Feeding strategy during pregnancy for ewes with a large litter size. 2. Effect on blood parameters and energy status.
AbstractIn 6 feeding trials with pregnant ewes, blood glucose concentrations were affected by litter size after day 84 of pregnancy. An increase in litter size decreased blood glucose during the last phase of pregnancy. At day 141 a sharp increase in glucose was seen. Ewes with ketosis had after day 126 of pregnancy a significant lower glucose concentration. beta -Hydroxybutyrate (BHB) and non-esterified fatty acids (NEFA) were also affected by litter size in the last months of pregnancy. With increasing litter size BHB increased more dramatically than NEFA concentrations. Ewes with ketosis had higher BHB and NEFA concentrations in the last month of pregnancy. Ewes on treatments with a higher metabolizable energy (ME) intake (rations with 60% of the energy originating from concentrates) had a higher glucose, a lower BHB and a lower NEFA concentration in the last month of pregnancy than ewes given a diet with 40% of the energy originating from concentrates. A lower incidence of ketosis on treatments with a higher energy intake was expected, but not seen. Probably, energy deficit is not the only factor inducing ketosis. With regression models the energy requirement of pregnant ewes with a body weight of about 85 kg during the last month of pregnancy was estimated. ME requirement in MJ per day for a ewe with a single, twin, triplet, quadruplet and quintuplet was 13.0, 15.9, 17.1, 18.4 and 19.1, respectively. The estimated energetic efficiency of conceptus growth was about 0.16. (Abstract retrieved from CAB Abstracts by CABI’s permission)