NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
WOOL-GROWTH IN SHEEP AS AFFECTED BY DIET
261
In so far as fibre-lengths affect the appearance of staple-length in such wools,
these figures illustrate one aspect of the difference between the groups. The
change in production, considered from the standpoint of fibre-length alone, was
marked in the basal-ration group, and the feeding of the starch supplement con-
ferred a small but significant advantage in respect of growth in fibre-length.
If the short fibres are included, this distinction between the groups tends to
be diminished and the effect of the different nutritional levels is reduced. The
position in respect of mean fibre-lengths with short fibres included is summarized
in Table VI.
TABLE VI.
Mean fibre-lengths, including short fibres.
Pre-experimental . . . . . . .
Experimental. . . . . . .
Per cent. change, mean. . . . . .
Group I
8.98
5.30
41.0
S. E.
±0.29
±0.30
±3.01
Group II
9.29
6.07
33.8
S.E.
±0.40
±0.26
±3.42
This points to the conclusion that the difference in production on the sample
areas was expressed more in other ways than in mere length of fibre grown, so that
the other factors of average fibre-fineness, and, possibly, the number of fibres
produced (i.e., number of active follicles) have to be taken into consideration.
(d) Average fineness. After counting and measuring the fibres, the sub-samples
were washed in benzene and their clean-dry weights were determined. From the
calculated total lengths of fibre and these weights, the values for fineness expressed
as length (in cm.) per unit weight (mgm.) were derived.
Even under ordinary conditions, some change in fineness might be anticipated
in all the animals, as the growth-periods cover two different stages in the matura-
tion of the lamb's coat. The two groups at the outset were well balanced as
regards fineness, and it will be seen that the different metabolic levels produced
markedly dissimilar effects. In all animals, except No. 19 (Group II), the wool
was distinctly finer at the end of the feeding period, and there is some general
262 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [IV, III
similarity between the changes in individual fineness and those in individual body-
weight (of. Tables I and VII).
TABLE VII.
Average fineness.
Group I
Animal
1
3
5
7
9
11
13
15
17
20
Mean
S. E.
Pre-exptl.
112
132
104
116
118.5
88
113
143
97
117
114.1
±5.02
Exptl.
167
206
159
163.5
191
124
175
281
159
132.6
175.8
±13.97
Per cent.
change
+49.4
56.1
52.9
41.0
61.2
40.9
54.9
96.5
63.9
13.3
53.0
±6.64
Animal
2
4
6
8
10
12
14
16
18
19
..
..
Group II
Pre-exptl.
89
114
94
105
98
113
119
125.5
114
162
113.4
±6.51
Exptl.
144
140
120
112
117
144
144
146
127
161
135.5
±4.95
Per cent.
change
+ 61.8
22.8
27.7
6.7
19.4
27.4
21.0
16.3
11.4
—0.6
21.4
±5.32
Differences of means : pre-experimental, 0.7 ; experimental, 40.3 ±14.82 ; percentage changes, 31.6 ±8.51.
These figures not only show responses of different magnitudes in the two
groups, there being less alteration of fineness in the starch-supplement group,
but also indicate a differential response as between length-growth and fineness.
In Group I the reduction of growth conditions to the basal ration led to a difference
in fibre-length production of 41 per cent. and a difference in fineness of 53 per cent.;
whilst in Group II the effect of the starch supplement was to limit the orders of
the reductions to 33.8 per cent. in length and 21.4 per cent. in fineness. That is
the administration of the starch supplement gave a level of fibre-production which
was nearer to that under pre experimental conditions, by affecting both fibre-
length and fineness ; but the proximity to the pre-experimental growth in Group II
(as compared with Group I) was achieved more by encouraging the coarser (less
fine) growth than by sustaining the fibre-length growth. In other words, the
WOOL-GROWTH IN SHEEP AS AFFECTED BY DIET
263
fibres tended to respond to the starch supplement more in the direction of greater
thickness (' diameter ') than in greater length-growth.
(NOTE :—The values for fineness as expressed in cm./mgm. are inversely proportional to the squares of
fibre ' diameters.') So far as the average fibre-growth is concerned, the situations are epitomized in
the average fibre-volumes produced under the two nutritional levels.
(e) Average fibre-volume. The factors of mean fibre-length and average fineness
can be combined to give measures of the volume of fibre-production. On the
assumption that the density of the fibre-substance remains constant in wools of
the same type, average fibre-volume is proportional to mean length upon average
fineness. These values are shown in Table VIII.
