!

Ii

I

Reprinted from Aurn,tr PnooucrroN, Vol, 10 part 1, pp. 59-66, February 1968

SOME RESPONSES OF HILL EWES AND LAMBSTO ARTIFICIAL SHELTER

C. R. Mrlrent

Uniuersity School of Agriculture, Newcastle upon Tyne

Trm objects of this investigation were to study the reactions of ewes andyoung lambs to artificial shelter in various weather conditions, and tomeasure the live-weight gain of lambs with and without access to shelter.Most previous studies on the effect of shelter on the live-weight performanceof sheep (e.g. Latham, 1874; Doney, 1963) compared one group of animalsconfined in a shed or yard with another group in the open. Thus shelterwas obligatory in these experiments. This is not typical of fleld conditions,especially on hill grazings, where shelter is usually optional.

The experiments described below were carried out on an upland permanentpasture, using small cross-shaped shelters. Although the results cannot beapplied to large woods or shelterbelts, the experiments did simulate a situationwhere sheep on free range have access to stells or to the cross-shaped andL-shaped walls common on hill grazings in the north of England.

MATERIAL AND METHODS

Observations were made each spring from 1958 to 1960 in two adjacent11-acre plots of Agrostis-Festucd pasture at Rothley East Shield, an exposedupland farm at 750 ft altitude in Northumberland (G. R. N2045090). Thevegetation of the two plots was similar (Miller, 1962) and both had asoutherly aspect. A small amount of natural shelter rvas provided in bothplots by gently undulating ridges and furrows, and by several shallow drainagechannels. However, animals were seldom seen sheltering there. The experi-ments all began in late April and lasted 50 days in 1958, 50 in 1959 and 43 in1960 (Table l).

Design. The shelters were made of corrugated iron, rvith each arm 10 ftlong and 3] ft high (Figure l). In 1958, four shelters were put in the westernplot and none in the eastern. In 1959, the four shelters were transferred tothe eastern plot, and were moved to new positions in this plot for the finalexperiment in 1960. Each plot was divided into twenty-four 140 ft squaresub-plots by canes with coloured flags. These enabled an observer to locateaccurately the position of sheep in the plots.

Animals. Twenty Blackface ewes with single lambs were assigned atrandom to each plot. The lambs were Blackface and Greyface (Blackface Q xBorder Leicester J) in 1958, but were all Greyface in 1959 and 1960. Eweswere fed about 1 10 g of ewe pencils per head per day on a group basis untilmid-May, except in 1959 when feeding stopped in late April. A11 lambs weredosed with bephemium embonate to eradicate Nematodirus spp. larvae. Inthe plot with shelter, two lambs died in 1958 and two ewes in 1960; in the plot

f Present address: Nature Conservancy Unit of GrouseNatural History Department, University of Aberdeen.

59

and Moorland Ecology,

ANrM. pRoD.-voL. 10. pT. 1

tI

1

I*

60 MILLER

without shelter, one ewe died in 1958 and 1959, and one lamb in 1960. Theelves died from enterotoxaemia and liver fluke, and the lambs from pulpykidney disease. In every case the surviving ewe or lamb was withdrawrfromthe experiment.

weather records. There was one small enclosure with meteorologicalinstruments adjacent to but outside each plot. The instruments includid adry bulb, a maximum and a minimum thermometer, and a bimetallic thermo-graph, all in a Stevenson screen, and a cup-counter anemometer set al 6! ftabove the ground. A singie recording anemometer set at 8 ft gave continuousrecords of wind speed. Average readings of the cup-counter anemometersand dry bulb thermometers from the two enclosures were used to measurewind speed and air temperature during observations of the shelteringbehaviour of the sheep. The records from the thermographs and therecording anemometer were used to describe the weather in different years(Table 1). Sunshine and rainfall were not measured but records from cockrePark, 9 miles to the east, and from Acklington, 12 miles to the north-eastwere used.

