(Table 1). As would be expected, the smaller Cheviot ewes
required a lower glucose infusion rate than Suffolk ewes
(7.4 mL/min[7.0–7.9 mL/min] vs 8.9 mL/min [8.4–9.3 mL/
min]; P < 0.0001). Overall, Cheviot ewes tended to have
higher circulating fasting glucose (2.6 mM [2.5–2.8 mM] vs
2.4 mM [2.2–2.6 mM]; P ¼ 0.068) and insulin (0.78 nM
[0.48–1.38 nM] vs 0.36 nM [0.24–0.66 nM]; P ¼ 0.052)
concentrations, and higher steady-state glucose concentrations
(2.5 mM [2.4–2.7 mM] vs 2.3 mM [2.2–2.5 mM];
P ¼ 0.065) than Suffolk ewes.
A significant interaction between maternal and fetal
genotypes was only observed for maternal fasting insulin
(P ¼ 0.021), with Cheviot ewes carrying Cheviot lambs
having higher fasting insulin concentrations than Cheviot
ewes carrying Suffolk lambs (P ¼ 0.019; Table 1). Further,
univariate analyses showed that lamb birth weight was
inversely correlated with ewe fasting insulin (r ¼0.34;
P ¼ 0.027), with a similar trend (P ¼ 0.072) shown by the
multivariate model.
Suffolk ewes gave birth to heavier lambs, irrespective of
lamb breed (6.2 kg [5.8–6.7 kg] vs 5.4 kg [4.8–5.9 kg]; P ¼
0.017). Independently of ewe breed, Suffolk lambs were
heavier than Cheviot lambs (6.2 kg [5.7–6.7 kg] vs 5.4 kg
[4.9–5.9 kg]; P ¼ 0.024), with a particularly marked difference
seen among lambs born to Suffolk ewes (P ¼ 0.010;
Table 1). However, Suffolk lambs born of Cheviot ewes were
lighter than Suffolk lambs born of Suffolk ewes (P ¼ 0.014;
Table 1). Similarly, Cheviot lambs born of Cheviot ewes
tended to be lighter than Cheviot lambs born of Suffolk
ewes (P ¼ 0.056;
Table 1