Inoculation of corn silage with Lactobacillus plantarum and Bacillus subtilis associated with amylolytic enzyme supply at feeding. 2. Growth performance and carcass and meat traits of lambs

The objective of this research was to investigate the effects of inoculation of corn silage and dietary supplementation of amylolytic enzymes, and their interaction, on lamb growth performance and carcass and meat traits. Whole-crop corn forage was treated either with water (untreated) or with Lactobacillus plantarum MA 18/5U at 1 × 105 cfu/g fresh forage combined with Bacillus subtilis AT553098 at 1 × 105 cfu/g fresh forage (inoculated) and ensiled for 170 d. Forty non-castrated Texel × Dorper male lambs were arranged in a randomized block design (n = 10) and then assigned to one of four diets, as follows: 1) untreated corn silage with no amylolytic enzyme supply (NI-NA); 2) untreated corn silage with amylolytic enzyme supply (NI-WA); 3) inoculated corn silage with no amylolytic enzyme supply (WI-NA); and 4) inoculated corn silage with amylolytic enzyme supply (WI-WA). α-Amylase (602 dextrinizing units/kg of dry matter (DM)) was supplied to the lambs at total mixed ration delivery. Inoculation of corn silage increased (P = 0.003) both digestible energy (DE) and metabolizable energy (ME) intake by 1.4 and 1.2 MJ/kg DM, respectively, and also resulted in higher average daily gain (ADG; P = 0.023) of lambs (233 vs. 212 g/d in lambs fed NI diet). In contrast, dietary supplementation with amylolytic enzymes had no effect on the DM intake (P = 0.90) or ADG (P = 0.15) of lambs. Moreover, inoculation, enzyme supplementation, and their interaction had no significant effects on carcass traits (P ≥ 0.06), commercial cut yield (P ≥ 0.26), chemical composition of meat (P ≥ 0.13), and meat tenderness and color (P ≥ 0.11). In terms of the fatty acid composition of longissimus muscle, inoculation of corn silage increased concentrations of saturated fatty acids (SFA; P = 0.035) from 46.2% to 47.6%, and reduced concentrations of unsaturated fatty acids (UFA; P = 0.035) from 53.8% to 52.5%, compared to the NI diet. Inoculation also reduced the UFA:SFA ratio (P = 0.031) from 1.17 to 1.11, a small but significant difference. Dietary supplementation with amylolytic enzymes did not alter (P ≥ 0.09) SFA, UFA, and polyunsaturated fatty acid concentrations, or their ratios. In conclusion, our results indicated that the silage inoculant examined in the present study is recommended for use in improving lamb production at the farm scale, whereas inclusion of amylolytic enzymes is not required under our experimental conditions.