TABLE VIII.
Average fibre-volume.
Pre-experimental . . . . . . .
Experimental . . . . . . .
Per cent. change, mean.
.
.
.
.
Group I.
0.080
0.032
60.2
S. E.
±0.0048
±0.0034
±3.53
Group II.
0.085
0.045
44.3
S. E.
±0.0059
±0.0028
±4.46
Since in Group I the change in mean length was of the order of 41 per cent.,
the remainder of the average change in fibre-volume, i.e., 19 per cent., must be
attributed to change in ' diameter '; similarly in Group II, with length accounting
for 34 per cent., the ' diameter ' may be considered as contributing 10 per cent. to
the average change in fibre-volume. Thus in the decrease of fire-growth due to the
basal ration, the growth in respect of length contributed approximately twice as
much as the change in thickness or ' diameter ', whilst in the decrease on the pre-
experimental condition of the starch-supplement group, the change in length was
responsible for about three times as much as the change in ' diameter'
The changes in the total production of clean wool on the defined areas (see
Table IV) were of the order of 67 per cent. and 50 per cent. in Groups I and II,
respectively, so that in each case there appears a margin beyond that attributable
to alterations in average fibre-volume. The practical difficulties in recording with
accuracy any actual change in the extent of a defined skin area on the living
animal preclude the possibility of estimating contributions from such a source.
Also differences in the amount of medullation present in the fibres affect the accu-
racy of the estimates of average fineness and fibre-volume.
(f) Estimated number of active follicles. The possibility of change in the
number of follicles actively producing fibres on any area has been frequently
264 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ IV, III
neglected in studies of wool-growth although such a phenomenon may conceivably
occur according to age, season, or nutritional supply to the follicle, and has been
demonstrated in the guinea-pig [ 12 ]. The observation that the starch-supplement
group tended to exhibit denser and bulkier staples, which was confirmed when the
samples of different wools from different areas were examined by an experienced
wool buyer, emphasized the desirability of considering this factor. As with the
other fleece characters, any difference between the two groups could reasonably
be attributed to the effects of the ration.
The estimates of number of active follicles were made from the clean-dry
weights of the sample and the zoned sub-sample, and the number of fibres included
in the latter.
TABLE IX.
Estimated number of active follicles (00 omitted).
GROUP I
Animal
1
3
5
7
9
11
13
15
17
20
Mean . .
S. E. . .
Pre¬
experi¬
mental
652
666
517
534
546
358
692
955
453
484
586
±52
Esperi¬
mental
558
523
422
473
414
323
473.5
779
384.5
397
475
±40
Per
cent.
change
—14.4
21.5
18.4
11.4
24.2
9.8
31.6
18.4
15.1
18.0
18.3
±2.02
Animal
2
4
6
8
10
12
14
16
18
19
..
..
GROUP II
Pre¬
experi¬
mental
524
551
492
379
335
756
784
908
688
822
624
±62
Experi-
mental
467
444
465
325
265
688
785
851
648
723
566
±63
Per
cent.
change
—10.9
19.4
5.5
14.3
21.0
9.0
+0.1
—6.3
5.8
12.0
10.4
±2.07
Differences of means : pre-experimental, 38 ± 81; experimental, 91 ± 75; percentage changes.
7.9 ± 2.89.
WOOL-GROWTH IN SHEEP AS AFFECTED BY DIET 265
Whatever may be the causes of the changes in the number of active follicles, as
shown by these estimates, the numbers are apparently lower in the basal-ration
group than in that receiving the starch supplement, although the differences are
not significant. Regarded from the aspect of percentage changes in individuals, the
alterations in Group I are greater than in Group II suggesting that this factor may
have contributed to the margin in fleece-production over and above that assessable
to the output of fibre-substance (volume) by the active follicles.
CONCLUSIONS.
The advantage in respect of gross fleece-weight conferred by adding the starch
supplement to the basal-ration is shown from the study of the defined sample areas
to be largely due to the greater activity of the follicles in the elaboration of fibre-
material. When the difference in fibre-production is expressed in terms of the
average fibre-volume, the starch-fed group showed a decrease on their performance
pirior to experiment of 44 per cent., as contrasted with a diminution of 60 per cent.
in the basal-ration group. (This omits the distinction due to the different periods
of time of pre-experimental and experimental growth.) The margin of difference
between the order of such estimated change in fibre-volume and that of the amount
of clean wool produced is possibly attributable to an- alteration in the number
of follicles which are actively producing fibres. In Group I, on the basal-ration,
18 per cent. fewer follicles were estimated to be operative, whilst in Group II the
estimated diminution was 10 per cent.; in the former, those which were producing
were doing so at the rate of 0.032 volume-units during the experimental period ; in
the latter their average volume-production was 0.045 units.
