The relation of certain pelleted feeds to bovine hyperkeratosis

Four tons of feed were mixed and then pelleted in one-ton lots. Two of the tons, Lots A and B, were pelleted with the rolls of the pellet mill lubricated with a lubricant (Lot I) that contained no chlorinated naphthalenes. Two calves were assigned to each lot of pellets and individually fed the amount of pellets they would eat twice daily. These calves remained normal throughout 135 days of feeding. There was no evidence of toxicity of these pellets.

The other two tons of pellets, Lots C and D, were pelleted with the rolls of the pellet mill lubricated with a lubricant (Lot II) that contained 3% of highly chlorinated naphthalenes. Two calves were assigned to each of these lots of pellets and were individually fed the amount of pellets they would eat twice daily. All of the calves developed clinical symptoms and gross and microscopic lesions of bovine hyperkeratosis. Lots C and D pellets were toxic when fed to calves under the conditions of this experiment.

Two calves were given oral administrations of the lubricant (Lot I) that contained no chlorinated naphthalenes. They each received a total of 50 grams of lubricant in 10 gram doses given in a period of eight days. These calves remained normal throughout the 56-day feeding period. This demonstrated that Lot I lubricant which was used in pelleting of Lots A and B pellets was not toxic when fed to calves.

The other calves were given oral administrations of Lot II lubricant. One of these calves was given enough lubricant so that he received a total of 2.5 milligrams per pound body weight of hexachloronaphthalene. The other calf was given enough lubricant so that he received a total of 5 milligrams per pound body weight of hexachloronaphthalene. These calves developed symptoms and gross and microscopic lesions of bovine hyperkeratosis very rapidly. This indicated that Lot II lubricant which was used in the pelleting of Lot C and D pellets was toxic when administered to calves.

Two calves received oral administrations of a 3% solution of hexachloronapthalene in corn oil. One calf received 2.5 milligrams of hexachloronaphthalene per pound body weight, and the other received 5.0 milligrams per pound body weight. Both developed symptoms of bovine hyperkeratosis very rapidly. The symptoms and lesions produced by the hexachloronaphthalene were very similar to those produced by the oral administration of Lot II lubricant and also those produced when Lot C and D pellets were fed. Vitamin A values dropped to levels indicative of deficiency; the calves became depressed, thin, and microscopic lesions were present in the kidney, liver, epididymis, seminal vesicles and parotid gland. This indicated that the toxic agent in Lot II lubricant was highly chlorinated naphthalenes.

It was demonstrated that a lubricant passed from the pellet mill rolls into pellets during the pelleting process, and that when this lubricant contained highly chlorinated naphthalenes, the pellets were toxic to cattle.