Abstract:
Proc. Aust. Soc. Anim. Prod. Vol. 18 SULPHUR SUPPLEMENTATION OF LUPIN GRAIN FOR SHEEP P.J. MURRAY*, S.I. GODFREY* and J. B. ROWE* SUMMARY Merino ewes, 16 months old, were fed wheat chaff every day and the equivalent of 250 g/d of lupin grain twice weekly. An introductory period of seven weeks was used to quantify differences in wool growth and liveweight gain between Different sulphur sources [2% gypsum, 12% fishmeal, 1.2% individual sheep. methionine or -1.2% hydroxymethyl-methionine (Mepron)] were then added to the Wool growth was lupin grain and fed for a further period of seven weeks. significantly increased only in the sheep fed lupin grain with the addition of Wool growth was decreased in the sheep fed lupin grain with the fishmeal. Liveweight gain was increased in the sheep addition of gypsum and Mepron. given methionine, Mepron and fishmeal. INTRODUCTION Feed available to sheep in the Mediterranean environment can be low in sulphur In (Jones et al. 1982) due to the low sulphur levels in the pasture. addition, lupins, which are widely used as a supplementary feed for sheep grazing dry pastures and cereal stubbles, are relatively low in sulphur amino The ratio of N:S for lupins is approximately 20:1, while the ratio of acids. N:S in rumen microbes is around 12:l indicating that lupins are deficient in the supply of sulphur for microbial production of sulphur amino acids. Grazing sheep given a lupin and sulphur supplement, in the form of gypsum, increased wool growth by 7% and liveweight gain by 13% when compared to sheep supplemented with lupins only (Peter et al. 1987). The supply of amino acids available to sheep, particularly the sulphur amino acids, can exert a considerable effect on the rate of wool growth (Wright 1971; Reis 1979). Increases in wool growth of up to 80% have been found in sheep fed diets and intra-abomasally supplemented with l-5 g/d of methionine (Reis and Schinkel 1963, 1964; Langlands 1970). However in some situations where animals have been supplemented with dietary methionine, responses have been variable (24% to 53%) depending on the quality of the diet and the quantity of methionine fed (Graceva 1969; Wright 1971; Doyle and Bird 1975). Methionine has been found to cause complete inappetance and reduce wool growth when fed at greater than 10 g/d (Langar et al. 1973). Furthermore when methionine is fed to sheep, over 80% is degraded in the rumen (Langar et al. 1973) and therefore ruxnen protected forms have been used where additional dietary methionine is required. Fishmeal derived from steam dehydrating fish offal is an excellent source of amino acids and contains approximately 2% methionine. Mepron is a commercially containing approximately degradation in the rumen. dairy cattle and was found (Cottle 1988). available analogue of hydroxymethyl - methionine, 66% methionine, that was designed to reduce its Mepron has been used as a methionine supplement for to increase wool growth by 23% in sheep fed lucerne Dietary inorganic sulphur can be utilised by rumen microbes to synthesize microbial protein (Bray and Till 1975). Sheep grazing forage sorghum and given access to a salt lick containing 10 % sulphur have been shown to have a 7% increase in wool growth when compared to sheep kept under the same conditions -without sulphur in the lick (Wheeler et al, 1980). * Sheep & Wool Branch, Western Australian Department of Agriculture, Baron-Hay Court, South Perth, W, A. 6151. 320 . Proc. Aust. Soc, Anim. Prod. Vol. 18 The objective of this experiment was to investigate the potential to improve wool production in sheep supplemented with lupin grain through provision of additional sulphur or sulphur amino acids. MATERIALS AND XETHODS Animals and experimental design Merino ewes aged 16 months and weighing 27.0 2 0.4 kg (mean + 8-e.) Prior to commencement of the experiment the in the experiment. shorn and drenched with Ivomec (Merck, Sharp and Dohme Australia Pty sheep were housed in individual pens throughout the experiment and available at all times. Feed intakes were measured daily. were sheep Ltd). water used were All was The experiment consisted of a covariate period, during which all animals received their respective diets without any sulphur supplements, followed by an experimental period in which the animals received their diets with various Animals were allocated to treatments on the basis of sulphur supplements. liveweight. Animals were then fed their experimental diets for seven weeks to There were ten sheep per measure the effect of the additives on wool growth. treatment except for the group not fed any sulphur supplement which had 15 animals. Wheat chaff (600 g/hd) was fed daily and lupins with sulphur Animals given the fishmeal supplements were given on Mondays and Thursdays, supplement received 160 g of lupins and 60 g of oats to balance the protein levels across treatments. The five treatments fed during the experimental period are summarised below: 1. 2. 3. 4. 5. Chaff (600 g/hd/d) plus lupins (the equivalent of 250 g/hd/d fed twice/ week) - the controls. Treatment 1 plus gypsum (20 g/kg lupins). Treatment 1 plus DL-methionine (12 g/kg lupins). Treatment 1 plus Mepron (12 g/kg lupins). Chaff (600 g/hd/d) plus lupins/oats (220 g) and 30 g Fishmeal (a total of 250 g/hd/d - fed twice/ week), The sulphur supplements were sprinkled on the lupins. Experimental Live weiqht experiment. measurements Animals were weighed at weekly intervals for the duration of the Wool production Clean wool growth was determined by clipping and measuring mid-side patches (10 x 10 cm). Mid-side patches were removed by small animal clippers (Oster, Milwaukee USA, blade size 40) at the end of the two week introduction period (and the wool discarded) and cut again after the sheep had been on their respective basal diets for a further five weeks (and the wool kept for production measurements). This wool, grown over a five week period when animals were fed on the basal diet, was used as a covariate in the statistical analysis. The wool grown during the subsequent seven week period was used to measure the effect of the sulphur additives. Rumen samples During the last week of the experimental period, samples of rumen fluid (20 ml) were taken by stomach tube from all animals, 29 h after the Monday lupin supplement containing sulphur additives were fed. The pH of the rumen-fluid was measured before the samples were acidified with concentrated sulphuric acid and stored at -2OOC for subsequent analysis for VFA's and ammonia concentration. 