In the present study, three primiparous lactating Holstein cows (260-285 d in lactation) were used in a 3 £ 3 Latin square design to assess the effects of three doses (0·0, 0·4 and 0·8 mg/kg body weight) of lipopolysaccharide (LPS, Escherichia coli 0111:B4) on changes in ruminal microbiota and ruminal fermentation. Ruminal pH was linearly decreased (P,0·001) by LPS challenge, and the concentrations of acetate, propionate, butyrate, total volatile fatty acids and amino N increased linearly (P, 0·001) according to the LPS dose. LPS infusion linearly decreased (P,0·001) the organic matter degradability of alfalfa hay and soyabean meal in the rumen, but did not affect (P.0·10) the gene expression of Na þ /K þ -ATPase and monocarboxylic acid transporter-1, -2 and -4. A plot of principal coordinate analysis based onunweighted UniFrac values and analysis of molecular variance revealed that the structure of ruminal bacterial communities in the control was distinct from that of the ruminal microbiota in the cattle exposed to LPS. At the phylum level, when compared with the control group, LPS infusion in the tested cows linearly increased (P,0·05) the abundance of Firmicutes, and linearly decreased (P,0·05) the percentage of Bacteroidetes, Tenericutes, Spirochaetes, Chlorobi and Lentisphaerae. To our knowledge, this is the first study to report that intravenously LPS challenge altered the ruminal bacterial microbiota and fermentation profiles. The present data suggest that systemic LPS could alter ruminal environment and ruminal microbiota composition, leading to a general decrease in fermentative activity.

Nine Holstein dairy cows were fed diets with increasing proportions of rapidly fermentable carbohydrates (RFCH) to investigate the effect on reticular pH, milk fat content (MFC), 18-carbon fatty acid proportions in blood plasma and milk, and bacterial community in buccal swab samples. Inter-animal variation was expected in terms of reticular pH response upon higher RFCH proportions, which would be reflected in the occurrence or not of milk fat depression (MFD). Moreover, this variation in occurrence of MFD was hypothesized to be related to differences in blood and milk fatty acid proportions and in the bacterial community in buccal samples. Cows were fed a total mixed ration throughout the experiment, which consisted of 4 periods: adaptation (d 0-4) and low (d 5-18), increasing (d 19-24), and high . During the increasing RFCH period, the standard concentrate (211 g of starch/kg of dry matter) was gradually and partly replaced by a concentrate high in RFCH (486 g of starch/kg of dry matter). The reticular pH was measured using a bolus and the time below pH 6.00 was calculated on a daily basis. On d 13, 14, 25, 27, and 28, plasma and milk samples were collected and analyzed for 18-carbon fatty acid proportions, and buccal swabs were collected for bacterial community analysis based on 16S rRNA gene amplicon sequencing. Inter-animal variation was observed in terms of reticular pH, which allowed us to divide the cows into 2 groups: tolerant (time below pH 6.00 ≤ 0.1 h/d) and susceptible cows (time below pH 6.00 ≥ 1.26 h/d). The lower reticular pH of susceptible cows was accompanied by lower MFC. Both groups already differed in reticular pH and MFC during the low-RFCH period. Furthermore, higher RFCH amounts did not decrease the reticular pH in either of the 2 groups. Nevertheless, MFD was observed in both groups during the high-RFCH period compared with the low-RFCH period. Lower MFC in animals with lower reticular pH or during the high-RFCH period was associated with a shift in 18-carbon fatty acids toward trans-10 at the expense of trans-11 intermediates, which was observed in plasma as well as in milk samples. Moreover, lower MFC was accompanied by shifts in the relative abundance of specific bacteria in buccal samples. Genera Dialister, Sharpea, Carnobacterium, Acidaminococcus, and uncultured genera belonging to the Betaproteobacteria were more abundant in situations with greater trans-10 proportions.

The current study was carried out to assess 2 hypotheses: (1) cows differ in susceptibility to a subacute ruminal acidosis (SARA) challenge, and (2) the milk fatty acid (FA) pattern can be used to differentiate susceptible from nonsusceptible cows. For this, 2 consecutive experiments were performed. During experiment 1, the milk FA pattern was determined on 125 cows fed an increasing amount of concentrate during the first 4 wk in milk (WIM). The coefficient of variation of several SARA indicative milk FA (i.e., C15:0, C18:1 trans-10, C18:2 cis-9,trans-11, and C18:1 trans-10 to C18:1 trans-11 ratio) increased, indicating that cows reacted differently upon the concentrate build-up. A first grouping was based on the milk fat C18:1 trans-10 proportion in the third WIM. Fifteen cows with the highest proportion of the latter FA (HT10) and their counterparts with low C18:1 trans-10 and equal parity distribution (LT10) were compared, which revealed that milk fat content and milk fat to protein ratio were lower for the HT10 group. From each of the HT10 and LT10 groups, 5 animals were selected for experiment 2. The subselection of the HT10 group, referred to as HT10s, showed a high proportion of C18:1 trans-10 at 3 WIM (>0.31 g/100 g of FA), a high level of C15:0 (on average ≥1.18 g/100 g of FA over the 4 WIM), and a sharp decrease of C18:1 trans-11 (Δ ≥ 0.25 g/100 g of FA during the 4 WIM). Their counterparts (LT10s) had a low milk fat C18:1 trans-10 proportion at 3 WIM (<0.23 g/100 g of FA), an average C15:0 proportion of 0.99 g/100 g of FA or lower, and a rather stable C18:1 trans-11 proportion. The HT10s group was hypothesized to be more susceptible to a SARA challenge, achieved by increasing amounts of rapidly fermentable carbohydrates in experiment 2. The HT10s cows had a lower nadir, mean, and maximum reticulo-ruminal pH; longer period of reticulo-ruminal pH below 6.0; and higher daily reticulo-ruminal pH variation compared with LT10s cows. Throughout experiment 2, HT10s and LT10s cows differed in levels of SARA indicative milk FA. Five animals, including one LT10s and 4 HT10s cows, experienced SARA, defined as reticulo-ruminal pH <6.0 for more than 360 min/d. These results indicate that it is possible to distinguish cows with different susceptibility to a SARA challenge within a herd by monitoring the milk FA composition when cows receive the same diet.

Aiming at solving the problem of power system simulation in the construction of ship maneuvering simulator, this paper modeled the power system of 7000DWT ship and completed the model simulation display in Unity3D. A set of user interface of ship handling system satisfying ergonomics is developed by modeling and simulating ship handling system. According to the final simulation results, the data of the real ship and that of the simulation are within the allowable error range, which can well observe the scene in which the navigation condition of the ship changes due to the adjustment of the bell on the Unity3D interface.