Fundamental nutrition principles form the basis for all successful livestock feeding systems. A better understanding of these principles makes it possible for the raiser to more efficiently convert low-cost raw materials into top-quality meat. These basic principles are just as important in the feeding of rabbits as they are in the feeding of cattle, swine or poultry. Feeding systems may vary in many respects from raiser to raiser, but each feeding system is based upon the same fundamental nutrition knowledge.
The primary purpose of rabbit feeding is to convert raw material consisting of grains and roughages, into a top-quality finished product in the form of meat. The production unit in this manufacturing process is the doe. A schematic illustration of this fundamental process might be given as follows:
Raw material (grains and roughages) + Production unit (does) = Finished product (meat)
A well-balanced ration is vital for growing rabbits.
The efficiency with which the production unit functions is dependent upon the nutrient composition of the raw material which is made available. This raw material must contain nutrients in the proper amounts and proportions in order to maintain the doe in top physical shape; and produce high-quality meat. Failure to provide adequate quantities of certain nutrients, or imbalances among the nutrients which are provided, may bring about the breakdown of the production unit and result in the inefficient conversion of the raw material. Nutrients which must be given special attention include protein, carbohydrates, fats, vitamins, minerals and water.
Proteins are made up of building units, which are called amino acids. There are some 23 individual amino acids which are required by rabbits for optimum growth and milk production. In a complete protein, these amino acids are tied together the same as bricks are tied together in a brick wall. The mortar between the bricks might be likened to the chemical bonds which tie one amino acid to another in proteins. If all amino acids are not present in adequate quantities, a complete protein cannot be built. In like fashion, a brick wall would not be complete if some of the bricks were not of the proper size or were missing entirely.
Some amino acids can be synthesized from chemical compounds which are found in the rabbit’s body. Other amino acids cannot be synthesized in this way and must be present in the feed in adequate quantities. Those amino acids which can be synthesized in the rabbit’s body need not be present at optimum levels in the feed, since slight deficiencies will not significantly limit growth or milk production. However, unless strict attention is paid to the amino acids which cannot be synthesized in the rabbit’s body and unless adequate quantities are provided in the feed itself, growth or milk production will be impaired. As a result, feed will be utilized less efficiently and the amount of feed required to produce a pound of rabbit will be greatly increased.
All rations for rabbits should therefore contain a combination of proteins so that all amino acids are provided in adequate quantities and the ratio among these amino acids is correct. A rabbit producer cannot expect the doe to maintain a top physical condition and at the same time convert raw material into meat unless strict attention is paid to the amino acid content of the ration.
Carbohydrates and fats provide the energy which is so essential for the normal activity of the rabbit. The amount of energy needed in a ration is determined by the amount of protein which is included. A very definite ratio between the energy in a ration and the protein must be maintained. Nutritionists call this the nutritive ratio. This ratio is the proportion of digestible proteins to the digestible carbohydrates and fat in the ration. For example, if a ration has a nutrition ratio of 1:5, this means that for each unit of protein in the ration, five units of carbohydrates and fat must be provided. This ratio is designated as narrow when the units of protein are more nearly equal to the units of carbohydrates and fat. When a greater number of units of carbohydrates and fat are provided per unit of protein, nutritionists say that the ration has a wide nutritive ratio. Another way of saying this is that for each unit of protein a certain number of calories of energy must be provided. The nutritive ratio, when designated in this way, is called a calorie-protein ratio.
Proper nutrition is essential for productivity in meat rabbits.
Research has shown that this nutritive ratio must be maintained at a very definite level which is determined by the use to which the feed is to be put. Different ratios must be provided when the rabbit is growing, when a doe is producing milk for her kits, or when a rabbit is simply being maintained in a non-breeding status. In many cases all of the essential amino acids have been provided in the ration, but the amount of energy is not sufficient so that the rabbit can utilize these amino acids efficiently. Practical feeding recommendations for rabbits take this nutritive ratio or calorie-protein ratio into consideration. The rabbit producer should be sure that no changes are made in the feeding schedule which will cause an imbalance between energy and protein.
The energy in a ration cannot be utilized efficiently unless adequate amounts of essential vitamins are provided. The energy in a ration is stored in the carbohydrates and fats. In order for this energy to be released, the carbohydrates and fats must be broken down by chemical agents which are called enzymes. These enzymes are present in the rabbit’s body in a non-active form. In order for them to become active, another chemical called a catalyst must be present. In order for a catalyst to become active, it must combine with a specific vitamin. For this reason, adequate quantities of vitamins must be provided in a rabbit’s diet in order to properly activate the catalysts which are so essential in the release of energy from carbohydrates and fat. If adequate quantities of the vitamins are not provided, proper quantities of active enzymes cannot be made available, the energy sources in the form of carbohydrates and fat remain intact, and energy is not made available for use by the rabbit’s body.
