamation so in focusing in blood or mangas and metabolites and also the metabolic pathways that could be involved in the liver and in the muscle muscle that are involved in heat production by the total mass and this was realized during the city speech this disease of Tamil Ohio at ena so concerning our results we could reproduce reproduce the decrease in body temperature in the bird that we're Taman manipulated as compared to the console ones in the clear blue here and we could see this until 28 days of age in our trials not later on and also we observe we took blood samples on these birds and we observe that in Tamil manipulated ones the tea tree concentration was lower suggesting perhaps that there eat production or metabolic at intensity was reduced as far as the stress of these birds we measured a tariff and on lymphocyte ratio that you heard about already and what was interesting interesting sorry was that in fact in the control group here submitted to hit in that flu you had an increase in this ratio that you could not see when you submitted the TM birds to the heat challenge there are tch birds so these birds were perhaps less stressed than this one as for a respiratory physiology we could observe changes also due to the German manipulation both determine manipulation and the heat challenge so the effect of the heat challenge is well known that it can decrease pco2 in in the blood but here also we observe changes due to determine manipulation of the eggs and we had an effect of determined manipulation of the saturation on of oxygen in the blood so these results suggested that there have been modifications of respiratory physiology of the birds and perhaps of their metabolic intensity to go further we sampled some muscle and we measured the expression of some genes that were involved in energy metabolism especially a PG C 1 alpha which is a transcription factor that regulates the mitochondria generation and activity and in fact in the birth that were determined manipulated we observed a decrease in the expression of this gene in the liver we had also results on the metabolic activity as shown by the reduced in TM group the reduction sorry of citrate synthase it activity which is an enzyme of the Krebs cycle so this suggests a limitation of mitochondria energy metabolism in these birds that were submitted to taman manipulation during embryogenesis and this could partly explain the reduction in in body temperature from these these chickens we also add some elements on the capacity of the birds for hitless and here on this graph we have a drone in fact the here you have the comb temperature that we measured by infrared imaging and the rectal temperature of the bird the internal temperature as a and as you can see when animals are at 21 degree here the graphs here you have a similar trend of a correlation between both temperatures at Neutrality so the more the the internal body temperature is high the more the common temperature is high and in fact when you put the animals under heat exposure the two of population don't react the same so as you can see there is no correlation anymore in the control birds but in the thermo manipulated ones in fact you have negative correlation that is here so in fact these animals are able here to in fact to to better dissipate the heat we also went further into the stage the study of the metabolic regulation and gene expression regulation in these models and this by studying as a transcription transcriptome sorry so all the the gene it's a high stupid study of the the gene that are expressed in the breast muscle in these groups and to try to discover new genes that could be affected in the muscle by the treatments and what we saw is that when you compare the control group and the TM group at thermal neutrality there are not so many genes that are modified by the the taman manipulation of the embryo these ones are mostly involved in metabolic regulations but when you submit the animals to heat to the heat challenge here and here as compared to their own control groups in fact you see that there are many more responsive genes that are differentially expressed in the TM group when they are submitted to heat as compared to the control group so in fact this bird are responding earlier or in an amplified manner to hit when they are exposed again to heat so they are somewhat prepared to respond to heat later on at the end of the finisher period and these genes are particularly involved in metabolic regulations chromatin modifications the vascularization of the muscles so that could have a link with the heat loss also and the stress response and then we went further in unraveling the making the mechanisms that are behind this by studying if there were epigenetic changes related to this response in fact epigenetic changes or changes in phenotype and gene expression that are in fact transmitted that can be transmitted to the next generation by mitosis and now sometimes also through the generation of animals and but that can be reversible so it's not genetic epigenetic and this is a related for example two changes chemical changes on the DNA so here the methylation of cytosine bases on DNA or also two changes in the protein on which DNA is wrapped and this will open or close [Music] in fact the chromatin the the way the DNA is is wrapped and it will open or not the DNA for transcription and then gene expression so we studied some modifications of this protein histones in our model so just in the animals that were control or taman manipulated but at thermal neutrality at 21 degree and we did this in the muscle the pectoralis major muscle but also in the hypothalamus that is the central tissue for thermoregulation and what we obtained it that they were in fact associated to changes in this it's tones there were regions in DNA that were a differential between the TM determine manipulated and the controls and more much more in the hypothalamus than in the pectoralis major