The value of animal behaviour records in pasture evaluation studies

THE VALUE OF ANIMAL BEHAVIOUR RECORDS IN PASTURE EVALUATION STUDIES BY

J . E . DUCKWORTH*

AND

D . W . SHIRLAW

University School of Agriculture, King's College, Newcastle upon Tyne

Until comparatively recently, grassland research has been concentrated on the establishment of grass rather than upon its utilisation by the grazing animal. As a result of the development of specialised strains of grasses and clovers, and the realisation that grassland should be managed as intensively as any other crop, it is now possible to establish good grass fields in most parts of the country, except those subject to prolonged drought . There are still, however, many unsolved problems associated with the utilisation of grassland and the development of methods of evaluating varying pasture types . Jones (1928) has shown that differences in the nature of swards can be associated with variations in grazing behaviour. He observed differences in the behaviour of sheep grazing on extreme types of herbage, and on a given sward, which was rotationally grazed after varying rest periods . Hodgson (1933) noted that as cattle remained on a restricted area for an increasing number of days, the time spent in grazing lengthened . Later work has been reported by Hancock (1954) . When computing rations for cattle, an allowance of starch equivalent is made to the maintenance portion of the diet to supply the energy used in grazing . Woodman (1954) has suggested that this allowance should vary with sward type . The amount of work involved daily in grazing has been repeatedly stressed by Wallace (1944) . Graves, et al (1933), using two groups of dairy cattle, have reported that the loss in body weight and the fall in yield were less when cows were fed cut grass indoors than when the same herbage was grazed "in situ" . This variation was related to a smaller intake of nutrients by the grazing cattle, and not to an increase in the energy required for grazing uncut grass . The authors do state, however, that the physical effort of grazing might be high enough, under certain conditions, to deter the cow from consuming to full capacity . There is little published data showing the *Now at Wye College, (University of London), Nr . Ashford, Kent .

relationship between animal behaviour and productivity as measured in terms of liveweight gain, but the results from trials at Cockle Park have indicated a possible relationship between these factors . In 1949 the behaviour of cattle was studied on three differing swards : (1) a permanent pasture of complex botanical composition ; (2) a Cockle Park type ley, and (3) a paddock consisting of both types of herbage . Nine shorthorn cattle were divided into three groups of similar average liveweight and each group was allocated, at random, to one of the paddocks . The cattle were weighed every fortnight, and their behaviour was observed over a twenty-four hour period, on five occasions during the summer . In each case the recording commenced early in the day . Hand lamps were necessary during the darkest period of the night . Each animal was recorded separately, and the records were continuous, every activity being noted immediately it was observed. The following activities were recorded : Grazing : This included the short periods of time spent in selecting the herbage . Cudding : Resting : This was recorded when the animals were lying down but not cudding. idling : This was the time spent resting, together with the time spent standing but not grazing or cudding . The relationship between animal behaviour records and productivity can be illustrated by correlating the various activities with the rate of liveweight gain . It is difficult, however, to interpret the relationship between these two factors since increases in liveweight cannot be measured accurately in a short-term experiment, and grazing records on any one day may not represent normal behaviour . A comparison of all the grazing records and the corresponding liveweight increase data gave a correlation of - •5 294 (n=16) which is significant at the •02 level . This negative relationship can be explained in two ways 139



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ANIMAL BEHAVIOUR, VI, 3-4

1 . High grazing times represent a waste of energy which directly affects liveweight gains . 2 . High grazing times indicate inefficient grazing, i .e . a low rate of food intake per unit of grazing time . This is caused by :

The results of these preliminary observations of grazing behaviour suggest that the efficiency of grazing, i .e . the time required to consume an optimum amount of food, may affect the rate of liveweight gain . It is believed that sward conditions, e .g . height, density, fibre and dry matter content, govern this efficiency . In this experiment the nutritional value of the sward was not assessed since the amounts of food eaten by the cattle were not successfully determined . In later experiments the technique for measuring the growth and consumption of grass was modified . In 1950, a second experiment was carried out . The original paddocks were sub-divided to give three plots, each of one acre . The same animals were used and the plots were rotationally grazed . Any surplus grass was cut and removed. The procedure adopted was identical for both the Old and New Grass paddocks, so that a comparison could be made between them . The food intake and the growth of grass was measured by the "difference" technique (Boyd, 1949). Twenty metal cages were available for each plot to protect the herbage from the grazing cattle . Although the average daily liveweight gain was 3 . 55 lb . on the New Grass, and only 2 . 94 on the Old Grass, the difference between the two was not statistically significant . The cattle on the New Grass spent less time grazing and more time cudding than those on the Old Grass ; the differences, however, were not statistically significant . There were no significant differences between the amounts of herbage grown or eaten on the two plots . It has been suggested that, in the 1949 trial, grazing was inefficient due to over-selectivity and that this was indicated by the negative correlation "Grazing X Liveweight Gain" . In 1950 this relationship declined from -'5294 (n=16), which was significant, to -' 1768 (n=22), which