Animal records. An animal rvas counted as sheltering if it was within aring of wooden pegs 17| ft from the centre of each shelter (Figure 1). Thisdistance, equivalent to five times the height of the shelter (5 h), was chosenon the basis of the data of Fanfilov (1936) and Nligeli (1946) on the reductionof rvind speed in the vicinity of a solid barrier. At a distance of 5 h to the lee,rvin.J speed is about 40\ of that in the open and is reduced to nearly zeroas the barrier is approached. on the windward side, the relative u'ind speeclis 90,".d at 5 h, reducing to about 60\ atthe barrier. Thus an animal standingwithin 5 h of the centre of a shelter would receive some benefit even if it wason the windrvard side.

counts of all animals standing in shelter and records of their distributionon 1:1200 scale maps of the trvo plots rvere made during ciaylight hours(i.e. from 06.00 to 20.00 hr G.M.T,). Da1,s and times of observation rverechosen to coyer all weather conditions as lu1ly as possibie, but the plots werenot visited more often than once every two hours on 91 counting days duringthe three experiments. In 1959 and 1960, when all animals were marked forindividual recognition, the mean distance between ewes and their lambs wasmeasured at every observation. Since the terrain was relatively flat and open,the locations of animals could be plotted accurately at distances of up to50 yd. The sheep soon became accustomed to the observers and were notdisturbed. Air temperaturc and wind speed rvere recorded at al1 observations,together with a note of whether the rveather was rainy, cloudy (>! cloudcover) or sunny (<f cioud cover).

All lambs rvere weighed on a spring balance within 12 hours of birth andat intervals thereafter. In 1958, rvorm infestation in the lambs rvas assessedat 6-7,9-10 and 11-12 weeks by the McMaster technique (Gordon andWhitlock, 1939).

statistical analyses. There were 529 counts of sheep in shelter from thethree experiments. These were classified by wind speed (0-5, 6-15 and 16-27mph) and air temperature (35-44,45-54 and 55-69"F). Since there weredisproportionate numbers of observations in the nine sub-classes, the datawere analysed by fitting constants (Snedecor, 1956). Ifthere was significantinteraction, analysis was by weighted squares of means. Analyses of variancewere calculated separately for the proportions of ewes and of lambs sheltering

PLATE I

Fig. I. One ewe and six lambs sheltering during heavy rain; air temperature46'F, wind speed 15 mph.

RESPONSES OF SHEEP TO SHELTER

in rainy, cloudy and sunny weather respectively, after angular transformationof the data.

Mean distances between ewes and lambs in the plot with shelter werecompared with those in the plot without shelter in rainy, cloudy and sunnyweather. Since sheep show a diurnal periodicity in behaviour (Tribe, 1949;Hughes and Reid, 1951), variations due to time of day had to be eliminatedfirst. This was done by classifying the observations for each plot by time ofday (oiz. dawn to 07.00 hr G.M.T., 08.00 to 10.00, 11.00 to 13.00, 14.00 to16.00 and 17.00 to dusk), calculating constants for these periods (Snedecor,1956) and adjusting the data in each weather category. A detailed accountof the calculations is given by Miller (1962). The significance of differencesbetween the plot means was assessed by I tests for paired variates.

The lamb weights were also analysed by fltting constants. After adjustingthe weights to a standard age (Warwick and Cartwright, 1958), constants werecalculated and the variation due to breed (in 1958 only), sex and age of damwas eliminated. Only the weights of individuals which survived to the endof the experiments were used for comparing plot means.

RESULTS

Weatlrcr. Mean temperature was lower, rnean daily sunshine lower andmean wind speed higher during the 1958 experiment than in 1959 and 1960(Table l). There was four times as much rainfall and over trvice as manydays of rain in 1958 as in 1959. Although there was 2.81 in. of rain in 1960,2'00 in. of this fell on 13 May and there were actually fewer days of rain thanin 1959. At Acklington it rained for 9\ of the experimental period in 1958but lor only'2-3\in1959 and 1960. Thus it was generally colder, mores'indy', less sunny and much wetter in 1958 than in 1959 and 1960.

TABLE 1

Weather during tlte experiments in 1958, 1959 and 1960

z+ nplre.jr8z rr". zz ap1.e.jls ir.. 22 AJ:13 J,*Mean temperature ('F) 4'7.0 49.0 49.2Mean wind speed (mph) 8.4 7.0 6.3Total rainfall (in.)i 4.33 1.05 2.81No. of day's of raint 30 (609'0) 14 (28%) 10 (23%)Duration of rainlall (hr)f 102.9 (9o//) 1,9.5 (2%) 26.1 (3%)Mean daily sunshine (hr)f 5.3 6.6 5.8

t From Cockle Park crop weather station, 9 miles east of Rothley.I From R.A.F. Acklington weather station, 12 miles north-east of Rothley.

