Crude glycerin decreases nonesterified fatty acid concentration in ewes during late gestation and early lactation1

Abstract

Crude glycerin is a gluconeogenic substrate in ruminants and may help to decrease the occurrence of pregnancy toxemia. The objective in this trial was to determine the effects of feeding a diet containing crude glycerin on DMI, milk yield, milk composition, and blood metabolites in periparturient ewes and lamb performance. One hundred eighteen 90 (±1.1)-d pregnant Santa Inês ewes were used. After lambing, 32 ewes (62.8 ± 1.3 kg BW) were allotted in a randomized complete block design defined by prelambing diet, BW, BCS, lambing date, type of birth (single or twin), and sex of offspring. Diets were isonitrogenous (13.0 ± 0.3% CP, DM basis), composed of concentrate and raw sugarcane bagasse (70:30 ratio, DM basis), and fed ad libitum daily. Crude glycerin (83.6% glycerol) levels were 0 or 10% (DM basis), corresponding to the experimental diets G0 and G10, respectively. From 8 until 56 d of lactation, DMI was determined. In the same period, once a week at 1000 h, the ewes were separated from the lambs and mechanically milked after intravenous administration of 10 IU of synthetic oxytocin. Three hours after the first milking, ewes were milked again and milk yield and composition were determined. Glucose, NEFA, and β-hydroxybutyrate (BHBA) were determined at -14, -7, 0, 7, 14, 28, and 56 d relative to lambing and insulin was determined at -14, -7, 0, and 7 d. Crude glycerin did not affect DMI (2.2 kg/d for G0 vs. 2.2 kg/d for G10; = 0.93) or milk production (171 g/3 h for G0 vs. 164 g/3 h for G10; = 0.66). However, there was a decrease ( = 0.01) in milk fat percentage (8.1% for G0 vs. 7.0% for G10) for ewes fed glycerin. Ewes fed the G10 diet had decreased ( < 0.01) NEFA concentration (0.27 mmol/L for G0 vs. 0.18 mmol/L for G10). There was an interaction between diet × time for glucose ( = 0.04), insulin ( = 0.05), and BHBA ( = 0.01); feeding glycerin increased glucose (5.61 mmol/L for G0 vs. 7.42 mmol/L for G10; < 0.01) and insulin concentrations (10.5 μIU for G0 vs. 24.5 μIU for G10; < 0.01) at parturition compared with G0. The BHBA was less ( = 0.02) on the day of lambing (0.40 mmol/L for G0 vs. 0.29 mmol/L for G10) and it was greater ( < 0.01) on d 56 for ewes fed the G10 diet (0.46 mmol/L for G0 vs. 0.61 mmol/L for G10). There was no effect of diets fed to ewes on lamb growth from birth to weaning. Crude glycerin improved energy balance of periparturient ewes, suggesting a reduced risk of developing clinical metabolic-related disorders. Crude glycerin can be added at 10% of ewes' diets without affecting DMI and milk yield.

Administration of glycerol-based formulations in sheep results in similar ovulation rate to eCG but red blood cell indices may be affected

“…In these studies, glycerol was supplemented at a percentage of inclusion on dry matter (DM) basis ranging from 3% up to 45%. Overall the metabolic effects described include an increase in glucose and a decrease in NEFA circulating concentrations [6,11,18]. Other studies in ewes also reported an increase in insulin [19][20][21], insulin-like growth factor-1 [20], and a decrease in urea circulating concentrations [20,21] after oral administration of 280 mL glycerol and 80 mL 1,2-propylene glycol daily for 4 days.…”

“…To identify the formulations and doses capable to induce a positive change in ewe's metabolic status we assessed their effects against those induced Letters indicate significant differences between D 0 and D 3 (before glycerol-based formulation administration) within the same group; p < 0.05 by M100. The latter dose has been indeed already evaluated for its effects on sheep metabolism and reproductive performance [8,16,18]. Obtained results shows that the high and moderate dose groups (G100, M75 and G75) showed no differences in mean glycerol plasma concentrations compared to the M100 one (Fig.…”

“…To verify whether the tested formulations were able to create a metabolic milieu suitable for the final follicular growth and thus for the conception period in the ewe, as described in previous studies [20], we compared the circulating concentrations of glycerol, glucose, insulin, urea and NEFA against those found in the M100 dose. This dose was taken from previous studies, being already evaluated for its effects on sheep metabolism and reproductive performance [8,16,18]. In the low dose groups, showing no alterations in plasma osmolality and RBC indices, the metabolic milieu was markedly different compared to that found in M100 (lower glycerol, glucose and insulin circulating concentrations, higher NEFA and urea circulating concentrations).…”

“…Thus, the objective of this study was to investigate the metabolic and osmotic effects of different doses of glycerol and glycerolpropylene glycol mixtures in Sarda sheep in order to identify those able to positively modify ewe's metabolic status without significantly affecting RBC indices. The highest dose of the glucogenic mixture was taken from previous studies, being already evaluated for its effects on sheep metabolism and reproductive performance [8,16,18]. Thereafter, to determine the ability of the selected glucogenic doses to promote ovarian function, we evaluated their effects on ewe's ovarian activity during an induced follicular phase, comparing them to the effects of the administration of a synthetic gonadotropin (eCG).…”

Technologies Used in Production Systems for Santa Inês Sheep: A Systematic Review

“…As for energy by-products, crude glycerin could be recommended for up to 10%, not affecting reproductive performance before and during the breeding season ( 42 ). In addition, it has a positive effect on the energy balance in the critical phases of late gestation and early lactation ( 43 ).…”