Production Composition Research Articles

Production and nutrient composition of forage legume fractions produced by juicing and leaf stripping

ABSTRACT The large-scale import of soybean products into the EU decreases the self-sufficiency of livestock production. The fractionation of grassland forage crops presents an opportunity to locally produce protein-rich feed for monogastrics. Two promising fractionation methods, twin-screw press juicing and leaf stripping, were evaluated in parallel in field experiments established in Norway and Sweden to compare the nutrient composition and yield of the resulting biorefined and residual fractions. The clearest delineation between the methods was in the ash-free neutral detergent fibre (aNDFom) concentration, with juicing producing a biorefined fraction with a lower aNDFom than leaf stripping. Variability in the allocation of crude protein (CP) and biomass to the biorefined fractions occurred in both methods between cuts and locations and is likely due to differing stand characteristics and inconsistency in machine functionality. Additional work is needed to understand how characteristics such as stand density, botanical composition, and plant phenological stage impact each fractionation method’s ability to allocate protein, fibre, and biomass into the resulting fractions. Future studies should focus particularly on determining standardised settings for leaf stripping machinery based on a range of stand characteristics to ensure consistency in the yield and nutrient composition of the resulting fractions.

МОЛОЧНАЯ ПРОДУКТИВНОСТЬ И КАЧЕСТВО МОЛОКА КОРОВ С РАЗНЫМИ ГЕНОТИПАМИ ЛЕПТИНА И ЛИНЕЙНОЙ ПРИНАДЛЕЖНОСТИ

A review of the scientific literature has shown that the genotype by loci of the Leptin (LEP) gene and linear affiliation to the leading Holstein breed of cows have an impact on milk productivity and the quality of their milk. The purpose of our research was to study the milk productivity and qualitative composition of the milk of Tatarstan-type cows with different genotypes according to the loci of the Leptin gene and linear belonging to the Holstein breed. The research was carried out in the conditions of the agricultural company "Agrofirma Rassvet" of the Kukmorsky district of the Republic of Tatarstan on the livestock of 79 cows of the Tatarstan type. The Tatarstan type is one of the leading dairy cattle breeds bred in the Republic of Tatarstan, and created by crossing the Kholmogorsky, Black and White, and Holstein breeds, while the bloodline was 1/8 Kholmogorsky + 1/16 Black and White + 13/16 Holstein. As a result of a molecular genetic study (PCR-RFLP), the animal population was sorted into groups, taking into account the genotype by the loci of the Leptin gene. The conducted studies have shown that in Tatarstan-type cows after the first lactation, the highest milk yield indicators, the amount of fat and protein in milk were noted in animals with the leptin gene genotypes LEP/CC and LEP/CT in comparison with peers of the LEP/TT genotype. However, in terms of the mass fraction of fat and protein in milk, the trend was reversed. Also, among the cows of the Tatarstan type, according to the first lactation, the highest values of milk productivity indicators (milk yield, amount of milk fat and protein) are in cows with the LEP/CC genotype of linear belonging to the Holstein breed, namely W. Ideal 933122 and R. Sovering 198998.

Impact of ultrasound processing of açai juice containing complex carbohydrates in human intestinal microbiota composition and metabolite production

The present study evaluated the impact of high-intensity ultrasound processing of potentially prebiotic açai juice containing complex carbohydrates (dextran and oligosaccharides) on human gut microbiota after in vitro colonic fermentation. The juice was subjected to an in vitro simulated digestion and human fecal fermentation. HPLC quantified the metabolites produced during fecal fermentation, and the 16 S rRNA sequencing evaluated the microbiota change. The gluco-oligosaccharides and dextran were resistant to in vitro digestion and promoted the fecal microbiota production of short-chain fatty acids (SCFAs). The sonicated juice markedly increased propionic and butyric acid production, reaching 11 g/L and 4 g/L, respectively. The potentially prebiotic açai juice improved the richness (25%) and diversity (22%) of the fecal microbiota, and the ultrasound processing increased richness (12%) compared to non-sonicated juice, which may contribute to overall host health. The study demonstrated that açai juice containing gluco-oligosaccharides and dextran has a potential prebiotic effect. Incorporating this juice into the diet might promote gut-beneficial bacterial growth, improving the gut microbiota and the health-promoting metabolites.

