A COMPARISON OF PROTEIN CONCENTRATES FOR WOOL GROWTH. W. F. COLEBROOK*, K. A. FERGUSON*, J. A. HEMSLEY,* J. P. HOGAN*, P. J. REIS* and R. H.

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1 A COMPARISON OF PROTEIN CONCENTRATES FOR WOOL GROWTH W. F. COLEBROOK*, K. A. FERGUSON*, J. A. HEMSLEY,* J. P. HOGAN*, P. J. REIS* and R. H. WESTON* Summary The value of 14 protein concentrates for wool growth was examined by offering 500 g/day of pelleted diets, each containing equal parts of lucerne hay and a concentrate, to -Merino wethers. Substantial differences in wool growth rate were found between sheep offered these diets; mean clean wool growth rates for groups of six sheep varied from 0.57-l-39 mg/cmq/day. The diets provided a wide range of protein intakes ( g/day) and, in general, wool growth increased with protein intake. Relatively high wool growth rates were obtained with liver meal, fish meal and whale oil meal. Wool growth response to varying proportions of whale oil meal and lucerne hay was linear within the range of g protein/day in the diet. I. INTRODUCTION There are many conflicting reports regarding the influence of dietary protein on wool growth. Fraser and Roberts (1933), Bowstead and Larose (1938) and Ferguson (1959) did not obtain responses in wool growth rate by increasing dietary protein intake. However, in a C.S.I.R. Report (Anon. 1936), evidence is given for a marked increase in wool growth due to the substitution of gluten for chaff in a series of isocaloric diets. Marston (1948) suggested that the rate of wool growth is principally determined by the supply of essential amino acids to the wool follicle subject to competing demands on this supply, and depending on the state of energy balance of the animal. Reis and Schinckel (1961, 1964) showed that g/day of casein infused into the abomasum of sheep substantially increased wool growth rate and they suggested that wool growth rate depended largely on the quantity and composition of protein reaching the abomasum. The few reports evaluating the capacity of various protein concentrates to stimulate wool growth rate are limited to a comparison of a small number of proteins, given at different levels of intake (Bezeau, Slen and Whiting 1960; Slen and Whiting 1955). At present it is not possible to predict the value of a protein concentrate for promoting wool growth from its chemical composition and digestibility of nutrients, because of the complexities of ruminant digestion and the lack of information regarding the nutrient requirements for wool growth. As a part of investigations into factors affecting wool growth, a study has been made of the relative merits of 14 protein concentrates, each given with lucerne hay at low levels of dry matter intake, but high proportions of the protein concentrates. II. MATERIALS AND METHODS (a) Experimental Design Thirty-six 2-year old Peppin Merino wethers with a mean body weight (ts.d.) of 33.8 t- 2.2 kg were housed in individual pens and were fed once daily; water KDivision lof Animal Physiology, C.S.I.R.O., Laboratory, Prospect, N.S.W. The Ian Clunies Ross Animal Research 397

2 was available ad libitum. Vitamins A and D3 were administered once every 12 weeks (500,000 i.u. of each). Body weights were measured weekly before feeding. During a preliminary period of 12 weeks, all sheep were fed on a pelleted diet of equal parts of cottonseed meal and lucerne hay, and were then allotted by restricted randomization into six groups according to wool growth measured during the interval 5-8 weeks after the start of the preliminary period (Table 1). In the experimental periods various protein concentrates mixed with lucerne hay were given as shown in Table 1. Restricted feed intakes were chosen to minimize changes in body weight, and high proportions of protein concentrates were given to permit high wool growth rates in accordance with the results of Reis and Schinckel (1961, 1964). All diets were ground and pelleted and given at a level of 500 g/day; sodium chloride (1% ) and ammonium molybdate (2.2 g/ 100 kg) were added to all diets. Throughout the experiment, one group of sheep (the control group) was fed the diet used in the preliminary period to allow measurement of seasonal variation in wool growth. (b) Wool Growth Wool growth of each sheep was measured from an area of approximately 100 cm2 defined by tattoo lines on the right midside. Wool was harvested at intervals of 4 weeks with Oster small animal clippers (size 40 cutter). Wool growth data presented refer to the interval 9-12 weeks (inclusive) after the start of each feeding period. Wool growth is expressed both in mg/cm2/day and in g/day/sheep, the latter being calculated from total patch wool x 6W213, where W is the body weight in kg of the sheep at the time the tattoo patch was applied (Ferguson 1958). Wool was cleaned as described by Ferguson (1962). (c) Analytical Nitrogen in feeds was measured by a Kjeldahl method; crude protein (C.P.) was calculated as N x Dry matter content was determined by oven drying at 105OC for 24h. III. RESULTS Mean body weight of the sheep at the start and the end (64 weeks) of the experiment differed by only 1.3 kg. Wool growth rates supported by the various diets given during periods 2-4 ranged from mg/cm2/day, whereas the protein intakes from these diets varied from g/day (Table 1). Since the rate of wool growth by the control group showed only a slight increase over the 12 month experimental period (Table l), wool growth data are presented here without correction. Wool growth and protein intake appeared to be positively related (Figure 1). The wool growth response to varying proportions of whale oil meal and lucerne hay, given in Period 5, was linear (Table 1, Figure 1). The wool growth rate of sheep fed the cottonseed meal diet plus 1% DLmethionine (Southsphere Chemicals feed grade methionine) was the same as that of sheep fed the cottonseed meal diet alone during the same feeding period (Table 1, Period 4). IV. DISCUSSION This study has shown that various protein concentrates, when given with equal parts of lucerne hay, produce a wide range of wool growth rates, and that 398

