[Music] Thank You Megan and very good morning ladies and gentlemen and so I have been asked to talk about the effect of faceless on feed digestibility and the scene has been already set by the previous speakers about heat stress but I will just add few points which i think is relevant when he talked about his stroke as mentioned by the previous speakers when he talked about heat stress we think about temperature high temperature which is not the case actually there are so many controlling issues so I would also briefly spend some time talking about some of these interacting factors then the focus of course I will review the literature which is available on feed digestibility which is very limited as well as conflicting contradictory data so we will try to make some sense out of what is available in the literature and finally I will talk about what he know about heat stress and what we don't know about heat stress and what is missing the knowns and unknowns what you see here for most part the current genetic lines have been developed and bred in temperate climates and whereas most of today's poultry as pointed out earlier is considered in the tropical in the tropical and subtropical regions in fact the prediction is during the next decade 85 percent of the poultry growth is going to take place in these regions which is the Asia which includes Asia Africa and South America with Asia leading the way most of the growth in the next ten years during the next 50 years it's going to be totally different Africa is going to come up on top so the question is the poultry is concentrated in the tropical climate and how applicable are the nutritional data which have been recommended by breeding companies based on the work which is done in thermo neutral conditions so this challenge for us is one of the questions we which we discussed during the proceedings today and the the term heat has has different meanings in different parts of the world in the tropics typically we find high higher temperatures ambient temperature experienced over a prolonged period of time and in fact temperature of 30 degrees is not considered unduly opera sea in a tropical country such as Bangkok 30 degrees is normal whereas you go to the temperate climate where we don't see chronic he stirs whereas what he sees acute heat stress short spells of high temperatures during the summer months so these are two different meanings we need to consider both these sorry and what happens is the heat stress when you look at the so Polti like all that all the animals actually experience heat heat stress when the temperature ambient temperature goes beyond a certain critical level and this particular upper critical temperature is about 35 degrees at the time of hat and decreases to about 24 or so after about three we three or four weeks so the point I'm making is a heat stress becomes important become becomes a concern only after a certain period of time about three weeks of aid but I'm going to revise this after listening to dr. ferry so the heat stress become only a issue when you go beyond one point five kilos I think better too we talk about the body weight given the fact the modern modern boilers are going faster and faster we are reaching the 1.5 bit earlier than previous year and 1.5 seems to be a very good number during which time the heats just become a real practical concern before that we don't have to worry much about the effect is only minor and as you know add the heat stress progresses there are a number of changes in the bird it's summer behavioral and physiological hormonal and motor body with negative effects on bird performance intestine and nutrient utilization so the last one is the one I'm going to talk about and the most recognizable this has been discussed earlier the most recognizable effect of heat stress is on feed intake reduction or feed intake but again as pointed out by others the the reduction what you see in growth or a production is greater much greater than what is see in the feed feed reduction and essentially it tells us there are something else is going on not we didn't take is a problem but there are also some some of the bullet undulate totally unrelated factors are playing a role the subject of heat stress is quite complex in fact highly complex and quite complicated and these are some of the factors which are actually complicating our understanding of heat stress just these are some of the major ones just to point out some there is different types of heat stress the most important one is acute versus chronic heat stress and there's also could be cyclically and continuous age stress and then we we are talking about relative humidity highlighted by ferry in his talk and then the acclimation can the birds get acclimated to heat stress continuous heat stress and the issue of body weight as well as genetics and the timing duration and severity of the particular high temperature so all these so this is something especially when if you go to the literature what you find is very quickly we realized their eyes lava you cannot actually make a good comparison between different sets of data because all are done under external conditions in a different ways just want to talk about two of these issues confronting issues the accurate versus chronic registers and so there are a number of things which happens in the protein digestion and metabolism when the birds undergoes heat stress and so these are different events and so we started protein digestion protein synthesis protein deposition protein breakdown and nitrogen retention the protein retention as such all these are affected by heat stress I just put a question mark for protein digestion because we are going to talk about it bit later first possibly there ifx but at this point they will keep it a question mark and protein and there is very little difference at least looking at the repressor between the acute versus chronic head stress in both cases we see protein synthesis is reduced protein deposition is reduced and plasma free amino acids are depleted especially for in the case of self amino acids and branch chain amino acids so that has some meaning in terms of M&S in nutrition then of course there's a big reduction in the nitrogen efficiency and there's a slight difference between these two in terms of protein breakdown in the case of acute when there's a short spell of high temperature we see quite a rapid increase in protein breakdown whereas in the case of chronic shortages there seems to be some sort of acclamation it sort of reduces as a time goes on and of course this issue raised and we see so in a tropical time not only probably in any part of the world that we see a range of relative humidities with high temperatures it could be very low or it could be fully saturated as we see typically see in some of the tropical areas so the important