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Hay in Your Bunny's Diet - Quality and Quantities for Healthy Digestion
Linda Sterett-Fogarty
From House Rabbit Journal Vol. 4, Nr. 7 - Summer 2002
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  • CONTRARY TO BELIEF , hay is not grown year round. Forage cannot be grown during a major portion of the year due to cold temperatures. Since animals need a continuous supply of food, the storing of hay is critical. The haying process allows us to harvest and store hay grown during favorable weather conditions for use during less favorable conditions. The process starts in the spring when the days become sufficiently warm and the length of daylight hours increases . This stimulates the plants that have been lying dormant over the winter to begin their growing process. Where our ranch is in Lincoln County, WA , this growing process usually begins in April. There are many variables that can affect this process, not the least of which is the temperature of the nights. April nights in this area can be in the 30s which causes a longer growing period. In order for good growth to begin, not only do the days need to have warm temperatures, but the nights need to have temperatures ranging above 40 degrees Fahrenheit.

    Grass will grow slightly faster in cooler weather than the legumes, such as alfalfa. Alfalfa grows best when the temperatures are hot. It typically takes approximately 60 days for new growth of alfalfa, 60 for mix hay, 60 for orchard grass, and 75-80 for timothy in Lincoln County .

    Alfalfa, which is a herbaceous perennial legume, originated near Iran . It has a high mineral content and contains at least 10 different vitamins. Alfalfa, if cut when all things are ideal, can run as high as 20% protein in the pre-bloom state to as low as 11% at the end of bloom.

    Timothy grass, a perennial bunchgrass, is a cool-season forage grass. It is slow growing and has a low yield in the field. It has been our experience that 1st and 2nd cutting timothy grass hay works well for animals with a delicate digestive system, skin problems, issues with diarrhea and weight problems. Timothy can, however, go as high as 18% protein just before bloom (we've never had one test this high) and can fall as low as 4-6% protein in the late bloom state.

    Orchardgrass (also known as "cocksfoot" in Europe, New Zealand , and Australia ) is native to Europe, North Africa , and parts of Asia but has been grown in North America for more than 200 years. It is a cool season grass that grows in clumps or tufts and has a fibrous root system. It starts growth early in spring, develops rapidly, and flowers during late May or early June, depending upon length of days and the temperature. Orchardgrass is more heat and drought tolerant than timothy grass. Orchardgrass grows rapidly at cool temperatures, is very productive in early spring and recovers quickly af ter cutting. Orchardgrass, in our experience, usually runs a bit higher on the protein scale than timothy. Researchers say it can run as high as 18.4% in early vegetative state, down to 8.4% in late bloom, but typically we find it runs approximately 12-14%.

    Mix hay is a mixture of alfalfa and some type of grass, typically orchardgrass. The percentages can vary from as little as 5% alfalfa vs. 95% grass to the complete opposite of 95% alfalfa vs. 5% grass, all dependent upon the percentages of the seed mixture that is ordered from the seed company and planted by the farmer. In some cases, a farmer will go into a field and overplant in an existing stand of either a legume or grass with the opposing seed and achieve somewhat of a mix. The downside of this method is that there is less consistency in percentage of legume vs. grass when comparing the bales, as wide fluctuations can occur over the course of the field . Our two most popular mixes are: 1) A l f a l f a , 30% Orchardgrass-brome grass mix, 70% 2) A l f a l f a , 40% Orchardgrass-brome grass mix, 60%

    Where our ranch is located in Eastern Washington , we get a 1st cutting (the fir s t crop taken off a field in any given year), a second cutting (the second crop taken off that same field in that given year), and possibly a third cutting (the third crop taken off that same field in that given year), provided Mother Nature complies and gives us enough sunshine, dry days, and warm nights. Mother Nature is, however, very unpredictable! You learn to make hay while the sun shines, as the old saying goes.

    First Cutting: The first growth off of a field for the year is the "first cutting." Many people erroneously feel that first cutting hay is not to be considered as good feed. We tend to disagree, provided it is of good quality and was cut when relatively immature (pre-bloom stage), before the plant is allowed to mature to the point where the stem becomes larger and coarser. This is when the lignin (an indigestible part of the fiber component associated with cellulose and hemicellulose in the cell wall) content has become sufficiently high so as to make the hay more unpalatable and indigestible and the nutritive value has declined greatly. This can happen with 1st, 2nd, or any cutting of hay if left growing too long.

    Second Cutting: Depending upon the temperatures of the days and nights, it typically takes 40-45 days for regrowth of alfalfa, mix hay, and orchardgrass , and 55- 60 days for regrowth of timothy. This is termed the "second cutting," which usually has a larger percentage of leaves to stems, has a finer and softer stem, has increased percentages of crude protein and crude fat, and has a lower crude fiber percentage (depending upon the stage of maturity at which it was cut) . More non-structural carbohydrates (starches and sugars) and protein are in the leaves than in the stems. These starches and sugars are very digestible and make the hay higher quality.

