The rapid restoration and renewal of the moso bamboo logging zone after strip logging has emerged as a key research area, particularly regarding whether nutrient accumulation and utilization in reserve zones can aid in the restoration and regeneration of the logging zone. In this study, a dynamic 15N isotope tracking experiment was conducted by injecting labeled urea fertilizer into bamboo culms. Logging zones and reserve zones of 6 m, 8 m, and 10 m widths were established. The conventional selective logging treatment served as a control (Con). Measurements were taken in May and October to assess the differences in nitrogen accumulation ability, utilization rates, and nutrient content across different organs in bamboo forests at different growth stages and under different treatments. Principal component analysis was conducted to evaluate and determine the importance of each indicator and strip logging treatment comprehensively. The results showed that various bamboo organs exhibited higher nitrogen accumulation and utilization rates during the peak growth period compared to the late growth period. Leaves had the highest nitrogen accumulation and utilization rates than the other organs. The average C content in various bamboo organs under different logging treatments exhibited subtle differences, irrespective of variation in logging width treatments. Bamboo culm exhibited the highest carbon accumulation. The C content in various bamboo organs was higher during the peak growth period than in the late growth period. The nitrogen content peaked in the leaves during the two growth stages and was significantly higher compared to the other organs. Most bamboo organs in the logging zones exhibited relatively higher nitrogen content than in the reserve zone and Con group. The P content was highest in bamboo leaves compared with other organs across the different strip logging treatments. Principal component analysis revealed relatively high absolute values of the coefficients for the C content, bamboo stump C content, and culm Ndff%. Log8 and Res10 zones had the highest comprehensive evaluation scores, indicating that Log8 and Res10 had the best effect on the promotion of nitrogen utilization and nutrient accumulation in various organs of moso bamboo.

To avoid a high body protein mobilization in modern lean sows during lactation, an adequate dietary amino acid (AA) supply and an efficient AA utilization are crucial. This study evaluated the effects of dietary CP and in vitro protein digestion kinetics on changes in sow body condition, litter weight gain, milk composition, blood metabolites, protein utilization efficiency and subsequent reproductive performance. We hypothesized that a slower digestion of dietary protein would improve AA availability and utilization. In total, 110 multiparous sows were fed one of four lactation diets in a 2 × 2 factorial design, with two CP concentrations: 140 g/kg vs 180 g/kg, and two protein digestion kinetics, expressed as a percentage of slow protein (in vitro degradation between 30 and 240 min): 8 vs 16% of total protein. Feeding sows the high CP diets reduced sow weight loss (Δ = 7.6 kg, P < 0.01), estimated body fat loss (Δ = 2.6 kg, P = 0.02), and estimated body protein loss (Δ = 1.0 kg, P = 0.08), but only at a high percentage of slow protein. A higher percentage of slow protein increased litter weight gain throughout lactation (Δ = 2.6 kg, P = 0.04) regardless of CP concentrations, whereas a higher CP only increased litter weight gain during week 3 of lactation (Δ = 1.2 kg, P = 0.01). On Day 15 postfarrowing, serial blood samples were taken from a subsample of sows fed with the high CP diets. In these sows, a high percentage of slow protein resulted in higher plasma AA concentrations at 150 and 180 min after feeding (Δ = 0.89, P = 0.02, Δ = 0.78, P = 0.03, mmol/L, respectively) and lower increases in urea at 90 and 120 min after feeding (Δ = 0.67, P = 0.04, Δ = 0.70, P = 0.03, mmol/L, respectively). The higher dietary CP concentration increased total nitrogen loss to the environment (Δ = 604 g, P < 0.01) with a reduction of protein efficiency (Δ = 14.8%, P < 0.01). In the next farrowing, a higher percentage of slow protein increased subsequent liveborn litter size (Δ = 0.7, P < 0.05). In conclusion, feeding sows with a high dietary CP concentration alleviated maternal weight loss during lactation when the dietary protein digestion rate was slower, but lowered protein efficiency. A slower protein digestion improved litter weight gain, possibly by reducing AA oxidation and improving plasma AA availability, thus, improving protein efficiency.

