Dr. Joe

Published on Thu, 01/12/2017 - 12:11pm

Dr. Joe

Nutrition Basics

By Joseph W. Ward, Ph.D

The cost of feedstuffs for livestock is has the greatest impact in determining profit for any livestock enterprise.   Proper nutrition is a key component of any successful livestock production system.  Using feeds efficiently and in the right qualities can significantly affect profitability and the health of your livestock.   Paying attention to nutritional needs of livestock can help you properly meet the animals’ dietary requirements, maintain and raise healthy productive animals and achieve your management goals.  Typically, feed usually accounts for the single largest input cost associated with any livestock enterprise.    In order to maintain an optimum balance between feed costs and production, feeds must be analyzed and these analyses used to formulate rations and/or supplements.    Feedstuffs vary widely in nutrient content due to location, maturity (harvest date), year, and other agronomic management practices.  
Using table values for feedstuffs maybe useful at times but it is very important to remember that they are average values and often do not reflect nutrient content of the feedstuffs that you are using on your operation.  Significant variations exists with on-farm harvested feedstuffs as well as purchased co-products and other commodities.  Having an accurate analyses of the nutritional content of your feedstuffs will help to eliminate costly mistakes of over estimating or understating the nutrient content of the feeds used in livestock rations.    
It is important to have an understanding of your livestock’s digestive process and some basic nutrition to effectively feed livestock.  Working with a reliable nutritionist and veterinarian to manage the nutrition and health care of your livestock can have a very positive influence on the profitability of your operation.  Having a basic understanding of frequently used terms is helpful communicating with your nutritional and health care providers.
All animals require a balance of nutrients for survival.  An animal receives nourishment through their diet.   Feed requirements are based upon the need for specific amount of various classes of nutrients.   The bodies of healthy animals select and collect nutrients and use them to carry out basic life functions to successfully eat, breathe, move and sleep. The nutrients are feed components that aid in these basic life processes.  Basic nutrients categories include: water, protein (amino acids), energy (carbohydrates fiber and fats), minerals and vitamins.  
Often water is not discussed in great detail.   Access to clean fresh water free of contaminants is the single most important nutrient for all livestock.  When water intake and/or water quality is not adequate, feed intake and animal performance will be reduced.    When determining if your water source is adequate for your livestock operation, several factors should be considered.  These include: location of water source, number of head needing access to the water source, animal size, the physical height of the waters in relationship to the height of the animals, air temperatures, humidity, distance between water sources, and water quality test results (mineral composition etc.).  
Nutrition is not simplistic and is influenced by a variety of biological and ecological factors.  The nutrient requirements are the amount of nutrients that animals needs for a specific purpose.  These are driven by the digestive system of the animal, age, sex, size, body condition, breed type, stage of production, animal’s purpose in the livestock supply chain and environmental considerations.  
Nutrient classes are defined by their chemical structure or by their function in metabolism.  The nutrient composition of a feed is the amount of specific nutrients contained in the feed.  Typically, nutrient composition is expressed as a percentage of the dry matter.  Published feed composition tables contain only average values.  Your feeds may be considerably different from average especially with forages.  Common information provided from a feed analysis or a composition table will include dry matter, crude protein, fiber, fat and minerals.   
Crude protein is determined by measuring the nitrogen content of feed and multiplying the nitrogen content of the feed by 6.25 since proteins typically contain 16 percent nitrogen.  Protein is one of the main building blocks of the body and is a major component of muscles, connective tissue and the nervous system.  Protein is composed of chains of amino acids and may contain several protein fractions which vary in solubility in the rumen.  Adequate dietary protein is essential for maintenance, growth, reproduction and lactation.  Not all nitrogen containing compounds are true proteins.
A common non-protein nitrogen (NPN) source is urea.  NPN compounds can have their nitrogen converted to microbial protein in the rumen under proper conditions.  A ruminant with an immature rumen cannot utilize NPN sources very well like urea since the rumen microbial population is not well established.  Urea should not be fed to animals that do not have a well-established rumen and microbial population.
Carbohydrates and fats provide energy for maintenance, growth, feed digestion, reproduction and lactation.  Energy is the nutrient required by ruminants in the greatest amount.  There are several methods for describing feed energy values.  These include: digestible energy, metabolizable energy, energy for maintenance, energy for gain, energy for lactation and total digestible nutrients (TDN).   TDN is the value commonly used in simple ration balancing.  The primary sources of energy for cattle are cellulose and hemicellulose from roughages and starches from grains.  Fats and oils have a high energy content but usually only make up a small portion of the diet.
Fiber is associated with the structural carbohydrates found in plants.  Microbes in the rumen are capable of digesting the fiber providing energy to ruminants.  Consequently, fiber limits the energy value of plants for non-ruminant animals.  A minimal amount of fiber is necessary to maintain a healthy rumen for cattle fed high grain rations.  Providing fiber for this reason is often referred to as “scratch factor”. Commodity feeds may have benefits in ruminant diets due to their fiber content.  Feedstuffs like soybean hulls, beef pulp and oats hulls are often included in diets to add fiber to the ration.
Minerals are compounded needed for metabolic function, immune function and structural integrity. Various minerals are required for growth, bone formation, reproduction and other body functions.  Minerals are classified as macro or micro minerals depending on the amounts needed.  Generally, macro minerals like calcium, phosphorus, magnesium, potassium, sodium, chlorine and sulfur are fed as a percentage of the ration.  Trace minerals or micro-minerals like iodine, cobalt, manganese, copper, zinc, iron and selenium are added in small amounts in parts per million (ppm) or mg/kg.  Mineral content is affected by the type and quality of the feedstuff.  Adding supplemental minerals to the ration is usually required to ensure that the proper amounts of the elements are available for the animal’s stage of production.
Vitamins are biological compounds that are active in extremely small amounts that play an important role in metabolic function.  Some vitamins act as antioxidants which help to prevent oxidative damage to cells.  Vitamins are typically categorized as either fat soluble or water soluble.  The fat soluble vitamins are A, D, and E and typically added to ruminant diets.  Rumen microbes’ manufacturer a large amount of the water soluble B vitamins.   When cattle are severely stressed and/or have a severely reduced microbial population they may benefit from supplemental B vitamins.
Cattle can utilize a variety of feedstuffs.  It is important for a livestock producer to know about the nutritional needs of their animals.  Cattle nutrition is not simplistic and is influenced by a variety of biological and environmental factors.  Being aware of these factors can help you understand the nutritional needs of your livestock.  Working with your feed representative, nutritionist and veterinarian can be excellent resources to provide you with the proper nutritional guidance for your livestock and to maximize the profits of your operation.   

The author, Joseph W. Ward, has a BS in Animal Science, a MS in Animal Nutrition from Purdue University and a Ph.D. from Oklahoma State University in Ruminant Nutrition.  Born and raised in Indiana on a livestock farm, Dr. Ward has consulted in Europe, the Far East, Oceania, and South Africa.  He has been active in animal production and animal feed manufacturing/processing since the early 80’s.  He is an organic inspector for crops, livestock and processing.  Currently, he serves as North America Product Manager for Phileo Lesaffre Animal Care. Dr. Joe can be reached at j.ward@phileo.lesaffre.com.