JIA-2018-09

2085 TIAN Xing-zhou et al. Journal of Integrative Agriculture 2018, 17(9): 2082–2095 Where, k is ruminal outflow rate and the value sets as 0.031 h. GP was calculated according to the following equation by Ørskov and McDonald (1979). y=a+b(1–e –ct ) Where, y denotes the volume of gas produced at time t, a describes the gas production from the immediately soluble fraction (mL), b is the gas production from the insoluble fraction (mL), c is the gas production rate constant for the insoluble fraction b (% h –1 ), t expresses incubation time (h), and a+b represents the potential extent of gas production (mL). 2.5. Statistical analysis All statistical analyses were performed using the SAS System version 9.1.3 (SAS Institute Inc., Cary, NC, USA). The replicate was considered the experimental unit in all of the statistical analyses. Differences in the forage yield and nutritional value were analyzed using Student’s t -test. Significant differences between parameters were assessed using a 2×8 (silage treatment×day) analysis of variance (ANOVA) test in chemical composition, anthocyanin composition, and silage fermentative parameters during the storage period (0–105 d). The statistical significances of the DPPH scavenging activity between the different dilutions (1/5–1) were detected using a 2×5 (silage treatment×dilution) ANOVA test. A 2×8 (silage treatment×incubation time) ANOVA test was also used for the difference in the gas production during the incubation time (0–96 h). Student’s t -test was also applied for the differences in the rumen fermentation parameters. Because the significant interactions ( P <0.05) between silage and storage day were observed for WSC, malvidin-3-O- glucoside (M3G), cyanidin (Cya), and total anthocyanins, the effect of storage day on these 4 parameters were reported. The IC 50 value was calculated from linear regression analysis by GraphPad Prism 5 software. Differences were considered statistically significant at P <0.05. 3. Results 3.1. Forage yield and nutritional value As shown in Table 1, there was no statistically significant difference ( P >0.05) for forage fresh weight content of sticky corn stover (SS) and anthocyanin-rich purple corn stover (PS). Compared to SS, PS had significantly higher ( P <0.05) DM yield, chemical composition yields (OM, GE, CP, NDF, and ADF), and total anthocyanin yield. In addition, PS did not affect ( P >0.05) DMI, DDM, RFV, and NE L for ruminants. 3.2. Chemical composition There was no interaction ( P >0.05) between treatment and time for the DM and CP, whereas anthocyanin-rich PSS showed higher ( P <0.05) levels of DM and CP compared to that of sticky corn stover silage (SSS; Table 2). The ash, OM, GE, NDF, and hemicellulose did not differ ( P >0.05) between silages and were unchanged ( P >0.05) throughout the experiment. The level of ADF increased rapidly ( P <0.05) prior to 7 d of ensilage, and then remained at relatively stable ( P >0.05) values. There was an interaction ( P <0.0001) between treatment and time was observed for the WSC. SSS had higher ( P <0.05) WSC content at 0 and 7 d of ensilage relative to the anthocyanin-rich PSS. The levels of WSC in both of silages were maintained in stable values ( P >0.05) from 14 to 84 d of ensilage, whereas WSC in Table 1 Comparison of forage yield and nutritional value of sticky corn stover (SS) and anthocyanin-rich purple corn stover (PS) Item 1) Treatment SEM 2) P -value SS PS Forage (kg ha –1 fresh) 11 790 12 000 278 0.623 DM (kg ha –1 ) 2 747 3 168 76.7 0.0138 OM (kg ha –1 DM) 2 572 2 949 66.2 0.0158 GE (Mcal ha –1 DM) 10 805 12 444 279 0.0142 CP (kg ha –1 DM) 181 229 5.03 0.0024 NDF (kg ha –1 DM) 1 586 1 782 40.2 0.0263 ADF (kg ha –1 DM) 676 796 17.8 0.0088 Anthocyanins (kg ha –1 DM) 1.04 7.44 0.145 0.0009 DMI (g kg –1 of body weight) 20.8 21.3 0.450 0.471 DDM (g kg –1 DM) 697 693 7.79 0.752 RFV (%) 112 115 2.48 0.576 NE L (Mcal kg –1 ) 1.27 1.25 0.0419 0.752 1) DM, dry matter; OM, organic matter; GE, gross energy; CP, crude protein; NDF, neutral detergent fiber; ADF, acid detergent fiber; DMI, dry matter intake; DDM, digestible dry matter; RFV, relative feed value; NE L , net energy for lactation. 2) SEM, standard error of the mean. Values represented the means of 3 replicates ( n =3).