Supplementation of young sheep with oats, lupins or sulphur adhered to lupins

Abstract

Proc. Aust. Soc. Anim. Prod. 1994 Vol. 20 SUPPLEMENTATION OF YOUNG SHEEP WITH OATS, LUPINS OR SULPHUR ADHERED TO LUPINS P.T. DOYLEA and K.M.S. CURTISB Industries Branch, Dcpt of Agriculture, Albany, W.A. 6330 Industries Branch, Dept of Agriculture, South Perth, W.A. 6151 SUMMARY In 3 separate experiments carried out in 3 years, supplementation with lupins (100 g/day), oats (120 o/day) or a lupin/oat mix (114 g/day) generally resulted in no significant differences in wool free a liveweight change or clean wool growth rate of young sheep grazing annual pastures. There were also no significant differences between these supplements for wool production, fibre diameter, staple length or strength of the wool grown. Addition of gypsum to lupins had no significant effects on any of the production parameters measured when compared to the other supplements. However, compared to unsupplemented controls, supplemented animals had higher (P < 0.05-0.01) wool growth rates through parts of the feeding period, and produced more (P c 0.01) clean wool with longer (P c 0.05) staples of higher (P c 0.01) strength. Differences between years in wool production and staple strength were highly significant (P c 0.01). Keywords: lupins, oats, sulphur, wool characteristics. INTRODUCTION On the south coast of Western Australia, young sheep are usually given grain supplements during late summer and autumn. Lupins have some advantages over cereal grains as they are easier to handle, are better prehended by sheep and can be spread across the pasture, and are less likely to cause digestive upsets. It is also considered that their higher protein content may be advantageous early in the dry period, when compared to high starch cereal grains (Gardner et al. 1993). In sheep fed lupins, addition of sulphur to a loose lick (Peter et al. 1987) or provision of SirominB (White et al. 1992) have increased liveweight and wool growth rates. Such responses may not occur when green pasture is available in summer-autumn (Doyle et aZ. 1992a, 1992b) or even during a long dry season (Doyle et al. 1992b). The 3 experiments reported here form part of a larger program which investigated the effects of sulphur and multi-element mineral licks on liveweight and wool production by young sheep. These experiments compared sheep performance when lupins, lupins + gypsum, oats or a lupin/oat mix were oiven as supplements. a MATERIALS AND METHODS The experiments were conducted at the Manurup annex, Mount Barker Research Station (34' ' ' 34 s 117 3l' between 1989 and 1992. The supplementary feeding treatments were: controls (C), E) supplemented only when necessary for survival; lupins at 100 g/sheep-day, fed in troughs (L, experiments 2 and 3) or spread across the pasture (LS, experiments 1 and 3); lupins + gypsum (LG) at 100 g/sheep.day, spread across the pasture in experiment 1 and fed in troughs in experiments 2 and 3; oats (0) at 120 g/sheep.day, fed in troughs; and lupins/oats mix (LO) at 114 g/sheep.day, fed in troughs. Supplements offered in troughs were given twice weekly and residues were collected when they occurred. Where lupins were spread across the pasture they were fed once weekly. There were 3 plots (1 ha each) of each treatment in a completely randomised design. Merino wether lambs, average starting liveweight 27-30 kg and born in July-August, were used in each experiment. They were stratified on the basis of liveweight and then allocated to plots (12 oiven in accordance with recommendations for the area and sheep/plot). Two summer drenches were b 00 additional drenches were given as necessary based on faecal cab counts. Prior to experiments 1 and 2, the lambs were exposed to lupins pre-weaning. Supplementary feedin g commenced (day 0) on 15 December 1989, 27 November 1990 and 19 November 1991, and continued for 153, 217 and 213 days in experiments 1, 2 and 3, respectively. The control sheep were fed lupins and hay from day 185 in experiment 2. Water was available from a trough in each plot. After supplementary feeding finished, the sheep grazed as 1 flock until shearing. The average nutritive characteristics in experiments 1, 2 and 3, respectively were: lupins, dry matter digestibility (DMD, %) 82, 89 and 92, nitrogen (N, g/kg DM) 50.5, 57.6 and 60.5, and sulphur (S, g/kg 206 Proc. Aust. Sot. Anim. Prod. 1994 Vol. 20 DM) 2.3, 2.7 and 2.5; oats, DMD 67, 78 and 76, N 12.5, 17.7 and 18.4, and S 1.3, 1.7 and 1.5. Adding gypsum at 15-20 g/kg lupins (Doyle et al. 1992b) increased the S content to 7.5, 4.2 and 5.5 g/kg IN. The lupin/oat mixture was comprised of 1upins:oats in the ratio of 1:3, 2:3 and 1:3 in experiments 1, 2 and 3, respectively. The sheep were weighed every 2 weeks and dyebands were inserted in mid side wool at 1 to 2 month intervals. Liveweights were corrected for the amount of wool present and wool free liveweight changes were estimated by regression analysis over periods when changes were linear. The sheep were not shorn 0 as lambs and the hogget shearin, was on days 228, 259 and 253 in experiments 1, 2 and 3, respectively. Total wool (fleece, belly, locks) removed from each sheep was recorded at shearing. Analysis of mid side fleece samples and dyebanded staples was carried out by the procedures listed by Gardner et al. (1993) and Thompson et al. (1994). Treatment effects within experiments were examined by analysis of variance, and effects on wool production and characteristics were examined