Acquiring the First Words by Persian Toddlers: A Longitudinal Study Using the MacAuthor-Bates Inventory

Introduction: A robust vocabulary improves all areas of communication. Vocabulary is critical to a child’s success to think and learn about the world. Expanding a child’s knowledge of words provides unlimited access to new information. This study describes the early development of comprehension and production vocabularies in a group of Persian-speaking toddlers.
 Materials and Methods: The mothers of 33 typical, Persian-speaking toddlers during 6 months (from 12-14 months to 19-21 months) completed the Persian McArthur-Bates communicative development inventories 7 times per month. The collected data were analyzed via the SPSS software, version 21, through non-parametric tests.
 Results: The results indicated that the only significant increase for both vocabularies was between 15 and 16 months (P comprehension=0.045 and P production=0.027). The development of phrase comprehension showed significant increases during six months (P<0.001). Further analysis of production vocabulary growth demonstrated the word spurt in each child (in different months and with different word levels). According to the figures, the composition of vocabulary production was different during the selected 6 months. Nouns were the largest group during the 50-, 100-, and 200-word stages; however, verbs presented a faster rate of development. Both genders showed significant changes during follow-ups (P<0.001) and there were no significant differences between the vocabularies of different genders (P>0.05).
 Conclusion: Persian-speaking children follow commonalities of lexical development reported for different languages; however, few differences could be traced between these children and their peers from other languages.

Effect of growing factors on production and fatty acid composition of sunflower schenes

Effect of growing factors on production and fatty acid composition of sunflower schenes

Bifidobacteria metabolize lactulose to optimize gut metabolites and prevent systemic infection in patients with liver disease.

Progression of chronic liver disease is precipitated by hepatocyte loss, inflammation and fibrosis. This process results in the loss of critical hepatic functions, increasing morbidity and the risk of infection. Medical interventions that treat complications of hepatic failure, including antibiotic administration for systemic infections and lactulose treatment for hepatic encephalopathy, can impact gut microbiome composition and metabolite production. Here, using shotgun metagenomic sequencing and targeted metabolomic analyses on 847 faecal samples from 262 patients with acute or chronic liver disease, we demonstrate that patients hospitalized for liver disease have reduced microbiome diversity and a paucity of bioactive metabolites, including short-chain fatty acids and bile acid derivatives, that impact immune defences and epithelial barrier integrity. We find that patients treated with the orally administered but non-absorbable disaccharide lactulose have increased densities of intestinal bifidobacteria and reduced incidence of systemic infections and mortality. Bifidobacteria metabolize lactulose, produce high concentrations of acetate and acidify the gut lumen in humans and mice, which, in combination, can reduce the growth of antibiotic-resistant bacteria such as vancomycin-resistant Enterococcus faecium in vitro. Our studies suggest that lactulose and bifidobacteria serve as a synbiotic to reduce rates of infection in patients with severe liver disease.

Accelerated multi-property screening of Fe–Co–Ni alloy libraries by hyper-heuristic combinatorial flow synthesis and high-throughput spark plasma sintering

High-throughput (HT) chemical synthesis facilitates accelerated materials discovery products. However, HT methods are limited by the need for expensive robotic systems, complicated methodology, and low yield. Hence, we developed a hyper-heuristic combinatorial flow synthesis (HCFS) device capable of composition gradient generation and production of an adequate mass of Fe–Co–Ni alloy nanoparticles. A library of 91 Fe–Co–Ni powder compositions was synthesized using this technique. A high-throughput spark plasma sintering (HT-SPS) methodology, along with the die design, was developed for combinatorial screening of multiple properties. 56 compositions were down-selected and consolidated into compositionally graded bulk samples using HT-SPS and subsequent annealing. The crystallographic, magnetic, electrical, and magnetic properties of the bulk library were assessed. The saturation magnetization (Ms) varied from 83.3 emu/g to 225.2 emu/g, coercivity (Hc) from 17.5 Oe to 78.4 Oe, resistivity (ρ) from 17.2 μΩ·cm to 986.7 μΩ·cm, and Vickers hardness (HV) from 41.9 HV to 281.7 HV. Novel Fe–Co–Ni compositions, e.g., Fe36.5Co55.1Ni8.4 and Fe22.6Co73.4Ni4, with a promising multi-property set, were identified for the first time. This study demonstrated that promising new compositions exhibiting multi-property optimization can be successfully discovered by our hyper-heuristic combinatorial chemical synthesis methodology.

