A basic introductory discussion on nutrition in birds
By Rich Barczewski
Understanding nutrition, especially when it comes to feeding our birds requires some basic knowledge about the discipline that many people lack. In this article, I hope to cover the basics so that you can have a better understanding about the subject.
Nutrition is the study of nutrients that are in feedstuffs and how they relate to the nutritional needs of the birds being fed. There are six basic nutrient classes and these include: Water, Carbohydrates, Proteins, Fats, Minerals and Vitamins. Each one of these nutrient classes can be complicated and deserves some individual discussion.
Whenever I discuss water, I always start out by saying that water is the single most important nutrient. Why? Because if I restricted all 6 of the nutrients at the same time, you would die from a lack of water before anything else. Water however, is the cheapest of the nutrients, is generally available and in most places, abundant. When we discuss water needs, we need to consider water quality as quantity is rarely an issue.
What does water do for the body? Water makes up about 90-95 % of the blood, and 45-65 percent of the body weight at maturity. It serves to transport nutrients and waste products, as a solvent and as a part of some metabolic chemical reactions. It is involved in body temperature regulation, lubricates and cushions joints and organs and maintains the shape of body cells. If you don’t provide enough water, you will notice a reduction in feed consumption, observe a weight loss due to dehydration, and death can occur in a few days with a severe restriction.
If your birds are being provided water that is coming out of a well that you are using for your family, it was most likely tested at some point to insure it is safe. Problems can occur with water when it contains too high a level of solids, too much sulfur or too much nitrate. We also want to make sure that our water does not contain any harmful bacteria that might make us or our birds sick. That said, for the most part, our birds are drinking the same water that we are drinking on the farm and would be considered safe.
That brings us to the second consideration, and that has to do with what we do with the water once it comes out of the faucet or hydrant, and goes to our birds. I usually tell folks that if they were not willing to drink the same water that their birds are drinking that they might want to reconsider how they are doing things. Water should be fresh and clean. Allowing water to stagnate in a can, bucket or tub is unacceptable for your birds. When that happens, care should be taken to clean out the containers and refilling them with fresh, clean water.
You need to remember that this is the cheapest feed you are going to get so you want your birds to drink as much as they want, whenever they want. For the most part, birds will consume about two times the weight of water as the dry feed that they consume.
In the winter, care needs to be taken to make sure your birds have water that is ice free, at least a couple of times per day and in the summer, avoid allowing the water to get hot. Nothing like a hot glass of water on a hot day? You would not want that and your birds don’t either. Other than that, water is also one of the easiest nutrients to understand and provide.
That brings us to carbohydrates. What are carbohydrates? Basically, carbohydrates are the nutrients in feedstuffs that provide energy to your birds. Typical sources of carbohydrate are corn, sorghum, barley, wheat, and oats but other feedstuffs such as bakery by-product meal, cookie meal, as well as a lot of grain milling by-products easily fall into that category as well.
You may be wondering what carbohydrates do in the body. Essentially, carbohydrates are a major source of energy in the body and they can serve as a source of heat and as building blocks for the other nutrients. Additionally, there are a couple of forms of carbohydrates that can be stored in the body.
Fats are another nutrient that can provided the body with energy, heat, insulation and protection. It is usually stored in the body as subcutaneous fat but it also can be found inside the body cavity, in the muscle tissue or between the muscles. Fats are highly digestible (upwards of 80 percent digestible) and a rule of thumb is that fats contain 2 ¼ times the energy that you would typically find in a carbohydrate or protein.
Many people look at fats as negatives (especially considering the obesity problem in our country), but in reality, we need some fat in our diet to transport fat soluble vitamins, for the synthesis of some hormone compounds, proper feather development and as part of the structure of the cell membranes.
Proteins are one of the nutrients that most folks pay attention to when they purchase feed for their flocks. Protein as is normally labeled on a feed bag is listed as crude protein, but proteins are actually made up of amino acids, some of which tend to be added to many poultry diets. Most livestock have 10 essential amino acids but poultry require 13 of the 22 naturally occurring amino acids. Crude protein is calculated by determining the amount of nitrogen in a feed and multiplying that number by 6.25. That number comes from the fact that protein is 16 percent nitrogen (100/16= 6.25).
Proteins are a major constituent of the soft tissues in the body, including the muscle and internal organs. Protein molecules are very large and they can vary in their chemical composition, physical properties, shape, solubility and biological function. Proteins are essential components in not only the blood, and soft tissue, but also in certain enzymes, hormones, immune system antibodies and in the transmission of genetic traits.