(a) A waste of time in selecting edible herbage while grazing a sward, which is variable in either botanical composition, or the stage of growth of individual groups of plants . (b) A low rate of food intake per bite . This may be governed by sward height, density or dry matter content.

The Old Grass plot was understocked carrying three cattle on four acres, since the productivity of the Old Grass was expected to be less than that of the ley which carried three cattle on three acres . This resulted in the herbage on the Old Grass paddock growing away from the cattle and becoming very variable in nature. Liveweight gains were inferior on this plot and grazing records were longer . This can be attributed to a highly selective type of gazing . There was no significant result when the cudding data were correlated with either records of grazing or the rate of liveweight increase . Two of the main factors which control the time spent ruminating are the amount and quality of the food eaten, i .e . its content of dry matter and fibre . It is reasonable to suppose that an increase in either constituent will result in an increase in cudding activity . Throughout the results, high cudding records were associated, although not significantly, with high liveweight gains (r= •2 340, n= 16) and low grazing times (r= •3 850, n=16) . It is unlikely that the high rate of cudding was due to a high fibre content, since animals eating this type of herbage would not make the best liveweight gains . It is, therefore, more likely to relate to high food intake and this view is supported by the fact that the correlation between cudding and liveweight gain, although not statistically significant, was positive .

Table I. A Comparison of the Data Recorded During 1950 on the Old and New Grass Plots Difference between means

S .E. of difference

n

Minimum difference for significance

Live wt. gains (lb./day/animal)

0 . 61

899

22

1 . 86

T'

51 . 1

26 .77

22

55 . 52

Time cudding in min .

33 . 0

32 . 12

22

67 . 69

Herbage grown

11 . 39

21 .98

198

43 . 06

Herbage eaten

13 . 34

9 .42

198

18 .369

grazing



DUCKWORTH &

SHIRLAW : ANIMAL BEHAVIOUR RECORDS IN PASTURE EVALUATION STUDIES

141

Table 11. Variance Ratios Calculated from the Data Recorded Daft 1950

Plots

Live wt . gain Grazing Cudding

Seasons

n 1 =1

n1=1

n2=13

n2 =13

1-44 19 .72** 3 .21

10 . 65** 19 . 23** 13-21**

I

Interaction plots X seasons

Animals

n 1 =1

n,=1

n2 =13

n 2 =13

3 .67* 6 .23** 0. 3

1 . 38 9 . 58** 4 .24*

i

*=significant at •05 * * =significant at •O1 was not . This indicates a decrease in selectivity of grazing in 1950, probably due to the intensification of grazing management . This increase in the efficiency of grazing may imply that there was a positive relationship between the time spent grazing and the amount of food consumed . If this were so, then the correlation between grazing and cudding may be expected to be positive . This coefficient when calculated was found to be positive, although not statistically significant . However, since the correlation between cudding and liveweight gain was significantly negative, it is probable that the increase in cudding and grazing times was due to some factor other than an increase in food consumption . It is possible that the fibre content of the herbage might govern both relationships, and, that as the herbage becomes more fibrous, it not only requires more cudding but also becomes more difficult to graze . The variation in fibre content, being seasonal, would have a greater effect within plots than between plots . It is interesting to note, from an analysis of the data recorded in 1950, that for liveweight gain and cudding, the seasonal variation was greater than the variation between plots . This is illustrated by Table II . It has been shown that animal behaviour records may be related to productivity and could be of value in pasture evaluation studies . The problem is complex and, before records of animal behaviour can be used to interpret variations in pasture productivity, measured in terms of liveweight gain or milk production, the individual and combined effects of all the factors causing variation in animal behaviour must be understood. It was apparent that visual records of grazing were not accurate, since they included the time spent in selecting the herbage to be grazed ; this will result in large variations where pastures