Sheltering by ewes qnd lambs. The ewes were seldom seen in shelter. Onayerage, 2-3/. sheltered in rainy and sunny weather and less than l/, incloudy conditions (Table 2). Wind speed had no significant effect on theirresponse to shelter. However, air temperature influenced the ewes in sunnyweather, since some sought shade in the shadows cast by the shelters when itwas warm. Thus 6\ were in shelter at 55*69"F compared with l-2\ atlower temperatures (P < 0.001).

Unlike the ewes, lambs often sheltered, especially when it was raining;

6t

62 IlvllLLER

ol.^ 9,e €h nc)

-.6.: N9c or aae a'= ath,= E ro'E= :9 -ro clC -6 On Nh

E ?\ \c..r .-hX 3-R xo* E^-VN

a-gtsc u :-l hhG 't -^Y ooOL o v)A tho a:E"T Zi 2Z VVEir : a qo.

a.i

.A

t=

IEicoa

I

i

I

lI

II

I

Il

II

II

.

.ao]C

! Us

tmt.-ta

s\oI

oO

o\

4

\H

-c9

1:e>6\oyo

.aJ\.=\NSElsooi4Pl-U'*t

v,a"

"a

'NO:-s.q

SrBq)o

%>

L

\\a)

?=F, -- .8 835 ZZ Zo ooE V VV=

o. qA

o\€ 6r orh o i -oN olrbohva

=f? lfQ hv o\r$ €-- fro+ 3o-$Y =!a

.+n nah -r6lI u?O.; noth-VN-

o-q-!F, cZ ...h ai.i z: zz zi=i-.--c

r$ l-e r.t rc)\O O\N€ \eAO sotCiod

! y? "?? oo.a =NY 9on oor*

-;

n |? ge Nrco K.R Sco e --

2aa.^=.: .Y .g:J!eo

9.-q^U^€;- €f" €Sic ?&- c .n9_ c;42As z{it,f;!

U.-o';ocie O A

RESPONSES OF SHEEP TO SHELTER

on average, 24/, were seen sheltering during rain but only about 6/, incloudy and sunny conditions (Table 2). There was no signiflcant response towind speed in cloudy weather. However, in rainy weather more lambs

sheltered at wind speeds of 6-15 mph than at 0-5 mph (P<0'01), and insunny rveather more sheltered at 16-27 than at 6-15 mph (P<0'05). They

clid not respond significantly to temperature in rainy weather, but in cloudyconditions more lambs sheltered at 35-44'F than at higher temperatures(P<0'001). In sunny weather they did the opposite, responding to hightemperature; over trvice as lnany sheltered at 55-69'F as at 45-54'F (P <0'05).In this respect they were like the ewes, but it was clear from field observationsthat this ivas mainly due to the lambs accompanying their dams when the

latter moved into shade in warm weather.Distcmces bety.een ewes and their lambs. Because of their different

responses to shelter, the correlation between the numbers of ewes and lambs

sheltering was lowest in rainy weather and highest in sunny conditions(Miller, 1962). This implies that in the plot with shelter the ewes were

separated more from their lambs during wet weather than in dry. Thispossibility was unforeseen in 1958 and distances between ewes and theirlambs rvere not measured until 1959 and i960.

There were over 100 observations in cloudy and sunny conditions but,because of the generally dry weather in 1959 and 1960, only 27 during rain(Table 3). Ewes and their lambs in the plot with shelter were more closelyassociated in cloudy and sunny weather than in rain (P<0'01). In the otherplot there were no significant differences in distances between ewes and lambsin the various weather conditions. Consequently the ewes and lambs in theplot with shelter were 10*4 ft (P<0'02) further apart in wet weather than

TABLE 3

Mean distances between ev,es and their lambs in plots tt'ilh qnd v'ithout slrclterin 1959-60

Mean distance (ft) betweenewes and lambs in plots

No. ol :!-_,--___,_-,-,__ SE of difference Level ofWeather observations with shelter without shelter between plots significance

Rainy 27 72+ 4'3 62+ 5'3 + 4'l P < 0'02Cloudy 116 58+2'1 66+2'6 +3'0 P<0'01Sunny 115 5l+2.1 60+2'6 +2'6 P<0'001

those in the plot without shelter. The position was reversed in dry weather,rvhen they were significantly (P <0'01) closer to one another in the plot withshelter.

