| Hay in Your Bunny's Diet - Quality and Quantities for Healthy Digestion |
From House Rabbit Journal Vol. 4, Nr. 7 - Summer 2002
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 .
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%
CUTTINGS OF HAY
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.
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.).
THE DIGESTIBILITY FACTOR
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.
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.
THE HAYING PROCESS
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.
PURCHASE AND STORAGE
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.