Nature has given the rabbit a unique way of providing for a part of this vitamin requirement. The rabbit has the habit of practicing coprophagy, or the consuming of its own droppings. The night pellets which are eaten are high in vitamins and go a long way toward making up the daily vitamin requirement. Present-day rabbits which are bred for high reproductive performance require more vitamins than can be provided in this way, however. This means that all rations should contain adequate quantities of all vitamins in order to insure the efficient utilization of dietary energy.
The process of converting raw material into meat requires that special attention be given to the mineral content of the ration. Those minerals include calcium, phosphorus, chlorine, iron and iodine. Calcium and phosphorus are involved in the building of bones and teeth, in the coagulating of blood, in essential milk production and are required for the proper functioning of muscles and nerves. Chlorine, which is provided in the form of sodium chloride or common table salt, is a component of essential gastric juices. In addition, chlorine is an important part of the mechanism which regulates the osmotic pressure in tissues. An adequate supply of iron must be provided in order to form the hemoglobin which is the oxygen carrier in red blood cells. If it were not for an adequate amount of hemoglobin and the oxygen-carrying ability of this compound, the rabbit could not survive. Iodine is needed in the formation of the hormone thyroxin. This hormone, which is secreted by the thyroid gland, is the regulator of metabolic rate. Iodine also promotes the growth of fur and is required if high-quality pelts are to be produced.
People often forget that water is an essential food nutrient, and is perhaps the most important of all nutrients which must be fed to any animal. Rabbits are no exception. All of the fresh, pure water they will drink should be provided. The amount of water which rabbits will drink will depend upon age, type of ration and season. An animal can do without food for a relatively long period of time before death occurs. However, no animal can live very long without water.
From an economic standpoint, lack of water will cause the rabbit’s fur to lose bloom and condition. Research indicates that fur growth will be reduced by as much as 1/5 when water intake is limited. Carelessness in not providing an adequate supply of clean, fresh, pure water should be avoided at any cost.
Amazing reproductive ability
Consider the scope of the reproduction job which the doe is expected to do as compared to other classes of livestock. Typical production results for a brood sow, a range cow, and a doe are presented in Table 1.
A brood sow weighing 400 pounds produces an average of two litters a year, or a total of 16 young. At weaning age, these 16 pigs will weigh 400 pounds. This means that the brood sow produces 100 percent of her body weight in young each year. A 1,000-pound range cow will produce a calf which at weaning time will weigh approximately 40 percent of her weight in the form of a calf in one year’s time.
People often forget that water is an essential nutrient. Fresh, clean water should be provided at all times.
A doe weighing 11 pounds, on the other hand, produces a total of four litters per year. Thirty young are produced and their total weight at weaning time is 120 pounds. This means that one 11-pound doe is expected to produce young equal in weight to 1,000 percent of her own body weight.
Because of this phenomenal reproductive performance, as much care should be exercised in formulating rabbit rations as is followed in formulating rations for swine and beef cattle. The nutritional know-how which goes into the feeding of hogs and beef cattle is a result of many years of painstaking research. If optimum results are to be obtained in the production of rabbit meat, present day knowledge should be used to a maximum, and more research should be done in order to obtain much-needed information.
Few people recognize the high-quality product which is being produced by rabbit raisers. An understanding of the value of the meat should be an added incentive to do everything that you can from a nutritional standpoint so as not to impair its excellent quality and fine reputation.
Rabbit meat is white, fine-grained, and delicately flavored. Every effort should be made to ensure that the ration which is fed does not impair these characteristics which are so important to meat quality. The nutritious value of the meat is another important factor to be taken into consideration. Rabbit meat contains more protein than either beef or lamb and rates second only to pork and poultry products in this respect. Even though the fat content of rabbit meat is higher than in beef, pork and poultry, its energy value expressed in calories per 100 grams compares favorably with these meat products.
The rabbit is a very efficient converter of low-cost raw material into a valuable, top-quality meat product. This should give you a better understanding of the basic principles of rabbit nutrition, and a greater appreciation of the phenomenal reproduction performance of the doe.
Reprinted from Rabbits, March/April, 1986.