Effect of dietary polyunsaturated fatty acids and zinc on plasma lipids and skin and hair coat condition in dogs
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Dietary effects on skin and hair coat were investigated in dogs. Twenty-four normal adult dogs were acclimated to a commercial diet (9% fat as is) for 12 weeks (phase I). For the next 12 weeks (phase II), the dogs were divided into three groups and fed one of three treatment diets (13% fat as is). Phase II diets used similar ingredients and similar nutrient profiles except that diet A contained lower yet adequate amounts of dietary zinc and linoleic acid (LA) than diet B. Diet C was similar to diet B in zinc and LA but contained more α-linolenic acid (ALA). An evaluation panel conducted skin and hair coat condition scoring on weeks 0, 4, 7, and 12 (phase I) and weeks 14, 16, 19, and 24 (phase II). Coat glossiness, softness, scale, greasiness, and overall condition were evaluated. Transepidermal water loss and skin hydration (HYDR) were determined at selected times using a Tewameter and Corneometer (both Courage + Khazaka Electronic, GmbH, Cologne, Germany), respectively. Plasma samples were also collected at selected times and used to determine phospholipid fatty acid profiles and zinc concentrations. The hypothesis was that increased LA and ALA plus zinc (diet C) would improve skin and hair coat conditions and fatty acid profiles compared with the other diets. Repeated-measures analysis of variance (parametric data) and Kruski-Walls analysis (categoric data) were used for data analysis. All three phase II diets caused significant improvements of both subjective and objective measures compared with the basal (phase I) diet. Diet B resulted in statistically significant improvements compared with diet A for skin scores and HYDR. Diet C's effects were not different from those of diets A and B but provided a desirable fatty acid balance. Improvements with increased total fat in the phase II diets were clearly seen, and the increased LA, ALA, and zinc combination also contributed to fatty acid balance.
author list (cited authors)
Hester, S. L., Kirby, N. A., Wright, A. S., Rees, C. A., Kennis, R. A., Zoran, D. L., & Bauer, J. E.