Lit'e-treight gain by lambs. The mean weight of the lambs in the two plotswas similar at the beginning of each experiment and remained so throughoutin 1959 and 1960 (Table 4). However, in 1958 the lambs with access toshelter rveighed 4'0+l'5 lb (P<0'05) less at 5 weeks than those without.This difference increased to 8'4*2'2lb (P < 0'01) at 1l weeks, when the sheep

were taken out of the plots and put back with the main flock. The lambs wereweighed again when they were weaned at 20 weeks after being 9 weeks withthe main flock. The weight difference between the two groups had decreasedto 5'3'12'6lb and was no longer statistically significant.

63

64 MTLLER

TABLE 4Mean w'eights of lambs with and v'ithout ctccess to srterter in r95g. 1959

and 1960

1959 Birth3

5

7

1960 Birth-)

5

Age Lambs LambsYear (weeks) with shelter (lb) without shelier (lb)1958 Birth g.g t}.z

5 32.6 36.611 55.3 $.720 74.2 79.5

SE, ol Level oldifference significance+0.52 NS+ 1.51 p<0.02+2.20 p<0.01+2-64 NS

+0.45+0.90+ 1.17+ 1.63

+ 0.57+ 1.33+ 1'82

Tric ho s t rong y lus eggs/g from lambs

11.427.237.849.3

10'325.838.0

with shelter without shelter935+232 597 +165518+ 164 419 + 16470+28 65+23

11.527.037.448.4

10'125.037.s

NSNSNSNS

NSNSNS

- -w''.ry infestation of lcmbs. This was assessed by faecar egg counts at

6-7 and 9-10 weeks in 1958 (Table 5). on each occasion the mel"n counts ofNematodirus ard rrichostrongyrru eggs were higher from lambs *iit u.""r,to shelter. The differences between plots werJnot significant but the con-sistently. higher egg counts irom lambs in the plot wiih shelter sulgest thatthey had a greater rvorm infestation. Ail rambi were aor.J ,ilr L.?hemiumembonate after the second egg count and one u'eek later a third count shorr eda sharp decrease in )'ettntodira.r esgs.

TABLE 5

Mean number o/Nematodirus spp. andTrichostron_ey.lus spp. eggs 1,er g offaeces from lambs with and without access to shettei'in tb"sa

Age(weeks)

6-79-10

11-12

with shelter

139+53391 + 64210 t 58

rvithout shelter

66+20285 + 5l185 + 62

DISCUSSION

There is no evidence that the ewes' behaviour was affected by high winds9i 19y temperatures during these experiments. Munro (lg62i foirnd thatBlackface ewes moved into topographic shelter when the wi"a sp'"eJ exceeded?4-*p\: pyticularly after a fall in temperature or if air teriperature wasbelow 32"F. However, wind speeds rarely exceede d,24 mphduring the presentstudy and temperatures never fell below freezing point. In faci more ewessheltered in sunny weather when temperatures exceeded 55"F than at anyother time. Even then only 6 \ on iverage were in shelter and the ewesmostly remained in the open irrespective of weather.

on the other hand, the lambs made much greater use of the shelters and

Nematodirus eggs/g from lambs

RESPONSES OF SHEEP TO SHELTER 65

were clearly sensitiye to high wind speeds and low temperatures. Presumablytheir smaller body size and shorter, less dense coats made them more suscept-ible to cold than the ewes. The lambs were particularly sensitive to wetting oftheir fleece and many more sought shelter in wet weather than in dry. Theseobservations are in general agreement with the conclusions of Alexander(1962) who showed that heat loss in young lambs was greatly increased bywind and by the evaporation ofwater from the fleece.

The reason for the depression of the mean weight of the lambs withaccess to shelter in 1958 is not clear. However, the evidence suggests thattheir poor performance was related to their free use of the shelters in the pre-dominantly wet weather which characterized that experiment. The ewesmostly remained in the open irrespective of weather and measurements ofdistances between ewes and lambs showed that the lambs were less closelyassociated with their dams when it was raining than when it was dry. Thusthe presence of the shelters in 1958 may have weakened the social bondbetween elve and lamb to such an extent that the lambs' milk intake wassignificantly reduced.

If the lambs with access to shelter did not get enough milk in 1958, onemight expect them to compensate by eating grass earlier and more often thanthose without shelter. Furthermore, by concentrating in the sheltered areasthey probably restricted their grazing to wet, trodden ground. Consequentlythey would have ingested more parasites and accumulated a heavier wormburden. This may explain the consistently higher counts of Nematodirus andTrichostrongylus eggs in the faeces of the lambs with shelter.

