Lice On Cattle Cause Economic Loss

Press, Volume CIV, Issue 30793, 3 July 1965, Page 9

Lice On Cattle Cause Economic Loss

(Bu

M. C. ARMSTRONG,

livestock superintendent of the

(Oy M. v*. AnoiJ itwiw, nvesiuGn, auptJU»tci»ucrti uj Department of Agriculture, Christchurch.)

Insidious economic loss from undetected lice infestation retarding growth and causing unthriftness in young beef cattle occurs frequently in late autumn, winter and early spring in all cattle-raising districts in New Zealand.

Infestations are most commonly due to the long-nosed sucking louse of cattle, called Linognathus Vituli, which is an active blood sucker. Its effects on the animal are loss of appetite, anaemia, weakness and loss of weight. Although other species of cattle lice do exist, namely, biting lice and short-nosed sucking lice, the general effects on the host and the control measures required are similar for all species. The biting lice do, however, cause greater irritation as a rule.

The long-nosed sucking louse is the largest cattle louse and it Is dark blue in colour. In moderate infestations it lays eggs most commonly on the dewlap, shoulders, neck, back, and the udder. The biting louse, called Damalinia Bovis is a small reddish-coloured louse which is commonly found at the base of the tail, on the shouders and along the back. The small blue sucking louse, called Solenoptes Capillatus, is commonly found about the head and neck, under the tail and around the anus. All these species of lice are specific for cattle and spread of infection is by contact with lousy cattle. Covers As infestations on cattle may be favoured and spread by covens, it is necessary to be on the look-out for trouble from lice when covers are being regularly used. It is important to remember that lice cannot live away from their hosts for more than a few days and that lousy sheep will not infest cattle and vice versa. The life cycle of cattle lice is a simple one in which the eggs hatch out within seven to 13 days after being laid, and the cycle from the egg of one generation to that of the next requires from 23 to 29 days for completion. As insecticides do not kill the eggs it is necessary, therefore, to repeat spraying or dipping with insecticide at a 17-day interval to get maximum eradiction from cattle, the skin and hair of which will not retain the insecticide for the same length of time as with sheep. Poor Freeing Field observations indicate that cattie lice tend to increase under conditions of poor nutrition and during hard cold winter climate when the intensity of daylight is low. The microclimate of the skin is favourable when the hair is long and thick. Infestations are most common and most important on cattle out on pasture where supplementary feeding is either absent or limited to a hay ration. Although the intention of this article is to alert beef cattle graziers to the importance of the control of lice on beef cattle over the winter-spring period, it must be pointed out to dairy farmers that young dairy cattle may become similarly infested by lice with consequent unthriftiness. Cattle graziers are strongly recommended to spray all cattle, especially voung cattle, with insecticide in late autumn, preferably in May of each year, as a routine

management practice to prevent heavy winter infestations of lice from building up. In the harder winter feed and climate areas a further preventive spraying in early August is recommended as good sound routine management. Unthrifty cattle infested with lice must be treated by spraying them with an insecticide and also by drenching them with an anthelmintic to control internal parasites. The advice of a veterinarian should be sought to obtain a recommendation for the best insecticides and anthelmintics from both the efficiency and economy points of view. Lice infested cattle also require a repeat spraying with insecticide at an interval of 17 days to kill the maximum number of newly hatched lice from eggs unaffected by the first spraying. Depending on facilities available, economic circumstances and numbers to be handled, the spraying can be carried out by simple hand pump, pressure pump with a gorse gun attachment, or a multiple nozzle cattle spray race which can be either fixed into the yards or mounted on a trailer as a mobile unit. In some dis-

tricts contractors have evolved mobile spray races capable of handling about six adults or 12 weaners at a loading. Experienced cattle owners in several districts are of the opinion, however, that elaborate spraying apparatus is not essential for successful application of the insecticide. A gorse spraying gun attached to a small motor driven pump feeding from a 44-gallon drum is adequate. About 30 to 40 head of cattle should be placed in a small yard with room to move freely and the operator can thoroughly wet them by spraying from a foot plank on the surrounding rails—necks, dewlaps and escutcheons should receive special attention. About one gallon of fluid is required per head for weaner cattle. Mixtures Special cattle insecticide mixtures containing detergents or adhesive ingredients are available and the modern insecticides for controlling lice on sheep may also be used successfully by the addition of a small amount of liquid detergent to facilitate penetration and adhesion.

Some modern insecticides must not be used on dairy cattle in milk because of the danger of residual contamination of the milk with insecticides dangerous for human health. Owners of dairy milking cows should not treat them with insecticides without the approval of a veterinarian or livestock instructor.