The mean length of fibre, all fibres included, did not differ significantly in the
two groups, but if the shorter fibres (which conceivably contribute little to the ap-
parent staple-length) are neglected, the average growth on the sample areas of
the starch-fed group was about 1 cm. longer than that on the areas of the basal-
ration group. The difference in rate of production due to the starch supplement
was manifested more as a difference in the fineness of the fibres, in the sense that
the fibres were maintained at a fineness nearer to their pre-experimental value than
were those grown in the basal-ration group the respective differences being, in
length. Group I 41 per cent. and Group II 34 per cent., and in fineness 53 per cent.
and 21 per cent.
DISCUSSION.
The addition of starch to the maintenance ration of young Cheviot sheep
produced a significant increase in both fleece-weight and body-weight. The increase
of fleece-weight was largely due to a definite increase in fibre-thickness, a slight
266 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ IV, III
increase in fibre-length, and possibly also to an increase in the proportion of follicles
sctively elaborating fibres. Additional carbohydrate in the diet therefore led to the
increased production of a substance predominantly protein in nature.
The depression of wool-production in the basal group might presumably be due
to one of two causes :—
(a) The protein in the diet might have been used mainly for supplying
energy. The influence of starch in increasing wool-production would
then be an illustration of the well-known protein-sparing action of
carbohydrates.
(b) The activity of the wool follicles might have been depressed by the low
energy-content of the basal diet. The addition of the starch would then
have increased the metabolic activity of the follicles, leading to increas-
ed rate of elaboration of their characteristic product.
The theoretical question at issue is whether the depression of wool-production
in the basal group was due to decreased activity of the wool-follicle, or to a defi-
ciency of the substances required for the material expression of that activity. It
is possible that both factors were involved.
The results of the experiment have an important practical application to
pastoral conditions. Owing to the protein nature of wool, it has been widely as-
sumed that reduced wool-production must be associated with deficiency of protein
in the pasture. Yet under drought or other famine conditions where sheep are
losing weight it is evident that any protein supplement fed will be used in the
first place as a source of energy. It is therefore obviously equally efficacious, and
usually more economic, to feed the cheapest available carbohydrate supplement of
high caloric value. Such a supplement, in the light of the experiment here record-
ed, may be expected not only to maintain normal body-weight, but normal wool-
production as well.
SUMMARY.
(1) One group of ten growing sheep was fed on a maintenance ration. A
second group of ten was fed on the same ration supplemented with maize starch.
(2) The starch produced a significant increase in both body-weight and gross
fleece-weight.
(3) The increase in gross fleece-weight was reflected in the weight of clean
wool.
(4) This increase was due to a definite increase in fibre-thickness, a slight-
increase in fibre-length, and possibly also to an increase in the proportion of folli-
cles actively elaborating fibres.
WOOL-GROWTH IN SHEEP AS AFFECTED BY DIET
267
(5) Theoretical interpretations and the practical applications of the experi¬
mental results are discussed.
ACKNOWLEDGMENTS.
We are indebted to Mr. J. Barritt, of the Wool Industries Research Associa-
tion, for nitrogen-estimation of the starch fed, and to Mr. W. Thomson, of the
Rowett Research Institute, for his care of the sheep throughout the experiment.
REFERENCES.
1. J. I. Hardy and J. B. Tennyson, J. Agric. Res., 1930, 40, 457.
2. J. F. Wilson, Nat. Wool Grower, 1931, 21, 23.
3. A. D. Weber, Proc. Amer. Soc. Animal Production, Jan. 1932, p. 228.
4. H. R. Marston and T. Brailsford Robertson, C. S. T R., Austral, Bull. No. 30, 1928.
5. H. R. Marston, C. S. I. R.,.Bull. No. 61, 1932.
6. A. H. H. Fraser and J. A F. Roberts, J. Agric. Sci., 1933, 23, 97.
7. J. E. Duerden, V. Bosman, and P. S. Botha, 18th Report of Dir. Vet. Services and Animal
Industry, Union S. Africa, 1932, p. 631.