None of the experiments suggested that small shelters to which sheep hadfree access in spring improved the live-weight production of lambs. SimilarlyCresswell, Thomson and Gill (1964) showed that optional shelter had noeffect on the live-weight gain of fattening Blackface wether lambs betweenNovember and February. Lambs will use shelters of this type, but they appearto be of no benefit and are perhaps disadvantageous in cold wet weather.Possibly shelter may be beneficial to ewes or young lambs in a severe springwith strong winds and prolonged snow. However, such conditions did notoccur during the experiments and are in any case unusual on most lambinggrounds in Britain.

SUMMARY

1. Experiments were done to assess the reaction of sheep to smallartificial shelters and to study the effect of these shelters on the live-weightgain of young lambs in the springs of 1958, 1959 and 1960.

2. Lambs sought shelter particularly when it was raining. They weresensitive to high wind speed and low temperature but did not usually shelterin mild dry weather.

3. Ewes were indifferent to rain and remained in the open in wet weatherwhile many of their lambs sheltered. They occasionally used the shelters forshade in warm sunny weather when their lambs usually went with them.

4. Because of these differences between ewes and lambs in their responseto shelter, during wet weather ewes were less closely associated with theirlambs where they had access to shelter than where there was no shelter.

5. In the wet spring of 1958, lambs with access to shelter gained weightmore slowly than those without shelter. It is postulated that the lambs with

66 MTLLER

shelter may have consumed less milk than the others due to a weaker socialbond with their dams.

6. None of the experiments showed that shelter improved the live-weightperformance of young lambs.

ACKNOWLEDGEMENTS

This study was financed by the Ministry of Agriculture, Fisheries and Food and I am :

grateful to them, to Professor M, M. Cooper in whose department the work was done and ito the late Mr E. Crompton for supervision. I wish to thank Dr R. W. Gloyne for advice,Mrs L. M. Miller for help in the field, Dr W. J. M. Black for help in making faecal eggcounts and Mr M. Campbell for facilities at Rothley East Shield farm.

REFERENCES :Ar-rxa.Norn, G. 1962. Temperature regulation in the new-born lamb. IV. The effect ol I '

wind and evaporation of water from the coat on metabolic rate and body temperature.Aust. J. agric. Res. 13: 82-89.

Cnrsswrr-r, E., THousoN, W. and Grlr-, J. C. 1964. The effect of shelter and of tallowdressing of the fleece on fattening Scottish Blackface lambs, Emp. J. exp. Agric. 32: 5l-54.

DoNr,v, J. M. 1963. The effects of exposure in Blacklace sheep rvith particular reference tothe role of the fleece. J. agric. Sci., Camb. 60 : 267 -27 3.

GonnoN, H. M. and Wurrlocr, H. V. 1939. A new technique for counting nematodeeggs in sheep faeces. ./. Coun. sci. ind. Res, (Aust.), 12: 50-52.

HucHEs, G. P. and Rsn, D. 1951. Studies on the behaviour of cattle and sheep in relationto the utilisation ofgrass. l. agric. Sci., Camb.41: 350-366.

Lntnart, P. R. 1874. On fencing and shelter of mountain sheep walks. Trans. Highl.agric. Soc. Scot.,4th ser. 6: 114-118.

MrrI,rn, G. R. 1962. Some effects of shelter, with particular relerence to the perlormanceand behaviour of sheep. Ph.D. Thesis, Uniu. Newcastle upon Tyne.

MuNno, J. 1962. The use of natural shelter by hill sheep. Anim. Prod. 4: 343-349.NAcELr, W. 1946. Weitere untersuchungen iiber die Windverhiiltnisse im Bereich von ;

Windschutzstreifen. Mitt. schweiz. Anst. forst l. Versuchs*'. 24 : 659 -7 37 .

PaNEnov, Y. 1936. [Experiments and research of All-Union Research Institute for Agri- r]

Forestry Melioration and Forest Management.l No. 6: (Shelterbelts), State Tech. ,'i

Printing Office, Moscow. tSNr,oEcon, G. W. 1956. Statistical Methods. 5th ed. Iowa State College Press, Ames, Ia. lTnrsr, D. E. 1949. Some seasonal observations on the grazing habits of she*p. Emp.

J. exp. Agric.17: 10G115.WARwrcK, B. L. and Cnnrwnrcur, T. C. 1958. Adjustment of milk lamb weaning weights

Ito a standard age. J. Anim. Sci. l7: 521-526.

(Receiued 6 February 1967) I

It;