by split plot analysis across experiments (years). Significant differences between supplement treatments in wool free liveweight gain, clean ~001 growth rate, total wool production and characteristics of mid side wool were rare. Hence statistical comparisons have been made between control and supplemented sheep. RESULTS For sheep fed in troughs, there were no residues after day 21 in experiment 1. In experiment 2, 1 replicate of 0 and LG did not consume grain until days 37 and 42, respectively. In experiment 3, most plots left some residues until day 21. After this, 0 and LO sheep (average of 3 plots) did not consume full rations until day 49, while 1 replicate of L and LG did not consume full rations until day 35. There were significant (P c 0.05-0.01) differences between supplemented and C sheep in wool free liveweight by day 61 in experiment 1 and by day 99 in experiment 2 (Figure 1). Liveweight of supplemented sheep was greater than that of controls for the remainder of feeding in experiment 2, but only on some occassions in experiment 1. In experiment 2, liveweights of LO sheep were on some occasions greater (P c 0.05-0.01) than those of 0 and LG sheep. In experiment 3, the liveweight of sheep receiving supplements was greater (P c 0.05) than C sheep on day 136, but not at other times. There were no significant differences between L and LG in any experiment. At various times during each experiment, C sheep lost more weight than those given supplements. The significant differences were: experiment 1, days 6-61, -73 vs. -45 g/day (se-d. -2.7, P < 0.05); experiment 2, days 73-209, -61 vs. -35 g/day (s.e.d. 6.2, P c 0.01); experiment 3, days 72-121, -57 vs. 18 g/day (s.e.d. 13.0, P c 0.01). After the period of supplementation in experiment 2, the controls gained more weight than supplemented sheep (days 209-266, 142 vs. 94 g/day, s.e.d. 12.4, P c 0.01) . In each experiment, there were significant differences (P c 0.05-0.01) between C and supplemented sheep in clean wool growth during supplementation: experiment 1, days 40-83, 4.9 vs. 6.1 g/day (s.e.d. 0.37); experiment 2, days 56-114,3.9 vs. 4.9 g/day (s.e.d. 0.34) and days 114-190' 2.7 vs. 4.2 g/day (s.e.d. 0.23); experiment 3, days 85-134, 3.1 vs. 4.1 g/day (s.e.d. 0.17). In experiment 1, there were no significant differences between C and supplemented sheep in wool production or wool characteristics (Table 1). In experiments 2 and 3, supplemented sheep produced more (P < 0.05-0.01) wool of higher staple strength and the position of break was earlier. Across the 3 experiments, supplementation increased (P c 0.05-0.01) wool production, staple length and staple strength, but had no effect on fibre diameter. The differences between years were highly significant (P < 0 -001) for wool production, fibre diameter, staple strength and position of break, and were significant (P < 0.01) for staple length. DISCUSSION Under the conditions of these experiments there were no differences between lupins, oats or a mixture of the 2 grains. The amounts of digestible DM provided by the supplements were similar, the protein content of the oats was always high for this grain and they were fed in troughs where wastage would be very low. Adding gypsum did not improve production of sheep fed lupins. This may be because there was sufficient S in other components of the diet or because it was not the primary limiting nutrient in the lupins or total diet (Doyle et al. 1992a) Although supplementation increased total wool production in this environment, there were no significant effects on fibre diameter. This is consistent with the findings of Gardner et al. (1993) for areas with a relatively long pasture growing season. However, in areas with a shorter pasture growing season there may be effects on fibre diameter (Rowe et al. 1989). 207 Proc. Aust. Sot. Anim. Prod. 1994 Vol. 20 Figure 1. Wool free liveweight of control (circles) and supplemented (pooled data for lupins, lupins + gypsum, oats and lupins/oats) (triangles) sheep in experiments 1 (a), 2 (b) and 3 (c). Vertical bars are s.e.m. 208 Proc. Amt. Sot. Anim. Prod. 1994 Vol. 20 Table 1. Total clean wool production (TCW, kg), fibre diameter (FD, pm), staple length (SL, mm), staple strength (SS, N/ktex) and date of position of break (POB, date) in control and supplemented sheep Staple strength did not exceed 30 N/ktex in any experiment and was markedly influenced by year. The effects of years were also large for wool production and other wool characteristics. This was due in part to differences between seasons as indicated by the different wool free liveweight patterns and wool growth rates measured, but also to differences in the timing of the hogget shearing. The practice of giving set amounts of supplement did not prevent weight loss in any of the experiments, and it would be necessary to increase the rates of supplementary feeding through autumn to maintain body weight. Regular adjustments to the amounts fed may be necessary if sound wool is to be produced from young sheep shorn in late winter or spring (Doyle et al. 1992a). ACKNOWLEDGMENTS We acknowledge support from the Wool Research and Development Corporation and technical inputs from S. Grylls, T. Plaisted, B. Love, J. Davies, L. Pearce, J. Sharpe and C. Hambley. REFERENCES DOYLE, P.T., LOVE, R.A., DUNLOP, R.H. and WHITE, C.L. (1992a). Aust. J. Exp. Agric. 32: 26771. DOYLE, P.T., LOVE, R.A. and PLAISTED, T. W. (1992b). Proc. Aust. Sot. Anim. Prod. 19: 371-4. 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