The aim of the study was to investigate whether increased inclusion of sugar beet pulp (SBP) alters retention of fat, protein, and energy when backfat (BF) is restored in early- and mid-gestation. In total, 46 sows were fed one of four dietary treatments with increasing inclusion of SBP providing dietary fiber (DF) levels of 119, 152, 185, and 217 g/kg; sows were assigned to one of three feeding strategies (FS; high, medium, and low) depending on BF thickness at mating and again at day 30 for the following month. On days 0, 30, 60, and 108, body weight (BW) and BF thickness were measured and body pools of protein and fat were estimated using the deuterium oxide technique. On days 30 and 60, urine, feces, and blood samples were collected to quantify metabolites, energy, and nitrogen (N) balances. On days 15 and 45, heart rate was recorded to estimate heat energy. At farrowing, total born and weight of the litter were recorded. In early gestation, BW gain (P < 0.01) and body protein retention increased (P < 0.05) with increasing fiber inclusion, while body fat retention increased numerically by 59%. The increase in BF was greatest for sows fed the high FS, intermediate when fed the medium strategy, and negligible for sows fed the lowest FS (P < 0.001). Nitrogen intake, N loss in feces, and N balance increased linearly, whereas N loss in urine tended to decrease with increasing inclusion of fibers in early gestation. Concomitantly, fecal energy output and energy lost as methane increased linearly (P < 0.001), while energy output in urine declined linearly. Total metabolizable energy (ME) intake therefore increased from 36.5 MJ ME/d in the low fiber group to 38.5 MJ ME/d in the high fiber group (P < 0.01). Changing the ME towards more ketogenic energy was expected to favor fat retention rather than protein retention. However, due to increased intake of ME and increased N efficiency with increasing fiber inclusion, the sows gained more weight and protein with increasing fiber inclusion. In conclusion, increased feed intake improved both fat and protein retention, whereas increased DF intake increased protein retention.
Feeding sows sugar beet pulp (SBP) has many known benefits, for example, increased satiety and high fermentability. This study investigates the ability of the sow to utilize energy for fat retention when replacing part of starch with dietary fiber. After a demanding lactation, sows need to restore body fat, and concomitantly avoid excessive protein retention, which will increase energy demand for maintenance and risk of locomotory problems. The hypothesis in this study is that energy from fermented fibers is more efficient for fat retention than dietary starch. In the study, sows had numerically greater fat retention when fed high concentrations of fiber from SBP, but concomitantly sows unintendedly also increased their protein retention, which in turn substantially increased their body weight. Sows were allocated to one of three feeding strategies depending on their body condition score (lean, medium, or fat) in early gestation, and backfat was efficiently restored in most sows within a month. In conclusion, although gestating sows have a high capability to utilize energy from fermentable fiber, they are disposed to protein over fat retention. These aspects need to be addressed in the nutrition of modern genotype sows.