Разработка элементов технологии возделывания малораспространненных видов многолетних луков на Среднем Урале

Abstract. In experiments conducted in 2021–2022. on the basis of the educational and experimental farm of the Ural State Agrarian University, studies were carried out on the influence of the feeding area and planting dates on the productivity and biochemical composition of perennial onions. The territory of the Middle Urals is located in a difficult climatic zone, with severe winters and warm summers. The weather in this area can change very quickly, and therefore, for cultivation in the Middle Urals, plants should be selected that will easily endure the vagaries of the weather, including green crops. These characteristics correspond to perennial onions, which are able to produce high yields of green leaves even in risky farming. Good resistance to pathogens, less susceptibility to pests compared to onions, as well as a wide variety of species that differ in external characteristics and taste make perennial onions excellent plants for obtaining valuable vitamin greens. The purpose of the study: to study the biological characteristics of perennial onions, as well as to find out the effect of the feeding area on their yield and biochemical composition. Methods. In the experiments, the following factors affecting the yield of perennial onions were investigated: leaf length, number of leaves per plant, the appearance of flower stalks, individual plant productivity. Results. In the course of the study, it was found that the highest yield is observed in all types of onions when grown with a distance in a row of 5 cm, the highest individual productivity was shown by batun onion plants when grown in a row with a distance between plants of 15 cm and slime onion with a distance between plants in a row of 25. In addition, there was a deterioration in the biochemical composition of the leaves of all the studied types of onions when planting in 2022 compared to 2021 and an increase in the concentration, electrical conductivity and acidity of cell sap in 2022 compared to 2021. Scientific novelty. Ledebur onion is the least studied of the onion species presented in the study, but it has good commercial and nutritional properties. Previously, this type of onion was not studied in the Middle Urals as a vegetable plant.

Multidimensional responses of grassland stability to eutrophication

Eutrophication usually impacts grassland biodiversity, community composition, and biomass production, but its impact on the stability of these community aspects is unclear. One challenge is that stability has many facets that can be tightly correlated (low dimensionality) or highly disparate (high dimensionality). Using standardized experiments in 55 grassland sites from a globally distributed experiment (NutNet), we quantify the effects of nutrient addition on five facets of stability (temporal invariability, resistance during dry and wet growing seasons, recovery after dry and wet growing seasons), measured on three community aspects (aboveground biomass, community composition, and species richness). Nutrient addition reduces the temporal invariability and resistance of species richness and community composition during dry and wet growing seasons, but does not affect those of biomass. Different stability measures are largely uncorrelated under both ambient and eutrophic conditions, indicating consistently high dimensionality. Harnessing the dimensionality of ecological stability provides insights for predicting grassland responses to global environmental change.

Structure and functional characteristics of zooplankton and food supply for nekton in the western Bering Sea

Structure and functional characteristics of zooplankton and feeding of the most abundant nekton species (pollock, herring and salmons) are analyzed using the data of ecosystem survey in the western Bering Sea in 2020 and compared with the structural indices for 2015−2019. The main patterns of composition and distribution of zooplankton and production of organic matter by zooplankton are determined. High values and turnover rate of production are noted for the non-predatory zooplankton (mainly copepods and euphausiids) in the eastern Anadyr Bay, the area at Cape Navarin, the shelf of Koryak coast, and the continental slope of Olyutorsky Bay. High production of predatory zooplankton (mainly hyperiids) is found on the slope of Karaginsky Bay, presumably because of these species transport from the southern areas with later stage of the seasonal succession. In autumn 2020, walleye pollock and pacific herring consumed from 15 to 55 % of the copepod, euphausiid and hyperiid production. This level of consumption did not affect their food supply because of very high turnover rate of these taxonomic groups of plankton. In the deep-water areas, salmons did not use more than 3 % of their food resource. Thus, the survey data indicate a good food supply for the most abundant nekton species in the western Bering Sea in the fall season.

Chemical composition and gas production kinetic parameters of sweet potato vine waste silage after preserved for short and prolonged periods

