Skip to main content Accessibility help

A model for the effects of energy nutrition on the pregnant ewe

  • Pamela A Geisler (a1) and Heather Neal (a1)


A computer-based model of the response of the ewe to energy nutrition during pregnancy is described, based on a previous analysis of energy requirements. A ewe of specified weight and body condition 30 days from conception, carrying a known number of lambs, is predicted to grow them to an optimal weight if the nutritional regime allows. Daily energy requirements of the ewe-foetus system are calculated as the sum of requirements for maintenance and for growth and are compared with the daily energy supplied.If the feed provides energy surplus to requirements, the ewe herself gains weight; otherwise, the ewe mobilizes her own reserves, within limits, to protect the foetus. If this does not produce the energy required for optimal growth, foetal growth is reduced.

Published experimental results are compared with predictions of the model when run under similar conditions; in general, predictions of total maternal weight at the end of pregnancy are within 5 % of those observed in the experiments. Model predictions of the effects of some particular nutritional regimes during pregnancy are presented and the sensitivity of the predictions of the model to certain of the assumptions made in its construction are discussed.



Hide All
Blaxter, K. L. 1962. The Energy Metabolism of Ruminants, p. 100. Hutchinson, London.
Edey, T. N. 1969. Prenatal mortality in sheep: a review. Anim. Breed. Abstr. 37:173190.
Everitt, G. C. 1968. Prenatal development of uniparous animals with particular reference to the influence of maternal nutrition in sheep. In Growth and Development of Mammals, Proc. 14th Easter Sch. agric. Sci., Univ. Nottingham, pp. 131157. Butterworth, London.
Geisler, P. A. and Fenlon, J. S. 1979. The effects of body weight and its components on lambing performance in some commercial flocks in Britain. Anim. Prod. 28: 245255.
Geisler, Pamela A. and Jones, C. Merryl. 1979. A model for calculation of the energy requirements of the pregnant ewe. Anim. Prod. 29: 339355.
Hammond, J. 1944. Physiological factors affecting birth weight. Proc. Nutr. Soc. 2: 812.
Jefferies, B. C. 1961. Body condition scoring and its use in management. Tasm. J. Agric. 32: 1921.
Ministry Of Agriculture, Fisheries And Food, Department Of Agriculture And Fisheries For Scotland And Department Of Agriculture For Northern Ireland. 1975. Energy allowances and feeding systems for ruminants. Tech. Bull. 33. Her Majesty's Stationery Office, London.
National Research Council. 1968. Nutrient Requirements of Domestic Animals. No. 5, Nutrient Requirements of Sheep. National Academy of Sciences, Washington, DC.
Prior, R. L. and Christenson, R. K. 1976. Influence of dietary energy during gestation on lambing performance, and glucose metabolism in Finn-cross ewes. J. Anim. Sci. 43: 11141124.
Robinson, J. J. 1977. The influence of maternal nutrition on ovine foetal growth. Proc. Nutr. Soc. 36: 916.
Robinson, J. J. 1978. Response of lactating ewes to variation in energy and protein intake. In Milk Production in the Ewe. (ed. Boyazoglu, J. G. and Treacher, T. T.), pp. 5363. Eur. Ass. Anim. Prod., Publ. 23.
Robinson, J. J., McDonald, I., Fraser, C. and Crofts, R. M. J. 1977. Studies on repro- duction in prolific ewes. I. Growth of the products of conception. J. agric. Sci., Camb. 88: 539552.
Robinson, J. J., McDonald, I., McHattie, I. and Pennie, K. 1978. Studies on reproduction in prolific ewes. 4. Sequential changes in the maternal body during pregnancy. J. agric. Sci., Camb. 91: 291304.
Robinson, J. J., Smart, R. I. and Pennie, K. 1978. The energy requirements of twinbearing ewes in late pregnancy and the extent of body tissue mobilization. Anim. Prod. 26: 390391 (Abstr.).
Russel, A. J. F., Doney, J. M. and Gunn, R. G. 1968a. Subjective assessment of body fat in live sheep. J. agric. Sci., Camb. 72: 451454.
Russel, A. J. F., Gunn, R. G. and Doney, J. M. 1968b. Components of weight loss in pregnant hill ewes during winter. Anim. Prod. 10: 4351.
Russel, A. J. F., Maxwell, T. J., Sibbald, A. R. and McDonald, D. 1977. Relationships between energy intake, nutritional state and lamb birth weight in Greyface ewes. J. agric. Sci., Camb. 89: 667673.
Thomson, W. and Aitken, F. C. 1959. Effect of plane of nutrition of ewe on fertility, reproduction and lactation. In Diet in Relation to Reproduction and the Viability of the Young. II. Sheep: World survey of reproduction and review of feeding experiments. Tech. Commun. Commonw. Bur. Anim. Nutr. No. 20, pp. 6776.
Treacher, T. T. 1970. Effects of nutrition in late pregnancy on subsequent milk production in ewes. Anim. Prod. 12: 2336.

A model for the effects of energy nutrition on the pregnant ewe

  • Pamela A Geisler (a1) and Heather Neal (a1)


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed