A comparative study between lignin down regulated alfalfa lines and their respective unmodified controls on the nutritional characteristics of hay

作者：Getachew G^*; Ibanez A M; Pittroff W; Dandekar A M; McCaslin M; Goyal S; Reisen P; DePeters E J; Putnam D H

来源：Animal Feed Science and Technology, 2011, 170(3-4): 192-200.

DOI：10.1016/j.anifeedsci.2011.09.009

• Alfalfa
• CCOMT
• COMT
• Down-regulation
• In vitro gas production
• Lignin

Altering lignin biosynthesis through genetic approaches impacts the digestibility of alfalfa (Medicago sativa L) in ruminant systems. Field-grown alfalfa lines engineered for reduced caffeic acid 3-O-ethyltransferase (COMT), caffeoyl CoA 3-O-methyltransferase (CCOMT), and their respective non-transformed controls were harvested four times, and samples incubated with or without tannic acid using a DAISY(II) Incubator and in vitro gas production methods. Lignin content was reduced in transformed lines compared with their non-transformed counterpart (P<0.05). Lignin content was reduced by 13% and 24% in CCOMT and COMT, respectively, compared with the corresponding controls. In vitro gas production measurements of the down-regulated lignin lines increased 6% and 14% gas production at 72 h in CCOMT and COMT lines, respectively, compared with their respective controls. These data were consistent with in vitro dry matter digestibility data at 24 h, which showed 4% and 16% higher digestibility. for CCOMT and COMT, respectively, compared with their respective controls. COMTNULL had lower (P<0.05) dry matter digestibility at all incubation times compared with the other three lines. COMT was superior in dry matter digestibility compared with its non-transformed counterpart (COMTNULL) (P<0.05) but the difference in dry matter digestibility between CCOMT and CCOMTNULL was not significant (P>0.05). The 8 h in vitro gas production was higher in COMT than its respective non-transformed control (P<0.001). The two down regulated lines yielded higher gas production at 72 h incubation compared with their respective controls (P<0.001). COMT was superior in 72 h gas production compared with CCOMT (P<0.001). The extent of gas production was improved in the low lignin lines by the addition of tannic acid, suggesting a potential benefit of combining these traits. The potential benefits of the down-regulated lignin trait in alfalfa and the interactions with tannin compounds in vitro systems need to be validated using animal feeding studies.

• 出版日期2011-12-22