Efficiency of Utilization of Metabolizable Energy during Pregnancy and the Energy Requirements for Pregnancy in Sheep

Abstract
A comparative slaughter experiment involving 138 mature Targhee ewes was conducted to determine the efficiency of utilization of metabolizable energy (ME) during pregnancy and the energy requirements for pregnancy in sheep. Of the 28 non-pregnant ewes 12 were killed in an initial slaughter group, 10 were fed ad libitum and six were fed at maintenance. The pregnant ewes were fed at approximately 1.5 or 2.0 times maintenance. Animals were individually fed a blended, pelleted 75% roughage and 25% concentrate diet that contained 2.41 kcal ME/gDM. Pregnant ewes were slaughtered at approximately day 70, 100, 125 and 140 of gestation. Non-pregnant sheep utilized ME for maintenance and gain with efficiencies of 65.7% and 56.0%, respectively. Efficiency of utilization of ME for pregnancy, conceptus development and fetal development was 16.1%, 12.5% and 12.2%, respectively. The NE contents of the diet for maintenance (NEm), gain (NEg), pregnancy (NEpreg), conceptus development (NEconceptus) and fetal growth (NEfetus) were 1.58, 1.35, 0.39,0.30 and 0.29 kcal NE/gDM, respectively. The daily net energy requirements for pregnancy and development of the conceptus over the last 85 to 100 days of gestation averaged 16.1 and 12.1 kcal NE/kg fetus, respectively. Daily heat production due to pregnancy was estimated as 85.0 kcal/kg conceptus. Copyright © 1974. American Society of Animal Science . Copyright 1974 by American Society of Animal Science.

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