Dataset Information

Variance of Zein Protein and Starch Granule Morphology between Corn and Steam Flaked Products Determined Starch Ruminal Degradability Through Altering Starch Hydrolyzing Bacteria Attachment.

ABSTRACT: The current study investigated differences of γ-zein protein contents and starch granule characteristics between raw and steam flaked corns and their influences on ruminal starch hydrolyzing bacteria (SHB) attached to corn grain. Two types of raw (Corn1 and Corn2) and their steam-flaked products (SFCorn1 and SFCorn2) were applied to explore physiochemical structures and SHB attachment. SDS-PAGE was conducted to detect γ-zein protein patterns, scanning electron microscope, and small angle X-ray scattering were performed to obtain starch granule morphology, while crystallinity, DQ starch, and DAPI staining were applied to quantify SHB. The steam flaking process destroyed γ-zein proteins and gelatinized starch granules. The median particle size of Corn1 and Corn2 starch granules increased from 17.8 and 18.0 μm to 30.8 and 26.0 μm, but crystallinity decreased from 22.0 and 25.0% to 9.9 and 16.9%, respectively. The percentage of SHB attached to Corn1 residues decreased (p = 0.01) after 4 h incubation, but SHB attached to SFCorn1 residues increased (p = 0.03) after 12 h incubation. Thus, the differences of γ-zein proteins and starch granule physiochemical structures between raw and steam flaked corn played an important role in improving the rate and extent of starch ruminal degradation through altering the process of SHB attached to corn.

SUBMITTER: Xu N

PROVIDER: S-EPMC6769831 | biostudies-other | 2019 Aug

REPOSITORIES: biostudies-other

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Variance of Zein Protein and Starch Granule Morphology between Corn and Steam Flaked Products Determined Starch Ruminal Degradability Through Altering Starch Hydrolyzing Bacteria Attachment.

Xu NingNing N Wang DiMing D Liu JianXin J

Animals : an open access journal from MDPI 20190829 9

The current study investigated differences of γ-zein protein contents and starch granule characteristics between raw and steam flaked corns and their influences on ruminal starch hydrolyzing bacteria (SHB) attached to corn grain. Two types of raw (Corn1 and Corn2) and their steam-flaked products (SFCorn1 and SFCorn2) were applied to explore physiochemical structures and SHB attachment. SDS-PAGE was conducted to detect γ-zein protein patterns, scanning electron microscope, and small ...[more]

PMID: 31470611

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Project description:Corn grain has a high starch content and is used as main energy source in ruminant diets. Compared with finely ground corn (FGC), steam-flaked corn (SFC) could improve the milk yield of lactating dairy cows and the growth performance of feedlot cattle, but the detailed mechanisms underlying those finding are unknown. The rumen microbiome breaks down feedstuffs into energy substrates for the host animals, and contributes to feed efficiency. Therefore, the current study was conducted to investigate the ruminal bacterial community changes of heifers fed differently processed corn (SFC or FGC) using 16S rRNA sequencing technologies, and to uncover the detailed mechanisms underlying the high performance of ruminants fed the SFC diet. The results revealed that different processing methods changed the rumen characteristics and impacted the composition of the rumen bacteria. The SFC diet resulted in an increased average daily gain in heifers, an increased rumen propionate concentration and a decreased rumen ammonia nitrogen concentration. The relative abundance of the phylum Firmicutes and Proteobacteria were tended to increase or significantly increased in the heifers fed SFC diet compared with FGC diet. In addition, the relative abundance of amylolytic bacteria of the genera Succinivibrio, Roseburia and Blautia were elevated, and the cellulolytic bacteria (Ruminococcaceae_UCG-014 and Ruminococcaceae_UCG-013) were decreased by the steam flaking method. Spearman correlation analysis between the ruminal bacteria and the microbial metabolites showed that the rumen propionate concentration was positively correlated with genera Succinivibrio and Blautia abundance, but negatively correlated with genera Ruminococcaceae_UCG-014 abundance. Evident patterns of efficient improvement in rumen propionate and changes in rumen microbes to further improve feed conversion were identified. This observation uncovers the potential mechanisms underlying the increased efficiency of the SFC processing method for enhancing ruminant performance.

Project description:Two separate experiments were carried out to evaluate the effects of incremental doses of 10 exogenous endo-acting α-amylase and exo-acting glucoamylase; 1LAT (bacterial α-amylase), 2AK, 3AC, 4Cs4, 5Trga, 6Afuga, 7Fvga, and 10Tg (fungal α-amylases, glucoamylases, and α-glucosidase), 8Star and 9Syn (fungal amylase-mixtures; experiment 1) and three exogenous proteases; 11P14L, 12P7L, and 13P30L (bacterial proteases; experiment 2) on in vitro dry matter digestibility (IVDMD) and in vitro starch digestibility (IVSD) of mature dent corn grain using a batch culture system. Incremental doses of the exogenous enzymes (0, 0.25, 0.50, 0.75, and 1.00 mg/g of dried substrate) were applied directly to the substrate (0.5 g of ground corn, 4 mm) in sextuplicate (experiment 1) or quadruplicate (experiment 2) within F57 filter bags, which were incubated at 39 °C in buffered rumen fluid for 7 h. Rumen fluid was collected 2-3 h after the morning feeding from three lactating dairy cows and pooled. Cows were consuming a midlactation total mixed ration (TMR; 1.60 Mcal/kg DM and 15.4%; net energy of lactation and crude protein, respectively). Three independent runs were carried out for each experiment. Data were analyzed as a randomized complete block design using run as the blocking factor. Dose was used as a fixed factor while run was considered a random factor. Linear, quadratic, and cubic orthogonal contrasts were also tested. In experiment 1, enzymes 2AK, 3AC, and 10Tg did not increase (P > 0.10) IVDMD and IVSD, whereas 0.25 mg of enzymes 1LAT, 5Trga, and 8Star increased (P < 0.01) IVDMD by 23%, 47%, and 62% and IVSD by 35%, 41%, and 58%, respectively, compared with the control. Enzymes 4Cs4, 6Afuga, 7Fvga, and 9Syn linearly increased IVDMD and IVSD (P < 0.01). Greatest increases in IVDMD (82.9%) and IVSD (85.9%) resulted with 1 mg of 6Afuga compared to control. In experiment 2, the lowest dose of exogenous proteases 11P14L and 12P7L increased (P < 0.01) IVDMD by 98% and 87% and IVSD by 57% and 64%, respectively, whereas the highest dose of 13P30L increased (P = 0.02) IVDMD by 44.8% and IVSD by 30%, relative to the control. In conclusion, IVSD and IVDMD were increased by one α-amylase, certain glucoamylases, and all proteases tested, with the glucoamylase 6Afuga in experiment 1 and the neutral protease 12P7L in experiment 2, increasing IVDMD and IVSD to the greater extents. Future in vivo studies are required to validate these findings before these enzyme additives can be recommended for improving the digestibility of mature dent corn grain.

Dataset Information

Variance of Zein Protein and Starch Granule Morphology between Corn and Steam Flaked Products Determined Starch Ruminal Degradability Through Altering Starch Hydrolyzing Bacteria Attachment.

Publications

Variance of <i>Zein</i> Protein and Starch Granule Morphology between Corn and Steam Flaked Products Determined Starch Ruminal Degradability Through Altering Starch Hydrolyzing Bacteria Attachment.

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