TROUBLE AMONG EWES

Dominion, Volume 30, Issue 41, 12 November 1936, Page 20

TROUBLE AMONG EWES

Hitherto Unrecognised Disease Discussed

CAUSE NOT ASCERTAINED

A disease affecting lactating ewes, which is marked by loss of condition, weakness, anemia, cessation of milk secretion, and usually death, is the of discussion by Mr. Allan Leslie, F.R.C.V.S., formerly head of the veter inary department of Lincoln College, m the second of his articles interpreting information gathered during researc^.''° r 1 at the college. The trouble was hitherto unrecognised. . , . The complaint usually appears about three to four weeks after lambing, and the course of the disease is general y spread over a few days to a tortnight, Mr. Leslie states. A brief description of the trouble was first given in the Canterbury Agricultural College , half-yearly veterinary research report (Marea, 1935). The immediate cause has not yet been revealed, although the conditions under which it develops are well defined. Available information shows that the trouble is definitely associated with the amount of milk the ewe produces as measured by the growth gains of the progeny. The condition is preventable by good pregnancy feeding or by extra care in management and feeding when this is not possible. Opinions of Sheepmen. Observant sheepmen in Canterbury, Otago and Southland have been able to supply information about seasonal loss from this trouble. Their views about causation and the factors which predispose were varied but of sufficient interest to record here. Among the various causes attributed to the condition were parasitic disease, death of the lamb causing the milk to “go through the ewe,” some form of plant poisoning, too rich feed, and mineral deficiency. Support for the view that the trouble was due to parasitic disease was based partly on the symptoms —loss of condition, weakness, scouring and death —and partly on tbe fact that heavy lotw of lambs and hoggets from worm parasites had occurred on the same pastures six months previous to the ewe deaths. Our own investigations have shown that worms were not responsible. A widely-held view that loss of the lamb always preceded death of the dam has since been found to be incorrect. Many ewes die at a time when the lamb is able to forage for itself. Recent work shows that death of very young lambs prior to death of the dam is generally due to inanition, the ewe having gone dry. The plant poisoning theory was based on circumstantial evidence only. Hillcountry men were more in favour of this idea because it was quite common for the ewes on the lowlands to develop the disease when those on the hills remained healthy. It was imagined that lowland stock had a better chance of getting some unknown, plant. Other Theories. The too rich feed hypothesis had most supporters. It was freely stated that the incidence was highest when there was an abundance of pasture. The view that a mineral deficiency was a possible cause was based on the observation that affected animals pined and wasted away. More interesting were the views regarding the parts played by the feed supply and its distribution, weather conditions, management and the number of offspring the ewes were rearing. The opinion was general that the trouble was commonest in the spring and early summer seasons, with an abundance of growth, and rare when the spring growth came away slowly. Dull weather seem, ed to favour the trouble. Hill-country men with adjoining lowlands claimed that the disease was confined rather rigidly to the ewes wintered on tussock, but subsequently shifted to richer feed on the flat at lambing. The disease "was considered to be rare among ewes wintered on the hills and. left there after lambing. Our own experiences are confirmatory of these views. It was freely stated that the best milking ewes were the most susceptible, and that, under intensive farming methods, twin bearers were more prone to attack than single bearers. Lambs of ewes that developed the complaint were usually doing remarkably well until interference with milk secretion occurred. Symptoms and Treatment. In the early stages the symptoms are vague and indefinite. The wool presents a bleached appearance, and the animal is dull and listless. Later signs of scouring are evident. In some eases a slight scour is the first noticeable symptom; it may persist when the feed is luscious. The appetite is good in the early stages, but later becomes variable, and is eventually lost. As the disease undermines the constitution of the ewe the milk yield decreases. Often affected ewes go dry sometime before death, but all do not die. Evidence of drying off is seen in the appearance, thrift, and growth rate of the progeny. When a large number of ewes are affected in a flock it is not unusual to see 20 or more lambs of only a few weeks old grazing together unconcerned about their dams. These lambs usually show evidence of having a good start in life. Later they become pot-bel-lied and unthrifty. Consequently the economic importance of the disease should not be assessed merely on the number of ewes that die.

Although the cause of this disease has still to be discovered, sufficient information has been collected to show that it is not only preventable but much can be done with flocks that are affected. According to field and experimental observations, the control of the trouble (save for isolated cases) seems to depend on balanced and adequate feeding during pregnancy, or, when this cannot be done; on controlling the Seed supply after lambing. The object of regulating the diet after lambing is to prevent excessive stimulation of milk in with depleted reserves, so that not produce unduly at the expense of their bodies. On one hill-country property evidence has been obtained which suggests that the trouble can be prevented by using a lime-phosphate-salt mineral mixture all the year rouud and exercising care iu making changes iu the diet after lambing. It stands to reason that dietry changes should be gradual for stock with low reserves, as the elimination of mineral matter in the milk is in' excess of that taken in the food no matter how good its quality may be. On lowland properties the feed supply after lambing may be controlled by rotational grazing. It can be made more binding by using hay and oat-sheaf chaff.