point is as pointed out earlier the relating limited will intensify or modified responses so the birds or any animal can actually withstand high temperatures at a low-grade humidity and vice versa just we'll go through the published date on field digestibility and which as I mentioned earlier is both limited as and contradictory and and also very limited data we have only two reports published on feed digestibility there are four nominees in digestibility and about seven on a meal before talking about digestibility I just want to make a comment on the terminology used to measure digestibility total tract digestibility versus evil digestibility so the strengths and limitations of each each of these terminologies have been debated for many many years but I'm going to go through area of this what I want to point out is prior to 1990s the total tract digestibility was widely used but currently the preferred method of digestibility evaluation is ileal digestibility mainly because of the fact the ileal digestibility overcomes the Huynh the effect of Hine guide microbes especially in terms of the sum of the macronutrients starch and protein and also it's avoids the any contamination from urine and especially for minerals all right and this is the first of the study conducted or published in 1997 and you see the name of very famous french scientists and in which the effect of high ambient temperature on three the distributors looked at this was done in just really description of the trial for we call broilers and constant temperatures for two weeks either 22 or 32 degrees but there were three treatments that is attribute of feeding 22 degrees at limit on feeding 32 degrees and we had they had a third row which was pea fed based on the daily feed intake of the 32 degree birds and total tract digestibility was measured and this these are the results and it clearly indicates so we have the 32 ad libitum 32 ad libitum and 32 perfed and as you can see the body weight gain was or the feed intake was ladies by body gateway nose almost half it was reduced by 50/50 around 50% whereas the field in deck reduction was only around 30 35 percent I hope thing and so again it highlights the feeling take is not total responsible for the loss of weight gain we see in heat stress birds looking at the digestibility the digestibility was decreased at high temperatures 32 degrees the decreases are not anything dramatic but except for a couple of the mineral digestibility and protein digestibility certainly we see there's a big drop in nitrogen retention and if you compare what is happening with the pair of at 22 degrees and you can see the diameter sorry the nutrient digestibility feed digestibility was not influence this a second paper on heat stress coming from Brazil and slightly different approach and three week old male boilers the treatments are imposed from three to six weeks of age two treatments 22 degrees and 32 degrees and again that stability was measured total tract digestibility in this case again and these are the results again you see the same again you see the same effect about body weight gain was reduced by about 35 percent but the feed intake was rate is only around 25 person or so so the feed intake does not explain all the performance reductions we RTC in the it stress conditions in this particular study there was no effect of temperature chronic temperature on that feed the disability pro there a distributor of protein and fat but you can see what is happening here in terms of retention of nutrients so it is telling us there is something happening very drastically dramatically after the absorption so maybe there is a effect of on the digestion - but something big is happening once the nutrients are absorbed and published data on amino acid digestibility briefly I'm going to the first report comes from the eunice of Sydney 1984 quite long time back and where they looked at the effect of temperature age as well as sex the gender undigestible termina acids and so this a brief summary of the results they found and these are the amino acid which were affected influenced by the temperature there's and you can see there are a number of amino acids which are given a superscript star and maybe they all said sex in to temperature interaction and what is happening at the high temperature the females were affected more than the female so there was a very clear then there's a sex effect and there was no effect between 30 days and 50 days and so and this is second study coming from the again this is from France and where they looked at the effect of ambient temperature on the gist ability of two different ingredients so I've been meal and the rapeseed meal and so again they had male and female broilers 22 degrees versus 32 degrees and the treatments are imposed from four to six weeks and again this was a total tract collection and total tract digestibility and what they found is the the effects seem to be ingredient different and there was no effect on soybean meal but there were significant effects in the case of rapeseed meal and just just like the units of Sydney study they also found the females were more sensitive to high temperature effects that 12% reduction was seen in females as against that only two or three percent in the male's and this is coming from iron again they have looked at the temperature into sex interaction just to your summary of the results and so there are three treatments 21 degrees 30 and 35 degrees for three hours a day is the accurate sort of 8/8 stress and and also which was given every day for one week where if the third treatment was given every day three hours of heat high temperatures for two more two weeks and what is clear is the acute heat stress also had a effect on that is three hours per day also had a effect on I'm an amino acid digestibility which was significantly decrease as you can see in this trial and giving more time to Akram I did not really have an effect in this particular study there was no difference between males and females and the study with this was in laying hands there are two three treatments consistent 21 degrees cyclic temperature of 35 degrees for 12 hours and 29 degrees for another 12 hours and third treatment was 35 degrees for 12 hours and 21 degrees for another 12 hours anyway the summary of this is think there was no difference in the total tract digestibility of any of the amino acids heat exposure and a mean there are seven reports which are available against CC it's just all over the place essentially there are four reports telling us there's no change effect on kme and there are two recording decreases in a meal at high temperature and those one report which actually says the Hemi was in so it's quite a contradictory data just like in here and just talk about minerals in one of the earlier studies we found we observe we