Corn kernel hardness, drying temperature and amylase supplementation affect live performance and nutrient utilization of broilers

Abstract

Drying temperature (DT) of corn can influence its nutritional quality, but whether this is influenced by endosperm hardness is not clear. Two parallel experiments were conducted to investigate the effects of 2 yellow dent corn hybrids with average and hard kernel hardness, dried at 3 temperatures (35, 80, and 120°C), and 2 supplementation levels of an exogenous amylase (0, 133 g/ton of feed) on live performance, starch and protein digestibility, and energy utilization of Ross 708 male broilers. Twelve dietary treatments consisting of a 2 × 3 × 2 factorial arrangement were evaluated using 3-way ANOVA in a randomized complete block design. In Experiment 1, a total of 1,920 male-chicks were randomly allocated to 96 floor pens, whereas 480 day-old chicks were distributed among 96 cages for Experiment 2. At 40 d, interaction effects (P < 0.05) were detected on BWG, FCR, and flock uniformity. Supplementation with exogenous amylase resulted in heavier broilers, better FCR and flock uniformity, only in the diets based on corn dried at 35°C. Additionally, interaction effects were observed on FCR due to kernel hardness and DT (P < 0.01), kernel hardness and amylase supplementation (P < 0.001), and DT and amylase supplementation (P < 0.05). Exogenous amylase addition to the diets based on corn with an average hardness improved FCR up to 2 points (1.49 vs. 1.51 g:g) whereas there was no effect of amylase on FCR of broilers fed diets based on corn with hard endosperm. Total tract retention of starch was increased (P < 0.05) in broilers fed diets based on corn with average kernel hardness compared to hard kernel. Corn dried at 80 and 120°C had up to 1.21% points less starch total tract retention than the one dried at 35°C. Supplementing alpha-amylase resulted in beneficial effects for broiler live performance, energy utilization, and starch total tract digestibility results. Treatment effects on starch characteristics were explored. Corn endosperm hardness, DT and exogenous amylase can influence the live performance of broilers. However, these factors are not independent and so must be manipulated strategically to improve broiler performance.

Keywords: amylase supplementation; broiler chickens; corn kernel hardness; drying temperature.

Figure 1

Effect of corn kernel hardness (average and hard) and drying temperature (35, 80, and 120°C) on FCR at 40 d. Means not sharing a common superscript (a-c) are significantly different (n = 8; P < 0.01) by Tukey's test.

Figure 3

(Panel A) Linear effect of corn Amylose:Amylopectin ratio (AM:AP) on FCR at 40 d in corn with average (P > 0.05) and hard (P < 0.001) kernel (FCR 0–40 d = 1.432 + 0.239*AM:AP; R² = 0.34). (Panel B) Linear effect of damaged starch determined as in vitro hydrolyzed starch on FCR at 40 d (P < 0.01) in corn with average (P > 0.05) and hard (P < 0.001) kernel hardness (FCR 0–40 d = 1.5394 − 0.016* damaged starch; R² = 0.34). Markers represent the eight means per treatment combination of kernel hardness (average or hard) and drying temperatures (35, 80, or 120°C) postharvest and lines the linear fit by kernel hardness.

Figure 2

(Panel A) Linear effect of amylose content on AMEn at 16 d in corn with average (P < 0.001) and hard kernel (P < 0.001) hardness. For average corn kernel hardness AMEn = 4,437.792 – 3,144.344* amylose:amylopectin ratio AM:AP (R² = 0.44). For hard corn kernel AMEn = 3,040.029 + 1,421.562* AM:AP (R² = 0.30). (Panel B.)Linear effect of CP retention assessed in excreta samples on AMEn at 16 d of age in corn with average (P < 0.001) and hard kernel (P < 0.001). For average corn kernel hardness AMEn = 1,152.539 + 29.676*CP retention (R² = 0.86). For hard corn kernel AMEn = 1,067.541 + 30.942*CP retention (R² = 0.79). (Panel C) Linear effect of starch digestibility evaluated in excreta samples on AMEn at 16 d of age in corn with average (P < 0.001) and hard kernel (P = 0.004). For average corn kernel hardness AMEn = −5,340.215 + 91.327*Starch dig (R² = 0.50). For hard corn kernel AMEn = −1,611.428 + 53.057*Starch dig. (R² = 0.17). Markers represent the eight means per treatment combination of kernel hardness (average or hard) and drying temperatures (35, 80, or 120°C) postharvest and lines the linear fit by kernel hardness.