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Effect of Vitamin A Supplementation on Reproduction of Ewes Grazed on Green and Dry Summer Ranges^{1, 2,}

The State College of Washington

Abstract

Hart and Guilbert (1933) found a high percent of abortions and still births in both cattle and sheep that had been carried on dry range. They reported that the animals showed symptoms of night blindness, capricious appetites, intermittent diarrhea, general unthrifty condition, and pulmonary complications. Pearson et al. (1945) stated that night blindness in sheep is one of the first symptoms of a vitamin A deficiency. This is usually followed by nervous disorders causing various degrees of incoordination. They also found that urinary calculi might occur as one of the late symptoms and may be the immediate cause of death. Similar findings are reported by Schmidt (1944).

Miller et al. (1942) found that with old ewes, 22 to 23 months were required to develop night blindness on a low carotene ration, whereas ewe lambs that had access to green grass as nursing lambs, required only 9 months. Gunn et al.

¹ Published as Scientific Paper No. 859, Agricultural Experiment Stations, Institute of Agricultural Sciences, The State College of Washington, Pullman, Washington.

² Submitted by the senior author in partial fulfillment of the requirements for the Ph.D. degree, The State College of Washington.

³ Present address: University of Florida, Gainesville, Florida. The assistance of C. E. Lindiey in some of this work is gratefully acknowledged.

⁴ Present address Regional Coordinator, Beef Cattle Breeding, University of Tennessee.