The crop-livestock system is responsible for a large proportion of global reactive nitrogen (Nr) losses, especially from China. There are diverse livestock systems with contrasting differences in feed, livestock and manure management. However, it is not yet well understood which factors greatly impact on the nitrogen (N) budgets and losses of each system. In this study, we systematically evaluated the N budgets of the crop-livestock production system from 1980 to 2050 in China by identifying the differences of 20 distinct livestock systems. During 1980 to 2010, the total N flow through the crop-livestock system increased from 21.4 to 49.7 Tg, with large variations in different input/output pathways, due to the strong livestock transitions of production towards to a monogastric and landless industrial system. Different systems contributed differently to the total N budgets in 2010. For example, the landless industrial system contributed 67% of livestock product N output, but accounted for 80% of total mineral N fertilizer use and feed N imports by the whole crop-livestock system. The mixed system had the highest rate of N use efficiency at system level due to high dependence on recycled N. N losses were diversely distributed by different systems, with the mixed ruminant system responsible for the majority of NH₃–N emission in livestock production, and the grazing ruminant system dominant in NO₃–N losses in feed production. The total N entering the crop-livestock system is estimated to be 53.9 Tg with total N losses of 41.3 Tg in 2050 under a business-as-usual scenario. However, this amount could be significantly decreased through combined measures that indicate a considerable potential for future improvements. Overall, our results provide new insights into N use and the management of livestock production.

Over the past decades, the global production of petroleum coke, a by-product of the oil sand industry, has increased with the growing importance of oil sands as a source of fossil fuels. A greenhouse study using Triticum aestivum and Deschampsia caespitosa was conducted to assess the growth and physiological effects of coke on plants. The plants were grown in cokes with or without a cap of peat–mineral mix and were compared to plants grown in a peat–mineral mix (control). Our results indicate that the selected plants can survive in coke; however, stress symptoms such as reductions in transpiration (45–91%) and stomatal conductance rates (44–92%) in T. aestivum, biomass in T. aestivum (5–83%) and D. caespitosa (43–90%), photosynthetic pigments in T. aestivum (32–68%) and D. caespitosa (33–44%) and proline concentrations in D. caespitosa (77–97%) were observed. Furthermore, potentially phytotoxic concentrations of nickel (47–69 μg g−1 in D. caespitosa) and vanadium (9.3–18.3 μg g−1 in T. aestivum and 4–27.8 μg g−1 in D. caespitosa) were found in some tissues while molybdenum accumulated in D. caespitosa shoots at concentrations reported, in other studies, to cause molybdenosis in ruminants. These results suggest that the plants growing in coke could experience multiple stresses including water stress, nutrient deficiencies and/or Ni and V toxicity. Capping coke with peat–mineral mix limited the stress symptoms and could improve revegetation success of coke impoundment sites. This study provides baseline data for future long-term field studies essential for developing coke management guidelines.

Improving digestibility, fermentation characteristics, and reducing greenhouse biogases to protect the environment without the use of synthetic materials is an important goal of modern-day farming and nutritionist. Plant extracts are capable of solving these. This is due to the digestive enzymes and the bioactive components capable of performing antimicrobial functions inherent in these plants. This study was aimed to investigate the effect of standard maize substrate treated with selected herbs and spices extracts on ruminal environmental biogas production and pressure during fermentation via biogas production technique. Herbs (Azadirachta indica leaves (T1), Moringa oleifera leaves (T2), Ocimum gratissimum leaves (T3) and spices (Allium sativum bulb (T4), Zingiber officinale rhizome (T5)) were harvested, air dried, and milled using standard procedures. Methanolic extracts of the herbs and spices were prepared and used as additives at different concentrations (50, 100, and 150 μL) to the maize substrate for in vitro biogas production. Data were analyzed using regression analysis. There were significant (P < 0.05) differences across all the treatments on the volume and pressure of biogas. The pressure and volume of biogas when compared with the levels tested showed differences (P < 0.05) across all the treatments for the prediction of volume from pressure of biogas. The pressure and volume of gas produced in vitro increased (P < 0.05) and biogases decreased (P < 0.05) by the substrate treated with herbs and spices but for the drum stick leaves which was similar for the levels of concentration tested. This means that the level tested had a pronounced mitigation effect on pressure of biogas and volume of biogas produced. It was concluded that the herb and spice extracts have the potential to improve rumen fermentation and reduce the production of biogases in ruminant diet.

Replacement of conventional feedstuffs with inexpensive and non-conventional ingredients such as quinoa may improve animal performance and the quality of their products. Quinoa supplementation is believed to have a good nutritive value as a ruminant feed, but evidence is scarce. The present experiment aimed to evaluate the nutritive value of whole, dried quinoa plant (Chenopodium quinoa) as a feed for ruminants. In the first experiment, the in sacco technique was used to evaluate nutrient disappearance and fermentation kinetics of quinoa. In the second experiment, the in vitro gas production technique was used to evaluate diets with substitution of clover hay with quinoa at 0 (Q0), 15 (Q15), 30 (Q30), and 45% (Q45) of the diets. Proximate analysis showed that quinoa contained about 18.6% crude protein (CP) with oleic acid, arachic acid, linoleic acid, and palmitic acid as the major fatty acids. The in sacco degradability showed that the “a” fraction of dry matter (DM) was low, while the fraction “b” was high for DM and CP. Replacing clover hay with quinoa did not affect gas or methane production; however, Q30 treatment quadratically increased (P < 0.05) its production. It is concluded that quinoa can be used as a feed for ruminants and can replace clover hay up to 45% in the diet.

