CATTLE BENEFIT FROM SPRAY

Press, Volume CIV, Issue 30745, 8 May 1965, Page 9

CATTLE BENEFIT FROM SPRAY

A TRIAL carried out in Victoria last year using a spray containing diazinon, which has been specially formulated for use against lice on beef cattle, points to the usefulness of spraying liceinfested cattle.

It is reported that the lice problem is also widespread in New Zealand, but is one which farmers, in the main, have done little about. A North Island farmer was recently concerned about the condition of his cattle and it was only after two had been killed and specimens sent to Wallaceville research station without result that it was noticed that the hide of the second beast was alive with lice. Every beast on the property was then sprayed and there was immediate improvement in their condition, particularly in those that had been in a run-down state.

The trial was conducted by Mr J. G. Mulholland, technical supervisor of Agserv Industries Pty., Ltd., of Melbourne,

on' Mr James Richardson’s Nerrin Nerrin station, 50 miles west of Ballarat. On June 23 last year, 92 Hereford and 15 Aberdeen Angus yearling heifers were weighed, e’artagged and randomly subdivided into three groups. One group of 36 animals was sprayed once and another group of similar number, which was sprayed the same day, was also sprayed for a second time on July 9. The third group of 35 was left untreated as a control. A oneinch gear pump developing a pressure of 1001 b per square inch and two spray pistols were used. The cattle were brought into a circular yard in batches of about 10 and the spraying was done by two operators standing on either side of the yard. An over-all coverage was achieved with particular care being taken to wet the head, brisket, underline, and escutcheon. About three-quarters of a gallon of spray mixture was applied per beast. All groups were drenched within a week of the initial weighing, and all remained on similar paddocks until the end of the trial on October 1.

Whereas the control group gained an average of 68.41 b, or 0.6841 b per day in this period, the group that had been sprayed once gained an average of 78.51 b, or 0.7851 b per day, or 14.8 per cent better than the controls, and the twice sprayed group showed an average gain of 116.41 b, or 1.1641 b per day, or 70.2 per cent better than the controls. At the conclusion of the trial very few lice could be found on the control group while no evidence of lice could be found on the other two groups. “The dying out” of lice in the control group might have been due to the warmer weather experienced towards the end of the trial period, said Mr Mulholland, as it was known that cattle lice were affected by dessication and would die out when ambient temperatures went above 70 degrees Fahrenheit. However, it was noted that the control group was rough in the coat, having retained most of the winter hair, whereas the other groups had shed most of their winter hair. This latter characteristic was considered to be an indication that cattle were doing well and might have been quickened by the freedom from external parasites.

The highly significant differences between the two treated groups supported the recommendation that for the eradication of lice within a season it was necessary to repeat spraying at an interval of 14 to 17 days so that all stages of the life cycle of the parasites were adequately covered by the residual effect of the spray chemical.

The insignificant results obtained by single spraying in June indicated that such treatment was inadequate to control lice for that season. However, a single spraying might be worthwhile if carried out in mid August. This would help to reduce the lice population and associated irritation and would be followed by a natural “dying out” of lice towards the end of September. As fat cattle were not used in the trial only an estimate of the economic gain from spraying could be made, said Mr Mulholland. However, it was felt that these results would apply equally to cattle being fattened and on an arbitrary figure of £l2 per 1001 b for young beef (this is an Australian study) and a dressing percentage of 50 per cent the gross returns from two sprayings would be an average of 57s 7d per beast. The chemical cost per beast for two sprayings was B|d so that the average net return per beast, excluding labour, was about 56s lOd. Hidden effects of spraying such as less pelt damage caused by rubbing against sharp objects and less damage to fences would also be classified as a return.

Mr Mulholland concluded from this work in Australia that it was an economical proposition to spray cattle at an interval of 14 to 17 days for control of cattle lice. One spraying in June with this chemical was not sufficient to give control. As the life cycles of cattle lice began in the late autumn and early winter it was recommended that spraying should be done at the end of May or in the early June period. It is suggested that for most farmers in New Zealand a gorse gun or a jetting gun would be suitable for spraying cattle.