Montgomery Clover Effect On Lambing

Press, Volume C, Issue 29554, 1 July 1961, Page 6

Montgomery Clover Effect On Lambing

T> ROLONGED grazing ot 1 ewes on a pure Montgomery red clover stand at Massey Agricultural College in 1959, and again in 1960 prior to, and during tupping, resulted in later lambing and a lower lambing percentage compared with ewes on ryegrass and white elover. Describing this experiment at the college's sheepfarmers' conference this week, Mr T. S. Chang, a lecturer in the sheep husbandry department, said that while it had been shown that a problem, existed under these rather extreme experimental conditions, he would not say that the same would happen under practical farming conditions. The Montgomery clover stand was sown in the spring of 1958, and at the beginning of January, 1959, one group out of an even line of five and a half year-old east-for-age Romney ewes was put on the clover, and another group of similar size went on to a ryegrass and white clover pasture. The elover group remained on this pasture until the end of April or beginning of May, when they were shifted back with the other group. Teaser rams with marking crayons were put out with the two

groups when they went on to the respective pastures. It was found that in 1959 the ewes grazing red elover lambed on an av- ! erage 17 days later than the other group and in 196« six days later, and over the two seasons the lambing percentage of the clover ewes was 53 per cent, less at birth (86 per cent, compared with 138). and 51 per cent, less one day after birth (71 per cent compared with 122 per cent). Was red clover really to blame? asked Mr Chang. A comparison of body weight of the two groups of ewes over the December to April-May period showed that the clover ewes maintained a fairly steady weight while the other ewes dropped back fairly sharply, but Mr Chang explained this by saying that on three occasions the ewes on ryegrass and white clover had had to be shut up on account of facial eczema danger, while those on the clover, which had a low spore count, had not had to be shut up, and an examination ot livers from the latter group showed that they had been unaffected by

Lave-weigiht was not the culprit, said Mr Chang. Similarly, the rams could not be held responsible as the three used had been rotated around the two groups at weekly intervals. On the o'her hand it had been found that Montgomery red clover contained an oestrogenic substance, which was a female sex hormone. Tests of samples of the clover with mice showed that it was highly oestrogenic. In excess this had some effect on the reproductive system of the ewes, but it was not known exactly what that effect was. The trouble was not due to failure or irregularity in the ewes coming into season, and only time would tell whether it was with fertilisation of the eggs or at implantation or in some other respect. Mr Chang said he had used a long period ot red clover grazing to show whether or not a problem existed. He said that he would Mke to proceed further with ewes being grazed on the clover for a month, two months, three months and four months to determine how much of the clover had to be taken to have the effects recorded in this experiment—whether It was only one blade or several hundred.