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Volume 59, 1928
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The Soil and Pasture in Relation to Pining and Bush Sickness in Sheep.

By R. E. R. Gremmett and Beatrice W. Simpson. (from Department of Agriculture, New Zealand, and the Rowett Research Institute, Aberdeen.)

(Communicated by B. C. Aston.)

The account given by McGowan (1) of “pining” in sheep, a disease which occurs in certain areas particularly in the south of Scotland, shows that there are many points of similarity, both in the symptoms and in the general environmental conditions under which, this disease is developed, with the disease of “bush sickness” as it occurs in New Zealand. The prediction was thus made by Aston (1924) that these two diseases may be of a similar nature (2).

As a result of a six months' transfer of one of us (R. E. R. Grimmett) from New Zealand to the Rowett Institute in 1927, under a grant from the Empire Marketing Board, an opportunity arose for the application of his experience of the soil and pasture conditions of “bush sickness” areas in New Zealand to a study of the related aspects of “pining” in Scotland. He accordingly spent some days in examining the field conditions in a “pining” area, and was fortunate in seeing “pining” sheep, some of which were recovering under treatment by administration of iron ammonium citrate. Samples of pasture were collected, with special precautions to avoid contamination by soil, and a large quantity of soil was obtained from one of the best known and most typical porphyrite “pining” hills. This was transferred to Aberdeen for use in pot experiments.

It has been shown by Aston (2) that the onset of “bush sickness” in sheep and cattle is due to the stock grazing upon pasture which has an abnormally low iron-content, although apparently not deficient in other respects and noted for its fattening qualities. The extreme anaemia which results may be cured by administering suitable iron compounds, such as iron ammonium citrate, or by removal of the stock to pastures rich in iron. The animals can then be returned to the former grazing and will thrive for a considerable period, before needing to be changed again.

Work by Aston and one of us (R. E. R. Grimmett) (2 and 3) has shown that “bush sickness” and iron-deficiency in New Zealand pastures are apparently to be associated with certain definite physiographic and soil-conditions, such as, a sandy soil with less than 5% of clay, resting on a pervious sub-stratum elevated considerably above the permanent water-table in a region, usually of fairly extensive level or undulating hill top, where the annual rain-Jall is high. Under such conditions, favourable to soil-aeration and leaching, the total amount of soluble iron in the soil at any one time is small, and it is only the pasture growing on the lower seepage areas which is rich in iron. The soil of the Patetere Plateau in the Roto-

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rua District, a typical “bush, sickness” area, is derived from rhyolite pumice, resting on a porous rhyolite tuff. Typical pasture and soil analysis from this area have been recorded by Aston (2). (Cf. Table 4).

In this connection it may be noted that McGowan (loc. cit.) in Ins description of typical “pining” country in Scotland, written at a time when he was unaware of the work on “bush sickness,” might have been outlining many of the features of typical “bush-sick” country in New Zealand. Thus he states that waterhead farms are generally free from “pining,” and, on the other hand, where only a small amount of green inflowland is present about stream sides, or tax arrangement of the fencing prevents sheep grazing on this herbage, such conditions favour the disease. Further (unpublished personal communication), he had observed the anaemia and on the basis of other work had made arrangements for the administration of iron to the effected sheep. These tests fell through for the time being, but subsequently further opportunity arose (in the summer of 1927) and the shepherd in charge reported a beneficial result from the administration of iron ammonium citrate.

Following on the observations of McGowan on “pining” an investigation, the details of which have not as yet been published, has been progress at the Rowett Institute into the relative mineral-contents of pasture from “pining” and “non-pining” areas, and in general the results show that the iron content is lower in the “pining” than in the “non pining” herbage. Certain results also suggest some difference in the manganese content. In this connection, in sampling pasture in “pining” and in “non-pining” land it must be noted that the herbage of a “non-pining” area is not necessarily all “non-pining.” The preventive condition may be due to the stock grazing for a portion of the time upon herbage growing on seepage areas or banks of streams in the main grazing, such herbage being relatively rich in iron. Such areas, being small, are liable to be overlooked in sampling, and thus faulty conclusions may be drawn from the analytical results. These areas should be sampled separately, in addition to taking samples from the main grazing, and any difference in composition should be borne in mind when considering differences between “pining” and “non-pining” pastures from the same locality.

When sampling pastures for iron and manganese analyses, special care must be taken to Bee that the herbage collected is free from soil or other contamination likely to affect the iron and manganese figures.