show a marked difference . The number of bites per minute of grazing time gives a fair indication of selectivity, whilst the total number of bites of grazing gives a more accurate picture of grazing activity. Records of time spent cudding do not give any information about the number of boli produced nor do they indicate the .actual number of chews of cudding . These factors may be important measures of behaviour . It was necessary, therefore, to develop an automatic behaviour recording apparatus which has been described in a previous issue of this Journal (Duckworth & Shirlaw, 1955) . Using this apparatus, a detailed study of animal behaviour under controlled conditions was carried out to determine fundamental relationships between food consumption and eating behaviour . In the spring of 1954, the apparatus was used to obtain a continuous record of the jaw movements of four cows over a period of five days, giving data for 20 "cow-days" . The cattle were housed in a specially equipped byre at Nafferton, the commercial farm of Durham University . Freshly cut grass was fed to the cows each day . The grass was obtained from different fields at various stages of growth . The variation in the herbage is illustrated in Table III . The cows were each fed 90 lb, of wet grass per day in three feeds of 30 lb . each. The three feeds were offered at 8 .30 a.m ., 12 noon and 5.30 p .m . Feed residues were bulked and weighed daily . The food offered each day was sampled and analysed for dry matter and fibre content . The weights of wet matter, dry matter and fibre consumed are referred to as the "feed variables ." To determine possible relationships between feed intake and behaviour records, correlation coefficients were calculated . Three aspects of the food consumed were considered, i .e . the weights of wet matter, dry matter and fibre . These data were correlated with the following aspects of



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ANIMAL BEHAVIOUR, VI, 3-4

Table III . To Show the Variation in the Herbage During the Five Days I

Dominant type of herbage

Day no.

~ % Dry matter

% Fibre in dry matter

I

Perennial Ryegrass (after rain) . .

18 . 862

28 . 4

2

Perennial Ryegrass

26 . 912

28 . 8

3

Cocksfoot (after rain)

17 . 45

28 . 7

4

Italian Ryegrass

23 . 15

23 . 5

5

Italian Ryegrass (after rain)

16 .925

24 . 9

eating behaviour : 1 . The number of jaw movements associated with eating. 2. The number of jaw movements associated with cudding . 3 . The number of boli produced during cudding . 4. The time spent eating . 5. The time spent cudding. 6. The number of miscellaneous jaw movements . In order to determine the single effect of any one aspect of the feed intake, e .g. the total weight of wet matter or fibre consumed, partial correlation coefficients were calculated . For each correlation coefficient there were 20 pairs of readings, and therefore "n"=18 . For the partial correlations "n" was reduced by I for each of the variables held constant . The Effect of Variations in Dry Matter and Fibre Contents on the Weight of Wet Grass Consumed From the data obtained from this trial, it was possible to investigate some of the effects of variations in dry matter and fibre percentages on the feed intake of the cattle . However, the fact that there was a constant weight of wet grass offered limited the maximum amount which could be eaten . Thus only the effect of any factor which tended to reduce appetite below this maximum could be recorded . A correlation between either the fibre precentage of the wet matter, or the dry matter percentage, with the weight of wet matter consumed may be artificially low . The correlation coefficient between the percentage of dry matter and the weight of wet matter consumed was--5787, which is significant at the -01 level . It would appear, therefore, that as the dry matter percentage increased the weight of wet matter consumed decreased . This is in agreement with the accepted theory that the weight of dry matter consumed is the factor limiting the animal's appetite .