The sweet potato (Ipomoea batata L.) culture produces by-products with animal feeding potential, such as vines. Given that sweet potato vines are seasonal and highly perishable, the adoption of conservation strategies such as silage becomes necessary to ensure their availability during food shortage periods. The knowledge of the optimal conservation period of this type of silage is limited, with very few studies available on this topic. The objective of this work was to evaluate the chemical composition, fermentative characteristics, and in vitro gas production kinetics of sweet potato vine silage after 45 and 120 days of conservation and to compare them with those of fresh sweet potato vine. The sweet potato vines were collected, cut into 2-3 cm pieces, and ensiled for 45 and 120 days. After this period, the nutritional value was determined using the standard methods of AOAC. The gas production and kinetics were fitted to the exponential equation proposed by Ørskov and McDonald. It was found that the sweet potato vine can be successfully preserved as silage, regardless of the conservation period, and that it shows a high potential for being used as an alternative food source for ruminants. In vitro dry matter and organic matter digestibility were not much different for the fresh sweet potato vine, and the silage was conserved for 120 days. However, the silage for 120 days had lower accumulated in vitro gas production compared to the fresh sweet potato vine. It was concluded that the silage conservation period did not produce significant changes in chemical composition or in vitro digestibility, with the sweet potato vine showing good nutritional values both fresh and after a conservation period. Therefore, sweet potato vine silage can be used as an alternative food source in ruminant diets.

Exploring the tropical acclimation of European and American hop cultivars (Humulus lupulus L.): Focus on physiology, productivity, and chemical composition

Hop (Humulus lupulus L.) cones are widely used by the beer industry to provide flavor, aroma, and bitterness due to the presence of α-acids, β-acids, and volatile oil components. Although the brewing sector plays an important role in Brazil’s economy, hops are entirely imported. In this study, we aimed to investigate the physiological acclimation potential, productivity, and chemical composition of four hop cultivars in a warm tropical region of Brazil. For this purpose, three North American-bred hop cultivars (‘Cascade’, ‘Chinook’ and ‘Triple Pearl’) and one European hop cultivar (‘Saaz’) that grew under tropical ambient conditions for two consecutive years were used. ‘Saaz’ and ‘Triple Pearl’ showed higher mortality and smaller photosynthetic rates, while ‘Cascade’ and ‘Chinook’ cultivars showed the best physiological and growth performance under a tropical-type climate. With a few exceptions, maximum quantum yield of photosystem II (PSII), chlorophyll content, and antioxidant enzymes activity were very similar between these two cultivars. A higher dry mass of cones was observed in ‘Chinook’ and ‘Cascade’, however, with a higher variability within each cultivar. Both cultivars increased the production of the dry mass of cones in the second year. The average concentration of bitter acids in ‘Cascade’ and ‘Chinook’ was below the expected values, but there was a considerable increase in the volatile oil content between the first and second year of cultivation. We concluded that 'Cascade' and 'Chinook', American cultivars, showed better development and lower mortality compared to 'Triple Pearl' (American cultivar) and 'Saaz' (European cultivar) under tropical climate conditions in Brazil. Although the concentration of bitter acids was lower than expected in the first two years, the concentration may increase with plant maturity.

Physical Exercise as Disease-Modifying Alternative against Alzheimer's Disease: A Gut-Muscle-Brain Partnership.

Alzheimer's disease (AD) is a common cause of dementia characterized by neurodegenerative dysregulations, cognitive impairments, and neuropsychiatric symptoms. Physical exercise (PE) has emerged as a powerful tool for reducing chronic inflammation, improving overall health, and preventing cognitive decline. The connection between the immune system, gut microbiota (GM), and neuroinflammation highlights the role of the gut-brain axis in maintaining brain health and preventing neurodegenerative diseases. Neglected so far, PE has beneficial effects on microbial composition and diversity, thus providing the potential to alleviate neurological symptoms. There is bidirectional communication between the gut and muscle, with GM diversity modulation and short-chain fatty acid (SCFA) production affecting muscle metabolism and preservation, and muscle activity/exercise in turn inducing significant changes in GM composition, functionality, diversity, and SCFA production. This gut-muscle and muscle-gut interplay can then modulate cognition. For instance, irisin, an exercise-induced myokine, promotes neuroplasticity and cognitive function through BDNF signaling. Irisin and muscle-generated BDNF may mediate the positive effects of physical activity against some aspects of AD pathophysiology through the interaction of exercise with the gut microbial ecosystem, neural plasticity, anti-inflammatory signaling pathways, and neurogenesis. Understanding gut-muscle-brain interconnections hold promise for developing strategies to promote brain health, fight age-associated cognitive decline, and improve muscle health and longevity.

