Western
Meeting of Poultry
Clinicians and Pathologists
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Clinicians and Pathologists
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Dietary Observations Associated With Turkey Cardiomyopathy David D. Frame Utah State University, Animal, Dairy and Veterinary Sciences Department, Turkey Research Center, 325 West 100 North, Ephraim, Utah 84627 USA
SUMMARY Spontaneous cardiomyopathy of turkeys (SC), also known as roundheart disease, is a prevalent circulatory disturbance afflicting turkeys raised at moderate to high altitudes. A condition in turkeys with enlarged hearts was first described in 1962. Since then possible genetic, management factors, and nutritional causes of the round-heart syndrome have been implicated. The objective of this presentation is to briefly describe SC as seen in Utah, and to propose possible ways to minimize economic loss associated with this disease. In Utah, SC occurs at two major periods (1). The first is during early brooding between 10 and 18 days of age. The prevalence and incidence rates are often greater in hen flocks at this age. Poults that succumb at this stage are usually large with well-developed musculature. A second spike of SC mortality is seen during late brooding and early growout. Toms four to eight weeks old are most likely to show this type of mortality pattern. Usually the dead turkeys are smaller than the flock average. Sometimes mortality continues at a low rate for weeks after the initial spike. We have shown that turkeys hatched from the same flock but raised at different altitudes will exhibit variable responses to SC. In one trial, poults raised at 100 m (330 ft) above sea level showed no clinical signs of SC, yet flockmates kept at 1670 m (5500 ft) had significant SC-associated mortality (unpublished data). Slowing the growth rate during the first four weeks will decrease incidence of STC. We have studied the application of low protein and reduced salt (NaCl) diets in the control of SC. Feeding a “less-than-conventional” protein level for the first three weeks decreased SC losses, but at the same time significantly depressed growth rate. It may not be economically worthwhile to use lower than recommended protein level because the decreased mortality did not offset the lost weight gain. Subsequent studies (2) using a reduced salt (NaCl) diet during the first three weeks of life significantly decreased SC mortality while only slightly inhibiting growth rate. Particularly in hens, the low salt groups rendered more cumulative pounds of marketable product at processing age. The greater livability offset the slight weight gain reduction. In 1999 (3) we conducted two pen trials to evaluate effects of dietary sodium (Na+) and chloride (Cl-) concentrations on live performance and deaths caused by SC. In both experiments, SC mortality was significantly reduced by the Low Na:High Cl treatment compared to the other treatments. Body weight and feed conversion ratio at 35 d of age were unaffected in both trials. As a spin-off from these last findings, we constructed a pilot study manipulating Cl- and K+ intake through the drinking water. This trial was conducted in battery brooders. Although no SC-associated mortality occurred, results of sampling heart and lung weights, lung volume, and plasma alanine aminotransferase levels suggest that a relationship between K+ and Cl- intake may be associated with a predisposition for, or protective effect against, clinical SC. Studies manipulating K+ and Cl- concentration in the finished starter feed are anticipated to be carried out in larger scale floor trials.
REFERENCES 1. Frame, D. D., 1991. Roundheart disease in Utah turkey flocks. Pages 95-96 in: Proceedings of the 40th Western Poultry Disease Conference. 2. Clark, F. D., D. D. Frame, R. E. Warnick, E. J. Kelly, and B. L. Roeder, 1995. Effects of lowered dietary sodium chloride on spontaneous cardiomyopathy mortality in turkeys. Pages 22-23 in: Proceedings of the 44th Western Poultry Disease Conference. 3. Frame, D.D., D. M. Hooge, and R. Cutler. 2001. Interactive effects of dietary sodium and chloride on incidence of spontaneous cardiomyopathy (round heart) in turkeys. Poultry Sci. 80:1572-1577. |
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