By-products of raw artichoke (RA) (Cynara scolymus L.) and boiled broccoli (BB) (Brassica oleracea, var. italica) were ensiled in plastic bags for 24 days. Then, chemical composition, nutritive characteristics, in vitro rumen degradability, in vivo digestibility and phytosanitary residue contents of the silages were evaluated. The fermentative parameters studied indicated that plastic bags were a suitable method to silage RA and BB by-products. Both silages had a high in vitro rumen DM disappearance at 72 h, although it was higher in the BB silage (96.8 vs. 82.1%). In vivo digestibility of DM was similar and high in both silages (78.5 and 80.0% in RA and BB), but crude protein and NDF digestibilities were higher in the BB silage (83.0 and 88.3% vs. 55.1 and 78.8%). No residues of analysed phytosanitary were found. In conclusion, silages of wastes from the processing of artichoke and broccoli were free from the analysed several phytosanitary residues, their nutritive value made them adequate for feeding ruminant animals and are an environmentally friendly way of disposal of such residues.

The effects of patchouli essential oil (PEO) as an alternative to antibiotics on ruminal methanogenesis, feed degradability, and enzyme activities were evaluated. The basal substrate was incubated without additives (control, CTL) and with monensin (MON, 6 μM/g DM) or patchouli essential oil (PEO, 90 μg/g DM) for 24 h. In three different runs, the gas production (GP) was recorded at 2, 4, 8, 12, and 24 h of incubation using a semi-automatic system. The results revealed that MON had decreased (P < 0.05) the net GP and CH₄ production and digestible and metabolizable energy relative to PEO supplementation. The in vitro truly degraded organic matter was not influenced by PEO application, while was reduced (P = 0.027) with MON. Both PEO and MON had similar reducing effect on the activity of carboxymethylcellulase (P = 0.030), in vitro truly degraded neutral detergent fiber (P = 0.010), NH₃-N concentrations (P = 0.012), acetate proportion (C2, P = 0.046), C2 to C3 ratio (P = 0.023), and total protozoal count (P = 0.017). Both additives recorded similar elevating potential on the α-amylase activity (P = 0.012), propionate (C3) proportion (P = 0.011), and microbial protein (P = 0.034) compared with CTL. Effects of MON and PEO on ruminal feed degradability, microbial enzyme activities, and total protozoa counts may be responsible for modifying rumen fermentation ecology. Addition of PEO may act as a desirable alternative rumen modifier for MON in ruminant diets.

Solid-state fermentation (SSF) of ammoniated corn straw was used to produce feed protein, followed by a toxicological assessment of the fermentation product. Results showed that through ammonification at 35 °C for 9 days and the subsequent SSF by the two fungi Penicillium sp. and Torula allii at 30 °C for 5 days, the contents of real protein and crude protein of the corn straw reached 29.66% and 35.41%, respectively. Toxicological assessment in mice showed that there were no significant differences (P > 0.05) for micronucleated polychromatic erythrocytes (Mn-PCEs) and sperm abnormality between dose groups and the control group. Malondialdehyde (MDA) levels and activities of superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) also showed no significant difference (P > 0.05) between tissues (heart, liver, spleen, stomach, kidney, and brain), which indicates that the fermentation product did not induce toxic effects and is safe to use as ruminant feed.

Thirty-nine plants naturally found in Brazilian Caatinga semiarid biome were screened using an in vitro fermentability testing focused in apparent organic matter digestibility (aOMD), gas, methane (CH₄), and short-chain fatty acid (SCFA) production. Three independent in vitro runs were carried out and plants were classified by CH₄ concentration as proportion of gas and per unit of apparent digested organic matter (aDOM). According to its CH₄ concentration on produced gas (mL/L), the plants were classified as low (> 110), medium (from 60 to 110), and high (< 60) anti-methanogenic potential. From evaluated plants, 3, 24, and 12 were classified as high, medium, and low anti-methanogenic potential. High anti-methanogenic potential plants Cnidoscolus phillacanthus (CnPh), Chloroleucon foliolosum (ChFo), and Anadenanthera macrocarpa (AnMa) produced 21.3, 34.3, and 35.9 mL CH₄/L of gas. Methane concentration for Myracrodruon urundeuva (MyUr) was 61.1 mL/L and classified as medium potential. However, CH₄ production per unit of aDOM was similar between MyUr and AnMa (3.35 and 2.68 mL/g, respectively). Molar proportions of acetate and propionate in SCFA produced by ChFo fermentation were 0.02 and 0.78 mmol/mol. Acetate to propionate ratios were 0.79, 0.03, 1.39, and 1.36 for CnPh, ChFo, AnMa, and MyUr, respectively. Greater aOMD were observed for Opuntia sp. and Calotropis procera (632 and 601 g/kg, respectively), which were classified as medium mitigating potential plants. AnMa, ChFo, CnPh, and MyUr are promising anti-methanogenic plants for ruminants. Selecting forages to feed ruminants in Caatinga is a potential strategy for enteric CH₄ emission reduction, and our in vitro results can support future research by indicating species to be evaluated in in vivo studies integrating mixed diets with performance, digestibility, and CH₄ production, yield, and intensity. Graphical abstract ᅟ