Small intestine histomorphometry of beef cattle with divergent feed efficiency

Background

The provision of feed is a major cost in beef production. Therefore, the improvement of feed efficiency is warranted. The direct assessment of feed efficiency has limitations and alternatives are needed. Small intestine micro-architecture is associated with function and may be related to feed efficiency. The objective was to verify the potential histomorphological differences in the small intestine of animals with divergent feed efficiency.

Methods

From a population of 45 feedlot steers, 12 were selected with low-RFI (superior feed efficiency) and 12 with high-RFI (inferior feed efficiency) at the end of the finishing period. The animals were processed at 13.79 ± 1.21 months of age. Within 1.5 h of slaughter the gastrointestinal tract was collected and segments from duodenum and ileum were harvested. Tissue fragments were processed, sectioned and stained with hematoxylin and eosin. Photomicroscopy images were taken under 1000x magnification. For each animal 100 intestinal crypts were imaged, in a cross section view, from each of the two intestinal segments. Images were analyzed using the software ImageJ®. The measurements taken were: crypt area, crypt perimeter, crypt lumen area, nuclei number and the cell size was indirectly calculated. Data were analyzed using general linear model and correlation procedures of SAS®.

Results

Efficient beef steers (low-RFI) have a greater cellularity (indicated by nuclei number) in the small intestinal crypts, both in duodenum and ileum, than less efficient beef steers (high-RFI) (P < 0.05). The mean values for the nuclei number of the low-RFI and high-RFI groups were 33.16 and 30.30 in the duodenum and 37.21 and 33.65 in the ileum, respectively. The average size of the cells did not differ between feed efficiency groups in both segments (P ≥ 0.10). A trend was observed (P ≤ 0.10) for greater crypt area and crypt perimeter in the ileum for cattle with improved feed efficiency.

Conclusion

Improved feed efficiency is associated with greater cellularity and no differences on average cell size in the crypts of the small intestine in the bovine. These observations are likely to lead to an increase in the energy demand by the small intestine regardless of the more desirable feed efficiency.     

Protective activity of the purified protein antigen of Erysipelothrix rhusiopathiae in pigs

We purified the protein antigen (P64), which contains 66 and 64 kDa proteins, from the alkaline extract (AE) of whole cells of Erysipelothrix rhusiopathiae strain Agata (serovar 5) to determine the protective activity of the antigen against E. rhusiopathiae infection in pigs. The serum titre of antibody against P64 rapidly increased in pigs immunized with 500 and 100 micrograms of P64 and reached maximum values at 3 weeks after the first immunization (1 week after the second immunization). However, the serum antibody titres were not increased in pigs immunized with 20 micrograms of P64 and in nonimmunized pigs. In the pigs immunized with live cell vaccine (acriflavin-fast attenuated strain Koganei 65-0.15), the serum titres of antibody against P64 also increased at 1-2 weeks after immunization. In a pig challenge test performed on immunized and nonimmunized pigs, all nonimmunized pigs showed typical clinical signs of swine erysipelas (fever, erysipeloid, arthritis), while all pigs immunized with 500 and 100 micrograms of P64 and live cell vaccine showed no clinical signs of this disease. In Western blot analysis, sera from pigs immunized with P64 and live cell vaccine strongly reacted with the 64 kDa protein. In contrast, the serum from nonimmunized pigs did not react with any proteins. From these results, it was suggested that a specific antibody against the 64 kDa protein could be increased in pigs immunized with P64 or live cell vaccine and that this anti-P64 antibody has a strong protective effect against E. rhusiopathiae infection in pigs.     

Prevalence of antimicrobial resistance in bacteria isolated from Great Cormorants (Phalacrocorax carbo hanedae) in Japan

Wild birds are recognized as disseminators of antimicrobial-resistant (AMR) bacteria into the environment. Here, we isolated AMR indicator bacteria from 198 Great Cormorant cloacal swabs collected in Shiga (n=90), Oita (n=52), Gifu (n=29), and Gunma (n=27) Prefectures, Japan, in 2018 and 2019. In total, 198 Aeromonas spp. and 194 Escherichia spp. were isolated, and their antimicrobial susceptibility was examined. Aeromonas spp. were resistant to colistin (8.6%), nalidixic acid (4%), and other antimicrobials (<2%), with 3.0% positivity for mcr-3. Escherichia spp. showed resistance to colistin (3.1%), ampicillin (2.6%), tetracycline (2.1%), and other antimicrobials (<2%). This study shows the presence of AMR bacteria in Great Cormorants, indicating that these birds potentially disseminate AMR bacteria.     

Potential of prolonged midseason drainage for reducing methane emission from rice paddies in Japan: a long-term simulation using the DNDC-Rice model

Water management practices, such as midseason drainage (MD) and intermittent irrigation, are effective in reducing methane (CH₄) emission from irrigated rice paddies. In a previous study in which two-year field experiments were conducted at nine sites across Japan, prolonged MD was found to reduce the seasonal total CH₄ emission by 30.5?±?6.7 % (mean?±?95 % confidence interval) compared with conventional MD without compromising rice grain yield. However, the degree of CH₄ reduction by water management is dependent on prevailing weather conditions. To estimate the mean effect of prolonged MD on CH₄ emission at the nine sites with rice straw application, we conducted a long-term (20 years) simulation using a process-based biogeochemistry model, the DNDC-Rice. The model adjusted using site-specific parameters was able to reproduce the measured magnitude of the total CH₄ emission and the suppressive effect of prolonged MD. The number of nonrainy days during MD explained the degree of CH₄ reduction for each site and all sites combined. In the simulation, mean reduction percentage was 20.1?±?5.6 % when acceptable prolonged MD (i.e., having less than 15 % yield loss) was applied compared with conventional MD. The discrepancy of the percentage between measurement and simulation was primarily attributable to longer nonrainy days during prolonged MD at several sites in the measurement than the mean of 20-year simulation. We therefore conclude that the long-term simulation better represents the mean reduction percentage of CH₄ emission by prolonged MD relative to conventional MD at the nine sites across Japan.     

Effectiveness of cyclic irrigation in reducing suspended solids load from a paddy-field district

The reduction of suspended solids, nutrients, and organic matter loads in drainage water from paddy fields is an important issue for water quality management in closed water areas in Japan. We evaluated the ability of cyclic irrigation to reduce the suspended solids load from paddy fields. In 2006 and 2007, we investigated water and mass balances during the irrigation period in a low-lying paddy-field district neighboring Lake Biwa, which is the largest lake in Japan. We confirmed that cyclic irrigation reduced effluent loads during the puddling season. With cyclic irrigation, 118 kg ha⁻¹ of suspended solids was returned to the paddy fields in 2006 and 199 kg ha⁻¹ in 2007. The effect of cyclic irrigation on the net suspended solids load can be represented by three ratios: the concentration ratio, which represents the ratio of the suspended solids concentration in drainage water to that in lake water; the cyclic irrigation ratio, which represents the ratio of the volume of reused water to that of irrigation water in cyclic irrigation; and the surplus irrigation water ratio, which represents the ratio of the volume of surplus irrigation water to that of irrigation water. The cyclic irrigation ratio and the surplus irrigation water ratio interact to determine the effect of cyclic irrigation on the net suspended solids load. Simultaneously increasing the cyclic irrigation ratio and decreasing the surplus irrigation water ratio will maximize the purification effect on drainage water from paddy fields.     

Effect of a novel rice fermented extract on gastric ulcers in horses

Gastric ulcers cause appetite loss, poor body condition, and colic in horses. This study investigated the protective effect of a rice fermented extract on the gastric mucosa in 17 healthy Thoroughbreds. For one month, horses in the rice fermented extract (nine horses) and control (eight horses) groups were orally administered a rice fermented extract (100%; 0.2 ml/kg, SID) and tap water (0.2 ml/kg), respectively. Gastric endoscopic images were obtained before and one month after rice fermented extract administration. The gastric ulcer score was lower after administration (median, 1; maximum, 2; minimum, 1) than before administration (median, 4; maximum, 4; minimum, 3) in the rice fermented extract group (P<0.05). In conclusion, the administration of a rice fermented extract for one month improves gastric mucosal lesions in Thoroughbreds with gastric ulcers.     

Numerical assessments of the impacts of climate change on regional groundwater systems in a paddy-dominated alluvial fan

Quantitative assessment of the impacts of climate change on groundwater levels is important for sustainable groundwater use. This study examined the Tedori River alluvial fan in Ishikawa Prefecture, Japan, where paddy fields occupy 45 % of the total area. A regional groundwater flow model simulated future groundwater levels in response to 38 climate change projections generated for each of three GCMs, using three GHG emission scenarios with the ELPIS-JP datasets. The numerical groundwater flow model consisted of a 1-D unsaturated water flow model (HYDRUS-1D) for estimating groundwater recharge and a 3-D groundwater flow model (MODFLOW). Variable parameters consisted of daily air temperature, precipitation, humidity, solar radiation, and wind speed, which influence groundwater through infiltration, evapotranspiration, snowfall, and snowmelt. Groundwater levels had both decreasing and increasing trends, depending on climate change. There were more decreasing than increasing trends, and the maximum groundwater drawdown during 2010–2090 was ~1 m. Groundwater level was most sensitive to change in rate of precipitation during the non-irrigation period. Variations of relatively low-intensity precipitation days, when daily precipitation was <10 mm, had an effect on groundwater level. These results contribute to development of adaptive and sustainable groundwater managements (e.g. land use management and pumping strategies) in the future.