During the Autumn of 1942 on parts of the Liverpool Plains was growing a heavy crop of Pat Hen. Practically no other vegetation could be seen. In the month of May conditions had become dry; the Fat Hen had matured, and was hard, fibrous and carrying heavy seed heads.
On several holdings where these conditions existed lambing had commenced about early April. In one case investigated 400 merino ewes with about 380 crossbred lambs up to eight weeks old at foot were grazing on this black soil country and feeding practically a whole diet of this dry weed. So far as could be seen there were no ill effects upon the ewes other than that they had practically no milk for their lambs.
In the case of the lambs the affect was quite different. It was seen that about 20 per cent. of these lambs were suffering from some muscular incoordination. They walked with a proppy gait. In some cases only the fore feet were effected, in others the hind legs only, in some both fore and hind were involved. In the latter cases the lambs were mostly seen to be lying down and would only hobble along if forced to walk. If forced to travel they rapidly got worse and would lie down refusing to stand or walk. The back was arched, the tall raised and constipation was present. No fever or other evidence of sickness was noticeable.
One or two of the badly affected cases were selected; they were slaughtered and a post-mortem conducted, which revealed that the blood, flesh, and all viscera were apparently normal, except the rumen which was distended with this weed in a doughy state. The omasum small and contracted; the almtnasum being full of the same weed, and in the same solid state. The stomach was packed to its full capacity. Little gastritis or enteritis was present.
There is little doubt that ingestion of this Fat Hen in its dry state had caused impaction giving rise to a toxic condition, setting up the symptoms described as above.
As this weed was growing practically all over this run and in the same state as in the paddock where this trouble occurred, it was impossible to remove the lambs to relief country. It was decided to give to them a laxative drench in their water, molasses and epsom salts being put in the drinking trough, and a feed supplement in the form of cut hay was also fed. Shortly after this the trouble disappeared.
Similar cases of this condition existed on several holdings on this type of country. The same symptonts and post-mortem lesions were seen in each case investigated, the same relief measures proving to be satisfactory in each instance.