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United Suffolk Sheep Association |
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J. S. Rook, D.V.M.
MSU Extension & MSU Ag Experiment
Station “Urinary calculi” refers to small, sand-like mineral deposits that precipitate in the urine and occasionally become large enough (or numerous enough) to obstruct the flow of urine. Clinically, the problem occurs in wether lambs, ram lambs and occasionally older intact rams. Due to the large size of the female urethra, calculi rarely affect ewe lambs. In the male, common sites for obstruction by calculi include: 1) the tip of the urethra (urethral process - the worm-like appendage on the tip of the penis) and 2) the S-shaped (sigmoid) flexure of the penis (due to the curves obstructing urine flow). When obstruction occurs, urine outflow ceases and pressure in the bladder begins to build. As the bladder distends with urine the lamb becomes painful and often acts colicky (uncomfortable, restless, kicks at belly, strains). If obstruction is incomplete, some urine may be observed dribbling from the end of the sheath. Continued urine buildup usually leads to: 1) expulsion of the obstruction and recovery until re-obstruction occurs, 2) rupture of the urethra and migration of the urine from the rupture site into the subcutaneous tissues along side the sheath and 3) rupture of the bladder and flow of urine into the abdominal cavity. Rupture of the urethra and rupture of the bladder both provide relief from the pain of the distended bladder and the lamb often appears to improve. However, waste products normally excreted in the urine remain inside of the lamb and begin to poison the animal. Death usually follows rupture in 2 to 3 days. Due to their "skunky" smell and taste (from the urine retention) affected lambs should not be slaughtered or marketed when obstructed. Treatment of individuals: Once lambs exhibit clinical signs of urinary obstruction, treatment involves surgery aimed at restoring urine flow. In some cases, removal of the urethral process at the end of the penis may provide relief. Usually, however, the penis is surgically bisected just below the rectum (above the level of obstruction) and sutured to the skin. This allows the lamb to urinate - much like ewe lambs. Flies and infection can complicate the procedure. Cost of this surgery can be an issue, however, the surgery usually is performed under local anesthesia and is not extremely involved. Surgery should be viewed as strictly a salvage procedure and not as an end to the problem. Instead, prevention of continued problems in the remainder of the lambs is of prime importance. Nutritional concerns and prevention: 1) Ca:P ratio: Urinary calculi formation in feeder lambs is closely related to nutritional management and the manner in which we choose to feed lambs. Midwestern lambs are usually finished on 1) a 35% protein supplement pellet & shelled corn, 2) alfalfa/roughage pellets and shelled corn, 3) hay and shelled corn, or 4) grain mixes. In any lamb ration it is important to maintain adequate amounts of both calcium and phosphorus - while maintaining at least a 2:1 calcium to phosphorus ratio. Typically, as lambs approach slaughter weight, consumption of concentrate (high in P and low in Ca) increases; while forage consumption (high in Ca and low in P) declines. As concentrate intake increases and forage intake declines this desirable 2:1 Ca:P balance reverses, creating ideal conditions for formation of urinary calculi. Typically, non-supplemented (i.e. no calcium added to the ration) high grain/low roughage lamb diets assume a 0.5:1 to 1.5:1 Ca:P ratio. To avoid this Ca:P imbalance first think about the way you feed your lambs and how your program changes as lambs approach finishing weights. Calculi problems often occur late in the feeding period as concentrate:forage ratio increases. The following "thumb rules" may be helpful with preventing calculi. 1)If you feed shelled corn and 35% protein supplement pellets make sure that the supplement pellet contains at least 4% Ca in the pellet – many brands do not! Even at 4% Ca, a 85:15 mix of shelled corn to pellets still only provides a 1.5 Ca:1 P ratio for a 110 pound lamb (Ex: 2% Ca in a 35% protein supplement pellet = .78 Ca:1 P ratio & 5% Ca in the pellet = 1.9 Ca:1 P ratio). Do not assume that ammonium chloride will solve the calculi problems. Look for a pellet with more calcium. 2) If you feed alfalfa pellets and shelled corn generally anything over a 60:40 shelled corn:alfalfa pellet mix will be imbalanced. Notice the Ca:P ratios in the following examples. Ex: A 50:50 corn:alfalfa pellet mix provides lambs with a 2.4 Ca:1P ratio. However a 70:30 corn:alfalfa pellet mix would produce a 1.4 Ca:1 P ratio. A typical finishing ration using 80:20 corn:alfalfa pellet mixes produces a 0.9 Ca:1 P ratio. If the 50:50 mix is exceeded, then Ca may need to be added. Much will depend on alfalfa pellet analysis. 3) If you feed hay and shelled corn a 50:50 mix of alfalfa hay and shelled corn is the upper limit - just like alfalfa pellets. However, remember that grass hays contain very little calcium when compared to alfalfa or clover hays. Calcium will need to be supplemented if grass hays are fed. 4) If you mix your own grain mix of corn and soybean meal you will usually need to add limestone at the rate of 1% to 2% of the diet. However, this will vary with the type of lambs and diet specifications. For a typical corn/soybean meal ration 1% limestone produces a 1.3 Ca:1 P ratio, a 1.5% limestone provides a 1.8 Ca:1 P ratio and adding 2% limestone yields a 2.4 Ca:1 P ratio. Compared to calculi losses, limestone is cheap. Other calculi issues: 1) Salt increases: Prevention & treatment of calculi problems should also include adding increased levels of salt to the diet. Customary salt levels of 0.5% to 1.0% of the concentrate can be gradually increased to the 2.0% to 3.0% level. Increased salt encourages water consumption and has a flushing affect on the calculi. 2) Ammonium Chloride at the rate of 8 lbs. to 10 lbs. per ton of concentrate can also be added to the feed to prevent calculi. However, protein supplement pellets, formulated for an 85:15 corn:pellet mix, would need to contain higher levels of ammonium chloride (since the pellet is to be diluted with corn). These higher levels often adversely affect consumption - thus the reason some feed companies add ammonium chloride in concentrates but not protein supplement pellets. 3) Clean water with enough space for lambs to drink is also important. Automatic waterers and tanks become extremely dirty as lambs go from feeder to waterer. Clean daily, assure proper function and make sure lambs don't have to wait in line to drink. Closing comments: In well-managed systems, losses from urinary calculi (“water belly”) are usually minimal. Major losses from calculi usually result from nutritional imbalances in calcium and phosphorus concentration and ratio and/or water consumption and/or diet formulation change issues. Lamb feeders can usually prevent calculi problems by adding adequate limestone, extra salt, and/or ammonium chloride to the feedlot diet. Regular cleaning of watering units is also helpful. However, even when rations appear adequate, occasional losses from urinary calculi can still be expected.
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