By David F. Jones, Ph.D., P.A.S.
Agri-King believes that capturing the nutritional value of feeds is the key to profit. Although we understand that forages are the foundation for all rations Agri-King will test all feedstuffs then build rations to maximize the use of home-grown ingredients. Agri-King has just made a large step forward in our ability to predict the energy needs of dairy cows. This is known as Agri-King Net Energy (ANE).
Gross energy is the total energy of a feedstuff. When fecal energy is determined and subtracted from GE the remaining energy is DE. If urinary and gaseous energy is then considered and subtracted out the remaining energy is ME. The final step is determining heat energy leaving NE once the heat is subtracted out. Net energy is the energy available for maintenance, milk and weight gain (work performed by the cow).
The rate-limiting step for converting GE to NE is digestibility. Low digestibility will generate greater fecal energy losses. However, as the digestibility of the feed is increased there will be less energy lost in the manure. This, in turn, provides more energy back to the cow for potential work. Urine, gas, and heat are small contributions to energy lost from the feed which is why digestibility has the largest impact on total energy available to the cow.
Starting with modern-day thinking total digestible nutrients (TDN) were adapted to the net energy of lactation (NEL). This was a good step as TDN is the sum of the digestible nutrient fractions (NFC, CP, Fat, and NDF) and represented as a percent of the DM and not as an energy unit. The net energy of lactation was first developed using TDN, but the units are Mcal/Kg (energy units). The NEL equation was adapted to use the metabolizable energy of production (MEp). Equations can also be found estimating NEL from the acid detergent fiber (ADF) concentration of a feed. It is important to understand the NEL equation used if you want to compare NEL values.
Years ago Agri-King developed its energy system (ENE) based on measurements of in vitro dry matter digestibility (IVDMD) and neutral detergent fiber digestibility (NDFd-30). The use of actual digestibility values allowed for improvement concerning over and underestimation of energy in a feedstuff that can occur with the NEL system.
Agri-King’s ENE system showed there are better ways to determine the energy of feedstuffs and lead the way to the development of Agri-King’s new ANE system. Agri-King net energy was developed by going back to the GE of feedstuffs and redeveloping the steps toward NE. Each nutrient analyzed (e.g. CP, starch, fat, etc.) in a feedstuff by Agri-King’s ANALAB is included in the calculation of ANE because each nutrient has its own NE value. The digestion of each nutrient was determined followed by the conversion from DE to NEL for the given nutrient. The NEL of each nutrient is then added together to determine the NEL of the feedstuff. The NEL of each feedstuff then contributes to the NEL of the ration which is then directly linked back to the energy requirement of the cow. By using the NEL of individual nutrients we have been able to improve the accuracy of energy prediction of a feedstuff. This significantly reduces the over and under estimation of energy that occurs in the industry.
The energy density of feedstuffs only serves a purpose if it is adequately applied to the ration fed to cows. By reducing over and underestimation of NEL with the ANE system rations are less likely to over or under feed ingredients such as corn. This can have significant benefits to the cows.
Agri-King’s ANE is a robust energy system that takes into account all the nutrients that can supply energy to a dairy cow and gives proper weight to each of those nutrients. The ANE system can be found with Agri-King’s proprietary ration balancing program and is, therefore, only available to Agri-King clients. AK