The objective of this study was to investigate the effect of lactic acid bacteria (LAB) inoculums on fermentation quality and in vitro digestibility of corn stover silage. Corn stover was ensiled without (control) or with Lactobacillus plantarum (LP), Enterococcus faecalis (EF), and Enterococcus mundtii (EM) for 45 days. The fermentation characteristics were assessed, and subsequent in vitro dry matter digestibility (DM-D), neutral detergent fiber digestibility (NDF-D), volatile fatty acids (VFA), methane (CH₄ ) production, cellulolytic bacteria proportions and their activities per corn stover silage were also determined. There was no significant difference (P>0.05) among the silage pH, lactic acid, crude protein (CP), water soluble carbohydrates (WSC) and lignocelluloses contents of different treatments. The relative proportions of Ruminococcus flavefaciens and Fibrobacter succinogenes, carboxymethyl-ocellulose and β-glycosidase activities, DM-D, NDF-D, and VFA production of in vitro incubation was higher (P<0.05) for silages inoculated with LP and EF than those of the control silage. Silage inoculated with LP showed the lowest (P<0.05) CH₄ production per unit yield of VFA, which was positively corresponded to the lowest (P<0.05) ratio of acetate to propionate. In summary, the ensiling fermentation quality and subsequent utilization of corn stover silage were efficiently improved by inoculated with L. plantarum.

Twenty-eight male, weaned Chinese Holstein calves ((156.8±33.4) kg) were used to investigate the effects of dietary forage to concentrate ratio (F:C) and forage length on nutrient digestibility, plasma metabolites, ruminal fermentation, and fecal microflora. Animals were randomly allocated to four treatments in a 2×2 factorial arrangement: whole-length forage (WL) with low F:C (50:50); WL with high F:C (65:35); short-length forage (SL) with high F:C (65:35); and SL with low F:C (50:50).  Chinese wildrye was used as the only forage source in this trial.  The grass in the SL treatments was chopped using a chaff cutter to achieve small particle size (~50% particles >19 mm).  Dry matter intake (DMI) and organic matter (OM) intake was increased by increasing both F:C (P<0.01) and forage length (FL) (P<0.05), while acid detergent fiber (ADF) and neutral detergent fiber (NDF) intakes were only increased by increasing the F:C (P<0.01).  The digestibility of NDF was increased as the FL increased (P<0.01), and it was also affected by interaction between F:C and FL (P<0.05).  Cholesterol (CHO) (P<0.01), leptin (LP) (P<0.05), and growth hormone (GH) (P<0.01) concentrations in plasma were increased as dietary F:C increased.  A significant increase in plasma triglyceride (TG) (P<0.01), insulin (INS) (P<0.05), and GH (P<0.01) levels was observed with decreasing dietary FL.  Ruminal pH values of calves fed with low F:C diets were significantly lower than those in high F:C treatment (P<0.05).  Increasing the F:C enhanced ruminal acetic acid (P<0.05) and acetic acid/propionic acid (P<0.01).  Fecal Lactobacillus content was significantly higher, while Escherichia coli and Salmonella contents were significantly lower in WL and high F:C groups (P<0.05).  Lower fecal scores (higher diarrhea rate) were observed in calves fed with SL hay compared to WL hay (P<0.05).  Denatured gradient gel electrophoresis (DGGE) bands and richness index (S) were significantly affected by the interaction between F:C and FL (P<0.05), under high F:C, band numbers and richness index from WL group were higher than that from SL group (P<0.05), whereas there were no differences between WL and SL groups under low F:C (P>0.05).  Microflora similarity was 50–73% among the different treatments.  It is concluded that the WL with high F:C (65:35) diet is suitable for weaned calves.

    This study was conducted to evaluate the effect of lactic acid bacteria and propionic acid on the fermentation quality, aerobic stability and in vitro gas production kinetics and digestibility of whole-crop corn based total mixed ration (TMR) silage. Total mixed ration was ensiled with four treatments: (1) no additives (control); (2) an inoculant (Lactobacillus plantarum) (L); (3) propionic acid (P); (4) propionic acid+lactic acid bacteria (PL). All treatments were ensiled in laboratory-scale silos for 45 days, and then subjected to an aerobic stability test for 12 days. Further, four TMR silages were incubated in vitro with buffered rumen fluid to study in vitro gas production kinetics and digestibility. The results indicated that all TMR silages had good fermentation characteristics with low pH (<3.80) and ammonia nitrogen (NH₃-N) contents, and high lactic acid contents as well as Flieg points. Addition of L further improved TMR silage quality with more lactic acid production. Addition of P and PL decreased lactic acid and NH3-N contents of TMR silage compared to the control (P<0.05). After 12 days aerobic exposure, P and PL silages remained stable, but L and the control silages deteriorated as indicated by a reduction in lactic acid and an increase in pH, and numbers of yeast. Compared to the control, addition of L had no effects on TMR silage in terms of 72 h cumulative gas production, in vitro dry matter digestibility, metabolizable energy, net energy for lactation and short chain fatty acids, whereas addition of PL significantly (P<0.05) increased them. L silage had higher (P<0.05) in vitro neutral detergent fiber digestibility than the control silage. The results of our study suggested that TMR silage prepared with whole-crop corn can be well preserved with or without additives. Furthermore, the findings of this study suggested that propionic acid is compatible with lactic acid bacteria inoculants, and when used together, although they reduced lactic acid production of TMR silage, they improved aerobic stability and in vitro nutrients digestibility of TMR silage.