Fifty-two multiparous sows (average parity 3.1 ± 0.9 and initial BW 245.6 ± 32.5 kg) were used to evaluate the effects of dietary standardized ileal digestible (SID) Lys-to-net energy (NE) ratios on nitrogen (N) utilization throughout a 24-d lactation period. Sows were randomly assigned to one of five isoenergetic feeding programs that provided equally spaced and increasing SID Lys-to-NE ratios between 2.79 and 5.50 g SID Lys/Mcal NE. The feeding programs were generated by blending the two extreme diets in varying proportions and were provided to sows immediately after farrowing (day 1) and until weaning at day 24 ± 1. Nitrogen balances were conducted between days 4 and 7, 12 and 15, and 20 and 23 ± 1 of lactation to represent weeks 1, 2, and 3, respectively, using total urine collection and fecal grab sampling. Contrast statements were used to determine the linear and quadratic effects of increasing Lys-to-NE ratios. Linear and quadratic broken-line and polynomial quadratic (QPM) models were used to determine the optimum dietary Lys-to-NE ratios for N retention in milk. The Bayesian information criterion was used to assess the best fit. Feeding program did not influence sow average daily feed intake (5.8 ± 0.1 kg), BW change (-8.2 ± 3.1 kg), or change in back fat thickness (-2.6 ± 0.7 mm) over the 24-d lactation period, but piglet average daily gain increased with dietary SID Lys-to-NE ratio (linear; P < 0.05). Sow N intake increased with increasing dietary Lys-to-NE ratio in weeks 2 and 3 (linear; P < 0.001). Whole-body N retention (N intake - N output in urine and feces) increased with increasing dietary Lys-to-NE ratio in all weeks (linear; P < 0.05). The N retention in milk tended to increase then decrease with increasing dietary Lys-to-NE ratio in weeks 1 and 2 (quadratic; P = 0.051 and P = 0.081) and the QPM showed optimal milk N retention at 4.28, 4.42, and 4.67 g Lys/Mcal NE for weeks 1, 2, and 3, respectively. Maternal N retention (N intake - N output in urine, feces, and milk) decreased and then increased in week 1 (quadratic; P < 0.01) and increased in weeks 2 and 3 (linear; P < 0.01) with increasing dietary Lys-to-NE ratio. Therefore, the SID Lys-to-NE ratio necessary to optimize milk N output is dynamic throughout lactation. A two-diet feeding program could be created to match optimal weekly or daily SID Lys-to-NE ratios, which could lead to improved piglet ADG and body weights at weaning.
Despite significant changes in nutrient and energy requirements as well as voluntary feed intake during lactation, sows are typically fed a single diet with a static nutrient and energy composition throughout the entire lactation period, which may not optimize milk output. Fifty-two sows were used to explore how various ratios of standardized ileal digestible (SID) Lys to net energy (NE) in lactating sow diets affect the growth of piglets and nitrogen utilization during a 24-d lactation period. Sows were randomly assigned to one of five feeding programs that contained equal amounts of energy and provided equally spaced and increasing Lys-to-NE ratios between 2.79 and 5.50 g SID Lys/Mcal NE immediately after farrowing. The dietary Lys-to-NE ratio did not influence sow daily feed intake, body weight change, or change in backfat thickness over the 24-d lactation period; however, piglet growth rate and body weight at weaning increased with increasing Lys-to-NE ratio. The SID Lys-to-NE ratio necessary to optimize milk nitrogen output was 4.28, 4.42, and 4.67 g SID Lys/Mcal NE during weeks one, two, and three of lactation, respectively. Therefore, it is possible to create a two-diet feeding program offering dynamic SID Lys-to-NE ratios as lactation progresses, which could lead to improved piglet average daily gain and body weights at weaning.

The study investigated the effects of dietary protein level and the inclusion of hydroponic barley sprouts (HB) on lactation performance, blood biochemistry and N use efficiency in mid-lactation dairy cows. Treatments were arranged in a 2 × 2 factorial design with 2 crude protein (CP) levels [16.8% and 15.5% of dry matter (DM)], with HB (4.8% of DM, replacing 4.3% of alfalfa hay and 0.5% of distillers dried grains with solubles (DDGS)) or without HB. Forty-eight multiparous Holstein dairy cows (146 ± 15 d in milk, 40 ± 5 kg/d of milk) were randomly allocated to 1 of 4 diets: high protein diet (16.8% CP, HP), HP with HB (HP+HB), low protein diet (15.5% CP, LP), or LP with HB (LP+HB). An interaction between CP × HB on dry matter intake (DMI) was detected, with DMI being unaffected by HB inclusion in cows fed the high CP diets, but was lower in cows fed HB when the low CP diet was fed. A CP × HB interaction was also observed on milk and milk protein yield, which was higher in cows fed HB with HP, but not LP. Inclusion of HB also tended to reduce milk fat content, and feeding HP resulted in a higher milk protein and milk urea N content, but lower milk lactose content. Feed efficiency was increased by feeding HP or HB diets, whereas N efficiency was higher for cows fed LP or HB diets. There was an interaction on the apparent total-tract digestibility of DM and CP, which was higher when HB was fed along with HP, but reduced when fed with LP, whereas the digestibility of ADF was increased by feeding low protein diets. In conclusion, feeding a low protein diet had no adverse effect on cow performance, while feeding HB improved milk and milk component yield, and N efficiency when fed with a high CP diet, but compromised cow performance with a low CP diet.

