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Foetal dwarfism in sheep—an effect of high atmospheric temperature during gestation

  • N. T. M. Yeates (a1)

The course of pregnancy was followed in three groups of Peppin-strain Merino ewes. Group 1 of seven ewes, maintained on a high plane of nutrition, all lambed; the mean birth weight of lambs was 8 lb. 6 oz. The six ewes in group 2, kept on a low plane of nutrition, all lambed; the mean birth weight of their lambs was 1 lb. 9 oz. lower (P<0·01). The seven ewes in group 3 kept on a low plane of nutrition and subjected daily to temperatures of 112° F. dry bulb, 92° F. wet bulb, produced only four lambs; the mean birth weight was 4 lb. 6 oz. less than those from group 1, and 2 lb. 13 oz. less than those from group 2 (P < 0·001).

Scale photographs of the lambs, and X-rays and measurements of their long bones, after dissection, showed that the lambs of group 3 were miniatures: their skeletons were much reduced in size, whereas low nutrition alone (group 2), caused little skeletal reduction.

The mechanism of dwarfing is not clear. However, fore-cannon bone lengths and liver weights, considered in relation to lamb birth weights indicated that it was not a nutritional effect.

This study was undertaken at the Physiology Department, University of Queensland. It is a pleasure to thank Prof. W. V. Macfarlane for the valuable facilities, and for his help and encouragement.

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This list contains references from the content that can be linked to their source. For a full set of references and notes please see the PDF or HTML where available.

G. Alexander (1956). Aust. Vet. J. 32, 321.

W. V. MacFarlane , P. R. Pennycuik & E. Thrift (1957). J. Physiol. 135, 451.

M. K. Shah (1956). Nature, Lond., 177, 1134.

J. Tepperman , F. L. Engel & C. N. H. Long (1943). Endocrinology, 32, 373.

L. R. Wallace (1948). J. Agric. Sci. 38, 93, 243, 367.

N. T. M. Yeates (1952). Aust. J. Agric. Res. 3, 68.

N. T. M. Yeates (1956). Aust. J. Agric. Res. 7, 435.

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The Journal of Agricultural Science
  • ISSN: 0021-8596
  • EISSN: 1469-5146
  • URL: /core/journals/journal-of-agricultural-science
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