This experiment was conducted to study the effect of molasses on the fermentation characteristics of mixed silage ensiled rice straw and vegetable by-products with alfalfa.  Mixture (202 g kg^–1 dry matter (DM)) consisting of rice straw, broccoli residue and alfalfa at the ratio of 5:4:1 was ensiled with three experimental treatments: (1) no additives (control); (2) molasses at 2.5% (M1); (3) molasses at 5% (M2) on a fresh matter basis of mixture, respectively.  All treatments were packed into laboratory-scale silos, and three silos per treatment were sampled on days 1, 3, 5, 14 and 30.  The result showed that the pH value of all mixed silages decreased gradually with the time of ensiling except for the control silage, in which a significant increase (P<0.05) on day 30 occurred.  The lactic acid content increased gradually with the time of ensiling and reached the highest value on day 14, and a marked decrease (P<0.05) was found in the control silage on day 30.  The changes of acetic acid content showed similar pattern with lactic acid content.  A trace amount of propionic and butyric acid contents were found in the three mixed silages during the fermentation period.  Comparing to the control, M1 and M2 treatments improved the fermentation quality of mixed silages as indicated by higher (P<0.05) lactic acid contents and lower (P<0.05) pH and ammonia-N contents.  The Flieg points also showed that M1 and M2 silages were well preserved, whereas the control silage had a bad quality.  Overall, the findings of this study suggested that adding molasses could improve fermentation quality of mixed silage, and M1 was more suitable for practical application.

   The aim of the current study was to investigate the effects of a lactic acid bacteria inoculant (Lactobacillus plantarum, LP), fibrolytic enzyme (EN), combination of LP and EN (LP+EN) on fermentation quality, nutritive characteristics and in vitro digestibility of total mixed ration (TMR) silages containing 0, 7.5 and 15.0% (on dry matter basis) of rape (Brassica campestris L.) straw (RS) (denoted as CTMR, LTMR and MTMR, respectively).  After ensiling for 60 days, TMR silages without additives were well preserved, but MTMR had higher pH than CTMR and LTMR. There were no differences in other parameters of fermentation quality, microbial composition, nutrition and in vitro digestibility between CTMR and LTMR except for yeast and mold number and crude protein (CP) content. CTMR and LTMR silage had higher CP content, in vitro neutral detergent fiber digestibility (IVNDFD) and in vitro acid detergent fiber digestibility (IVADFD), lower acid detergent fiber (ADF) content than MTMR silage.  LP and EN decreased pH and increased dry matter (DM) recovery of TMR silages. LP+EN improved the fermentation quality, nutritive characteristics and in vitro digestibility of TMR silages, showed by lower pH, ADF content, higher lactic acid content, in vitro dry matter digestibility (IVDMD) and IVNDFD.  Therefore, It was suggested that TMR silage contained 7.5% RS on a DM basis and treated with LP+EN can be as a useful feed for ruminant.

The objectives of this study were to evaluate the effect of hexanoic acid (HA) supplementations (0, as the control, CON; 0.05%, HA1; 0.1%, HA2; 0.2%, HA3) on β-carotene, and ascertain the way and key factors of HA influencing β-carotene content of alfalfa (Medicago sativa L.) after ensiled in an oxygen-free and dark conditions for 10, 40, and 80 d (from May to August, 2021). This was achieved by examining the dynamic change of β-carotene, activities of β-carotene-related enzymes, and bacterial community succession of ensiled alfalfa, using operon crtNM identification, crtE gene quantitation, and single-molecule real-time sequencing technology. The results revealed that when compared with the fresh material, terminal alfalfa silage treated with different level of HA supplementations (0, 0.05%, 0.1%, 0.2%; fresh weight basis) increased β-carotene content up to 2.86%, 85.8%, 159%, and 133%, accordingly. Meanwhile, alfalfa silage treated with higher levels of HA (0.1% and 0.2%) showed superior effects compared to those treated with lower levels of supplementation (0 and 0.05%). HA supplementation specifically facilitated the increase abundance of Lactobacillus kullabergensis and the emergence of L. senioris. Multiple linear regression models inferred that L. kullabergensis, L. apis, L. saniviri, L. senioris, peroxidase, phytoene desaturase, and lycopene β-cyclase positively regulated β-carotene. Conversely, L. rennini and L. brevis adjusted β-carotene, negatively. Positive regulations of the above bacterial species and enzymes had a stronger role in increasing β-carotene than L. rennini and L. brevis. In conclusion, the β-carotene increase of ensiled alfalfa may be regulated by HA supplementation via multiple positive factors, including 4 special Lactobacillus species (L. kullabergensis, L. apis, L. saniviri, and L. senioris), and 3 vegetative β-carotene-related enzymes (peroxidase, phytoene desaturase, and lycopene β-cyclase).