The importance of nutrition as a factor in resistance of sheep to certain parasites was emphasised by Dr. I. Clunies Ross, director of the McMaster Animal Health Laboratory, University of Sydney, at yesterday's session of the annual conference of Inspectors of Stock.
Considerable addition had been made to the knowledge of distribution of the more important parasites of sheep during the last two years, said Dr. Ross. It was now evident that the northern distribution of certain of the large bowel parasites of sheep was prevented by rainfall and temperature differences of the north compared with the south. One worm, for example, which was very prevalent in the southern States of the Commonwealth and in southern New South Wales, had not been found further north than Goulburn. On the other hand, a large bowel parasite went further north to the central tablelands. There was also evidence that certain small bowel parasites of sheep were able to develop at low winter temperatures, and this fact influenced the production of harmful effects by these in the early spring.
Much information had also been gained as to the pathogenic importance of certain species about which little was previously known. It had been found that the small stomach and intestinal worms could cause fatal infections in Iambs and that the symptoms shown in such cases were very different from those caused by the large stomach worms. The large bowel parasite was also found to be capable of causing marked effects in young lambs.
There was no doubt that one of the most effective means of controlling losses was by improved nutrition, added Dr. Ross. The most satisfactory method of achieving this was the improvement of pastures. In certain cases where sheep had been run on improved pastures there was little to choose in body weight between treated and untreated sheep, although the treated animals showed a slight increase in wool production. The quantity and quality of wool were probably a more sensitive indication of the effects of parasite infestation than body weight. Trials in Tasmania showed that although the body weights of sheep treated and untreated for a certain parasite were approximately the same, the former group produced only between 6 and 15 per cent. of tender wool, whereas the untreated lot cut 59 per cent. tender fleece.
Owing to the somewhat revolutionary nature of the views expressed, and the fact that hand feeding has commenced in some parts of the State, the address by the senior veterinary surgeon of the department (Mr. C. J. Sanderson), on drought feeding of sheep, was of particular interest to the stock inspectors.
"When production is aimed at," stated Mr. Sanderson, "it is difficult to feed too much protein, yet when simply keeping the animal alive is the object it is easy to feed too much. The object of drought feeding should be to limit the ingestion of protein to the maintenance requirements of the animal only. The success of the maize feeding of sheep in experiments conducted by the department was due probably to its proteins being suitable for maintenance but not for growth. This drought feeding experiment may have far-reaching results. Its success has already upset the conviction that sheep could not be fed on grain alone for an extended period. Further, it has demonstrated that sheep do not require bulk in their ration and roughage to fill their large digestive organs and promote digestion.
"It would seem that experimental work In feeding sheep in very dry times must be concentrated in discovering the minimum protein requirements of sheep at various ages," added Mr. Sanderson. One of the lessons to be learned is that concentrates containing large percentages of protein are certainly not required, and indeed do more harm than good. The feeding of proteins demands the provision of other food constituents in quantities to balance the ration, and it must be remembered that the main object of drought feeding is to keep the animal alive at the least possible cost."
Whilst dealing with the general subject of stock licks, Mr. Sanderson gave an example of what a "go-getter" salesman was disposing of to farmers. An analysis of a specific salt lick, claimed to be a tonic and a proved preventive of fluke, worms, and black disease, showed it to be 95 per cent. soluble in water, and 5 per cent. insoluble in water. Of the soluble portion 91 per cent. was found to be common salt, whilst the solid fraction consisted of charcoal, free sulphur, calcium carbonate, iron compounds, and a small amount of vegetable matter. The price of the lick was £11/5/ a ton f.o.r. Sydney. It would be noted that, except for very small amounts of other ingredients, the lick consisted of common salt, which, for stock purposes, varied in price from £4/5/ to £7/12/ per ton. The main risk of using such a mixture was that purchasers would probably put their faith in it, and neglect to use the approved cure recommended by the Department.
Mr. Sanderson was emphatic on the necessity for the correct feeding of cattle. There was a tendency today to move away from the microbic cause of sterility, for instance. It was conceivable that poor methods of feeding and rearing calves, combined with a premature mating, played a big part in the ultimate poor breeding capacity of the animal.
The control of specific diseases of animals in the State was provided for by the Stock Disease Act, said Professor J. D. Stewart. The enforcement of any legislation which interfered with the business activities, and perhaps the privileges of the people, was always resented unless the objects were properly appreciated. In regard to laws affecting diseases of animals Inspectors of stock had exceptional opportunities. Being brought into actual contact with the persons directly affected they were able to justify the necessity for the application of certain restrictions by explaining the nature of the disease. A sympathetic acceptance of the inevitable was further encouraged by pointing out how the Department was able to help them to overcome the trouble. He said, "help them" advisedly because there seemed to be a growing tendency on the part of stock owners to look to the Department to carry out all that was to be done without any expense, and at very little inconvenience to themselves. This attitude was quite wrong as an outbreak of disease was really a personal misfortune to the stockowner, the cost of which he must bear as with other misfortunes. The lawful concern of the Department was to see that certain specific diseases of animals were controlled, and, If possible, eradicated for the benefit of the State as a whole.
With regard to the incidence of disease, there were predisposing causes capable of inducing a certain condition of the system, or group of organs which rendered them susceptible to disease. These predisposing causes were often hereditary, and the recognition of this fact by stock breeders provided them with the first line of defence. In the past many breeders had gone in for "in-breeding" and "line-breeding" to increase production without due regard to the fact that such an increase threw additional strain on the system. Unless a sound constitution was maintained, the vitality of the progeny was lowered.
Feeding must always be considered, continued Professor Stewart. It mattered not how well a beast might be bred; it could not develop to the full and fight against disease unless it received sufficient nourishment. Mineral deficiency diseases often offered complex problems owing to the inter-dependence of the mineral elements In fodder. If a ration already contained sufficient of any mineral matter a further supply might not only lower the dietetic value of the whole, but lead to diseases of the kidneys.
In stressing the importance of good animal husbandry in the prevention of disease, Professor Stewart said that "Keep the young beast thriving" was a good motto to follow. This applied particularly to dairy cattle, yet it often happened that a heifer from a high test cow failed to come up to expectations simply because she had been insufficiently fed and cared for from weaning. Moreover, she often came In affected with tuberculosis. Finally, a good sanitary environment would prevent the incidence of those diseases, grouped generally as "filth diseases," more effectively than any method of vaccination. Any tendency to allow vaccination to become a substitute for cleanliness should be strongly combated.