3 TABLE 1 Eflect of Type and Amount of Protein on Wool Growth. Groups of six sheep were fed mixtures of diflerent protein concentrates and lucerne hay as indicated in columns 3 and 4, for periods of 12 weeks (16 weeks in Period 4). Values for wool growth, expressed as clean dry wool, are the means for six sheep. 399

4 there is a positive relationship between wool growth rate and protein intake both between different proteins and within the same protein concentrate (whale oil meal) given at different levels. The data are consistent with the hypothesis of Reis and Schinckel (1964) that wool growth rate is largely dependent on the quantity and composition of protein reaching the abomasum. Ferguson (1959) failed to change wool growth rate by increasing the dietary protein content above 8% in a series of diets containing maize, peanut meal and wheaten and lucerne hays. However, Hogan and Weston (1967) have shown that with two of the diets (7.5 and 18.3% C.P.) used by Ferguson the amount of non-ammonia nitrogen passing through the pylorous was similar (8.1 and 8.8 g/day), indicating a substantial loss of nitrogen from the high protein diet. This was probably due to the deamination of the protein by the rumen microflora (McDonald 1952; Chalmers and Synge 1954). On the basis of the data presented in this paper, the conclusion made by Ferguson (1959) that wool growth rate will not increase when the C.P. content of the diet exceeds 8% is not generally applicable. It is clear that all diets studied here do not behave in the same manner as those used by Ferguson (1959); whale oil meal gave increasing wool growth rates

5 up to 50% C.P. in the diet. With the other protein concentrates studied it is not possible to determine whether the relationship between wool growth and protein intake is due to the amount of protein or to any differences that may exist between proteins in their capacity to stimulate wool growth. The relatively poor wool growth response to bloodmeal was somewhat surprising especially in view of its high C.P. content (90%), its high digestibility and its resistance to rumen microbial deamination (unpublished work by the authors). Abomasal administration of bloodmeal also failed to stimulate wool growth indicating that the lack of response to bloodmeal per OS was not necessarily due to deamination of the protein in the rumen (Colebrook, unpublished data). Marston (1932) observed that bloodmeal supplements fed to grazing sheep improved wool production but these data are difficult to interpret because of body growth and unknown feed intakes. The lack of response to the addition of methionine to the cottonseed meal diet may be attributed to the ability of rumen micro-organisms to degrade amino acids (Hungate 1966); the deamination of methionine has been demonstrated by Lewis and Emery (1962). It is unlikely that differences between the diets in energy content were entirely responsible for the range in wool growth rates observed ( mg/cm2/day in Periods l-4) since the range of digestible organic matter provided by these diets was only g/day (values estimated from the data of Schneider 1947). Furthermore, when varying levels of whale oil meal were given (Period 5) there were only small differences in body weight changes during this period (+1.6, +0.6, +0.6 and +1.3 kg/12 weeks for the diets containing 20, 35, 50 and 65% whale oil meal respectively), indicating little difference in the net energy value of these various diets. V. ACKNOWLEDGMENTS The authors are indebted to Miss S. Munro and Miss L. Younger for technical assistance throughout the course of this experiment. VI. REFERENCES A NON. (1936). Rep. Coun. scient. ind. Res. Aust., No. 10, p. 40. B EZEAU, L. M., SLEN, S. B., and W HITING, F. (1960). Can. J. Anim. Sci. 40: 37. BOWSTEAD, J. E., and LAROSE, P. (1938). Can. J. Res. 16D: 361. CHALMERS, M. I., and SYNGE, R. L. M. (1954). J. agric. Sci., Camb. 44: 263. FERGUSON, K. A. (1958). Proc. N.Z. Soc. Anim. Prod. 18: 128. FERGUSON, K. A. (1959). Nature, Land. 184: 907. FERGUSON, K. A. (1962). Aust. J. biol. Sci. 15: 720. FRASER, A. H. H., and ROBERTS, J. A. F. ( 1933 ). J. agric. Sci., Camb. 23: 97. HOG.AN, J. P., and W ESTON, R. H. (1967). Aust. J. agric. Res. 18 (In press). HUNGATE, R. E. (1966). The Rumen and its Microbes pp (Academic Press: New York). LEWIS, T. R., and EMERY, R. S. (1962). J. Dairy Sci. 45: 765. MCDONALD, I. W. (1952). Biochem. J. 51: 86. MARSTON, H. R. ( 1932). Rull. Coun. scient. ind. Res. Melb., no. 61. MARSTON, H. R. (1948). Aust. J. Sci. Res. B. 1: 362. REIS, P. J., and SCHINCKEL, P. G. ( 196 1). Aust. J. agric. Res. 12: 335. REIS, P. J., and SCHINCKEL, P. G. ( 1964). Aust. J. biol. Sci. 17: 532. SCHNEIDER, B. H. ( 1947). Feeds of the World. Their Digestibility and Composition. (West Virginia Agricultural Experimental Station: Morgantown, Va.). SLEN, S. B., a,nd WHITING, F. (1955). J. Anim. Sci. 14: