Ir- I OFI. ORNL P 1340 4 Pero 56 21. ti • : MICROCOPY RESOLUTION TEST CHART NATIONAL BUREAU OF STANDARD ; -1963 ... LEGAL NOTICE This report was prepared as an account of Government sponsored work. Neither the United States, nor the Commission, nor any person acting on behalf of the Commission: A. Makes any warranty or representa- tion, expressed or implied, with respect to the accuracy, completeness, or usefulness of the information contained in this report, or that the use of any information, appa- ratus, method, or process disclosed in this report may not infringe privately owned rights; or B. Assumes any liabilities with respect to the use of, or for damages resulting from the use of any information, apparatus, method, or process disclosed in this report. As used in the above, “person acting on behalf of the Commission" includes any em- ployee or contractor of the Commission, or employee of such contractor, to the extent that such employee or contractor of the Commission, or employee of such contractor prepares, disseminates, or provides access to, any information pursuant to his employ- .. .. .. .. •: ......: :.. : ::: inting r P - his employment with such contractor. Orno-p-1340 JUN 24 1965 O CONF-6050709-JP DISTANCE TRAVELED BY SHEEP ON WINTER RANGE -- G. M. Van Dyne and J. L. Van Horn Radiation Ecology Section, Oak Ridge National Laboratory Oak Ridge, Tennessee, and Animal and Range Sciences Department Montana State College, Bozeman, Montana jirrasin TŁ Ao un prinwly owa I ricate; or with the Commuilon, or bo imployment mie such contractor. disseminatas, or provider eccus to any informatioo purmat to die er sin bot or contract such employw or contractor of the Commulon, or ovaploys of aucb cor.tructor prepardı, sloys or coarctor of the Conclusion, or emplo: to the wore, "per og stogoo baball of the Commisolan" includemay bu ol vy Laformaatio, appuntu, method, or procon diminead in this report. B. AsNmu may labtuuas with respect to the un of, or lor damages resulting from the of any loformation, apparatu, method, or proco.. dixcloned la this report may not infringe racy, colaplotasiu, ci unahulome of the information contaiand to this roport, 03 that to we A. Mala ray narranty or reprenotation, expround or implied, with respect to the accu- Suto, nor the Commiuloa, sor day perico acun on behalf of the Commission: report me profurod u w account of Goverament sponsored work. Neitho the Vallad LEGAL NOTICE - of such contractor, to the extent that m- Range livestock often must travel considerable distances in securing their daily forage intake. The energy expenditure for grazing is espe- cially important if livestock are consuming submaintenance diets which often is the case on winter ranges. Little is known, however, about the magnitude of the distances traveled by grazing livestock (Cresswell and Harris, 1959; Cresswell, 1957) or about the energy expenditure in grazing (Reid et al., 1958; Blaxter, 1962). In the present study distance traveled and elevation climbed by sheep on a foothill winter range in Montana were measured and used to calculate energy expenditure, which was compared to climatic variations and to dietary chemical composition, measured with esophageal fistulated sheep. METHODS A band of 800 ewes were grazed from January through March 1960 on a range dominated by bluebunch wheatgrass (Agropyron spicatum). The topography and vegetation of this range are further described by Van Dyne, et al. (1964) who used esophageal fistulated yearling and mature ewes in the band to collect forage samples in morning and afternoon grazing periods. The band was allowed to freely choose areas to graze but was turned when passing the property boundary. The band returned each night to one of three camps where continuous records were made of temperature, relative humidity, and wind movement. The total area grazed from these camps was about 1620 ha with elevations varying from 1450 to 1730 m. On 31 days when fistula forage collections were made the route of travel of the band was marked on aerial photographs with a scale of 1:7920. During midwinter three wethers were equipped with "rangemeters" to measure the distance traveled. Our rangemeters were similar to those of Cresswell and Harris (1959) except that a single shaft was used in order to prevent snagging on rocks and brush. Travel records were ob- tained for 1 sheep-days. On days when all three wethers were used, the average distances traveled were 6.6, 7.6, and 6.9 km. The relative distance traveled by the band was determined from the routes mapped on aerial photographs. For the same dates, individual sheep travel was 1.6 times that of band travel. This factor was used to calculate dis- tance traveled by individual sheep from band-travel data. A contour map (U. S. Geological Survey) was used to calculate, to the nearest 12.2 m, the elevation climbed by the sheep. Only the elevation climbing a slope was counted; descending a slope was assumed to be equivalent to walking on level ground. The energy expenditure required for grazing was calculated by using values reported by Blaxter (1962) for vertical and horizontal movement, respectively, .322 and .030 kcal/m for a 50 kg sheep. Field studies were completed as part of Montana Agricultural Ex- periment Station Research Project MS-1100. Statistical analyses and the paper were completed in the senior author's present position. "PATENT CLEARAPAT.C?TAISED. RELEASE TO THE PUBLIC IS APPROVE 2. PROCEDURES BRE ON EILE LA THE LIG SECTION, LXXIV-1 RESULTS Climatic characteristics.--Average climatic characteristics are given in Table 1 for 29 of the 31 days in which distance grazed was measured (the first two dates were not included because of calculation of lag effects). Climatic conditions were highly variable during this winter grazing period as indicated by the high coefficients of vari- ation and the wide ranges of variables. Calculated energy expenditure .--The energy expenditure due to graz- ing activities (excluding mastication of food) for a 50 kg sheep averaged 235 + 62 kcal/day. Less than 3% of the calculated total energy expen- diture was used for climbing. from 85 to 280 m were climbed each day and horizontal movement varied from 4.1 to 13.2 km/day. There was no relation of elevation or distance grazed to the day in the winter which might be expected if advancing stages of gestation greatly affected the movement of the sheep. Energy expenditure and climate.--The simple linear correlations be- tween total energy expenditure and different climatic variables (Tele 1) were not high, and would not be expected to be so, but are usefui in a relative way in understanding influences of climate on energy expen- diture. Energy expended in grazing was not related to average temperatures but was inversely related to the change in temperature during morning grazing periods (8-10 am) and was directly related to temperature change durine afternoon grazing periods (3-5 pm). It was not feasible to meas- ure distance or elevation grazed separately during morning and evening grazing periods, thus the correlations are between total daily energy expenditure and temperature changes during part of the day. These data suggest that decreasing temperature during the morning grazing period, during the total daily grazing period, or during the total 24 hr period were partially responsible for, or associated with factors responsible for increasing the energy expended in grazing. The calculated energy expended for both horizontal and vertical movement were inversely corre- lated with these three climatic variables. Average relative humidity both during the morning grazing period and during the day were related inversely to energy expended for graz- ing, and had more influence than temperature relationships on energy expended. Wind movement and wind speed appeared to have more influence on energy expenditure than did either temperature or relative humidity. All measures of wind movement and of wind speed were inversely related to energy expenditure, which was, however, more closely related to total wind movement than to average wind speed. Total wind movement and average wind speed relatiorships differed because the length of the grazing period was not constant during the winter. There was no appreciable lag influence of climatic variables on energy expenditure because the correlations between temperature, rela- tive humidity, and wind speed based on one-day averages were similar to those based on two-, three-, and four-day weighted averages. Regression of energy expenditure on climate .--The four climatic variables having the highest simple linear correlations with energy expenditure were selected as independent variables for a multiple LXXIV-2 Tubide 1. Ciwillertallco vi od domestlu, Glutury old olu're uxwilleur: ww lollus during my dayo wis - vinwr rugo. Confridont u Varintown Trullould Me:1000 to whero fxpanded .02 • Oy 157 10) .) 97 .17 32 *- 23 13 13" 9979828 Tuinlue: Averso l'ur line day Average for procodiny nalil Averige 111 w gmz111 Avurugo in je gruring Averope for lar parlad Change in the day 111ongo in preced1118 nlphie Thange 111 min grazinu. change in a grasinin Chiangu in 24 hr porlou kluline Hualdity: Avaruuso for tini Juy Average for protoding night Averigu ini ua ruzing Averno in um gruzing Average for 24 hr perlud Change din tbe day Change in Hocoding night Chuango in an in.ing Change in po rucing Change in 24 hr periud Wind: Miles in any Avaruyo upood in day Miler in procoding night Average orood in night Milan in 24 hr period Average spood in 2 hr Errotu: Anorage a'-day tomjerture Avuruge 2-day rolativo luulolly Average 2-day vind spood Average 3-day tenpenture Average 