Effects of maternal factors on the metabolic profile throughout pregnancy in dairy sheep

Objectives: Physiological states as pregnancy and lactation modify metabolism in sheep. The aim of this study was to evaluate the influence of pregnancy features (parity and type of pregnancy) on the maternal metabolism in high yielding Lacaune dairy sheep. Material and methods: The study was carried out in a single commercial farm on 334 Lacaune dairy sheep, classified by age (187 mature and 147 maiden ewes), parity (145 multiparous vs. 42 primiparous) and type of pregnancy (161 single vs. 173 multiple). Fasting plasma samples were collected at two points during pregnancy mid and late-pregnancy (74±5 and 141±3 d, respectively) and postpartum (52±5 d after delivery). The following metabolic parameters were considered: plasma ß-hydroxybutyrate (ß-OHB), nonesterified fatty acids (NEFA), glucose, lactate, urea, cholesterol, triglycerides and fructosamine. Differences among groups and interactions were evaluated with ANOVA and Kruskal-Wallis test when non-normal distributed. Results: ß-OHB was higher during gestation in mature than in maiden ewes (0.58±0.20 vs. 0.37±0.11 mmol/L; P< 0.0001) at mid pregnancy, (0.67±0.34 vs. 0.55±0.21 mmol/L; P< 0.0001) and late pregnancy, but did not differ with age at postpartum (0.78±0.25 vs. 0.74±0.23 mmol/L; P> 0.05). During gestation ß-OHB was not affected by type of pregnancy, although, postpartum ß-OHB was lower in ewes that had carried out single gestation than in those with multiple pregnancy (0.59±0.27 vs. 0.65±0.31 mmol/L; P< 0.01). At mid pregnancy NEFA were lower in mature than in maiden ewes (0.46±0.22 vs. 0.57±0.17 mmol/L; P< 0.0001); whereas NEFA were higher in mature at late pregnancy and postpartum (0.67±0.29 vs. 0.55± 0.18 mmol/L; P< 0.0001 for late pregnancy); (0.50±0.18 vs. 0.44±0.16 mmol/L; P=0.004 for postpartum). At late pregnancy, ewes carrying a single pregnancy showed lower NEFA than those with multiple foetuses (0.57±0.25 vs. 0.67±0.25 mmol/L; P< 0.0001). Glucose levels during gestation did not differ with age, however, at postpartum mature ewes had lower levels than maiden ewes (67.90±6.44 vs. 74.63±7.54 mg/dl P<0.0001). Glucose during gestation was higher in ewes carrying a single gestation at mid (65.45±15.48 vs. 60.44±8.82 mg/ dl; P< 0.004) and late pregnancy (71.84±14.62 vs. 67.37±12.53 mg/dl; P<0.003) but did not differ postpartum. Lactate was lower in mature ewes at mid pregnancy (16.34±8.73 vs. 18.85±10.13 mg/dl; P<0.003), and postpartum (11.13±6.90 vs. 12.07±5.64 mg/dl; P<0.01), but it was similar at late pregnancy and did not change by type of pregnancy. Urea was higher in mature ewes at mid pregnancy (57.44±11.23 vs. 39.95±7.86 mg/dl; P<0.0001) and postpartum (67.56±15.01 vs. 58.18±13.53 mg/dl; P<0.0001), but lower at late pregnancy (41.44±10.70 vs. 42.31±8.81; P<0.048). Urea was higher at late pregnancy in ewes carrying a single gestation (43.29±10.15 vs. 40.45±9.50 mg/dl; P<0.004). Cholesterol was higher during gestation in mature than in maiden ewes (P<0.0001). However, at postpartum cholesterol was higher in maiden ewes (108.79±21.76 vs. 100.44±21.74 mg/dl; P<0.001) and it was not affected by type of pregnancy. Triglycerides were higher in mature ewes (23.51±8.04 vs. 19.29±7.33 mg/dl; P< 0.001) at mid pregnancy. At postpartum, triglycerides were higher in maiden ewes (17.73±8.62 vs. 15.07±4.37mg/dl; P<0.001) and did not differ with type of pregnancy. Fructosamine was higher at mid gestation in mature ewes (310.77±31.63 vs. 275.47±30.58 umol/L; P<0.0001) and at the same time, it was affected by type of pregnancy (289.75±36.95 vs. 300.30±33.90 umol/L for single and multiple pregnancies respectively; P=0.013). The daily average milk yield during the lactation was not different between primiparous and multiparous (312.42±130.68 vs. 339.6±0.142.9 L; P>0.05); before getting pregnant, primiparous produced less than multiparous (1.71±0.62 vs. 2.07±0.67 L; P<0.05), and after conception primiparous produced the same as multiparous (1.11±0.38 vs. 1.07±0.46 L; P>0.05). Milk yield was not affected by type of pregnancy. Conclusions: The present data reveal interactions among maternal factors (age and type of pregnancy) physiological status (pregnancy and lactation) and time of pregnancy on the metabolism of dairy ewes, which be related to health and productivity.