so the dancer was much larger in the brain than in in the muscle and in fact we try to know what where the password that could be affected by this epigenetic responses and here again we addresses on Alman metabolic processes stress response but also transport immunity cell cycle regulation neurogenesis cellular processes so to conclude on this earlier thermal manipulations so only heat stimulation has long-term positive effects on survival in males later exposed to a cute heat so we are now studying with partners in Africa in West Africa ow this could be interesting in really [Music] living tropical humid conditions so this is a more applied study we have shown that the physiology and metabolism of these chickens are change in the long term so that could be linked to a reduction in heat production and enhanced Hitler's inducing D'Amato lowrance there are also modifications in hypothalamic DNA methylation and histone post translational modification so these epigenetic mechanisms I told you about and this could regulate gene expression is in how models so now the question is to know if we can transfer this to the progeny and we have experiments on koalas running to see if the this treatment applied on eggs in a first-generation can have effect on thermal tolerance engine and these mechanisms in the next generation up to down to four generations and so is it possible to increase the bird adaptive capacities we answer yes and this could be through the combinations of both genetic and management epigenetic approaches besides others that we talked about today and we have also to have a look to all performance parameters including economic environmental and social parameters and including also work on mid quality and other performance data so I have finished now and I wish to thank all the is involved in this work thank you very much dr. Cole a very interesting talk I presume that there will be questions the first one is with early acclamation also work for layers and breeders well this is a good question because for example for breeders if we could treat the breeders and not the terminal crossing it would be less animals to treat in the end futures etc in fact we we plan to do such experiments and we also work on on the quail in fact for the the layers there have not been studies with the same term and manipulation that we we did but during late embryogenesis and this was not so convincing but obviously it's a it would be interesting to go further into the these two days and layers and in fact in Queens these birds are well it's another model but they are laying and then we will also study the performance parameters on egg laying etc dr. : there is a question there as to you know in what breed did you do your first experiments in and does it can you immediately transfer this to say our traditional commercial breeds with her which are used in practice mostly in fact it could be applied quite easily because it's up to thirty nine point five degrees and 65 percent relative humidity twelve hours a day but it's a it's a risk for the you know for the hatchery to to try this so we we plan also to to make trials with commercial batteries but I know I have been talking with Brazilian colleagues and they said that in Brazil there were at the hatchery commercial archery were experimenting such not perhaps not exactly the same Tamil manipulation but it was a something they were experiencing already so this one completely different question which i think is interesting also the first one you see heat stress being an oxidative stress did you observe a reduction of oxidative imbalance of the thermal manipulation I mean were these birds less susceptible to oxidative stress in general or did you see any markers of oxidative stress being changed in fact we in the term and manipulation with heat we did not measure such a mechanisms we did it with cold manipulation I did not talk about it but we also tried called manipulations and in fact in this case there were changes in antioxidant enzyme activities just after hatch so obviously the the the increase in temperature or the decrease in temperature during incubation may induce oxidative stress and perhaps the animal recovers from heat and can can better perhaps cope with this but we have not the results in this particular model okay maybe one last question would it be a sufficient to precondition the embryo or the young chick you sort of touched briefly on this issue when you were reviewing the literature so after hatching could that work also or after etching it was yes it worked it was work from yeah and also the bezel yo and but it's at three or five days of age you increase temperature ambient temperature up to thirty seven point five at 38 degrees for 24 hours and here again there is a change in t3 concentration in the blood and a better heat tolerance less mortality at the end so this this can be also interesting but you have to find a way to condition the chick so I I know that in Venezuela I've tried some systems with a smaller artificial chambers to have a homogeneous temperature on the chicks to try to get the effect on the long term oh that's there's one last question there which is there any data of the effect of combining early stimulation and in oval feeding for the moment we have not experiences but in fact interval feeding yes it's also another way to change the while the here the nutrient content of the egg that could be easily applied at the same time at during late embryogenesis at e18 for example when at the time when when vaccine are used there have been worked also from uni in Israel about this and other groups and it could be yes we could try to combine to get benefits from for example energy or micro nutrients in the egg from the beginning to help the the chick the later chicken chicken took to cope with the under mental change or increased robustness of the birds thank you very much it was a really interesting talk thank you [Applause] [Music]