EFFECTS OF DAILY OR WEEKLY FEEDING OF WHEAT ON WOOL PRODUCTION. M. K. HILL*, M. J. WATSON and G. L. McCLYMONT

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1 EFFECTS OF DAILY OR WEEKLY FEEDING OF WHEAT ON WOOL PRODUCTION M. K. HILL*, M. J. WATSON and G. L. McCLYMONT Summary Non pregnant Merino ewes were fed for survival on isocaloric wheat rations given either daily or weekly. Wool production of the group fed weekly, measured by cutting wool from a patch on the mid-side, was 55% higher than that of animals fed daily. Liveweights and rate of liveweight change did not differ significantly. Nutritional implications of this result are discussed. I. INTRODUCTION When pastures are severely depleted by drought, it is common practice in Australia to maintain sheep on grain rations given once or twice weekly. The effect of such intermittent feeding on wool production is not well defined. Franklin (1951, 1952) observed an increase in fleece weight as the feeding interval was extended, but Franklin et al. (1955) and Briggs, Franklin and McClymont (1957) found no effect. The use of fleece weights of survivors in comparing feeding treatments,. evident in all of these studies, introduces bias when differential mortality rates occur. This study of the effect on wool production of daily or weekly feeding of an all-wheat ration to sheep individually penned is part of a larger survival feeding investigation being conducted by one of us (MJW). II. MATERIALS AND METHODS Eight non-pregnant, adult, medium Peppin Merino ewes were shorn and fed as a group in a pen from June 21, 1966 for 40 days on 300 g wheat plus 300 g lucerne chaff per head per day. The sheep were then paired in decreasing order of liveweight and one of each pair was allotted at random to. weekly or daily feeding treatments. They were individually penned and introduced over three weeks to an all-grain ration of 300 g of wheat per day and this feeding regime continued for a further four weeks. The weekly animals were then gradually introduced to intermittent feeding during a three week adaptation period and on October 6, 1966, the beginning of the experimental period, they received their first 7-day ration of 2100 g of wheat. The wheat used throughout the experiment contained 89% dry matter, and 13.8 % crude protein in the dry matter: and the ration was supplemented with 1.5 % *Department of Livestock Husbandry, University of New England, Armidale, N.S.W. TDepartment of Biochemistry and Nutrition, University of New-England, Armidale, N.S.W.

2 finely ground limestone, 0.33 % NaCl, and 1% of a mineral-vitamin mix.* Each animal had a 9 x 9 cm square, tattooed on its right mid-side on June 24, Every two weeks wool was harvested from within this area using Oster clippers fitted with a size 40 cutter, and liveweights were measured. Wool samples were weigh.ed after overnight drying at 1 OO C, scoured, again dried overnight and reweighed. Sa.mples were scoured in 100 ml beakers with successive washings of aqueous solutions (based on Turner et al. 1953) containing (i) 0.18% v/v Teepol 610 (Shell Chemical (Aust.) Pty. Ltd.) at 55 C (ii) 0.23% v/v Teepol plus 0.27% W/V sodium carbonate at 50 C, (iii) 0.14% V/V Teepol plus 0.14% W/V sodium carbonate at 50 C (iv) water at 45OC, and were filtered through a 75 micron aperture sieve after each washing. The mean wool data shown in Figure 1 were not used for statistical analysis; instead relative wool growth values were used in an analysis of variance. The relative wool. growth values were calculated for each animal at fortnightly intervals during the experimental period by expressing mean daily wool production as a percentage of that measured during the preliminary period. One animal fed weekly died eight weeks, and one of the group fed daily died five weeks before the conclusion of the experiment. The absence of a time x feeding interaction simplified the estimation of the missing values which were calculated from the mean constant, derived for each daily production of the survivors in each animal from the formula: group and a Where I represents mean daily wool production of the missing animal in periods one (in the preliminary period) to n, the period before death (in the experimental period), and M represents mean daily production of the survivors in each group during the corresponding periods. III. RESULTS Changes in liveweight, wool growth rate and the course of the experiment are shown in Figure 1. During the preliminary period, mental groups performed similarly in animals fed weekly had a slightly greater liveweight when rate of liveweight change during animals which later formed the two wool production and liveweight change, experithough the experimental treatduring the experimental ments began.. Differences in liveweight were not significant period, nor was there a progressive increase in the variation in liveweight of* the group receiving wheat daily as may occur when sheep are fed daily as a group (Franklin 195 1). After the introduction of the weekly feeding treatment, a marked divergence in wool growth rate in there was no effect on two groups averaged 55% during the experimental period. favour of the weekly fed animals (P<O.O5) occurred, while liveweight. The difference in wool production between the IV. DISCUSSION With diets based on roughages, decreasing the frequency of feeding tends to decrease net energetic efficiency (Graham 1967) which is partly attributable to the * Premix Fielders Ltd., Tamworth. 50

3 inverse relationship between level of intake and digestibility (Blaxter, Graham and Wainman 1956; Raymond, Harris and Kemp 1955). Absence of any significant divergence in bodyweight in the present study indicates these effects are not present with wheat diets at survival levels of feeding. The observation that wool production may be increased by extending the interval between feeds (Franklin 195 1, 1952) is supported by the present study- In group feeding, the difference is probably not due to a reduced efficiency of conversion among daily fed animals resulting from luxury consumption by more aggressive individuals, since there is a linear relationship between wool growth rate and food intake up to high levels (Coetzee 1965). For feeding frequency alone to influence wool production without affecting Iiveweight, wool,synthesis must be highly sensitive to the factor responsible. Reis and Schinckel ( 1963) have refocussed attention on the role of protein nutrition in wool growth, and an alteration in protein digestion might most readily account for the results obtained in the present study. An increase in the amount of amino acids absorbed under the weekly feeding regime could result from (i) an increased proportion of dietary protein escaping ruminal fermentation, or (ii) an increase in protein synthesis by rumen microbes. With intermittent feeding, the higher rate 51

