Abstract:
A COMPARISON OF TWO MANAGEMENT STRATEGIES WHEN FEEDING WHEAT TO SHEEP DURING DROUGHT J. P. LANGLANDS* AND J. L. WHEELER* Summary During drought, the wool production of grazing ewes which were stocked at 17.1 sheep per hectare and received an average of 463 g wheat and 7 g limestone per head daily, was greater than that of similar sheep receiving the same ration in yards. At no time did the quantity of herbage on pastures which were not grazed during the drought differ significantly from that on pastures which were grazed; wool production of sheep grazing the different pastures was similar in the postdrought period. I~ I. INTRODUCTION When pastures are sparse, sheep appear to expend a great deal of energy in grazing (Lamboume and Reardon 1963; Arnold McManus and Dudzinski 1965) and may cause much! damage to the pasture. For these reasons it is sometimes recommended that during drought, sheep should be removed from pasture and should be .maintained in yards until the drought breaks and pasture growth is resumed. The effect of this practice on the productivity of the sheep and of the pasture during a drought and in the immediate post-drought period was examined in .the .experiment described here. 1 II. MATERIALS AND METHODS e .. The experiment was located at the C.S.I.R.O., Pastoral Research Laboratory, 10 miles south of Armidale, which has a mean annual rainfall of 80.5 cm (3 1.7 in). Rainfall during the 18 month period to August 1966 was 74.4 cm, 42.7 cm below average. A E-year-old pasture of Phalatis tuberosa and Trifolium repens, with a history of frequent fertilizer application, was used. It was grazed intermittently for 18 months and by August 1966 herbage availability was comparable with. that of similar pastures which had been stocked continuously at 14.8 sheep/ha (6/ac) i At this time the area was subdivided into `eight paddocks each of 0.53 ha. , t Seventy-two Merino ewes aged six years were kept in yards for' 29 days from July 15 to August 9, 1966, and were given twice weekly a ration equivalent to 463 g wheat and 7 g ground limestone per head per day. The sheep were weighed at the start and finish of this preliminary period. On August 9, the sheep were randomized into eight flocks of nine sheep, and four flocks (Treatment A) were transferred to four of the eight paddocks, ' . :C.S.I.R.O.. . Pastoral Research Laboratory, Armidale, N.S.W. selected at random, giving a stocking rate of 17.1 sheep/ha (6.9/ac). Stock were excluded from the remaining four paddocks, and both the grazing sheep and the four flocks that remained in yards continued to receive the wheat and limestone ration given during the preliminary period. On October 5, 57 days later, two more flocks were transferred to the experimental pastures (Treatment B), and the remaining two flocks were transferred on November 4, 30 days later (Treatment C), when supplementary feeding of all sheep was terminated. At approximately monthly intervals from July 15, 1966, all sheep were weighed, and dyebands (Chapman and Wheeler 1963) were applied to a wool staple on the -midside of each sheep. On January 4, 1967, 61 days after the end of supplementary feeding, all sheep were shorn, and dyeband staples were processed to estimate daily clean wool production during each month of the experiment. Pasture availability was estimated each month using the coring technique described by Hutchinson ( 1967) until November 4, and thereafter with the capacitance meter described by Johns, Nicol and Watkin ( 1965). `\ III. RESULTS Daily wool growth for each monthly period was adjusted by covariance analysis for wool growth in the preliminary period, and analyses of variance were made on the adjusted mean values for each. flock. The mean values for each treatment are given in Table 1. Wool growth increased when the sheep were transferred to pasture. Over the whole experiment, wool grown by sheep grazed for 61 days (Treatment C) and for 91 days (Treatment B) was 79 and 89% respectively of that grown (890 g) by sheep grazed for 148 days (Treatment A). Mean values for liveweight and daily liveweight change are given in Table 2. TABLE 1 Mean daily wool growth, g/sheep 46 TABLE 2 Mean liveweightf (kg) and daily liveweight change, g/sheep Liveweight increased as soon as the sheep were transferred to pasture and tended to stabilize after four to eight weeks. On November 4, when supplementky feeding ended, the mean liveweights of Treatments A, *B and C were 47.8, 44.9 and 39.8 kg respectively. At the end of the experiment the mean liveweight for Treatment A was 5 kg greater than that for Treatment C. The mean values for total herbage and green material available are given in Table 3. During th,e experiment, there was an increase in available herbage on all pastures. There were no significant differences between treatments in available herbage or in the daily rate of change in available material. IV. DISCUSSION The results of this experiment do not support the suggestion that during drought wheat should be given in yards rather than at pasture. Wool production of sheep fed at pasture was greater than th,at of comparable sheep given the same ration in yards, and differences between treatments in pasture productivity in the post-drought period could not be detected either by measurements of the pastures or of the productivity of the sheep grazing them. It was to be expected that during the drought the sheep receiving Treatment A, which had access to pasture in addition to the wheat, would produce more wool than sheep receiving wheat alone (Treatments B and C). It was also expected that in the post-drought 47 TABLE 3 Total and green herbage available (kg dry matter per hectare* > period when wheat was no longer given, sheep receiving Treatments B and C would be more productive since they were grazing pastures which had not recently been grazed. No differences between treatments were observed in the post-drought period and it is concluded that any damage to the pasture under *Treatment A was small. Possibly herbage intake during the drought `was reduced by supplementary feeding which might be expected to reduce any damage to the pasture resulting from the heavy stocking rates imposed. This possibility is consistent with the findings of Allden and Jennings ( 1962) and Holder ( 1962) that the herbage intake of sheep was reduced when they were given a supplement. Different results might have been obtained in this study if still heavier stocking rates had been used, more or less wheat had been given, or if the drought had continued. . The values for pasture availability observed in the early months. of the experiment are higher than those normally associated with *drought conditions. This is attributed to the use of a coring technique,. a method that .appears to provide a better estimate of the forage. available to grazing sheep than .do mowing procedures which, particularly on heavily &azed pasture, may give substantial underestimates. ,V. REFERENCES ALLDEN, W. G., and J ENNINGS , A. C. ( 1962). Proc. Aust. SOC. Anim. Prod. 4: 145. A RNOLD , G. W., MCMANUS, W. R., and D UDZINSKI , .LM. L. ( 1965). Aust. J. exp. Agric. Anim. Husb. 5: 396. t C HAPMAN , R. E., and W HEELER , J. L. ( 1963 ) . Aust. J. `Sci. 26: 53. H OLDER , J. M. ( 1962). Proc. Aust. Soc. Anim. Prod. 4: 154. HUTCHINSON, K. J. ( 1967). J. Br. Grassld. Soc. 22: 13 1. J OHNS, G. G., NICOL, G. R., and WBTKIN, B. R. (1965). J., Br. GrassId. Soc. 20: 2 12. .. L AMBOURNE, L. J., and REARDON, T. F. (1963). Aust. J. agric. Res. 14: 272.. 48