ARCHIVE FILE
This article was published in 1959
See the original document
INSTITUTE OF INSPECTORS OF STOCK OF N.S.W. YEAR BOOK.
Infertility in Sheep Grazing on Red Clover
E. A. FARLEIGH, B.V.Sc., Veterinary Inspector, Glen Innes
INTRODUCTION
Up to recent years many reports from various workers in Western Australia would have suggested that infertility associated with grazing of clover-dominant pastures was limited to that State. However, this has been found to be incorrect since 1952, when infertility similar in many respects to the findings in Western Australia was seen in the Northern Tablelands of N.S.W. The outstanding difference was that the infertility is associated with red clover and not subterranean clover.
The nature of the disease is identical with the findings as reported by C.S.I.R.O. (1952):—
1. Failure of ewes to become pregnant despite repeated service.
2. Lambs dying within several hours of birth, and dystocias caused by ewes making little or no attempt to deliver lambs.
3. Prolapse of the uterus.
4. Udder and milk development in both virgin ewes and wethers.
An additional finding which is contrary to that of Bennetts (1958) is that three Jersey-cross steers on one property showed definite udder development. This consisted of fatty tissues, with no secretion of milk in evidence.
The oestrogenic principal found in Western Australia has been identified as an isoflavone known as genistein, which is not a true oestrogen but what is known as a pro-oestrogen. (C.S.I.R.O., 1952.)
Genistein has been isolated from both red and sub.clover and shown to be oestrogenic. Bradbury and White (1954.)
CASE HISTORIES
Property No. 1
The holding is situated 10 miles north-west of Glen Innes, N.S. W.; on red basalt country and purchased in 1950.
No pasture work had been done in previous years but large areas had been growing fodder crops such as oats and maize. A programme of pasture improvement was carried out from 1951 onwards. Nearly 800 acres now are sown out of 2,000. Red clover has, in the main, been the clover of choice, with phalaris and perennial and Italian rye. White and subterranean clover form part of the mixture in some paddocks. Red clover has become well established over the years and has dominated the pastures.
The lambing percentages from 1950 to 1956 show a rapid fall as the country improved.
TABLE 1.
Lambing Percentages, 1950 to 1956
In a test-mating carried out early in 1957, 21 ewes which had failed to lamb in 1956 were served with raddled rams and 7 lambs were born.
In 1957, more accurate figures indicating the causes of the low lambing percentages were available.
In one mob of 103 Border Leicester-cross ewes mated with Dorset Horn rams, 98 lambs were marked-95%. These sheep had been purchased in 1954.
Of 307 strong wool Merino ewes which consisted of 20% of the original ewes and descendants of the original flock, 71 lambs were marked (23%). In this mob, six ewes prolapsed and 22 died. 54 dead lambs were counted; so that roughly 40% of lambs were dropped but many failed to survive.
405 (2,4 and 6-tooth) Merino ewes, joined to Merino rams, resulted in 185 lambs being marked (40%). There appeared to be little difference in the 4 and 6-tooth groups as far as troubles were concerned, but it appeared that few of the 2-tooths were in lamb.
In this mob, 11 ewes died, 4 had prolapses and 59 dead lambs were counted.
Early in 1958, a number of uteri were collected from ewes that were considered infertile and were sent for slaughter. In one consignment of 41 uteri, only one showed any cystic condition. Each of three adjacent cotyledons bore a distinct cyst, the largest being 3/16" in diameter. Six uteri showed thinning of the walls and uterine enlargement; the general appearance suggesting twin pregnancies except that there was no sign of cotyledonary development or other evidence of gravidity. This has not been reported in "Clover Disease" cases before.
The result of the 1958 lambing, which was a semi-drought year showed some improvement and supplementary feeding was carried out with oats during the winter. The comparison of various paddocks is set out hereunder:—
TABLE 2.
Lambing Difference in Selected Paddocks
| Paddock No. 7 | Paddock No. 3 | Paddock No. 1 | |
|---|---|---|---|
| No. of Ewes | 118 | 152 | 127 |
| Lambs Marked | 75 | 81 | 140 |
| Dead Lambs | 9 | 10 | 25 |
| Dead Ewes | 1 | 1 | 16 x |
| Percentage Marked | 64.4 | 53.3 | 79 |
x (Nine due to suspected Pregnancy Toxaemia.)