4 of ingestion evident on the first day of feeding could be expected to induce a high rate of passage through the rumen, particularly when fodders of small particle size are used (Blaxter, Graham and Wainman 1956). This, together with a depression in early rumen fermentation, resulting from a reduction in the microbial population during fasting (Coop 1949; Meiske et al. 1958) could result in an increased proportion of dietary protein escaping deamination in the rumen, and elevation in plasma amino acid concentration, and an increase in wool growth. Although the measurement techniques differed, the 55% difference in wool production between weekly and daily fed animals in the present study, and the 510% difference between survivors recorded in the data of Franklin (195 1) deserves comment. Franklin s diets included wheaten chaff, which could retard the rate of passage of feed through the gut (Campling, Freer and Balch 1963) and the level of feeding used in his work, 4.25 lb (1.93 kg) starch equivalent (S.E.) per week, was higher than that used in the present study (1.5 kg S.E. per week). If. with intermittent feeding, an increase in feeding level caused an increase in the time taken to consume the ration, the,effects accompanying an initially high rate of passage could be offset by subsequent slow feeding. Data derived from Briggs, Franklin, and McClymont (1957) included in Table 1 do show that the percentage of the total weekly grain ration consumed during the first three days of feeding declined as feed level was increased. Results from the present study in Table 1, while not strictly comparable because of the different grains used, support this hypothesis. A feeding regime which causes an increase in the proportion of the ration consumed early in the feeding period would also accentuate rumen microflora depletion. In intermittent grain feeding programmes; the concentration and composition. of endosperm protein may be important. If an acceleration in rate of passage accompanies intermittent feeding, then the absolute amount of protein escaping ruminal deamination will vary with protein concentration of the grain. Increasing the protein concentration of grain-based rations may therefore increase the difference in wool production between sheep given feed at daily or weekly intervals. The chemical TABLE 1 Rate of consumption of grain by. groups of sheep given their ration for seven days. at one time. 52

5 composition of dietary protein, so far as it affects the succeptibility of protein to ruminal deamination, might also influence the wool growth response. Briggs, Franklin and McClymont (1956) found maize produced significantly~ higher fleece weights than other grains given at weekly intervals. This effect may have arisen not only from a higher protein concentration in the grain, but also from the known resistance of zein to ruminal deamination (McDonald 1952). An increase in amino acid availability could cause increased wool growth without materially affecting energy balance and liveweight. In this experiment the difference in wool nitrogen would represent approximately 0.45 kg clean wool or 2.3 kg liveweight (as muscle) per year. It is suggested that the size of the grain, its physical characteristics, its energy value, the concentration and composition of the protein, the presence or absence of roughage, and the level of feeding may all affect the magnitude of the wool growth response attending the intermittent feeding of grain-based rations for the survival of sheep. V. ACKNOWLEDGMENTS The authors are grateful for the financial assistance provided by the Australian Meat Research Committee. The technical assistance provided by Mr. A. G. Faint, Department of Livestock Husbandry, University of New England, Armidale, is also gratefully acknowledged. VI. REFERENCES BLAXTER, K. L., GRAHAM, N. McC., and WAINMAN, F. W. ( 1956). Br. J. Nutr. 10: 69. BRIGGS, P. K., FRANKLIN, M. C., and MCCLYMONT, G. L. (1956). Aust. vet. J. 32: 299. BRIGGS, P. K., FRANKLIN, M. C., and MCCLYMONT, G. L. (1957). Aust. J. agric. Res. 8: 75. CAMPLING, R. C., FREER, M., and BALCH, C. C. (1963). Br. J. Nutr. 17: 263. a s COETZEE, C. G. (1965). S. Afr. J. agric. Sci. 8: 327. COOP, I. E. (1949). N.Z. Jl. Sci. Technol. A. 31: 1. FRANKLIN, M. C. (1951). Aust. vet. J., 27: 326. FRANKLIN, M. C. (1952). Aust. J. agric. Res. 3: 168. FRANKLIN, M. C., MCCLYMONT, G. L., B RIGGS, P. K., and C AMPBELL, B. L. (1955). Aust. J, agric. Res. 6: 324. GRAHAM, N. McC. (1967). Aust. J. agric. Res. 18: 467. MCDONALD, I. W. (1952). Biochem. J. 51: 86. MEISKE, J. C., S ALSBURY, R. L., H OEFER, J. A., and L UECKE, R. W. ( 1958). J. Anim. Sci- 17: 774. RAYMOND, W. F., HARRIS, C. E., and KEMP, C. D. (1955). J. Br. Grassld. Soc. 10: 19. REIS, P. J., and SCHINCKEL, P. G. (1963). Aust. J. biol. Sci. 16: 218. T URNER, HELEN, HAYMAN, R. H., R ICHES, J. H., R OBERTS, N. F., and W ILSON, L. T. (1953). Did. Rep. Div. Anim. Hlth. Prod. C.S.I.R.O. Aust. no. 4 (Ser. S.W.,-2): 53