3-day rulative humidity Avuruge f-day vind speed Average 4-Way temperture Avorio 4-duy relative humidity Averno 4-day vind spoed 181 11 141 13 Bar a huge 38 02528 13.0 1.1 3.1 14.7 41.8 3.8 Diele: Crudo protein Ether extract Lignin Cullulude Array_BeLive: Kral for vertical work hiul for horizontal vork 'Total expand ture 4.6 2.2 12.9 36.9 linear regression analysis. The following equation was obtained: Y = 305 - 2.0 x + 1.9 X, -0.9 X-0.3 XL 60, R = 0.44 where y is energy expenditure, X, is change in temperature during the morning grazing period, X, is change of temperature during the afternoon grazing period, X, is average relative humidity during the morning grazing per- iod, and °x4 is the miles of wind movement during the day. The relative importance of these variables in influencing energy expenditure, as judged by standard partial regression coefficients, was X > X2 > X > X, . The high standard error of estimate in this model precludes precise prediction of energy expenditure from climatic variables. Additional climatic variables (with standard partial regression coefficients) were included in a second model to determine their partial influence on energy expenditure as follows: average daytime temperature (-2.40), average temperature of preceding night ( .24), average temper- ature during morning grazing period (1.83), average temperature during the afternoon grazing period (1.20), average temperature for the 24 hr period (-.74), average daytime relative humidity (1.36), average rela- tive humidity of preceding night (3.30), average relative humidity dur- ing morning grazing period (-.40), average relative humidity during afternoon grazing period (-.15), average relative humidity for the 24 LXXIV-3 hr period (-3.82), average wind speed for the 24 hr period (-.34), and calculated total energy expenditure for grazing. Average relative humidity of the preceding night and of the 24 hr period had most influence on energy expenditure. For this model R = .63 and Sy.y = 62 kcal. However, in contrast to the first model, none of the data points deviated from the value calculated from this model by more than two standard errors of estimate. Relation of diet and energy expenditure .--Dietary composition data for the dates on which grazing distance was measured were selected from those reported by Van Dyne et al. (1964). The percent crude protein and lignin in the diets were directly correlated to energy expenditure. Percent ether extract was apparently not related to energy expenditure and percent cellulosc was inversely related to energy expendit:ire. DISCUSSION Blaxter (1964) recently reported estimates of maintenance require- ments for sheep in indoor trials of about 1.5 megcal/day, whereas, in various grazing experiments it averaged about 2.3 megcal/day. He found the maintenance energy requirement for cattle, calculated from indoor studies, was 11.5 megcal/day; whereas, estimated from grazing studies it was 19.2 megcal/day. Thus, under grazing conditions the estimated main- tenance requirement is about 50% greater than under indoor conditions. Two major reasons for the discrepancy in maintenance requirements indoors and on pasture or range are (1) energy expended in grazing activ- ities, and (2) climatic stresses. In the present study the sheep traveled an average of about 7.6 km per day and climbed about 155 m per day. The energy expenditure for this movement in grazing for a 50 kg sheep totaled about 235 kcal/day. The energy requirement for fasting catabolism of a 50 kg sheep is about 1320 kcal/day. Thus, the energy expended for move- ment in grazing represents almost 20% that required for basal maintenance. The true value of energy expended in grazing is probably somewhat higher than the above figures because (1) the estimate of elevation climbed is minimal, (2) it was assumed the energy expended for descent was equal to that for walking over level terrain, and (3) considerable energy is expended in moving against the wind or in maintaining posture with the wind at the animal's back. Furthermore, Graham (1962) indicates the energy cost of grazing per se is 0.6 to 0.8 kcal/hr/kg body weight of the sheep. These figures appear high but will be used for purpose of discussion. Assuming 4 hr of actual grazing the energy cost for a 50 kg sheep would be about 140 kcal/day, which amounts to about 10% of the basal requirement. Intake of digestible energy was not measured in this study, but in research on mature annual range in periods of similar dietary crude pro- tein content (Van Dyne and Lofgreen, 1964), a 50 kg sheep would consume 1700 kcal of digestible energy. Using these data as an approximation to the consunption of digestible energy by sheep on the foothill winter range, the importance of energy expenditure in grazing is shown. The energy expenditure in movement in grazing and in