Strong evidence has been advanced by Dickenson (4) that King sand “coasty disease” is of the same nature as “bush sickness” and on that island the affected soil is largely composed of shell grit with up to 50% of calcium carbonate in the soil. This is of interest as it has been found that the application of lime to “bush sickness” pastures does not improve the pasture and materially increases the severity of the disease, presumably owing to the depressing action of the lime upon the solubility of the iron salts. (Cf. Gile (5) and Johnson (6).)

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Present Investigation.

The work outlined briefly below, while admittedly preliminary in character owing to the short space of time available, has brought out one or two points of interest. It has followed two main lines, namely (1) a series of pot experiments (2) a study of certain soils and pastures from “pining” and non-pining” areas and a comparison with cultivated pasture.

Pot Experiments.—This series of experiments, which formed the main line of work, was designed to test the effect of various chemicals when applied to the soil or culture medium, on the iron and manganese content of the crops. The main points tested were the effect of (a) lack of drainage (b) the application of organic matter (c) the application of iron in various combinations (d) the application of sulphur either in the free state or as ferrous sulphate (e) the application of lime, on the composition of the crops. These factors were chosen in view of the results obtained in the “bush sickness” investigation.

Five series of pots were set up: in three of which sand was the medium, in the fourth “pining” soil, and in the fifth arable soil was used. The sand was of granite origin from an Aberdeen pit. The nature of the “pining” soil will be referred to later. The arable soil was from a field in the Institute farm. Ordinary 11′ flower pots were used and these were well coated on the inside with, high melting point paraffin wax prior to filling, in order to prevent any contamination from the pot. Where drainage was not wanted the holes at the base were stopped up with corks soaked in wax. The arrangement of the pots in four of the series is shown in Tables 1-3, where the analytical data for the crops are given. The results of the other series are omitted owing to lack of growth. This was the series where 5% of humus mixture was incorporated with the sand, some of the pots being drained and some undrained. The pots in the series where sand was used were inoculated with two ounces of “pining” soil.

The experiment was started on August 14th, each pot being planted with 4 oat seedlings, 4 pairs of mustard seeds, 3 red clover seedlings and 3 cocksfoot seedlings, but only the oats and the mustard grew. The pots were out in the open until September 12th, when owing to inclement weather, they were taken into a room in the building. They were watered from time to time, as required, with distilled water, all the drained pots being treated alike in this respect. Growth having ceased by October 24th, the plants were cut ½” above the soil level, the oats and mustard being kept separate. The crop from each pot was weighed green; again after drying at 100°, and on the dry material, determinations were made of total ash, iron, and manganese. For the methods of analysis, see paper by Godden and Grimmett (7).

The analytical data for the different series are set out in Tables 1, 2, and 3.

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Table 1.
Series “A.” Each pot contained 24 lbs. of sand on top of 1 lb. of granite chips.
Subseries (a) drained Subseries(b) undrained
Treatment and Crop Crop Wgt. Dry Gms. Percentage on Dry, Matter Crop Wgt. Dry Gms. Percentage on Dry, Matter
Ash Fe. Mn. Ash Fe. Mn.
1. Control, Oats 0.573 17.32 0.025 0.011 0.808 17.27 0.019 0.082
Mustard 0.504 20.30 0.028 0.011 0.187 19.85 0.027 0.033
2. Ferric Oxide, 2cwt. Per acre. Oats 0.729 18.52 0.019 0.009 0.709 17.37 0.020 0.072
Mustard 0.290 19.22 0.027 0.007 0.363 18.37 0.021 0.029
3. Ferric Oxide, 2 cwt. And sulphur 1cwt. Per acre Oats 0.601 21.53 0.017 0.027 0.725 18.28 0.025 0.091
Mustard 0.556 22.64 0.032 0.022 0.066 18.07 0.057 0.069
4. Ferrous Sulphate 1cwt. Per acre. Oats 0.706 16.20 0.020 0.019 0.749 18.78 0.023 0.092
Mustard 0.252 18.92 0.026 0.010 0.350 18.34 0.038 0.032
5. Ferrous Phosphate 1 cwt per acre. Oats 0.676 18.14 0.021 0.012 0.628 18.15 0.023 0.078
Mustard 0.418 21.57 0.028 0.007 0.211 18.34 0.032 0.034
6. 5% of K “ball clay” and 1 cwt. Ferrous sulphate per acre. Oats 0.483 15.86 0.020 0.029
Mustard 0.918 21.07 0.015 0.007

The sand contained 1.14% Fe2O3 and 0.019% Mn2O3 soluble in concentrated hydrochloric acid and only a trace of each soluble in citric acid.

