We investigated the variation in microbial community and fermentation characteristics of whole-plant corn silage after treatment with lactic acid bacteria (LAB) and organic acids. The fresh corn forages were treated with a combination of L. acidophilus and L. plantarum (106 CFU/g fresh material) or a 7:1:2 ratio of formic acid, acetic acid, and propionic acid (6 mL/g fresh material) followed by 45 or 90 days of ensiling. Silages treated with LAB showed increased lactic acid content and decreased pH after 45 days. Although treatment with LAB or organic acids decreased the common and unique operational taxonomic units, indicating a reduction in microbial diversity, the relative abundance of Lactobacillus was elevated after 45 and 90 days compared with control, which was more distinct in the organic acid groups. Moreover, we found higher levels of acetic acid and increased abundance of Acetobacter in silages treated with organic acids whereas undesirable microorganisms such as Klebsiella, Paenibacillus, and Enterobacter were reduced. In summary, the quality of corn silages was improved by LAB or organic acid treatment in which LAB more effectively enhanced lactic acid content and reduced pH while organic acid inhibited the growth of undesirable microorganisms.

Sirtuin type 1 (SIRTl) and AMP-activated protein kinase (AMPK) play important roles in regulating energy metabolism, cell proliferation and differentiation, ageing, apoptosis, and metabolism. The effect of 100, 200, and 400 μm Resveratrol (RES), an activator of SIRT1, on apoptosis of bovine intramuscular adipocytes was investigated by nuclear staining, flow cytometry, quantitative real-time polymerase chain reaction, and western blotting. Results show that RES inhibited adipogenesis, decreased cell viability, and increased apoptotic rates in a dose-dependent way. RES up-regulated SIRT1, AMPKα, forkhead box O1 (FOXO1), hormone-sensitive lipase (HSL), lipoprotein lipase (LPL), caspase-3, and Bax; and down-regulated peroxisome proliferator-activated receptor-gamma (PPARγ), fatty acid synthase (FAS), and Bcl-2, at both mRNA and protein level. The effect of RES was abolished by addition of sirtinol (an inhibitor of SIRT1). This is the first study demonstrating a role for AMPK-SIRT1-FOXO1 signalling pathway in regulating apoptosis in bovine intramuscular adipocytes. Our findings provide important information on the mechanism by which RES controls deposition of cattle intramuscular fat via adipocyte apoptosis.

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The effects of three different feeding systems on beef cattle production performance, rumen fermentation, and rumen digesta particle structure were investigated by using 18 Limousin (steers) with a similar body weight (575±10 kg) in a 80-d experiment. The animals were equally and randomly divided into three treatment groups, namely, total mixed ration group (cattle fed TMR), SI1 group (cattle fed concentrate firstly then roughage), and SI2 group (cattle fed roughage firstly then concentrate). The results showed that the average daily gain was significantly higher in cattle receiving TMR than in those receiving SI1 and SI2 (p<0.05). Consumption per kg weight gain of concentrate, silage, and combined net energy (NEmf) were significantly decreased when cattle received TMR, unlike when they received SI1 and SI2 (p<0.05), indicating that the feed efficiency of TMR was the highest. Blood urea nitrogen (BUN) was significantly decreased when cattle received TMR compared with that in cattle receiving SI1 (p<0.05), whereas there was no difference compared with that in cattle receiving SI2. Ammonia nitrogen concentration was significantly lower in cattle receiving TMR than in those receiving SI1 and SI2 (p<0.05). The rumen area of cattle that received TMR was significantly larger than that of cattle receiving SI1 (p<0.05), but there was no difference compared with that of cattle receiving SI2. Although there was no significant difference among the three feeding systems in rumen digesta particle distribution, the TMR group trended to have fewer large- and medium-sized particles and more small-sized particles than those in the SI1 and SI2 groups. In conclusion, cattle with dietary TMR showed increased weight gain and ruminal development and decreased BUN. This indicated that TMR feeding was more conducive toward improving the production performance and rumen fermentation of beef cattle.