grazing per se probably amounts to more than 20% of the digestible energy which was consumed. Our data show energy expenditure in grazing is more important than rarely walk more than four miles (6400 m), and hardly ascend more than LXXIV-4 100 m each day." The current research area and conditions are similar to many ranch operations in the Mountain and Intermountain states, and maximum elevation climbed and distance grazed, respectively, 280 m and 13.2 km per day, were more than twice Blaxter's "extremes." The relations between the measured climatic variables and energy expenditure can only be interpreted in a general way. It was possible to obtain climatic measurements only at stations located at the bedground locations, but the microclimate where the sheep were grazing during the day could have been considerably different. This factor may be partially responsible for the relatively low correlations which were obtained. Wind, relative humidity, and temperature influenced energy expendi- ture in decreasing order of importance. This ranking is expected when considering the flock behavior. During periods of high wind the band did not "spread" well and often would "bunch," at least temporarily, leeward to wind barriers. Greatest movement of the band occurred during periods of low wind movement and low relative humidity, although these relationships were complex. The partial correlation coefficients were : relative humidity-wind, -.36; relative humidity-total energy expenditure, - 21; and wind-total energy expenditure, -.27. The lack of importance of temperature is shown by the following four "data points" which represent the days on which the two highest and two lowest values for energy expenditure were found: Average temper- Average relative Total wind move- Calculated total ature during hwidity during ment during the energy expendi- the day, OF the day,, percent day, miles t ure, kcrui 42 152 137 77 min 60 153 244 406 342 Thus, wide extremes in average daily temperature had little influence on total energy expenditure. The importance of wind as an environmental influence on the ener- getics of the grazing sheep extends beyond its influence on the behavior pattern. High wind greatly increases the convective heat loss from the sheep and decreases the insulative properties of the fleece. SUMMARY Distance traveled by a band of sheep grazing on a foothill range of about 1620 ha in south-central Montana was measured in the winter of 1960. The band's travel route during 31 days was plotted on aerial photographs. The distance traveled by three wethers in the band was measured for 41 sheep-days with metering devices harnessed to the sheep. The average distance traveled by individual sheep was 1.6 times that measured from aerial photographs for band travel. Wind movement, temperature, and relatie humidity were measured winterlong. The cal- culateu distance traveled by sheep in the band averaged winterlong was 7.6 km. Elevation climbed each day, determined from 12.2 m interval contour maps, varied from 85 to 280 m. Energy expenditure for grazing, calculated using Blaxter's constants of .030 and .322 kcal/m respecti- vely for horizontal and vertical movement for a 50 kg sheep, varied from 137 to 406 kcal/day per sheep. The average energy expenditure LXXIV-5 for grazing, 235 I 62 kcal/dsy of which less than 3% was expended for climbing, represents about 20% of the basal metabolic requirement. Dietary samples collected from seven esophageal fistulated ewes grazing in the band were analyzed for crude protein, ether extract, lignin, and cellulose which averaged, respectively, 7.0, 3.1, 14.8, and 41.6% Jur- ing the winter. Wind movement was the most important climatic variable affecting energy expenditure by the grazing sheep. There was no apparent lag influence of climate on energy expenditure for grazing. LITERATURE CITO Blaxter, K. L. 1962. Energy metabolism of ruminants. Hutchinson & Co., Ltd. London. 329 pp. Blaxter, K. L. 1964. Utilization of the metabolizable energy of grass. Proc. Nutr. Soc. 23:62-71. Cresswell, E. 1957. A new technique for sheep behavior studies. British J. Animal Behav. 3:119. Cresswell, E. and L. E. Harris. 1959. An improved rangemeter for sheep. J. Animal Sci. 18:1447-1451. Graham, N. McC. 196:289. 1962. Energy expenditure of grazing sheep. Nature Reid, J. T., A. M. Smith, and M. J. Anderson. 1958. Difference in the requirements for maintenance of dairy cattle between pasture- and barn-feeding conditions. Proc. Cornell Nutr. Conf. pp. 88-94. Van Dyne, G. M. and (i. P. Lofgreen. 1964. Comparative digestion of dry annual range forage by cattle and sheep. J. Animal Sci. 23:823-832. Van Dyne, G. M., 0. 0. Thomas, and J. L. Van Horn. 1964. Diet of cattle and sheep on winter range. Proc. West. Sect. Amer. Soc. Animal Sci. 15:LXI. - - home LXXIV-6 - S. END DATE FILMED 9)/ 1 /65 .