Effect of replacing corn with hulled and hulless or low-amylose hulless barley varieties on growth performance and carcass quality of italian growing-finishing pig

ABSTRACT: A study was conducted to evaluate the effect of diets based on hulled or hulless (normal- and low-amylose) barley varieties on growth performance and carcass characteristics in heavy growing-finishing pigs for the production of protected designation of origin (PDO) Italian products. The study was performed with 40 gilts and 40 barrows (Italian Duroc × Italian Large White). Four diets were formulated: 1) corn-based diet (control), 2) control diet with 80% of a normal-amylose hulled barley variety named Cometa (Cometa), 3) control diet with 80% of a normal-amylose hulless barley variety named Astartis (Astartis), and 4) control diet with 80% of a low-amylose hulless barley variety named Alamo (Alamo). The diets were formulated according to 3 growth phases (P1, 40 to 80 kg BW; P2, 80 to 120 kg BW; and P3, 120 to 170 kg BW), with the same Lys:DE ratio (2.60, 2.20, and 1.80, respectively in P1, P2, and P3) according to the NRC requirements for P1 and P2 and according to requirements for high-performing pigs for P3. The diets were analyzed for their in vitro starch digestion potentials (predicted glycemic index, pGI) and for their resistant starch (RS) contents. In P1, P2, and P3, the Alamo diet had the numerically lowest RS contents and greatest pGI values, whereas the control diet had the numerically greatest RS contents and the lowest pGI values. Throughout the study, the pigs fed Cometa and Alamo diets grew faster (P < 0.01) than those fed the control diet, whereas pigs receiving Astartis diet grew in a similar manner to those receiving all the other diets. Pigs fed Cometa and Alamo achieved greater final BW (P < 0.01) compared with those fed the control diet. The pigs receiving the Astartis diet had a mean final BW similar to that of the pigs fed other diets. Throughout the study, the control group had a lower grams per megacalorie DE (P < 0.01) compared with the pigs fed diets with barley, whereas the gain per megacalorie of DE (G/Mcal DE) was greater (P < 0.01) for the pigs fed hulled barley compared with the pig fed hulless barleys. No difference in carcass characteristics was found among treatments (P > 0.05). This study showed that diets based both on hulled and hulless barley might be suitable for the heavy pig breeding intended to the production of Italian PDO products. In addition, hulled or low-amylose hulless barley could be valuable to support maximum pig growth performance without affecting carcass composition.