When this correlation coefficient is corrected for variation in the percentage of fibre, h owever. i t is reduced to -1266 which is not significant . It is possible that fibre content has a more important effect than dry matter percentage and that the close correlation between dry matter and fibre percentage calculated to be -8428, is the main factor underlying the apparent negative correlation between dry matter percentage and wet matter consumed. There was a high negative correlation between fibre percentage and wet matter consumed (- . 6234) . When this coefficient is corrected for variations in the percentage of dry matter it is reduced to - •3 188 which is not significant . It is clear that high dry matter and fibre percentages tend to restrict the weight of wet matter consumed . Of the two, the fibre percentage has the greater effect since the negative correlation between the percentage of fibre in the diet, and the weight of wet matter consumed is higher than that between the percentage of dry matter and the weight of wet matter consumed . This is emphasised by the fact that when the correlation between the dry matter percentage and the weight of wet matter consumed is corrected for variations in fibre percentage, the effect is greater than that obtained when the correlation between the fibre percentage and the weight of wet matter consumed is corrected for variations in dry matter . The logical conclusion is that fibre intake can be a major factor controlling the animals' appetite . The fibre percentage of the herbage can affect the amount consumed in two ways : (a) An increase in fibre percentage may be associated with an increase in the amount of fibre consumed, and it is possible that this may control appetite . (b) Herbage with a high fibre content may be unpalatable, resulting in a reduced feed intake.

DUCKWORTH & SHIRLAW : ANIMAL BEHAVIOUR RECORDS IN PASTURE EVALUATION STUDIES

The Effect of Variations in the Weights of Wet Matter, Dry Matter and Fibre Consumed on the Eating Behaviour of Cattle The correlation between the number of bites of eating and the weight of wet matter consumed was -5516, which is significant at the -02 level . When this is corrected for the effect of variation in the weights of dry matter and fibre consumed, it is reduced to - •4589, which is significant only at the 0 . 1 level . As the weight of wet matter consumed increased the number of bites of eating decreased . There are two possible explanations for this : (a) Table III shows that the greatest variation in dry matter content of the herbage was caused by rain before cutting . The cows were fed a weighed quantity of wet matter and it is possible that an increase in the weight of wet matter consumed was mainly due to water lying on the surface of the leaves of the grass, and not to an increase in the weight of grass consumed . In this event, a negative correlation between the weight of wet matter consumed and the number of bites of eating would be expected. (b) The increase in the weight of wet matter consumed may not be entirely due to the effect of surface water, but may be associated with a genuine decrease in the dry matter percentage of the herbage . The negative correlation may indicate that in this case less bites and possibly less energy are required to eat a given weight of grass . Under these circumstances, there would be a positive correlation between the number of bites of eating and the dry matter percentage . When calculated this correlation was found to be only -0532 . This indicates that variation in the amount of surface water on the herbage caused the correlation between the number of bites of eating and the weight of wet matter consumed, to be negative . The number of bites of eating were not significantly correlated with either the weight of dry matter or fibre consumed, although in the latter case the coefficients were sufficiently high to suggest a possible relationship, indicating that

143

food with a higher fibre content may require more chewing before swallowing . Very short grass with a low fibre content, may be swallowed without any chewing at all . The correlation between the time spent eating and the number of bites of eating was •4 563, which is significant at the -05 level . This indicates that (a) The results obtained when the time spent eating are correlated with the feed variables will be similar to those obtained when the number of bites of eating are correlated with the same feed variables . The similarity between the coefficients is shown in Table IV. (b) The correlation, although significant, shows that some variation in the speed of eating did occur, otherwise this coefficient would have been unity . The correlation coefficient between the time spent eating and the weight of wet matter consumed was - •6 166, which is higher than that between the number of bites of eating and the weight of wet matter consumed . As the weight of wet matter eaten increased, the number of bites of eating decreased, but not to such a great extent as did the time spent eating ; the cows therefore, must have eaten the greater weight of wet matter at a faster rate of jaw movement, indicating a positive relationship between the weight of wet matter consumed and the speed of eating, expressed as bites per minute . This correlation was calculated and the resulting coefficient was positive but not significant (3924) . The highest speed of eating was also associated with low dry matter and low fibre percentages in the herbage . This type of herbage is highly palatable and palatability may be positively correlated with the speed of eating . It has already been suggested that herbage with a high fibre content is unpalatable . In this experiment fibre and dry matter percentages were positively correlated . This could give the impression that herbage with a high dry matter content is unpalatable. Herbage with a high dry

Table IV . A Comparison of the Correlation Coefficients Between the Feed Variables and Bites of Eating and Time Eating Wet matter consumed Bites of eating Time eating

..

