Abstract
In a previous publication 1 the writers have reported a study of a condition of stiffness in swine, in which inadequate mineral nutrition was found to be a cause of the trouble. In this study the experimental animals had been so housed that they were never exposed to direct sunlight. The present paper describes a repetition of a portion of the previous experiment to study how the results might be modified were the pigs exposed to sunlight.
The ration used consisted of 200 lbs. yellow corn meal, 100 lbs. wheat middlings, and 75 lbs. oil meal—a ration very low in calcium.
In the spring of 1924, 4 pure bred Duroc pigs were placed on this ration in a pen on the north side of the colony house as in previous studies. A second group of 4 was placed on the same ration in a pen on the south side of the house opening on a cement run-way outside, 7 × 12 ft., thus giving the pigs access to direct sunlight. The experimental animals were so selected and distributed between the two pens that the comparative chemical and pathological studies could be made upon litter mates. Over an experimental period of four months, all of the pigs in the no-sunlight group developed the characteristic stiffness, while none of the pigs in the other group showed any signs of the trouble.
At the end of the four-months period the pigs were killed for routine pathological examination of the bones. On chemical analysis the femurs of the sunlight group were found markedly higher in ash content than those of their litter mates fed the same ration without sunlight.
The comparison between the sunlight and no-sunlight groups was repeated the following winter.
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