The distinctive short-term response of late-pregnant prolific ewes to various doses and mixtures of propylene glycol and glycerol drenching

Pregnancy toxemia (PT) is the most frequent metabolic disorder for ewes in late pregnancy. Although propylene glycol (PG) and glycerol (GLY) are common glycogenic supplements for treating PT in ewes, the relative benefit of these supplements is not clear. In a previous study, it was demonstrated that PG was mainly effective in reducing the β-hydroxybutyrate acid (BHB) concentration, whereas GLY was more effective in increasing the plasma glucose concentration. Therefore, the objectives of the present study were to determine the effects of drenching various doses and combinations of PG and GLY to late-pregnant ewes in order to obtain a simultaneous increase in glucose and a decrease in BHB. Sixty-six multiparous Afec-Assaf ewes bearing at least two fetuses were used in 3 consecutive experiments. In all experiments, blood samples were collected twice before drenching (at 0630 and 0645 h), then the ewes were drenched with each supplement at 0700 h, and blood samples were taken every hour for 12–14 h post-drenching. In experiment 1, ewes were drenched either with 1) Control (CTL1, n = 6) – 55 mL water, 2) PG100 (n = 6) – 106 mL of PG, 3) GLY100 (n = 6) –108 mL of Koforin (containing 80 % glycerol, 15 % water, and 5 % ash), 4) PG50 (n = 6) – 53 mL of PG, and 5) GLY50 (n = 6) – 54 mL of Koforin. The plasma glucose concentration was higher after the GLY50 (P = 0.03) and GLY100 (P = 0.01) treatments than in CTL1. The plasma BHB concentration was lower after the PG50 (P = 0.001) and GLY50 (P = 0.02) treatments and tended to be lower in the PG100-treated ewes (P = 0.10) than in the CTL1 ewes. In experiment 2, ewes were drenched with 1) Control (CTL2, n = 6) –55 mL water, 2) MIX50 (n = 6) –26.5 mL PG + 27 mL Koforin, and 3) MIX100 (n = 6) –53 mL PG + 54 mL Koforin. No differences were observed among treatments for the main blood metabolites. In experiment 3, ewes were drenched with 1) Control (CTL3, n = 6) – 110 mL water, 2) MIX200(1:1) (n = 6) –106 mL PG +108 mL Koforin, and 3) MIX200(3:7) (n = 6) – 63.4 mL PG +150.6 mL Koforin. The plasma glucose concentrations were 17.8 % and 20.9 %, respectively, higher in the MIX200(1:1) and MIX200(3:7) ewes than in the CTL3 ewes (P < 0.01). The plasma BHB concentrations in the MIX200(1:1) and MIX200(3:7) ewes were 42 % and 47 %, respectively, lower than in the CTL3 ewes (P < 0.03). The NEFA concentration in the MIX200(1:1) and MIX200(3:7) ewes was 60 % and 57 %, respectively, lower than in the CTL3 ewes (P = 0.008). In conclusion, MIX200(1:1) and MIX200(3:7) were the most effective approaches to increasing glucose and reducing the BHB and NEFA concentrations concomitantly in the plasma of late-pregnant ewes.