    Third Cutting: If the growing season is long enough on any given year, it may be possible to secure a third cutting. In regions that lie south of our location, the growing season is longer and hotter, making alfalfa the prime hay crop, and often as many as four or five cuttings may be taken from a single field.

    The third cutting is typically very soft hay that is primarily leaves with very few small stems. While beautiful to look at, it can be "rich" (high in nutrients, having a high Relative Feed Value or RFV, and low in fiber). It is our opinion that third cutting hay does not contain sufficient fiber content to be the only hay in the diet of most rabbits. It can, however, be used in conjunction with a higher fiber, good quality, relatively immature 1st or 2nd cutting hay, and creates greater variety and interest in the chewing experience. We suggest that you feed the different hays at different meals so as to eliminate waste.

    The stage of maturity at which forages are cut (whether it be 1st, 2nd, or 3rd) has a major influence on the quality of that forage. Forage crops generally decline in nutritive value as they mature. As forage plants mature, it is typical for an increase in Acid Detergent Fiber or ADF to occur.

    ADF is the percentage of highly indigestible plant material in a forage comprised of cellulose and lignin. A low ADF value indicates greater digestibility and therefore "better quality" hay. ADF values are important because they reflect the ability of an animal to digest the forage. As ADF increases, digestibility usually decreases. Neutral Detergent Fiber or NDF is the percentage of cell wall material in the hay that is partially available to the animal and is made up of cellulose, hemicellulose, and lignin. As the NDF percentages increase, the dry matter intake will generally decline (meaning the animal will consume less). NDF is very important because it estimates that fraction of forage that, if it is to be used by the animal, must first be broken down by gastrointestinal microorganisms. Lignin is a non-carbohydrate substance that is the main factor in- fluencing the digestibility of plant cell wall material. As lignin increases, digestibility, intake and animal performance usually decrease, and the percentage of ADF and NDF increases. Simultaneously there is a decline in the Crude Protein (the total amount of nitrogen in a forage indicative of its ability to meet an animal's protein needs). Thus, Relative Feed Value ( an index that ranks forages relative to the digestible dry-matter intake) declines with maturity.

    The complex carbohydrates that are in hay include hemicellulose, cellulose, and lignin, forming the cell wall of the plant. This provides fiber in the animal's diet and is important to a healthy gastrointestinal system. The solubles or digestible part of the hay is primarily the cell contents. As the plant matures, the hemicellulose changes to cellulose and is not as digestible, which leads back to the timing of the cutting being a critical factor in the quality of the hay. It is not so much the cutting but the maturity of the plant at the time it is harvested. If the hay is cut when relatively immature it is higher in nutrients and darker green in color, but given more growing time, that same hay will be more mature, larger and coarser, have a higher cellulose content and will not be as digestible nor as nutritious; it's all a matter of timing and what Mother Nature allows you to do. Leaves of both grasses and legumes contain a much greater concentration of digestible nutrients than do stems.Therefore, as the proportion of leaves to stems becomes higher with each successive cutting, it is easy to understand how the nutritive quality of the successive cuttings (1st vs. 2nd vs. 3rd) becomes higher. The only way in which a 1st cutting could be higher in nutrition would be if the 2nd and 3rd cutting forage being compared were both allowed to become far too mature so as to decrease digestibility, nutrition, and intake, compared to a pre continued on next page bloom 1st-cutting forage of the same type (alfalfa, timothy, orchardgrass,etc.).

    Let's say for the sake of comparison, that you are feeding your rabbit a portion of a 2nd cutting hay that was cut when the plant was relatively immature, the nutrition and digestibility are high, and the cellulose content is low. Your rabbit would be able to digest more of the nutrients out of this hay and would achieve maintenance or weight gain depending upon the size of the servings and the dynamics of this particular animal and his environment/ work load. If this same field of hay had been allowed to grow for another week, for example, the indigestible portion of the plant would have increased, making the hay less nutritious and less palatable, and the amount of digestible energy that the animal is able to extract from that hay is decreased. It would now become necessary to feed a larger size portion of this more mature hay to achieve the same maintenance.

    This digestibility factor is the determining factor as to how much "good" your rabbit will get out of a particular type of hay. You can feed a large volume of hay that is low on the digestibility scale and keep the rabbit at his ideal body weight, but if feeding a highly digestible hay (hay that has a high RFD and is high in nutrients) one would obviously need to feed a smaller amount to maintain the rabbit at his ideal body weight. Within the confin e s of each cutting (1st, 2nd, 3rd) it is possible to have varying percentages of "digestibility" depending upon the stage of maturity of the plant at the time of harvesting. Therefore, we take issue with those that out-of-hand discount a 1st cutting of hay, stating it will always be too "stemmy or coarse." Nothing could be further from the truth, in fact, it is our belief that many animal owners could benefit from feeding a good quality, relatively immature 1st cutting hay. The nutritional level is usually more consistent with the needs of the typical pet animal, and the added benefit to the rabbit's gastrointestinal and digestive tract of this higher fib e r percentage can be invaluable. If you have fed a beautiful, dark green, leafy 2nd or 3rd cutting hay and your rabbit has experienced diarrhea, there is a good chance that your rabbit could benefit from the binding qualities of the higher fiber content of the 1st cutting hay, as long as it was cut before it became too mature.