Iron and manganese availability drives primary production and carbon export in the Weddell Sea

Next to iron (Fe), recent phytoplankton-enrichment experiments identified manganese (Mn) to (co-)limit Southern Ocean phytoplankton biomass and species composition. Since taxonomic diversity affects aggregation time and sinking rate, the efficiency of the biological carbon pump is directly affected by community structure. However, the impact of FeMn co-limitation on Antarctic primary production, community composition, and the subsequent export of carbon to depth requires more investigation. In situ samplings of 6 stations in the understudied southern Weddell Sea revealed that surface Fe and Mn concentrations, primary production, and carbon export rates were all low, suggesting a FeMn co-limited phytoplankton community. An Fe and Mn addition experiment examined how changes in the species composition drive the aggregation capability of a natural phytoplankton community. Primary production rates were highest when Fe and Mn were added together, due to an increased abundance of the colonial prymnesiophyte Phaeocystis antarctica. Although the community remained diatom dominated, the increase in Phaeocystis abundance led to highly carbon-enriched aggregates and a 4-fold increase in the carbon export potential compared to the control, whereas it only doubled in the Fe treatment. Based on the outcome of the FeMn-enrichment experiment, this region may suffer from FeMn co-limitation. As the Weddell Sea represents one of the most productive Antarctic marginal ice zones, our findings highlight that in response to greater Fe and Mn supply, changes in plankton community composition and primary production can have a disproportionally larger effect on the carbon export potential.

Regulating the plant density influences to the weed infestation, productivity and chemical composition of seeds of true hemp Cannabis sativa L.

Regulating the plant density influences to the weed infestation, productivity and chemical composition of seeds of true hemp Cannabis sativa L.

Life in the dark: Impact of future winter warming scenarios on carbon and nitrogen cycling in Arctic soils

The high Arctic region is warming faster than other areas globally, with widespread decreases in snow cover and longer growing seasons. This is expected to greatly influence plant-microbial carbon (C) and nitrogen (N) cycling and thus ecosystem functioning, particularly when soils remain unfrozen during the dark winter period and no photosynthesis is possible. To better understand this response, we studied the effects of different winter warming scenarios on soil C and N dynamics. We collected intact soils cores from two contrasting biomes from Svalbard, namely a moss-dominated peat mire and purple saxifrage-dominated dry tundra heath. In the laboratory, we used an Arctic annual light regime and three contrasting winter temperature regimes to simulate a range of climate scenarios: (i) current climate in which the soils were frozen in winter and thawed in the summer, (ii) a year 2050 regime in which the soils were both frozen and thawed in winter, and (iii) a year 2100 regime in which the soils remained unfrozen during winter. We monitored greenhouse gas (GHG) emissions (CO2, CH4 and N2O) and nutrients in soil solution (DOC, NO3−, NH4+, P) over a one-year period. In the peat mire, warmer winters increased CO2 emissions due to increased microbial activity but had little effect on methane or N2O fluxes. Warmer winters also decreased dissolved organic carbon and nutrients in soil solution. In the dry tundra heath, warmer winters increased nitrate availability but did not greatly alter CO2, CH4 or N2O gas fluxes or other nutrients. Warming in the dry tundra health induced earlier spring flowering and shifts in vegetation composition. Overall, we present clear evidence that warmer winter conditions are likely to alter C and N cycling in Arctic soils, with implications for plant productivity and vegetation community composition.

High-latitude vegetation changes will determine future plant volatile impacts on atmospheric organic aerosols

Strong, ongoing high-latitude warming is causing changes to vegetation composition and plant productivity, modifying plant emissions of biogenic volatile organic compounds (BVOCs). In the sparsely populated high latitudes with clean background air, climate feedback resulting from BVOCs as precursors of atmospheric aerosols could be more important than elsewhere on the globe. Here, we quantitatively assess changes in vegetation composition, BVOC emissions, and secondary organic aerosol (SOA) formation under different climate scenarios. We show that warming-induced vegetation changes largely determine the spatial patterns of future BVOC impacts on SOA. The northward advances of boreal needle-leaved woody species result in increased SOA optical depth by up to 41%, causing cooling feedback. However, areas with temperate broad-leaved trees replacing boreal needle-leaved trees likely experience a large decline in monoterpene emissions and SOA formation, causing warming feedback. We highlight the necessity of considering warming-induced vegetation shifts when assessing land radiative feedback on climate following the BVOC-SOA pathway.

