Abstract

Sorghum bicolor (L.) Moench is the world's fifth mostly cultivated cereal after wheat, corn, barley, and oats. Although originated in Ethiopia, the United States is the leading producer and exporter of grain sorghum worldwide. In Africa, it is the second most widely grown crop after corn and mainly cultivated in the arid and semi-arid regions of the continent. Its hardiness to environmental stress and low costs of production has made it a more viable forage crop for animal consumption in marginal agricultural regions. In this study, twelve sorghum varieties were evaluated for their forage quality based on their agro-morphological traits and cell wall composition. Results of the agro-morphological trait analysis showed that black-seeded Sudangrass had the lowest dry weight compared to the sweet sorghum cultivars (Sugar Drip, Rex and Ramada) and this was significant at 90 days after sowing (DAS). This was reflected on its low in vitro digestibility and thus its low forage quality. In addition, the Sudan grasses exhibited a significant decrease in their fresh and dry weights, stalk diameter, leaf width and leaf number with advancing plant maturity. This correlated with their forage quality thus the best cutting time point for the Sudan grasses was at 75 DAS. Results of fiber fraction, nutritive analysis and in vitro digestibility indicated that Sugar Drip had the highest forage quality as evident from its low lignin content, high Relative Feed Value and highest Net Energy of Lactation at and this was significant at 90 DAS. This was followed by Rex, Ramada, MN1054, white-seeded Sudangrass, GK Aron and black-seeded Sudangrass. Grain sorghum cultivars were harvested at grain maturity and results of in vitro digestibility of their cell wall components were slightly comparable to sweet sorghum. However, Sohag was significantly superior to LG35 in terms of its RFV and in vitro digestible dry matter. Single nucleotide polymorphisms (SNPs) in one of the lignin biosynthesis genes; caffeic acid 3-O-methyltransferase (COMT) were evaluated for their effect on forage quality. The detected SNPs is expected to affect protein function. No correlation was noted between the COMT SNPs and lignin content and accumulation in the studied cultivars. Likewise, the detected SNPs did not have any effect of forage quality.

Department

Biotechnology Program

Degree Name

MS in Biotechnology

Date of Award

2-1-2020

Online Submission Date

July 2019

First Advisor

Fouad, Walid

Committee Member 1

Assem, Shireen

Committee Member 2

El-Fawal, Hassan

Document Type

Thesis

Extent

113 p.

Rights

The author retains all rights with regard to copyright. The author certifies that written permission from the owner(s) of third-party copyrighted matter included in the thesis, dissertation, paper, or record of study has been obtained. The author further certifies that IRB approval has been obtained for this thesis, or that IRB approval is not necessary for this thesis. Insofar as this thesis, dissertation, paper, or record of study is an educational record as defined in the Family Educational Rights and Privacy Act (FERPA) (20 USC 1232g), the author has granted consent to disclosure of it to anyone who requests a copy.

IRB

Not necessary for this item

Comments

Special thanks to Dr. Ashraf, director of the Regional Centre for Food and Feed for his assistance in all the forage analysis. I would love to express my heartfelt gratitude to the African Graduate Fellowship and the Student Support Grant without which my wonderful study and research experience in AUC would not have been possible. Thank you so much for the golden opportunity given to me as a beneficially of Egypt’s first-class higher education.

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