BACKGROUND: Promoting the synchronization of glucose and amino acid release in the digestive tract of pigs could effectively improve dietary nitrogen utilization. The rational allocation of dietary starch sources and the exploration of appropriate dietary glucose release kinetics may promote the dynamic balance of dietary glucose and amino acid supplies. However, research on the effects of diets with different glucose release kinetic profiles on amino acid absorption and portal amino acid appearance in piglets is limited. This study aimed to investigate the effects of the kinetic pattern of dietary glucose release on nitrogen utilization, the portal amino acid profile, and nutrient transporter expression in intestinal enterocytes in piglets.
METHODS: Sixty-four barrows (15.00 ± 1.12 kg) were randomly allotted to 4 groups and fed diets formulated with starch from corn, corn/barley, corn/sorghum, or corn/cassava combinations (diets were coded A, B, C, or D respectively). Protein retention, the concentrations of portal amino acid and glucose, and the relative expression of amino acid and glucose transporter mRNAs were investigated. In vitro digestion was used to compare the dietary glucose release profiles.
RESULTS: Four piglet diets with different glucose release kinetics were constructed by adjusting starch sources. The in vivo appearance dynamics of portal glucose were consistent with those of in vitro dietary glucose release kinetics. Total nitrogen excretion was reduced in the piglets in group B, while apparent nitrogen digestibility and nitrogen retention increased (P < 0.05). Regardless of the time (2 h or 4 h after morning feeding), the portal total free amino acids content and contents of some individual amino acids (Thr, Glu, Gly, Ala, and Ile) of the piglets in group B were significantly higher than those in groups A, C, and D (P < 0.05). Cluster analysis showed that different glucose release kinetic patterns resulted in different portal amino acid patterns in piglets, which decreased gradually with the extension of feeding time. The portal His/Phe, Pro/Glu, Leu/Val, Lys/Met, Tyr/Ile and Ala/Gly appeared higher similarity among the diet treatments. In the anterior jejunum, the glucose transporter SGLT1 was significantly positively correlated with the amino acid transporters B0AT1, EAAC1, and CAT1.
CONCLUSIONS: Rational allocation of starch resources could regulate dietary glucose release kinetics. In the present study, group B (corn/barley) diet exhibited a better glucose release kinetic pattern than the other groups, which could affect the portal amino acid contents and patterns by regulating the expression of amino acid transporters in the small intestine, thereby promoting nitrogen deposition in the body, and improving the utilization efficiency of dietary nitrogen.

Soybean proteins (pro) and soybean peptides (pep) are beneficial to the growth and metabolism of Limosilactobacillus reuteri (L. reuteri). However, whether they could assist L. reuteri in inhibiting intestinal pathogens and the inhibition mode of them is still unclear. In this study, a co-culture experiment of L. reuteri LR08 with Escherichia coli JCM 1649 (E. coli) was performed. It showed that pro and pep could still favour the growth of L. reuteri over E. coli under their competition. The inhibition zone experiment showed the digested soybean proteins (dpro) could improve its antibacterial activity by increasing the secretion of organic acids from L. reuteri. Furthermore, digested soybean peptides (dpep) could enhance nitrogen utilization capacity of L. reuteri over E. coli. These results explained the patterns of dpro and dpep assisting L. reuteri in inhibiting the growth of E. coli by regulating its organic acid secretion and the ability of nitrogen utilization.