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Table 2.
Series “D” Each pot contained 24 lbs. of “Pining” soil* on top of 1 lb. of “Pining” stones. The analytical data are for the oats-only.
Crop wgt (Dry) Grams. Percentage of Dry Matter.
Ash% Fe.% Mn%
1. Control, undrained 0.100 13.84 0.025 0.280
2. Control, drained 0.188 15.97 0.017 0.0181
3. Ferrous sulphate 1 cwt. Per acre 0.175 16.02 0.022 0.169
4. Basic slag. 2½ cwts. Per acre 0.390 18.95 0.018 0.213
5. Ppd. Chalk, 5.2 tons per acre 0.950 20.11 0.019 0.051
6.Sulphur, 2½ cwts. Per acre 0.191 15.69 0.020 0.170
7. Superphosphate, 2½ cwt. Per acre- 0.372 19.47 0.021 0.195

[Footnote] * For analysis of this soil see Table.

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Table 3.
Series “E.” Each, pot contained 24 lbs. arable soil* on top of 1 lb. granite chips.
Crop Wgt. (Dry) Grams. Percentage on Dry Matter
Ash% Fe.% Mn.%
1.Control—
Oats 0.224 17.87 0.020 0.013
Mustard 0.529 20.00 0.043 0.006
2. Ppd. Chalk 3.1 tons per acre—
Oats 0.194 16.93 0.032 0.007
Mustard 0.764 22.13 0.038 0.005

A comparison of the results for the crops which, grew show that, in most cases, the percentages of iron is higher in the mustard, than in the oats, while the reverse is true for manganese.

In the sand-cultures (Table 1) the various chemicals applied appear to have had but little effect during the relatively short time of growth, except that sulphur, either free or as sulphate, has slightly raised the percentage of manganese in the crop.

Drainage conditions, during the relatively short period of growth, had no influence on the percentage of iron, but on the other hand had a marked effect on the manganese content of the plant. Thus the manganese content of the oats from the undrained pots (Series A, Table 1) is on the average about six times that of the oats from the drained pots. The difference in the mustard is slightly Jess. The water-logged and mildly reducing conditions appear to have had more effect on the manganese than on the iron, in rendering it available. This might be expected as the higher oxides of manganese are known to be more readily reduced than those of iron.

It will be noted that the addition of 5% of clay in pot 6 of this series had no definite effect on either the iron or the manganese content of the crop.

The series grown on the “pining” soil (Series D, Table 2) offers the most interesting comparisons. On this soil the mustard seedlings failed to grow, possibly owing to their higher requirements of iron, and in the limed pot became markedly chlorotic prior to dying off. The iron content of the crop is throughout fairly uniform in all the pots. Again, however, the manganese is much higher in the oats grown in the undrained pot. The application of lime, on the other hand, has definitely depressed the percentage of manganese in the crop. Other manurial treatment appears to have been without effect in this direction. It should be noted that, while the percentage of iron in the crop from this series is approximately the same as that in the crop grown on sand, the percentage of manganese is more than ten times as high in the crop grown on “pining” soil, as that grown on sand. This high manganese content was apparently reflected during the ashing of the crop, the material burning with almost explosive violence.

[Footnote] * This soil gave:—Clay. 1.25%. Loss on ignition, 11.52%. Total, Fe2O3 3.05% Mn2O3 0.11%, and had a lime requirement equal to 0.31% CaCo3.

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The chief point in the case of the plants grown in the arable soil is the alteration in the iron-manganese ratio. Both the oats and the mustard grown on the arable soil have a higher percentage of iron than manganese, the reverse being true for the crops on the “pining” soil.

The percentages of iron and manganese in the sand, “pining” and arable soils, taken in conjunction with the percentages of these elements in the crop grown in these media suggest that the manganese is more easily taken up from the soil by the plant than is iron.

Soils and Pastures.—Samples of pasture from “pining” and “non-pining” areas in the same locality were collected with all precautions to avoid soil contamination, and the soil underlying the “pining” grazing was also sampled. A large sod was also cut out from the “pining” pasture. It was transferred to the Institute and divided into two portions. One half was planted in soil brought from the same area as the turf and the other half was planted in arable soil from the Institute farm. These cultures were made in wooden boxes. After removing the old growth they were left out in the open and from each turf two cuttings (the first on September 17th, and the second on October 6th) of the new growth were taken when the grass was about 2′-3′ high. The cuttings from each box were mixed and analysed. The results from the two samples were practically identical and it could hardly have been expected that the change in the underlying soil could produce any effect in so short a time. They serve, however, to show that the turf was uniform in character and these turves will be kept through the winter and during the next season will be cut regularly to imitate sheep-grazing and the material analyzed to determine whether changing the subsoil has had any influence on the iron and manganese content of the herbage.

