Effect of dietary crude glycerin on growth performance, nutrient digestibility and hormone levels of Iberian crossbred pigs from 50 to 100Â kg body weight

The aim of this study was to determine the effect of crude glycerin addition on the growth performance, nutrient digestibility and blood hormone levels of Iberian crossbred pigs kept under intensive conditions. The study was carried out with 80 crossbred pigs (Iberian gilts×Duroc boars) of both sexes over a 101-d period (54±3 kg initial BW). Treatments were arranged in a 2×2 factorial design, the factors being dietary treatment (control or 10% glycerin) and gender (barrow or gilt). Crude glycerin was included as a replacement for wheat in diets formulated to provide equal net energy and digestible lysine levels. Glycerin-fed pigs had higher average daily gain and average daily feed intake than pigs fed the control diet (P<0.05). No differences were found in the gain to feed ratio. With regard to the gender, barrows consumed more feed, grew more and reached a higher final BW compared with gilts (P<0.05). Nutrient digestibility was not affected by the glycerin content or the gender. However, there was a tendency for acyl-ghrelin levels to be higher in glycerin-fed pigs (P=0.058). Also, gilts showed increased concentrations of acyl-ghrelin and lower insulin compared with barrows (P<0.05). In conclusion, 100 g/kg of glycerin can partially replace wheat without affecting feed efficiency or nutrient digestibility in Iberian crossbred pigs. However, further research is needed to clarify the potential relationship between glycerin inclusion levels in the diet and the plasmatic levels of hormones related to feed intake and energy balance control.