Skip to main content Accessibility help
×
Home

A model for calculation of the energy requirements of the pregnant ewe

  • Pamela A Geisler (a1) and C. Merryl Jones (a1)

Abstract

A computer program is described which allows the calculation throughout pregnancy of the energy requirements of a ewe of any weight carrying any number of foetuses. The calculations rely on a prediction of potential lamb birth weight, from which a foetal growth curve of weight against time from conception is generated. Tied to the foetal growth curve are the growths of the placenta and fluids, while growth of the uterus is related to the ewe's weight at mating. Weights are converted to energy through energy density curves applicable through pregnancy for each component. An efficiency factor converts this energy requirement into a metabolizable energy requirement. With assumptions on the maintenance requirements for the ewe-foetus system, the total requirement for energy during pregnancy is calculated.

Predictions from the model are compared with other estimates of energy requirements available in the literature. The sensitivity of the predictions of energy requirements for the pregnant ewe to variations in the assumptions made in the construction of the model is discussed. The most important assumptions are those on the maintenance requirements for the ewe-foetus system. Effects on the predicted energy requirements of varying either the efficiency for foetal growth or the gestation length are also discussed.

Copyright

References

Hide All
Agricultural Research Council. 1965. The Nutrient Requirements of Farm Livestock. No. 2, Ruminants. Agricultural Research Council, London.
Bradford, G. E. 1972. The role of maternal effects in animal breeding. VII. Maternal effects in sheep. J. Anim. Sci. 35: 13241334.
Cloete, J. H. L. 1939. Prenatal growth in the Merino sheep. Onderstepoort J. vet. Sci. Anim. Ind. 13: 417558.
Dickinson, A. G., Hancock, J. L., Hovell, G. J. R., Taylor, St C. S. and Wiener, G. 1962. The size of lambs at birth—a study involving egg transfer. Anim. Prod. 4: 6479.
Donald, H. P. and Russell, W. S. 1970. The relationship between live weight of ewe at mating and weight of newborn lamb. Anim. Prod. 12: 273280.
Eaton, O. N. 1952. Weight and length measurements of foetuses of Karakul sheep and of goats. Growth 16: 175187.
Field, A. C. and Suttle, N. F. 1967. Retention of calcium, phosphorus, magnesium, sodium and potassium by the developing sheep foetus. J. agric. Sci., Camb. 69: 417423.
Geisler, Pamela A. and Neal, Heather. 1979. A model for the effects of energy nutrition on the pregnant ewe. Anim. Prod. 29: 357369.
Geisler, P. A., Newton, J. E. and Mohan, A. E. 1977. A mathematical model of fertilization failure and early embryonic mortality in sheep. J. agric. Sci., Camb. 89: 309317.
Graham, N. McC. 1964. Energy exchanges of pregnant and lactating ewes. Aust. J. agric. Res. 15: 127141.
Hunter, G. L. 1957. The maternal influence on size in sheep. J. agric. Sci. Camb. 48: 3660.
Joubert, D. M. 1956. A study of pre-natal growth and development in the sheep. J. agric. Sci., Camb. 47: 382428.
Laird, A. K. 1966. Dynamics of embryonic growth. Growth 30: 263275.
Langlands, J. P. and Sutherland, H. A. M. 1968. An estimate of the nutrients utilized for pregnancy by Merino sheep. Br. J. Nutr. 22: 217227.
Malan, A. P. and Curson, H. H. 1936. Further observations on the body weight and crown-rump length of Merino foetuses. Onderstepoort J. vet. Sci. Anim. Ind. 7: 239249.
Meat and Livestock Commission. 1975. Feeding the Ewe. Tech. Rep. No. 2. Meat and Livestock Commission, Bletchley, Milton Keynes.
Ministry of Agriculture, Fisheries and Food, Department of Agriculture and Fisheries for Scotland and Department of Agriculturefor Northern Ireland. 1975. Energy allowances and feeding systems for ruminants. Tech. Bull. 33. Her Majesty's Stationery Office, London.
Rattray, P. V. 1974. Energy requirements for pregnancy in sheep. Proc. N.Z. Soc. Anim. Prod. 34: 6777.
Rattray, P. V., Garrett, W. N., East, N. E. and Hinman, N. 1974a. Efficiency of utilization of metabolizable energy during pregnancy and the energy requirements for pregnancy in sheep. J. Anim. Sci. 38: 383393.
Rattray, P. V., Garrett, W. N., East, N. E. and Hinman, N. 1974b. Growth, development and composition of the ovine conceptus and mammary gland during pregnancy. J. Anim. Sci. 38: 613626.
Robinson, J. J., McDonald, I., Fraser, C. and Crofts, R. M. J. 1977. Studies on reproduction in prolific ewes. I. Growth of the products of conception. J. agric. Sci., Camb. 88: 539552.
Robinson, J. J., Smart, R. I. and Pennie, K. 1978. The energy requirements of twin bearing ewes in late pregnancy and the extent of body tissue mobilization. Anim. Prod. 26: 390391 (Abstr.).
Russel, A. J. F., Doney, J. M. and Reid, R. L. 1967. Energy requirements of the pregnant ewe. J. agric. Sci., Camb. 68: 359363.
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.
Sykes, A. R. and Field, A. C. 1972. Effects of dietary deficiencies of energy, protein and calcium on the pregnant ewe. III. Some observations on the use of biochemical parameters in controlling energy undernutrition during pregnancy and on the efficiency of utilization of energy and protein for foetal growth. J. agric. Sci., Camb. 78: 127133.
Wallace, L. R. 1948. The growth of lambs before and after birth in relation to the level of nutrition. J. agric. Sci., Camb. 38: 93153, 243-302, 367-401.
Winters, L. M. and Feuffel, G. 1936. Studies on the physiology of reproduction in the sheep. IV. Fetal development. Univ. Minnesota, agric. Exp. Stn, Tech. Bull. No. 118.
Young, B. A. and Corbett, J. L. 1972. Maintenance energy requirement of grazing sheep in relation to herbage availability. I. Calorimetric estimates. Aust. J. agric. Res. 23: 5776.

A model for calculation of the energy requirements of the pregnant ewe

  • Pamela A Geisler (a1) and C. Merryl Jones (a1)

Metrics

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