Dephosphorylation of Nitrate Reductase Protein Regulates Growth of Rice and Adaptability to Low Temperature

Nitrate reductase (NR) is an important enzyme for nitrate assimilation in plants, and its activity is regulated by post-translational phosphorylation. To investigate the effect of NIA1 protein dephosphorylation on the growth of rice and its adaptability to low temperature, we analyzed phenotype, chlorophyll content, nitrogen utilization, and antioxidant capacity at low temperature in lines with a mutated NIA1 phosphorylation site (S532D and S532A), an OsNia1 over-expression line (OE), and wild-type Kitaake rice (WT). Plant height, dry matter weight, and chlorophyll content of S532D and S532A were lower than those of WT and OE under normal growth conditions but were higher than those of WT and OE at low temperature. Compared with WT and OE, the nitrite, H2O2, and MDA contents of S532D and S532A leaves were higher under normal growth conditions. The difference in leaf nitrite content between transgenic lines and WT was narrower at low temperature, especially in S532D and S532A, while H2O2 and MDA contents of S532D and S532A leaves were lower than those in WT and OE leaves. The NH4+-N and amino acid contents of S532D and S532A leaves were higher than those of WT and OE leaves under normal or low temperature. qRT-PCR results revealed that transcription levels of OsNrt2.4, OsNia2, and OsNADH-GOGAT were positively correlated with those of OsNia1, and the transcription levels of OsNrt2.4, OsNia2, and OsNADH-GOGAT were significantly higher in transgenic lines than in WT under both normal and low temperature. Phosphorylation of NR is a steady-state regulatory mechanism of nitrogen metabolism, and dephosphorylation of NIA1 protein improved NR activity and nitrogen utilization efficiency in rice. Excessive accumulation of nitrite under normal growth conditions inhibits the growth of rice; however, accumulation of nitrite is reduced at low temperature, enhancing the cold tolerance of rice.

215 Effects of Reducing Crude Protein with Supplementation of Six Essential Amino Acids and Glutamate on Growth and Backfat of Finishing Pigs

This study evaluated the effects of low CP diets on growth performance of finishing pigs. Seventy-two pigs (54 kg BW) were allotted to 3 treatments (8 pens/treatment) based on RCBD with sex and initial BW as blocks. Pigs were fed for 56 d until 120 kg BW based on 3 phases (P1/2/3 for 21/17/18 d, respectively). Treatments were CON (18.0, 13.8, 12.7% CP for P1/2/3; supplementing Lys, Met, Thr, and Trp); LCP (13.5, 11.4, 10.4% CP; supplementing Lys, Thr, Trp, Met, Val, and Ile); and LCPG (14.1, 12.8, 11.1% CP; LCP + Glu to match % Glu with CON). All diets met NRC requirements and had 2.6 Mcal/kg NE. Growth performance and backfat thickness were measured by phase. At d 56, blood and fecal samples were collected to analyze blood parameters and fecal microbiota. Data were analyzed using SAS 9.4. Overall, the growth performance and backfat thickness did not differ among treatments. BUN of LCPG was lower (P < 0.05) than CON (4.03 to 6.05 mg/dL), whereas the insulin of LCPG was greater (P < 0.05) than CON (222 to 116 pmol/dL). Relative abundance of Streptococcaceae in CON (6.1%) was greater (P < 0.05) than LCP (2.0%) and LCPG (2.3%), whereas the abundance of Erysipelotrichaceae of CON (1.8) was greater (P < 0.05) than LCP (0.9%). Colectively, when Lys, Thr, Trp, Met, Val, and Ile were provided sufficiently and NE was maintained, CP can be reduced by 2.6% without affecting growth performance and backfat thickness compared to conventional diets with Lys, Met, Trp, and Trp. Feeding low CP diets reduced harmful bacteria, and Glu supplementation further enhanced nitrogen utilization and glucose metabolism. Application of low CP formulation with supplementation of 6 essential amino acids to finishing pigs can be successful, when NE is matched and further beneficial with Glu supplementation.

293 Effect of Supplementing Rumen-protected Methionine on Blood Parameters and Ruminal Metabolites in Lactating Holstein Dairy Cows

The aim of the present study was to evaluate the effects of reducing dietary crude protein (CP) levels and supplementing rumen-protected methionine (RPM) on blood parameters and ruminal metabolites in lactating Holstein dairy cows. A total of 30 lactating Holstein dairy cows (60 ± 7 d in milk; mean ± SD) were randomly assigned to 1 of 2 treatments: diet containing 17.3% CP without RPM (control group; CON); diet containing 16.4% CP with supplementing 15.0 g/d of RPM (treatment group; RPM). All repeated, continuous data were subjected to PROC MIXED procedure of SAS (SAS version 9.2, SAS Institute Inc., Cary, NC.). The results related to blood showed that cows in RPM group exhibited lower concentration of blood urea nitrogen than that in CON group (P < 0.001). Moreover, there were no differences among treatments on concentrations of aspartate transaminase, alanine transaminase, alkaline phosphatase, globulin and albumin (P > 0.05). In ruminal metabolites, microbial CP (MCP) of dairy cows in RPM group was higher compared with CON group (P = 0.006). The concentrations of butyrate, valerate and isovalerate of RPM group were higher than that of CON group at 2h after feeding (P < 0.05). In conclusion, lower dietary CP with RPM supplementation could improve nitrogen utilization of dairy cows and synthesis of MCP in rumen, as well as change volatile fatty acids production at 2h after feeding.

Alfalfa preservation methods and use in ruminants’ diet

В статье представлены материалы, характеризующие основные способы консервирования люцерны, такие как заготовка на сено, сенаж и силос. Консервирование — это процесс создания условий, которые подавляют рост и активность патогенных микроорганизмов. Люцерна важна для животных из-за высокого содержания белка и аминокислот, но нуждается в эффективных методах консервирования с тем, чтобы использоваться крупным рогатым скотом в течение всего года. В обзорной статье авторами отмечается важность заготовки кормов в оптимальные сроки созревания растений для снижения уровня сырой клетчатки и повышения переваримости питательных веществ. По данным зарубежных исследователей, большое значение для сохранности питательных веществ корма имеет содержание влаги: в сене — не более 15%, в силосе — 45–65% и в сенаже — 35–40%. В настоящем обзоре представлены сведения о важности использования при заготовке корма консервантов, таких как бактериальные инокулянты и химические вещества, для ингибирования нежелательных микроорганизмов. В статье рассматривается значительное влияние люцерны и кормов из неё в качестве единственного корма на увеличение потребления сухого вещества, переваримость питательных веществ, прирост живой массы, утилизацию азота, удой молока, более полноценный состав жирных кислот в мышцах животных, а также на значительное снижение выбросов СН4 и снижение риска развития руминального ацидоза. Люцерна — наиболее перспективный корм для животных, поэтому основное внимание следует уделять факторам, влияющим на процесс консервирования и использования консервантов для лучшей сохранности питательных веществ. This article deals with the production of hay, haylage and silage from alfalfa. Preservation is a process preventing growth and activity of pathogenic flora. Alfalfa is a valuable crop due to high concentrations of protein and amino acids. However, effective preservation techniques are required allowing its availability throughout the year. To reduce crude fiber content and increase nutrient digestibility plant material should be harvested at optimal times. According to foreign literature water content has the most significant impact on feed nutritional value: in hay — up to 15%, silage — 45–65%, haylage — 35–40%. Bacterial strains and chemicals have the ability to inhibit the spread of pathogenic microorganisms and are the most common preservatives. Including alfalfa in livestock diet positively affects dry matter consumption, nutrient digestibility, weight gain, nitrogen utilization, milk yield, fatty acid composition in muscles but at the same time significantly reduces СН4 emission and the risk of ruminal acidosis. Alfalfa is the promising forage and therefore, its preservation needs to be accurately performed to maintain its nutritional value.