Abstract:
HOOF GROWTH A POSSIBLE INDEX OF NUTRITION IN GRAZING ANIMALS J. L. WHEELER* Summary Hoof growth rates were measured independently of wear on young Merino ewes set stocked on five variously treated pastures. Responses in hoof growth rate closely paralleled those in wool production and bodyweight change in winter but not at other times. The measurement is readily and accurately made and attention is drawn to its potential as a supplementary index of nutrition in grazing trials. I. INTRODUCTION The potential of hoof growth rate as a supplementary measure of animal response to pasture treatments is currently being examined at this Laboratory. Nail growth in man and laboratory animals has been suggested as an index of nutrition (Anon 1960) and some information is accumulating, especiall y for the rat, but there appear to be no reports in the literature on factors other than pathogens affecting hoof growth in domestic animals. Methods of measurement of nail growth that are independent of wear are reviewed by Babcock (1955). A general review is given by Godwin (1962) and relevant literature on human nail growth is discussed by Hamilton, Terada and Mestler (1955). Nail growth in rats was retarded by dietary deficiencies especially protein (Godwin 1959), and lack of Vitamin A, illness and immobilization are variousl y reported to reduce nail growth rates in man and rats (Godwin 1962). Godwin' s ( 1959) finding that in rats low temperatures reduced nail growth and the confirmation of this with sheep (Wheeler, unpublished data) is important if it is to be used as an index in grazing animals, as this precludes direct season to season comparisons until a temperature correction factor can be calculated. II. MATERIALS AND METHODS Groups of four sheep on five plots of an experiment comparing methods of improving winter nutrition of grazing sheep were used. The full experiment involves 24 treatment combinations: hooves were measured in the sheep on the plots listed in Table 1. Linear hoof growth rate (LHGR) was determined at monthly intervals on the maiden Merino ewes used in this study by measuring the migration of a fine horizontal saw kerf on the hoof away from a reference point made by *C.S.I.R.O., Division of Animal Physiology, Armidale, N.S.W. 350 Pasture Treatments TABLE 1 :'Grazing deferred on half the plot from March until July. $100 kg elemental N as ammonium nitrate split into March, May, August applications. tattooing a black dot in the skin 3-4 mm above the skin/hoof junctio n (Figures 1 and 2). Measurements were taken on both claws of both legs. Wool growth was measured by clipping a sample at intervals from a 7 x 7 cm patch defined by tattooed lines in the mid flank position. The wool was scoured and oven dried, and this data was used to partition between seasons the total clean wool production found at shearing. Mean fibre diameter was determined by an air-flow technique (Anderson 1954) modified by Chapman (unpublished data). Sheep were weighed monthly. III. RESULTS AND DISCUSSION For simplicity of presentation, results are tabulated as relative treatment responses on four plots only (Table 2). A positive effect from the second of Fig. l.-Method of marking an d measuring hooves. 351 Fig. 2.-Method of marking and measuring hooves. TABLE 2 Relative respomes in body weight, hoof growth and wool production to pasture treatmmts 1962-3 Significance levels determined by t test on orignal figures following analysis of variance. NS = P>O.O5, * = P<O.O5, ** = P<O.Ol, *** = P<.OOl. 'f i.e. (Treat.2/Treat.S) x 100. $ i.e. (Treat.4/Treat.3) x 100. 9 i.e. (Treat.4/Treat.S) x 100. 11 Ratio of body weights (period means). y From beginning to end of period. any pair of treatments gives rise to ratios of more than 100. Mean values for the parameters are given in Table 3. Pasture treatments produced responses in LHGR that were broadly similar those in the other parameters. The correlations between LHGR and both wool growth and bodyweight change were close (r = .889 and .860; P< .OOl) in winter but there was no correlation at other times. The possibility of using the relationship for prediction of wool growth over short periods is thus not promising. TABLE 3 Values for body weight, hoof growth and woo~l production 1962-3. (Means pasture treatments) of 5 Hoof growth ered that it will grazing animals and physiological is an accurately and readily observed parameter and it is considprove a useful supplementary index of nutritional status in once further information has been obtained on the nutritional factors controlling it. IV. ACKNOWLEDGMENTS Thanks are due to Mr. C. Mulcahy for technical Chapman, C.S.I.R.O., Ian Clunies Ross Laboratory, for to Mr. P. F. May, C.S.I.R.O., Division of Mathematical Dr. R. G. Petersen, North Carolina State University, assistance. V. REFERENCES A A B NDERSON assistance, to Mr. R. E. wool measurements and Statistics, Armidale, and Raleigh, for statistical of Textile Institute 45: 3 12. , S. L. (1954). The air-flow of measuring wool fibre fineness. Journal NON . (1960). A study of nail growth. Nutrition Reviews. 18: 112. ABCOCK , M. J. (1955). Methods for measuring fingernail growth rates in nutritional studies. Journal of Nutrition 55: 323. GODWIN, K. 0. ( 1959). Experimental study of nail growth. Journal and Dietetics 3: 105. of Nutrition 69: 121. GODWIN, K. 0. ( 1962). Skin, hair and nail in protein nutrition. World Review of Nutrition H AMILTON , J. B., T ERADA , H., and M ESTLER , G. E. (1955). Studies of growth throughout the lifespan in Japanese: Growth and size of nails and their relationship to age, sex, heredity, and other factors. Journal of Gerontology 10: 401.