8. P. J. Du Toit, A. I. Malan, and J. W. Groenewald, 18th Report of Dir. Vet. Services and
Animal Industry, Union S. Africa, 1932, p. 611.
9. A. T. King, Trans. Faraday Soc., 1933, 29, 258.
10. A. T. King and J. E. Nichols, Trans. Faraday Soc., 1933, 29, 272.
11. J. A. F. Roberts, J. Text. Inst., 1930, 21, T. 127.
12. D. H. Strangeways, J. Agric. Sci., 1933, 23, 359.
ON THE INCIDENCE OF STOMACH WORMS IN LAMBS IN THE
NORTH OF SCOTLAND AND THEIR CONTROL BY PROGRES-
SIVE SECTIONAL GRAZING.
BY
DAVID ROBERTSON, PH.D. B.Sc. (AGR.), N.D.A.,
Lecturer in Agricultural Zoology, North of Scotland College of Agriculture
AND
ALLAN H. H. FRASER, M.D., M.B., CH.B., B.Sc.,
Rowett Research Institute, Aberdeen.
(Reprinted from the Journal of Helminthology, Vol. XI, No. 4, October 1933 )
INTRODUCTION.
Recent investigations carried out by the senior writer on the incidence of para-
sitic helminths in the alimentary tract of sheep in the north of Scotland have
demonstrated heavy losses in lambs due to parasitic gastritis. In the autumn
of 1932 six severe outbreaks were recorded in the counties of Kincardine, Aberdeen
and Moray, but no doubt this number would have been greatly exceeded had it
been possible to make a comprehensive survey. Some idea of the severity of the
disease may be judged by the fact that several farmers lost from 10-20 per cent. of
their lambs.
The usual predisposing cause was observed in each case, namely, over-stocking
attended by failure to move the lambs on to fresh ground when symptoms of
parasitic infestation were apparent.
Postmortem examination of diseased lambs revealed that the lesser stomach
worm, Ostertagia circumcincta was present in very much larger numbers than any
other parasite. O. trifurcata sometimes occurred in small numbers but no attempt
was made to separate the two species. The Table below gives the numbers and
species of helminths found in two typical cases of parasitic gastritis.
A further 6 untreated lambs from different areas were autopsied but no record
of the actual numbers of worms present was taken. A close examination of the
abomasum contents was made, however, and in each case the number of O. circum-
cincta far exceeded that of H contortus or any of the intestinal worms found
present. It may, therefore, be concluded that parasitic gastritis in lambs in the
north of Scotland is mainly due to O. circumcincta and that any control measures
( 268 )
STOMACH WORMS IN LAMBS AND THEIR CONTROL
269
directed with a view to checking the disease should be carried out against this
parasite.
TABLE I.
Showing the number and species of helminths found in the intestinal tract of 2 lambs
suffering from parasitic gastritis.
Organ
Abomasum
Small intestine .
Large intestine .
Caecum . .
Species
Ostertagia circumcincta
.
.
. .
Hœmonchus contortus
.
.
.
.
Nematodirus
filicollis
.
.
.
.
Trichostrongylus vitrinus .
.
.
.
Cooperia curticei
.
.
.
.
.
Monodontus trigonocephalus . . .
Chabertia ovina
.
.
.
.
.
Oesophagostomum venulosum . . .
Trichuris ovis
.
.
.
.
.
NUMBER
Morayshire
Killed
26th October
1932
16,930
53
1,238
256
98
7
19
8
8
Kincardineshire
Killed
16th September
1932
18,110
76
1,981
162
354
2
26
..
12
The fact that in Scotland H. contortus occurs in sheep in relatively small num-
bers compared with O. circumcincta is not without interest. Generally speaking in
U. S. A. and South Africa the reverse is the case, H. contortus being more important
from an economic point of view than O. circumcincta, although according to a recent
report on parasitic diseases in U. S. A. (1932) the lesser stomach worm is stated to
be more common in some parts than others, particularly on the West Coast. A
similar state of affairs exists in Australia, for according to Seddon and Ross (1929),
H. contortus is of the greatest importance as the cause of parasitic gastritis in New
South Wales and Queensland, but to a less extent in the Southern Australian States
where infestation with O. circumcincta appears to be more common.