The sheep in paddock No. 1 were bought only one month before lambing and were in fat condition. 25 ewes had to have assistance at lambing. The difference in the lambing percentages is marked.
This year a pilot flock of 200 sheep has been selected; consisting of groups of 50 2-tooth, 50 4-6 tooth, 50 aged ewes and 50 aged ewes from Paddock 1 that were bought last year. A comparison of mating behaviour by raddling rams, and the lambing, will be watched closely.
Difficulties at lambing over the years have been failure of the cervix to dilate, and failure of the ewes to deliver the lamb due to apparent lack of interest. The owner reported that the ewes commence to lamb, then cease trying and rejoin the mob. This could be due to uterine inertia.
Property No. 2.
This property is of only 160 acres. There are 70 acres sown to pastures and a further 50 acres are top dressed but not sown. 40 acres are natural grass. Pastures were sown first 7 years ago and consisted mostly of red clover and rye grass. Subterranean clover was sown 4 years ago but apparently did not do well and has since been discarded in any mixture.
The owner experienced trouble soon after sowing his pastures and the low percentages and difficulties at lambing resulted in his ceasing to breed 4 years ago. His practice since has been to buy ewes in lamb and raise lambs from them.
In 1958, however, he mated 93 ewes which had been born on the property; mostly 3 and 4-year-old, and some 2 years old. These had been run as dry sheep since birth and never had been mated. At the same time he mated 57 ewes that had been bought the previous year in lamb and had marked 75%. Table 3 shows some of the differences between the bred and bought sheep following the 1958 lambing.
TABLE 3.
Comparison of Bought and Bred Sheep
| 93 Bred Sheep | 57 Bought Sheep | |
|---|---|---|
| Dead Lambs | 28 | 2 |
| Dry Ewes | 18 | 2 |
| Caesarian operation | 12 (3 died) | Nil |
| Died unable to lamb | 6 | Nil |
| Percentage marked | 31 | 84 |
12 ewes were assisted at lambing and most lambs lived. 100 lambs were marked; giving a total of 66% from both mobs.
Difficulties at lambing were due to the failures of the cervix to dilate and lack of interest of the ewes to attempt to lamb.
During the Caesarian operations it was noted that a cystic condition of the endometrium of the uterus was in evidence, so particular notice was taken in later operations; these being carried out by a private practitioner.
All cases examined showed the typical cystic condition. Specimens submitted to Glenfield Research Station resulted in the following report: "Uterus showed very marked lesions considered typical of "Clover Disease" as originally described by Bennetts et al. of Western Australia. These were prominent, endometrial cysts, ranging in size from about ¼" by ½". Some of the smaller ones were in the intercotyledonary spaces, while larger ones were mainly close against the cotyledons; two or three sometimes occurring together."
Examination of wethers on the property over the years has shown a high percentage secreting milk and showing definite udder development. Prosthitis has been a constant trouble here for some years, and some trials to treat this condition were conducted on the property in 1956.
DISCUSSION
It appears that in the New England region of NSW., red clover causes the same "Clover Disease" as reported by Bennetts in Western Australia. What is not explained, however, is why the condition is apparently not more widespread, as red clover is one of the dominating species in many pastures throughout this area and the pasture pattern on the properties investigated does not appear to differ from that found on many other properties.
The infertility apparently is permanent, but the development of cysts was much more noticeable on the second property investigated.
The C.S.I.R.O. at Chiswick, Armidale, has co-operated by taking pasture samples from several paddocks on Property No. 1 and is comparing the oestrogenic content of the red clover with the content in red clover on Chiswick itself. Results are not yet to hand with regard to these analyses.
SUMMARY
The presence of Clover Disease on two properties in the New England region of NS.W. due to Red Clover is discussed.
The apparent affect on steers, a difference from the Western Australian findings, is mentioned.
The appearance of the uteri suggesting twin pregnancies has not been reported elsewhere.
REFERENCES
Bennetts. H. W. (1958)-"A Nutritional Dilemma": 12
Bradbury, R. B. and White, D. E. (1954)- Vit. and Horm., 12; 208
C.S.I.R.O. (1952)-- Infect. Dis. in Sheep Grazing on Sub. Clover, 2; 6.