Failure to have enough protein in the diet can result in reduced growth rate and feed efficiency. It can impact the body by causing anemia and infertility, or by reducing hormone and enzyme function and overall productivity. In feeds, protein can come from both animal and plant sources and most feedstuffs contain some protein, however supplemental sources from plants are typically the oil seed meals like soybean oil seed meal, peanut meal, canola meal, sunflower meal and the like. The most common animal protein supplements are meat and bone meal, fishmeal, and by-product meals from the slaughter industry.
The next group of nutrients are the minerals. Minerals are inorganic, solid, crystalline chemical elements and are divided into two categories based on how much of the mineral is typically included in the diet. These categories are the macro minerals and the micro minerals. The macro minerals include calcium, phosphorus, potassium, sodium, chlorine, magnesium and sulfur, while the micro minerals include cobalt, copper, fluorine, iodine, iron, manganese, molybdenum, selenium and zinc.
One important thing to remember with minerals is that just because some is good, more is not necessarily better. While you can see deficiency symptoms when not enough of the mineral is in the diet, with certain ones, there may be a toxicity symptom that occurs when feeding too much. Additionally, there are species differences with the mineral requirements and that is why you should never feed a ration that has been formulated for one species, to another species.
Considering minerals, calcium, phosphorus, magnesium, copper and manganese have functions in skeletal formation and maintenance. Phosphorus, sulfur and zinc are important in protein synthesis while iron and copper function in oxygen transport in the body. Sodium, chlorine and potassium function in both fluid balance and regulation of the body’s acid base balance, while calcium, phosphorus, potassium, magnesium, iron, copper, manganese, and zinc all serve as either activators or components of enzyme systems. Finally, calcium, phosphorus, cobalt and selenium have relationships with specific vitamins in the body.
You may have heard of some of the common conditions related to mineral deficiencies. For example, deficiency of calcium and/or phosphorus can result in rickets, a condition that results in a softening of the bone. Specifically, in poultry, calcium and phosphorus is important for egg production and when calcium is lacking in the diet, birds will lay thin shelled eggs. Zinc deficiencies can result in poor feather development. The two minerals of specific concern for toxicity is fluorine and selenium. You still need them in the body, however, too much can result in death.
Vitamins are the last group of nutrients that I will discuss. In general terms, vitamins are divided into two specific groups. The fat-soluble vitamins and the water-soluble vitamins. Specific differences between the two groups include the fact that fat soluble vitamins are absorbed into the body along with fat in the diet. Additionally, they can be stored in the body and are generally excreted from the body through the fecal matter. Water soluble vitamins are not stored in the body and are generally excreted through the kidneys.
The fat-soluble vitamins include vitamins A, D, E and K. Vitamin A is associated with vision, bone formation, egg production and hatchability. Too much Vitamin A can be toxic and unfortunately symptoms of hypervitaminosis are similar to the symptoms observed when animals don’t get enough of the vitamin.
Vitamin D is also associated with bone formation (specifically the absorption of calcium and phosphorus) and this vitamin is associated with those two minerals. One issue with poultry is that there are different forms of vitamin D. Most farm animals can get their vitamin D requirement when D2 is put into the ration, however with poultry, vitamin D3 is required. In cases where birds are given vitamin D2 as a mistake, rickets often occurs.
Vitamin E is an antioxidant and deficiency of this vitamin can cause problems with the muscle tissue in many farm animals, and reproductive failures as well. Vitamin E is associated with the mineral selenium.
The final fat-soluble vitamin is Vitamin K. Vitamin K functions in blood clotting. Deficiencies of vitamin K can cause spontaneous hemorrhages and increased blood clotting times. Since some rodenticides use anticoagulants as their active ingredients, Vitamin K is often given as an antidote when a cat or dog gains access to and consumes rodents killed by these types of poisons.
The water-soluble vitamins include all the B vitamins and vitamin C. The B vitamins include: thiamine, riboflavin, pantothenic acid, niacin, pyridoxine, biotin, folic acid, choline, vitamin B-12, inositol and para-aminobenzoic acid. Many of these vitamins serve as co-enzymes for various metabolic reactions in the body. Some specific deficiency symptoms in birds occurs with thiamine (Head retraction), riboflavin (curled toe paralysis), biotin and choline (perosis in chicks), folic acid (cervical paralysis in turkeys), B-12 (hatching problems). In addition to the B vitamins, the water-soluble group also includes Vitamin C which functions in collagen formation.
In writing this short piece on nutrition in birds, I hoped to give you just a little background on nutrition. The field of nutrition is far more complex and you need to be aware that some individuals spend their entire working career in this field, applying their knowledge in balancing rations to meet the needs of the animals/birds that they are attempting to feed. If you have more interest in the field, you may want to acquire a text book on the subject to learn more.