Dry matter consumed

Fibre consumed

- •5 516*

0 117

3 307

- •6 166*

0029

2244

*Significant at **Significant at

•02 •0 1



1 44

ANIMAL BEHAVIOUR, VI, 3-4 Table V. The Relationship Between the Number of Chews Cudding and the "Feed Variables" . Level of significance

5309

05

Chews cudding x dry matter consumed (fibre and wet matter held constant)

- •2 140

Nil

Chews cudding x wet matter consumed (fibre and dry matter held constant)

2794

Nil

Chews cudding x fibre consumed (wet and dry matter consumed held constant)

matter and low fibre content could be palatable and consumed in maximum quantities . It is also possible that the cows ate fastest on the low dry matter, low fibre herbage because their appetites were not being fully satisfied, it being logical to suppose that an animal will eat at a greater speed when it is hungry, than when its appetite is partially satisfied . There was also a variation in the speed of eating between the cows. On each of the five days Cow I consumed the least amount of herbage and this was associated with a low speed of eating. This suggests that the animal that eats at the slowest rate, eats the least amount of grass . The Effect of Variations in the Weight of Wet Matter, Dry Matter and Fibre Consumed on the Cudding Behaviour of Cattle Three aspects of the cudding behaviour of the cattle were recorded during this trial : (a) The number of chews of cudding. (b) The number of boli produced during cudding . (c) The time spent cudding . The total number of chews of cudding were not significantly correlated with either the weight of wet matter or the weight of dry matter consumed . The correlation between the number of chews cudding and the weight of fibre consumed

was significant . These correlations are given in Table V . It appears that the factor governing the number of chews of cudding is the weight of fibre which the animals consume . An increase in the number of chews of cudding can be associated with an increase either in the number of chews per bolus, or in the number of boli produced . There was no significant correlation between the number of chews per bolus and either the weight of fibre consumed or the fibre percentage of the diet . On the other hand that between the total number of chews cudding and the number of boli produced was •6 145, which is significant at the •01 level . An increase in the number of chews of cudding was therefore associated with an increase in the number of boll produced . Under these circumstances a positive relationship would be expected between the number of boli produced and the weight of fibre consumed . Examination of Table VI shows that although the total correlations between the number of boli and the weight of fibre consumed and between the number of boli and the weight of dry matter consumed are significant (at the •0 5 and • 1 level respectively), the second order partial correlations are not . These results suggest that the number of boli produced are significantly increased by the

Table VI . Correlation Between the Number of Boll Produced and the "Feed Variables" II r, .

Level of significance

Number of boll x wet matter consumed . .

- 1837

Nil

Number of boll x dry matter consumed . .

•4309

0.1

..

4468

0 . 05

Number of boli x fibre consumed

Number of boli x wet matter consumed (fibre and dry matter consumed held constant)

-1276

Nil

Number of boli x dry matter consumed (wet matter and fibre consumed held constant)

2 133

Nil

2681

Nil

Number of boll x fibre consumed (wet and dry matter consumed held constant)

..

DUCKWORTH & SHIRLAW : ANIMAL BEHAVIOUR RECORDS IN PASTURE EVALUATION STUDIES combined effect of an increase in the weight of fibre and dry matter consumed, although neither fibre nor dry matter have a significant effect by themselves . The fact that the correlation between fibre and boli was higher than that between dry matter and boli might indicate that fibre had the greater effect. These results indicate that the number of boli produced is dependent on the weight of the more fibrous material in the diet . Finely ground food may not be cudded at all, whereas very fibrous material may be regurgitated more than once for subsequent chewing . On a uniformly fibrous diet the number of boli produced might be related to the amount of food consumed . On a diet of grass, however, it would be difficult to utilise this relationship, since grass is a very variable material . The correlation between the time spent cudding and the total number of chews of cudding was •5 308 which is significant at the -02 level ; that between the time spent cudding and the number of boli produced was •8 781, which is significant at the -001 level . These results show that the time spent cudding is more closely associated with the number of boli produced than with the number of chews cudding. The only "feed variable" significantly correlated with the time spent cudding was the weight of fibre consumed (r= •4 44, significant at the •0 5 level) . This correlation is no longer significant when corrected for variations in the weights of wet and dry matter consumed . The Relative Merits of Time Studies and Records of Jaw Movements The correlation coefficient between the number of bites of eating and the time spent eating was significant at the -05 level indicating a relatively constant speed of eating . In this trial little advantage has been gained by recording the individual bites of eating . Hancock (1954) has shown that with the grazing animal, the intensity of eating varies considerably . Under these conditions records of jaw movements are of greater value than time studies. No significant second order partial correlation was obtained, when the time spent cudding was related to any of the feed variables . The total number of chews of cuddmg, however, was significantly related to the weight of fibre consumed, and it has been suggested that the number of boli produced was associated with the weights of both dry matter and fibre consumed . It can be concluded that the more detailed in-