Cadmium (Cd) contamination in the soil potentially hampers microbial biomass and adversely affects their services such as decomposition and mineralization of organic matter. It can reduce nitrogen (N) metabolism and consequently affect plant growth and physiology. Further, Cd accumulation in plants can pose health risks through vegetable consumption. Here, we investigated consequences of Cd contamination on fertilizer value and associated health risks following the application of biogas residues (BGR) to various soil types. Our results indicate that the application of BGR to all soil types significantly increased dry matter (DM) yield and N uptake. However, the Cd contamination negatively affected DM yield and N recovery from BGR in a dose-dependent manner. Organic N mineralization from BGR also decreased in Cd-contaminated soils. The highest DM yield and N recovery were recorded in sandy soil, whereas the lowest values were observed in clay soil. Cadmium was accumulated in spinach, and health risk index (HRI) associated with its dietary intake revealed that consuming spinach grown in Cd-contaminated soil, with or without BGR, is unsafe. Among the soil types, values of daily intake of metals (DIM) and HRI were lowest in clay soil and highest in sandy soil. However, the application of BGR curtailed HRI across all soil types. Notably, the application of BGR alone resulted in HRI values < 1, which are under the safe limit. We conclude that soil contamination with Cd reduces fertilizer value and entails implications for human health. However, the application of BGR to the soil can decrease Cd effects.

Nitrogen (N) cycle is one of the most significant biogeochemical cycles driven by soil microorganisms on the earth. Exogenous humic substances (HS), which include composted-HS and artificial-HS, as a new soil additive, can improve the water retention capacity, cation exchange capacity and soil nutrient utilization, compensating for the decrease of soil HS content caused by soil overutilization. This paper systematically reviewed the contribution of three different sources of HS in the soil-plant system and explained the mechanisms of N transformation through physiological and biochemical pathways. HS convert the living space and living environment of microorganisms by changing the structure and condition of soil. Generally, HS can fix atmospheric and soil N through biotic and abiotic mechanisms, which improved the availability of N. Besides, HS transform the root structure of plants through physiological and biochemical pathways to promote the absorption of inorganic N by plants. The redox properties of HS participate in soil N transformation by altering the electron gain and loss of microorganisms. Moreover, to alleviate the energy crisis and environmental problems caused by N pollution, we also illustrated the mechanisms reducing soil N2O emissions by HS and the application prospects of artificial-HS. Eventually, a combination of indoor simulation and field test, molecular biology and stable isotope techniques are needed to systematically analyze the potential mechanisms of soil N transformation, representing an important step forward for understanding the relevance between remediation of environmental pollution and improvement of the N utilization in soil-plant system.

The use of goats for meat production faces challenges from environmental and nutritional factors. Urea is an affordable non-protein nitrogen source commonly utilized in ruminant nutrition. The objective of this study was to investigate nitrogen utilization in goats fed low-quality hay supplemented with molasses blocks containing urea. Twenty Anglo-Nubian doelings were individually housed in metabolic cages and provided with chopped Buffelgrass (Cenchrus ciliaris) hay ad libitum. Goats were randomly assigned to four urea levels (0, 2, 4, and 6%; n = 5 per treatment) in molasses blocks for a duration of 30 days. A negative nitrogen balance (-2.458 g/day) was observed in doelings consuming blocks without urea, compared with a positive balance (0.895 g/d) for those consuming the 6% urea blocks. Block nitrogen intake significantly increased with urea level, but urea supplementation did not affect dry matter (DM) or neutral detergent fiber (NDFom) intake or digestibility. A minimum crude protein (CP) requirement of 8% for maintenance in doelings consuming low-quality forage with a urea-based supplement was determined through regression analysis between CP intake (% of DM) and N balance (r2 = 0.479; p < 0.002). The value of 8% of CP obtained in this study is similar to several previous studies reported in the literature, but in this case, the increments in CP came exclusively from urea. In this study, increasing the urea content of molasses blocks up to 6% significantly increased nitrogen intake, retention, and balance in goats. These results contribute to a better understanding of nitrogen utilization in goats fed low-quality hay with urea supplementation.