The results of the mechanical and chemical analysis of the “pining” soil are given in Table 4 and for the purposes of comparison similar data for two samples of soil from “bush sickness” areas in New Zealand (Cf. Aston loc. cit.) are quoted.

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Table 4.
Analysis of “Pining” and “Bush-sick” soils.
Mechanical Analysis.
“Pining” Soil. “Bush-Sick” Soil
% (S/181)% (R/976%
Fine Gravel 15.75 1.3 19.8
Coarse Sand 16.74 30.5 38.8
Fine Sand 15.82 27.4 14.9
Silt 18.16 18.6 8.4
Fine Silt 11.40 8.5 5.3
Clay 1.10 2.3 0.8
Moisture 8.94 1.6 1.0
Loss on Ignition 11.16 9.8 9.1
Matter Soluble in Dilute HCI. 0.96 — —
100.03 100.0 98.1
Stones and Gravel 31.3 4.5 13.6
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Chemical Analysis. (On soil dried at 100°).
Nitrogen 0.45 0.222 0.255
P2O5 (Total) 0.14 0.01 0.03
P2O5 (Available) 0.023 0.004 0.002
K2O (Total) 0.46 0.07 0.08
K2O (Available) 0.024 0.015 0.019
CaO Total 0.061 0.44 0.47
MgO Total 0.45 0.15 0.20
Fe2O3 (Total) 2.60 — —
Fe2O3 (Cit. Sol.) 0.052 0.103 0.04
Mn2O3 (Total) 0.19 — —
Mn2O3 (Cit. Sol.) 0.043 — —
Lime Requirement 0.52% CaCO3 —

The following additional figures from “bush-sick” soils are given for comparison.*

Mn2O. (total) (L 1122) 0.43%
Mn2O3 (total) (L 1123) 0.39%
Mn2O3 (citric soluble) (Te Pu and Mamaku) 0.03—0.06%
Fe2O3 (total) (Te Pu and Mamaku) 1.00—1.39%
Lime Requirement (K 446) 0.37% CaCO3
Lime Requirement (H 513) 0.38% CaCO3

It will be seen that the Scottish “pining” soil and the New Zealand “bush-sick” soils have a very similar mechanical composition. They are sandy silts or of coarser texture, with a clay content of 2% or less. The “pining” soil is more amply supplied with available phosphate and potash, but has less lime, though more magnesia. The lime requirement of the “pining” soil is high (5.2 tons of CaCo3 per acre) and this is indicated by the nature of the flora, which consists mostly of fine-leaved fescue but no clover. The citric soluble iron in both types of soil is low, although the iron soluble in hydrochloric acid is higher in the “pining” than in the “bush-sick” soil.

Table 5 shows the composition of the herbage from “pining” and “non-pining” areas in the same locality and for comparison the fissures are given for the herbage from a cultivated field at the Institute sampled at about the same date.

[Footnote] * See Transactions New Zealand Institute, vol. 44, p. 298. New Zealand Journal of Agriculture, vol. 17, p. 259, vol. 28, p. 387.

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Table 5.
Pasture Samples, Percantages on Dry Matter.
“Pining” Grass. Porphyrite Hill% “Non-pining” Grass. Sandstone Hill.* % R.R.I. Cultivated Grass. Laich Field. %
Dry Matter 100 100 100
Nitrogen 3.14 2.72 3.70
Total Ash 6.79 6.63 7.26
CaO 0.32 0.56 1.12
Na2O 0.03 0.04 0.48
K2O 3.58 3.31 2.67
P2O5 0.91 0.66 0.89
Cl 0.63 0.79 0.79
Fe 0.013 0.014 0.025
Mn 0.106 0.049 0.016
So3 1.01 1.13 0.94

The herbage from the “pining” pasture shows a similar iron content to that of this “non-pining” pasture, but has a ranch higher manganese content. The cultivated grass has a much, higher iron and a much lower manganese content than either of the other samples. The manganese: iron ratio shows very considerable differences, being 8:1 in the “pining” grass, 3.5: 1 in the “non-pining” grass, and 0.64: 1 in the cultivated grass.