321 Proc. Aust- Soc, Anim, Prod. Vol. 18 RESULTS There was no significant difference in intake of lupins or chaff between the respectively). treatments (mean2s.e. across treatments of 24921 and 59lk6, Liveweight gain and wool growth measured during the final seven weeks of the experimental period are summarised in Table 1. The average clean wool growth rate for all the sheep in the experiment was 8.1 g/m2.d, The sheep fed fishmeal grew significantly more (P<O.O5) wool, and the sheep in the treatments fed the gypsum or Mepron grew significantly less wool (P<O.O5) than those in the control treatment . Liveweight gain was significantly increased (P<O.OS) by the addition of methionine (34%), Mepron (28%) and fishmeal (34%) to the lupin supplement. Table 1 Effect of addition of sulphur to a lupin supplement on liveweight change (g/d) and wool growth (g/m2.d) of sheep fed wheat chaff Values in the same different (P<O.OS) column with different superscripts are significantly The measurements made on fluid samples taken from the rumen are summarised in Table 2. The sheep fed fishmeal as a sulphur additive to their lupin supplement had significantly lower (P<O.O5) total VFA and ammonia concentrations than all other treatment groups. Table 2 Effect of addition of sulphur to a lupin supplement on rumen pH, total volatile fatty acid (VFA) concentration (mmol/l) and ammonia concentration (mg NH,-N/l) of sheep fed wheat chaff DISCUSSION The increases in liveweight gain in response to sulphur supplementation requirement for additional sulphur with lupin -indicate an animal supplementation. Inorganic sulphur (gypsum) was as effective in increasing liveweight gain (20%) in this experiment as found by Peter et al. 1987 (13%). However the 7% decrease in wool production with sheep supplemented with gypsum in this experiment contradicts the report by Peter et al. (1987) and Wheeler et al. (1980) where a non significant 7% increase in wool growth was found. A 322 Proc. Aust. Soc, Anim, Prod- Vol. 18 major difference between these experiments was that sheep in this experiment where individually fed with the sulphur being added to the lupins and therefore In the study of Peter et al, individual intakes of animals were recorded. (1987) and Wheeler et al. (1980) the sulphur was included in a mineral mix/lick with animals grazing pasture and therefore it was not possible to measure intake of gypsum or pasture for individual animals. The absence of any difference in liveweight gain between sheep given methionine or Mepron indicates that either the chemical treatment of the Mepron was unsuccessful in protecting it from rumen microbial degradation or that the chemical treatment was such that it reduced absorption of amino acids from the small intestine. The only positive wool response recorded to the additives given was for fishmeal. It is possible that the methionine provided by the fishmeal (0.7 The lower g/d) was better protected than that provided by the Mepron (2 g/d). concentrations of rumen VFA's and ammonia in sheep fed the fishmeal supplement further suggest that the responses in liveweight and wool growth were as a result of increased supply of bypass nutrients rather than increased rumen fermentation and more microbial protein synthesis. A lack of wool growth response to inorganic sulphur, Mepron or methionine may be an indication that although additional methionine was available for liveweight gain a balanced amino acid spectrum, as found in the fishmeal, was lacking with these treatments and prevented expression of increased wool growth. The technical assistance of Mr W. Toon, Mrs R. Bradley and members of the Sheep and Wool Branch who assisted in this experiment is gratefully acknowledged. Mrs J. Speijers is gratefully acknowledged for her assistance in the statistical analysis. This work was supported in part by the Wool Research and Development Fund on the recommendation of the Australian Wool Corporation. REFERENCES BRAY, A. C. and TILL, A. R. (1975). In 'Digestion and Metabolism in the Ruminant', p 243, editors I.W. McDonald and A. D. I.Warner. (University of New England Publishing Unit: Armidale). COTTLE, D.J. (1988). Aust. J. Exp. Agric. 28: 179, DOYLE, P. T. and BIRD, P. R. (1975). Aust. J. Agric. Res. 26: 337. GRAVECA, L.V. (1969). Ovcevodstdo NO.2 p-34. (cf. Nutr. Abstra. 39: No.8185) JONES, MB., RENDIG, V.V., TORELL, D-T. and FISHER, H.M. (1981). Aust. J. Agric, Res. 32~47. LANGAR, P., BUTTERY, P. J. and LEWIS, D. (1973). Proc. Nutr. Soc. 32, 86A. LANGLANDS, J. P. (1970). Aust J. Exp. Agric. Anim. Hush. 10: 665. PETER, D. W., BUSCALL, D. J. and YOUNG, P., (1987). In 'Herbivore Nutrition Research', P 203, editor Mary Rose. (Australian Society of Animal Production). REIS, P. J. (1979). In 'Physiological and Environmental Limitations to Wool Growth', p-223, editors J. L. Black and P-J. Reis. (University of New England Publishing Unit, Armidale). REIS, P. J. and SCHINCKEL, P. G., (1963). Aust, J. Biol. Sci. 16: 218. REIS, P. J. and SCHINCKEL, P. G., (1964). Aust. J. Biol. Sci. 17: 532. WHEELER,- J. L. ROCKS, R. L. and HEDGES, D. A., (1980). Proc. Aust. Soc. Anim. Prod..l3: 297. WRIGHT, P. L. (1971). J. Anim. Sci. 33: 137. 323