[Music] as indicated in the presentation of these videos dedicated to only pigs and poultry energy is very important in terms of cost and in terms of role on performance of animals but how is energy evaluated and more specifically how is net energy evaluated if we look at the energy utilization in animals we have to start first from gross energy gross energy is the heat of combustion of the feed but the problem is that gross energy is not really fully available to the animal you have some energy losses first in the feces and then in the gas and in the urines when you subtract these losses from gross energy you get first digital energy or de and then metabolizable energy or amy but in pigs and in poultry gas energy is rather negligible and usually it is neglected in addition in poultry feces and urine are mixed and then only the ami concept is used for poultry so you have plenty of factors affecting energy directivity and metabo and me over the ratio but the most important factors that will be that should be considered in that will be totally ignored in that presentation and we'll focus more on the next step which concern net energy so this next step which is very important includes the so-called heat increment that is a loss of energy and the ratio between net energy or any is is called k or the efficiency of me for net energy but one first difficulty when you talk about net energy is that heat increment is a concept but it is not measured directly indeed when you look at heat production of an animal you measure the total reproduction of that animal that is easy but that heat production over one day period for instance here is rather variable and it is incr it is including different components a major component of reproduction which is the minimum reproduction over a day and which is constant obtained under fasting condition is the so-called fasting reproduction or fhp but you have also some heat production related first to the physical activity of the animal and then to the feed utilization so this activity and feed utilization or feed heat production are mostly related to the fact that the animal is ingesting feed and is digesting metabolizing and using that energy for its requirements so what we call heat increment at the end is the addition of activity production and feeding production and also as shown on that figure heat increment which is the most important parameter we are looking for is then equal to total heat production minus fast angle production so if we include this uh hip increment value as heat production minus fasting in production in our previous diagram you can obtain the net energy value which is equivalent now to me minus production plus fasting reproduction