    Many pet owners with whom we deal buy hay based on its visual appeal-dark green, leafy, soft. This equates to hay that is very high in nutrients, high in protein, possibly high in fat, high in calories, and definitely low in fiber. The consumerdriven hay market has continued to demand ever more "beautiful" premium hay, and it is our belief that we now have on a consistent basis, hay that is almost "too rich" for the normal house pet. In addition to this "premium" hay, many owners feel that more is better and are feeding ever increasing amounts of treats, vitamins, minerals, and supplements, whether the rabbit really needs them or not! In fact, one might say, we are killing them with kindness. If you choose to feed premium hay, then cut down on the treats and supplements.

    We recommend that you look at the hay choices available in any given year, buy samples of the types you think are most likely to work, and go feed them out. This ensures a successful outcome in providing a menu that your rabbit will eat and one that will be good for him. Most importantly, observe your rabbit's appearance frequently. You can develop an "eye" for the current body condition of your rabbit and adjust the size of portions up or down as needed.

    Swathing: The hay is harvested with a piece of equipment called a "Swather." This is a self-propelled mowing machine with a set of rubber rolls that the hay passes through. This roller crimps the stems at intervals of 2 1/2 - 3 inches which allows quick evaporation of stem moisture and decreases drying (curing) time. The shorter the drying time, the higher the nutritive value of the hay. The swather then shoots the hay out the back end of the machine in a continuous row called a "windrow."

    Curing: The curing process is a drying out of the moisture in the hay to 14%. This occurs by a combination of air (wind) and sun. The shorter the cure-time, the less top-bleaching can occur from the sun. This process, if everything is ideal, typically takes 4 days in our fields. Usually the conditions are less than ideal and the process can take 7 days.

    Hay Turning: As hay dries in the field, the top of the swath dries more rapidly than the bottom. Hay-turning is a process of flipping the windrow upside down (moving the wetter material to the upper surface) to increase the speed of the drying process and to make the hay uniform in dryness to ensure no slugs (small, wet clumps of twisted hay). This turning process is only done when nature has provided a less than ideal curing period.

    Hay Baling: The hay baler is a piece of equipment that picks up the hay and lifts the windrow from the field surface, going next into a compression chamber where the hay is packed and formed into a bale, and a tying mechanism that completes the bale. Typical DM ( Dry Matter ) losses during hay baling vary between 2% and 5% of the yield, with the loss equally divided between pickup and baler chamber losses. Pickup loss is highest when the baler is being pulled too fast. Chamber loss is greatly affected by crop moisture content, with drier material having greater loss. When hay is baled at night, leaf moisture is higher, similar to stem moisture, and chamber loss can be cut by 50%. We typically bale hay during the middle of the night when the days become too hot to bale during the daylight hours and achieve the proper moisture percentage. This moisture content, if it can be achieved, allows for a more beautiful and more nicely packed bale that allows for "peeling off" of a flake. If it is not possible to achieve this moisture content during the baling process, the bale, while having the same nutritive value, will fall apart more easily when the strings are cut and will be messier to feed. There is also a greater chance for this dry-matter loss (shatter quality) to exist in this drier hay. We always strive for this proper moisture content, but Mother Nature does not consistently provide the right circumstances, so we do the best we can. Our 2-string bales typically weigh 90-110 lbs. We use no drying agents or preservatives on any of our hay.

    Bale Wagon: The bales are removed from the field by means of a bale wagon. This machine is self-propelled and picks up the bales on a platform and then through a series of hydraulic maneuvers stacks them on the bed of the wagon. Once the correct number of bales is "on-board", the wagon can be driven to the stacking area at the edge of the field. The wagon can automatically stack the hay by raising the bed of the wagon into an upright position, and driving out from underneath the "s tack" while hydraulic "feet" push against the stack, holding it in place.

    Purchasing Your Hay: At our barn, August through November are the best months for hay purchases. The supply is normally ample at that time of the year as the crops are being harvested for the current year, the price is the best of the season, and the choice range is widest. Once a particular type of hay has been sold out, that type of hay will not be available again until the next year's crops are grown. Hay is only grown during a portion of the year so if you are purchasing hay during a time other than the growing season, the hay you are purchasing is being stored at a storage location. Large amounts of hay (hundreds of thousands of tons) are stored either in covered barns or in professionally tarped stacks in Eastern Washington , where humidity is low.

    Storage at Your Location: Hay that has been properly harvested and baled, and has been stored properly will last for several years in the bale. Bales that have been opened are best stored at room temperature or cooler in a dry location out of sunlight (which can leach nutrients). A garbage can or similar container that is not air tight works well. Your hay needs to breathe, as it naturally has a moisture content that, when enclosed in a sealed bag or container, can cause the growth of mold. Do not store your hay in sealed plastic bags. Properly stored, carefully selected highfiber hay can provide your rabbit with a healthy diet year round. Knowledge of hay will help you to feed your rabbit the right kinds and right amounts.

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