HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Freetly, H. C. Articles by Leymaster, K. A. Search for Related Content PubMed PubMed Citation Articles by Freetly, H. C. Articles by Leymaster, K. A.

Relationship between litter birth weight and litter size in six breeds of sheep¹

ARS, USDA, U.S. Meat Animal Research Center, Clay Center, NE 68933

² Correspondence: P.O. Box 166 (phone: 402-762-4202; fax: 402-762-4209; e-mail: freetly{at}email.marc.usda.gov).

Abstract

Metabolizable energy requirements of the ewe increase during pregnancy due to increases in fetal and maternal metabolism. Fetal metabolism is related to total weight of the fetuses. Fetal number is a primary contributor to fetal weight. Litter birth weight represents the culminated fetal growth of the litter and can be used to estimate the effect of fetal metabolism on energy requirements of the ewe. We hypothesized that litter weight in sheep would increase at a decreasing rate with increasing litter size. Birth weights of lambs born to yearling (11 to 15 mo) and mature ewes (>34 mo) were collected on litters born to Dorset, Rambouillet, Suffolk, Finnsheep, Romanov, and Composite III ewes mated to produce straightbred lambs. Litter birth weight expressed as a function of litter size increased at a decreasing rate and the quadratic term differed from zero for mature Rambouillet, Suffolk, Finnsheep, Romanov, and Composite III litters (P < 0.042). The quadratic coefficient differed among breeds. In yearlings, litter weight increased at a decreasing rate for Suffolk ewes (P = 0.002). The quadratic term for the relationship between litter weight and litter size did not differ from zero for Finnsheep (P = 0.39) or Romanov litters (P = 0.07). The hypothesis that litter weight increases at a decreasing rate with increased litter size is supported by experimental results.

Key Words: Breed • Ewe • Litter

This article has been cited by other articles:

				C. J. Lupton ASAS CENTENNIAL PAPER: Impacts of animal science research on United States sheep production and predictions for the future J Anim Sci, November 1, 2008; 86(11): 3252 - 3274. [Abstract] [Full Text] [PDF]

				C. Lacroux, F. Corbiere, G. Tabouret, S. Lugan, P. Costes, J. Mathey, J. M. Delmas, J. L. Weisbecker, G. Foucras, H. Cassard, et al. Dynamics and genetics of PrPSc placental accumulation in sheep J. Gen. Virol., March 1, 2007; 88(3): 1056 - 1061. [Abstract] [Full Text] [PDF]