The literature on the control of stomach worms by the administration of
anthelmintics is extensive and it is well known that H. contortus can be readily
controlled by dosing with copper sulphate. Unfortunately O. circumcincta is much
less susceptible to the action of anthelmintics and no drug which will remove this
parasite effectively from the abomasum has as yet been discovered.
Control of stomach worms by a system of folding pastures has long been advo-
cated, and some of the results obtained by this method for H. contortus have been
270 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ IV, III
highly successful. Such a system of control is based on the nature of the life cycle
of the parasite, which has been worked out in detail by Veglia (1916). There does
not appear to be any complete account of the life cycle of O. circumcincta, but most
workers are of the opinion that it follows the same course as H. contortus in which
the succession of events is as follows :—
The eggs laid by the mature females in the abomasum reach the ground in the
fæces and the larvæ hatch out in about 24 hours. These feed on certain bacteria
in the fæces and must pass the next two stages of their development on the ground
before they are capable of infecting the sheep. The time taken to reach the infec-
tive stage may vary from 3 days to several weeks, depending on the temperature
and degree of moisture present.
It can be readily understood that the time taken for the newly hatched larvæ
to reach the infective stage is the all important factor in regard to the introduction
of any system of control by progressive sectional grazing of the pastures. In this
connection Taylor (1929) states for both H. contortus and O. circumcincta that,
' although in this country development would rarely be delayed because of excessive
dryness, the temperature is usually below that best suited to the larvæ and it can
only be in our warmest weather that they reach the infective stage in less than 10
days'.
Assuming that the larvæ of O. circumcincta require a period of ten days to be-
come infective it follows that any system of progressive sectional grazing whereby
the lambs are shifted on to clean pasture every 10 days should give complete con-
trol. Before advising control measures along these lines, it was decided to carry
out a preliminary experiment with a view to gaining information on the following
points:—
(1) The extent to which stomach worm infestation of lambs can be reduced
by a system of progressive sectional grazing.
(2) Whether 10 days is a safe maximum period to allow between successive
shifts in reducing infestation from O. circumcincta.
(3) The degree to which lambs can become infected when put to graze with
their infested dams on clean pasture.
The experiment was undertaken jointly under the north of Scotland College of
Agriculture and the Rowett Research Institute, the latter providing all facilities for
the investigation.
PLAN OF THE EXPERIMENT.
A three acre field of excellent third year's grass which had never carried sheep
was fenced into equal portions. Both portions were on a gradual slope and compar-
able in every respect as regards grazing and drainage.
STOMACH WORMS IN LAMBS AND THEIR CONTROL
271
Six Blackface ewes and their twelve twin Greyface lambs approximately six
weeks old were put into one half of the field on 25th May 1932, and allowed to
graze over the whole 1½ acres up to the 28th August 1932.
TABLE II.
Showing the number of eggs per gram of fœces from lambs at 6 weeks old.
P.=Progressional group
P. 1=85
P. 2=66
P. 3=66
N. P.= Non-progressional group
N. P. 1=75
N. P. 2=52
N. P. 3=81
An equal number of ewes and lambs were allowed to graze only 1-10th of the
other half at one time, the ewes and their lambs being changed to clean sections at
10-day intervals. A temporary fence of sheep stakes and wire-netting served to
confine the animals.
Both groups of lambs were selected as nearly alike as possible with respect to
age, weight and condition. The average weights of the progressional and non-pro-
gressional groups were 23.4 lbs. and 23.9 lbs. respectively.
Prior to the commencement of the experiment the ewes and lambs were sub-
mitted to fæcal examination for the presence of stomach worms. Fæcal cultures
demonstrated the presence of a moderate to heavy infestation of both H. contortus
and O. circumcincta in all the ewes.
Three lambs from each group were submitted to egg counts by the Stoll method
(Table II). The fæces were removed by hand, the method being to insert the small
finger into the rectum.
Since it is not possible from an examination of eggs to determine the species of
worms present, fæcal cultures were made. Approximately 90 per cent. of the
migrating larvæ were identified to be O. circumcincta, the remaining 10 per cent.
being Nematodirus and Trichostrongylus species. A lamb from the same source and
similar in age and weight to those submitted to fæcal examination was autopsied
and examined for helminths. The abomasum yielded 76 O. circumcincta but no
H. contortus, while the small intestine, colon and cæcum contained no helminths.
It may be concluded therefore that both groups of lambs commenced the experi-
ment with an initial infection of helminths consisting almost entirely of O. circum-
cincta.
G