These results are borne out by a number of analyses previously made of other samples of grass from “pining” soil and “non-pining” areas in the south of Scotland, the figures for which were,

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Range: of Variation.
Iron Content. Manganese Content. Mn: Fe Ratio.
“Pining” Grass “Non-pining” 0.005—0.013 0.038—0.064 7.6—3.9
Grass 0.011—0.024 0.026—0.050 4.2—1.7

Whilst it may be suggested that the nature of the flora may have some influence on the iron content it is doubtful if this is the principal factor. Thus although the above “pining” herbage was of poor quality botanically and devoid of clover, the New Zealand “bush sickness” herbage was of good quality and contained abundance of clover, and yet both had a very poor iron content.

“Whether the high manganese-iron ratio in the “pining” pasture has any significance or not, it is not yet possible to say. Very little is known at present as to the influence of a high manganese content or a high manganese-iron ratio of a diet on the health of stock. An investigation is, however, in progress at the Rowett Institute along these lines and will, it is hoped, throw further light on the subject. It may be a point of interest to note in passing, that, in the pot experiments, the application of lime, which on such highly acid soil as that in the “pining” areas might be expected to give a marked improvement in the herbage, resulted in a decided diminuition in the

[Footnote] * This “non-pining” area included some seepage and streamside pasture which was not separately sampled.

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manganese content of the crop without affecting the iron content which was already at a low level.

Summary.

The pot experiments recorded above are admittedly tentative and cover too short a growing period. It is hoped, however, to continue the work and obtain the results for mature plants. In the meantime it appears that on a given culture-medium lack of drainage is the most potent factor in increasing the manganese content and the manganese: iron ratio of the crop. Liming on the other hand tends to decrease both of these.

It would appear desirable to make a fuller survey of soils and pastures of the “pining” districts with a view to correlating soil texture and the physiographic features of the country with the iron and manganese content of the herbage and to make a further study of the effects of liming and of the application of iron-rich fertilizers.

We desire to acknowledge our indebtedness to Dr. J. B. Orr, Director of the Rowett Research Institute, and to Mr. W. Godden in whose department the work was carried out, for facilities granted, and for their interest taken and advice given in this investigation, and to Dr. J. P. McGowan for placing at our disposal his wide knowledge of “pining” disease.

References.

(1.) McGowan, J. P. and Smith, W. G. (1923). Scottish Journal of Agriture, 5, 274.

(2.) Aston, B. C. (1912) Trans. N.Z. Inst., 44, 288. (1924) Trans. N.Z. Inst., 55, 720. N.Z. Journal of Science and Technology, 1, 216. N.Z. Journal of Agriculture, 28, 215, 301, 381; 29, 14, 84, 333, 369. (1925) N.Z. Journal of Agriculture, 30, 1. (1926) N.Z. Journal of Agriculture, 32, 365. Trans. N.Z. Inst., 56, 733. (1927), N.Z. Journal of Agriculture 35, 96, Trans. N.Z. Inst., 58, 179. 536.

(3) Grimmett, R. E. R. (1927) N.Z. Journal of Agriculture, 34, 289.

(4.) Dickenson, C. G. (1927), Australian Veterinary Journal, 3, 82.

(5.) Gile, P. L. (1920), Journal of Agric. Research, 20, 33.

(6.) Johnson, M. O. (1924), Hawaii Agric. Experim. Stn. Bull. No. 52.

(7.) Godden, W. and Grimmett, R. E. R. (1928) Journal. Agric. Science (in press).

Since the above was written a considerable amount of fresh information concerning the calcium content or pastures and the effects upon the animal of a calcium-deficient diet has been gathered. In view Of the very low calcium content of the “pining” pasture and the high lime requirement of the soil, it therefore seems possible that in this case the Iron deficiency may be accompanied and the ill effect upon the animal aggravated by a deficiency of lime. The interesting possibility would thus arise of a simultaneous deficiency of mineral elements whose action under the peculiar soil conditions existing is such, as to render them to a considerable extent mutually exclusive. This suggestion, which owing to considerations of distance. Is made upon the responsibility of R. E. R. G. alone, is rendered more feasible by the fact that in areas adjoining those where “pining” exists, other workers have reported various obscure troubles in sheep, which are suspected of being due to some mineral deficiency. It will be noted that the herbage from the cultivated field has double the quantity of lime found in that from the “non pining” sandstone hill, which in turn has nearly double that found in the herbage from the “pining” porphyrite hill.

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