saw that mineral digestibility was decreased and here again we don't usually look into this but again it tells us a minerals are also affected in fact very severely affected in this particular study what they did was they colostomy they use customized Birds where you are able to collect the urine and the excrete are separately and what they found was there is no effect on the mineral output in the form of excreta but they were major effect in urine output as well as the urine mineral content and both were increased at high temperatures and you can see the numbers what they are reporting and quite significant differences in the effects are quite significant for calcium phosphorus sodium and potassium and also magnesium so what do we makes sense of all this data at least I going by the extra data and it's very difficult to make any link between the way this information what we have in the published data and the in a very truly quantitative matter we can only assume and guess few things as despite these inconclusive evidence what I'm saying is nutrient digestibility is certainly from what he know based on the effect of high temperatures on in test time I think there is nutrient digestibility will be affected by a stress but the the reductions are minor compared to what is seen nutrient utilization what happens after the absorption what happens after the absorption the post absorptive metabolic nutrition is more dramatically affected by high temperatures I like this particular Court which was which is from a very famous person and there are known norms they are known unknowns typically fits in very well with a lot of scientific issues including heat stress and then of course there are unknown unknowns you know talk about unknown unknowns because they don't know what they are and but we we know what is known what happens in the heat stress the performance effected and the feed intake is reduced and the feed intake does not explain everything and then of course there are known unknowns we know a lot of things are happening in the intestine level as you can see all these things which have been discussed previously by the previous speakers it is all integrity is number one there's leakage of the gut there is quite of big issues there and you can just see what exactly is happening there are some some of their sauce endogenous eminence it losses are increased there's decreased blood flow the car gene expression is affected amine acid transport is affected inflammation of internal intestine is increase and also there is change so some of these how they interact with each other and how they but certainly we know that the intestine is affected during heat stress and I think this is a very important issue especially given the fact that antibiotics are banned oh it's banned in most countries some of these issues the issues of the intestine is coming to the forefront it will be a serious concern in the future when he lose the use of antibiotics so it almost puts a conclusion the current knowledge and protein met Wilson has been obtained under thermal neutral condition so what does it mean do we have to come up with the different values for amino acid digestibility I don't think so maybe in the future maybe we can do a correction if that's important but like I said that stability effect is minor compared to what is happening after the absorption and so that will impact on eminence recommend this are unknown ideal amino acid balance I would I think it will be affected especially in terms of three onin because even the importance of three onin in the intestinal health and certainly there's some evidence that sulfur - it's a maybe we are to consider slightly higher ratios etc anyway as a conclusion I just referred to something which was said in 1998 better knowledge of the effects of heat exposure overall and am nasod metabolism is first necessary agree and unfortunately in the last 20 years we are not moved still we are saying the same thing maybe in the next 20 years maybe there's some answer thank you [Applause] [Music] thank you very much Ravi that was a very important message I think now we should get some questions I suppose oh this is a very the first one it's interesting I think because you you report you mentioned a number of literature reports that we're looking at acute see each stress versus chronic heat stress and there are definitely differences and so could you comment on the your the limiting temperature for acute versus chronic heat stress for layers and broilers depending on production stage because you know there's a you know there's some hints being given in the literature on that probably very clear but what I can tell you what I did was and I reviewed what has been done in the literature and for example acute temperature like acute heat stress there is there was one report we are actually 35 degrees for 15 minutes we had a very negative impact on you know the performance the digestibility not digestibility but the overall performance of the bird so it's just one report and I think we are talking about body weight here it depends on the body weight and of course as the bird boots you know puts on more body body weight the heat production increases and then even a small increase is going to have a big effect so I think that will be very difficult oh yeah this the high fiber ingredients that's an interesting one ours well I think a very good question yeah I think there will be that's in my opinion if you have heating corn soy soy diets I don't think we are going to see big difference between thermal neutral and hate stress conditions because that's when you look at the numbers which are coming from tropical countries like for corn soy dyes which is around 85 that's normal rate but we don't know what will happen when you as you increase your by-product level I would expect that's going to be different between thermal neutral condition but I have no supporting data at all yeah and maybe we should also address the question about the phytase and you know the as you as you mentioned this this huge drop in phosphorus retention do you think we should do go into that direction it's essentially seem to indicate the phosphorus retention is our victim and that's just one study it certainly highlights there's some issue with mineral retention okay but I don't know whether we should revise the phytase recommendations I think we have to go back to the companies involved and sort of talk to them about it and but when you look at the data in coming from tropical countries with the use of phytase borne ash and all this they seem to be working alright at least but again these are some of the unknowns we don't know so I think as we are running short of time Mittal I'm afraid we'll have to keep the questions for later thank you very much ravi thank you for this interesting talk [Applause] [Music]