Surveying the genomic landscape of silage-quality traits in maize(Zea mays L.)

Despite the longstanding importance of silage as a critical feed source for ruminants,its quality improvement has been largely overlooked.Although numerous quantitative trait loci(QTL)and genes affecting silage quality in maize have been reported,only a few have been effectively incorporated into breeding programs.Addressing this gap,the present study undertook a comprehensive meta-QTL(MQTL)analysis involving 523 QTL associated with silage-quality traits collected from 14 published studies.Of the 523 QTL,405 were projected onto a consensus map comprising 62,424 genetic markers,resulting in the identification of 60 MQTL and eight singletons.The average confidence interval(CI)of the MQTL was 3.9-fold smaller than that of the source QTL.Nine of the 60 identified MQTL were classified as breeder’s MQTL owing to their small CIs,involvement of more QTL,and large contribution to phenotypic variation.One-third of the MQTL co-localized with DNA marker-trait associations identified in previous genomewide association mapping studies.A set of 78 high-confidence candidate genes influencing silage quality were identified in the MQTL regions.These genes and associated markers may advance marker-assisted breeding for maize silage quality.

Comparison of forage yield,silage fermentative quality,anthocyanin stability,antioxidant activity,and in vitro rumen fermentation of anthocyanin-rich purple corn(Zea mays L.) stover and sticky corn stover

The objective of this study was to observe the forage yield, silage fermentative quality, anthocyanin stability, and antioxidant activity during the storage period and in vitro rumen fermentation of anthocyanin-rich purple corn （Zea mays L.） stover （PS） and sticky corn stover （SS）. Forage yield of corn stover was weighed and ensiled with two treatments： （1） hybrid sticky waxy corn stover （control）, and （2） hybrid purple waxy corn stover （treatment）. Samples were stored in mini-silos for periods of 0, 7, 14, 21,42, 63, 84, and 105 d. The results showed that PS had significantly higher （P〈0.05） yields of dry matter （DM）, organic matter （OM）, gross energy （GE）, crude protein （CP）, neutral detergent fiber （NDF）, acid detergent fiber （ADF）, and total anthocyanins than that of the SS. Anthocyanin-rich purple corn stover silage （PSS） showed higher （P〈0.05） levels of DM and CP relative to the sticky corn stover silage （SSS）. Although anthocyanin-rich PSS displayed a lower （P〈0.05） level of pelargonidin-3-glucoside （P3G）, it had higher （P〈0.05） levels of peonidin （Peo） and pelargonidin （Pel） compared to the control. Delphinidin （Del） and malvidin （Mal） were not detected in SSS during the ensilage period; in PSS, Del was no longer detected after 7 d of ensilage. Specifically, total anthocyanins in anthocyanin-rich PSS decreased rapidly （P〈0.05） prior to 7 d of ensilage, and then remained at relatively stable （P〉0.05） constants. Compared to the anthocyanin-rich PSS, SSS displayed significantly higher （P〈0.05） pH value and ammonia nitrogen （NH3-N） content. Propionic acid （PA） at 0 d and butyric acid （BA） during the entire study period were not detected, whereas anthocyanin-rich PSS showed a higher （P〈0.05） level of lactic acid （LA） than that of the SSS. Compared with the SSS extract, anthocyanin-rich PSS extract showed a higher （P〈0.05） level of 2,2-diphenyl-1-picryihydrazyl （DPPH） scavenging activity and displayed a lower （P〈0.05） half maximal inhibitory concentration （IC50） value. Moreover, anthocyanin-rich PSS reduced （P〈0.05） gas production （GP）, and displayed lower levels of immediately soluble fraction and ratio of acetic acid （AA） to PA at 12 h, but the other parameters were unaffected （P〉0.05） relative to the control. Taken together, the results indicated that： （1） anthocyanins could be stable in silage; （2） anthocyanin-rich PSS showed better silage fermentative quality and stronger antioxidant activity; and （3） anthocyanin-rich PSS had no negative effect on rumen fermentation parameters.

Effect of Bacillus amyloliquefaciens and Bacillus subtilis on fermentation, dynamics of bacterial community and their functional shifts of whole-plant corn silage

Background:Bacillus amyloliquefaciens(BA)and Bacillus subtilis(BS)are usually used as feed supplements directly or bacterial inoculants in biological feeds for animals.However,few research have reported the effects of BA and BS on fermentation characteristics and bacterial community successions of whole-plant corn silage during ensiling.If the BA and BS inoculants have positive effects on silages,then they could not only improve fermentation characteristics,but also deliver BA or BS viable cells to ruminants,which would play its probiotic effect.Therefore,the objectives of this study were to investigate the effects of BA and BS on the fermentation,chemical characteristics,bacterial community and their metabolic pathway of whole-plant corn silage.Results:Freshly chopped whole-plant corn was inoculated without or with BA and BS,respectively,and ensiled for1,3,7,14 and 60 d.Results showed that BA and BS inoculations increased lactic acid concentrations of whole-plant corn silages compared with control,and BA inoculation decreased acetic acid concentrations,whereas BS inoculation decreased fiber contents and increased crude protein(CP)content.Higher water-soluble carbohydrate contents and lower starch contents were observed in BA-and BS-inoculated silages compared with that in control.The decreased CP content and increased non-protein nitrogen content were observed in BA-inoculated silage,which was consistent with the higher amino acid metabolism abundances observed in BA-inoculated silage.In addition,it was noteworthy that BA and BS inoculations increased the metabolism of cofactors and vitamins,and decreased the relative abundances of drug resistance:antimicrobial pathways.We also found that the bacterial metabolism pathways were clearly separated into three clusters based on the ensiling times of whole-plant corn silage in the present study.There were no significant differences in bacterial community compositions among the three groups during ensiling.However,BA and BS inoculations decreased the relative abundances of undesirable bacteria such as Acetobacter and Acinetobacter.Conclusion:Our findings suggested that the BS strain was more suitable as silage inoculants than the BA strain in whole-plant corn silage in this study.

Effects of Different Additives on Silage Qualities of Corn Stalks

[ Objective] To explore the effects of different additives on the fermentation qualities and chemical composition of corn stalk silage. [ Method] The corn stalks were fermented in preservative of silage supplemented formic acid and formic aldehyde for 50 d, and the fermentation qualities and chemical composition of silage were examined. [ Result] Supplementation of formic acid improved fermentation qualities and increased the content of crude protein and soluble carbohydrate, while the content of crude protein was lower in the control silage. Supplementation of formic aldehyde alone did not enhance the fermentation qualities of silage. Supplementation of both formic acid and formic aldehyde （ especially at a ratio of 3：1 ） markedly improved the fermentation qualities of silage than that of formic acid alone. [ Conclusion] Supplementation of formic both acid and formic aldehyde can improve the fermentation qualities of corn stalk silage.