JIA-2018-09

2087 TIAN Xing-zhou et al. Journal of Integrative Agriculture 2018, 17(9): 2082–2095 anthocyanin-rich PSS was greater ( P <0.05) than the SSS at 105 d of ensilage. 3.3. Anthocyanin composition As shown in Table 3, cyanidin-3-glucoside (C3G) did not differ ( P >0.05) between silages, and remained relatively constant ( P >0.05) throughout the experiment. Delphinidin (Del) and malvidin (Mal) were unable to be detected in SSS during the entire ensilage period; in PSS, Del was not detected after 7 d of ensilage. Pelargonidin-3-glucoside (P3G) decreased rapidly ( P <0.05) prior to 7 d of ensilage, and then remained at relatively stable ( P >0.05) values. Of interest, the level of P3G in the SSS was greater ( P <0.05) than that of the anthocyanin-rich PSS. Differently, Peonidin (Peo) and pelargonidin (Pel) levels decreased rapidly ( P <0.05) prior to 14 d of ensilage, and the means of Peo and Pel in the anthocyanin-rich PSS were greater ( P <0.05) than that of the control. There were interactions ( P <0.0001) between silage and storage day for the levels of M3G, Cya, and total anthocyanins. The M3G in anthocyanin-rich PSS increased ( P <0.05) prior to 21 d of ensilage compared to the SSS. M3G did not differ ( P >0.05) at 42 and 63 d of ensilage in both of two treatments, whereas the sample at 84 and 105 d of ensilage also showed higher ( P <0.05) M3G in anthocyanin-rich PSS than in SSS. Cya in anthocyanin-rich PSS was greater ( P <0.05) than the SSS at the beginning of the fermentation (0 d), but the level of Cya was unaffected ( P >0.05) in both SSS and anthocyanin-rich PSS from 7 to 84 d of ensilage, and anthocyanin-rich PSS also displayed a higher ( P <0.05) level of Cya at 105 d of ensilage compared to the SSS. Total anthocyanins of SSS and anthocyanin-rich PSS showed different trends because total anthocyanins in SSS did not change ( P >0.05) throughout the experiment, whereas the values in anthocyanin-rich PSS tended to decrease in response to increasing storage day. Particularly, total anthocyanins content in anthocyanin-rich PSS was greater ( P <0.05) than that of the SSS at the whole experimental period. 3.4. Silage fermentative quality The pH value dropped rapidly ( P <0.05) during the first 7 d of ensilage, and then the levels remained between 3.5 and 4.0 throughout the remainder of the experiment. Particularly, anthocyanin-rich PSS displayed a lower ( P >0.05) level of pH value relative to the control (Table 4). Although the level of NH 3 -N increased ( P <0.05) prior to 21 d of ensilage, NH 3 -N mean in PSS was significantly lower ( P <0.05) than that of the control. The levels of LA and AA increased rapidly ( P <0.05) during the first 7 d of ensilage, and LA in the anthocyanin- rich PSS was greater ( P <0.05) than that of the SSS. PA at 0 d and BA during the study period were not detected for either of the two silages. 3.5. DPPH scavenging activity As shown in Table 5. DPPH scavenging activity of SSS and PSS extracts increased with increasing concentration in dilute solution, reaching a maximum at 73.5 and 81.1%, respectively, and the values remained relatively constant ( P >0.05) after 1/3 dilution. As expected, DPPH scavenging activity mean in the anthocyanin-rich PSS extract was greater ( P <0.05) than that of the control. Accordingly, PSS extract showed a lower ( P <0.05) level of IC 50 compared to the SSS extract (0.65 µg mL –1 vs . 2.80 µg mL –1 ). 3.6. In vitro rumen fermentation The level of GP increased ( P <0.05) during the first 72 h of incubation time, and then remained relatively constant ( P >0.05) throughout the remainder of the experiment (Table 6). Of interest, SSS showed a higher ( P <0.05) level of GP compared to the anthocyanin-rich PSS. Moreover, SSS showed a significantly higher ( P <0.05) content of the value a, and no significant differences ( P >0.05) were observed in the b, c, a+b, OMD, ME, and ED compared to PSS (Table 7). As shown in Table 8, there were no significant differences ( P >0.05) in the ruminal fluid pH value, NH 3 -N concentration, and individual VFAcontent of PSS and SSS. However, SSS showed a significantly higher ( P <0.05) ratio of AA to PA at 12 h of incubation time compared to the anthocyanin-rich PSS. 4. Discussion 4.1. Forage yield and nutritional value Anthocyanins showed the potential tomitigate photooxidative injury in leaves by shielding chloroplasts from excess high- energy quanta and scavenging reactive oxygen species, thereby effectively protecting plant skin from damage by ultraviolet rays (Neill and Gould 2003; Tattini et al . 2014). Meanwhile, the purple color could also help to camouflage a plant, which was likely to have a survival advantage over plants of other colors (Schaefer and Rolshausen 2006). As a result, PS was inclined to produce higher forage and chemical composition yields. However, anthocyanins were found to have some negative effects on the intake and production of animals, resulting from the lower palatability due to its bitter taste (Jöbstl et al . 2004). One study did show that anthocyanins could have a negative effect on digestive enzymes and the epithelial lining of the digestive tract (Davis and Milner 2009). Nonetheless, reports state