145

formation obtained by the use of a recording apparatus is of greater value than that obtained from time studies alone . If time records can be utilised in animal behaviour studies, they will be obtained more accurately by using an automatic recorder, rather than relays of observers . Summary and Conclusions The results of two field trials carried out at Cockle Park Research Station during 1949 and 1950 have been described. Behaviour records on different types of sward were compared and related where possible to liveweight gains . From these results it was concluded that animal behaviour records might be of use in pasture evaluation studies, but that more basic knowledge of the subject was required . An automatic recording apparatus was developed so that experiments of a more fundamental nature could be undertaken . The apparatus has been described in a previous issue of this Journal . It has been used with cattle, housed indoors, to investigate fundamental relationships between the jaw movements of cattle and the intake of wet matter, dry matter and fibre . The results of this experiment can be briefly summarised . 1 . It appears that high dry matter and fibre percentages restricted the weight of wet matter consumed . Of the two, the fibre percentage had the greater effect, and it is concluded that the amount of fibre consumed is a major factor controlling appetite . 2 . No significant relationship between the bites of eating and food consumed was recorded . It is probable that this was largely due to the fact that the variation in dry matter and fibre percentages which did occur was caused by surface water (rain) and not to a genuine variation in the nature of the grass itself. It is important in experiments of this type that cattle are fed to appetite, and are not controlled at a level below maximum intake . Under these circumstances studies of animal behaviour and the factors affecting food intake can be studied together . 3 . There was a significant negative relationship between the time spent eating and the amount of wet matter consumed, indicating that the animals ate the greater amount of wet matter at a faster speed. 4 . The highest speed of eating was associated with herbage with a low dry matter and fibre content . i t is possible that this type of herbage

146

ANIMAL BEHAVIOUR, VI, 3-4

is palatable and that palatability is associated with speed of eating . 5 . It is suggested that herbage with a high dry matter and low fibre content could be palatable and would be consumed in maximum quantities . 6 . There was no relationship between the number of chews cudding and the weights of either the wet or dry matter consumed . There was, however, a positive correlation with the amount of fibre consumed . 7 . There was no significant relationship between the number of boli produced and the feed variables . The time spent cudding was closely correlated with the number of boli produced, and therefore, as expected, there was no relationship between the time spent in cudding and the feed variables . It is concluded that before records of jaw movements can be utilised to determine the amount and quality of food consumed, or to indicate the efficiency of grazing, a great deal of fundamental research on cattle housed indoors must be undertaken . Before studies with free grazing cattle can be commenced, it will be necessary to modify the present radio link be-

tween the animal and the recorder, to enable several animals to graze together . REFERENCES Boyd, D . A . (1949) . Experiments with leys and permanent grassland . J. Brit . Grass!. Soc ., 4, 1-10. Duckworth, J. E. & Shirlaw, D . W . (1955). The development of an apparatus to record the jaw movement of cattle. Brit . J. anim. Behav., 3, 56-60 . Graves, R. R., Dawson, J. P ., Kopland, D. V . & Mosely, T. W. (1933) . The feeding value for milk production of pasture grasses when grazed, when fed green, and when fed as hay or silage . Tech . Bull. 381, U.S. Dept . Agric. Hancock, J. & McMeekan, C . P. (1954). Studies of grazing behaviour in relation to grassland management, pt . III . Rotational compared with continuous grazing. J. agric . Sci., 45, 96-103. Hodgson, R. E . (1933) . The influence of pasture management upon the grazing habits of dairy cattle . J. agric. Res., 47, 417-424 . Johnstone-Wallace, D . B., & Kennedy, K . (1944) . Grazing management practices and their relationship to the behaviour and grazing habits of cattle . J. agric. Sci., 34,190-197 . Jones, M. G. (1928) . Comparison of pastures by means of sheep. Welsh J. Agric ., 4, 183-205 . Woodman, H . F . (1954). Rations for Livestock . Bul. 48, Min. Agric. Fish . Fd. Accepted ,for publication 19th August . 1957 .