Effects of cashew nut shell extract and monensin on in vitro ruminal fermentation, methane production, and ruminal bacterial community

The objective of this study was to evaluate the effects of cashew nut shell extract (CNSE) and monensin on ruminal in vitro fermentation, CH4 production, and ruminal bacterial community structure. Treatments were as follows: control (CON, basal diet without additives); 2.5 μM monensin (MON); 0.1 mg CNSE granule/g DM (CNSE100); and 0.2 mg CNSE granule/g DM (CNSE200). Each treatment was incubated with 52 mL of buffered ruminal content and 500 mg of total mixed ration for 24 h using serum vials. The experiment was performed as a complete randomized block design with 3 runs. Run was used as a blocking factor. Each treatment had 5 replicates, in which 2 were used to determine nutrient degradability, and 3 were used to determine pH, NH3-N, volatile fatty acids, lactate, total gas, CH4 production, and bacterial community composition. Treatment responses for all data, excluding bacterial abundance, were analyzed with the GLIMMIX procedure of SAS v9.4. Treatment responses for bacterial community structure were analyzed with a PERMANOVA test run with the R package vegan. Orthogonal contrasts were used to test the effects of (1) additive inclusion (ADD: CON vs. MON, CNSE100, and CNSE200); (2) additive type (MCN: MON vs. CNSE100 and CNSE200); and (3) CNSE dose (DOS: CNSE100 vs. CNSE200). We observed that pH, acetate, and acetate:propionate ratio in the CNSE100 treatment were lower compared with CNSE200, and propionate in the CNSE100 treatment was greater compared with CNSE200. Compared with MON, CNSE treatments tended to decrease total lactate concentration. Total gas production of CON was greater by 2.63% compared with all treatments, and total CH4 production was reduced by 10.64% in both CNSE treatments compared with MON. Also, compared with MON, in vitro dry matter degradabilities in CNSE treatments were lower. No effects were observed for NH3-N or in vitro neutral detergent fiber degradability. Finally, the relative abundances of Prevotella, Treponema, and Schwartzia were lower, whereas the relative abundances of Butyrivibrio and Succinivibrio were greater in all treatments compared with CON. Overall, the inclusion of CNSE decreased CH4 production compared with MON, making CNSE a possible CH4 mitigation additive in dairy cattle diets.

Influence of the energy and carbohydrate additive “Tanrem” on milk productivity and milk composition of cows of Holstein breed

The highest sensitivity to deficiencies in feeding is shown by highly productive cows Holstein breed that has become widespread both in Russia as a whole and in the Urals region. Against the background of many advantages of the breed, there are problems with reproduction and negative energy balance after calving. An innovative approach in feeding is the enrichment of the ration of animals with the energy and carbohydrate additive “Tanrem”, nutrients of which being natural prebiotics and energy sources, are able to activate metabolic processes. The purpose of the research was to study the effect of the energy and carbohydrate additive “Tanrem” on milk productivity and milk composition of cows of Holstein breed. Scientifi c and economic experiment was carried out in LLC “Agro-Alliance” in the Chishminsky district of the Republic of Bashkortostan. For the experiment cows of Holstein breed for the third lactation were selected in the amount of 40 animals, which were provided with the same conditions of housing. In order to select the optimal dosages of the additive the animals were divided into 4 groups. Cows of the 1st control group received the main ration adopted on the farm. Cows of the experimental groups consumed a ration enriched with the energy and carbohydrate additive “Tanrem” in a daily dose, respectively: group 2 – 250, group 3 – 500 and group 4 – 750 g/head. For 305 days of lactation the superiority of cows of the 2nd, 3rd and 4th experimental groups on the control was as follows: 198,2 kg or 2,39 % (p < 0,05), 458,8 kg or 5,53 % (p < 0,001) and 408,9 kg or 4,93 % (p < 0,001), respectively. The data obtained indicate the expediency of enriching the ration of dairy cows with the energy and carbohydrate additive “Tanrem”. The economic analysis confirmed the established fact and indicated that the most effective rate of application of the tested additive is 500 g/head per day.

Decoupled growth and grazing rates of diatoms and green algae drive increased phytoplankton productivity on HNLC sub‐Antarctic plateaux

AbstractThe combination of iron limitation and microzooplankton grazing controls phytoplankton productivity and taxonomic composition in high‐nutrient low‐chlorophyll (HNLC) regions. While increased productivity and diatom contribution triggered by iron enrichment support this view, direct measurements of underpinning group‐specific growth and grazing rates are scarce for the Southern Ocean. To assess these rates, we conducted dilution experiments coupled to high‐performance liquid chromatography and flow‐cytometry in sub‐Antarctic waters on and off Campbell Plateau, southeast of Aotearoa‐New Zealand. Off the plateau, growth and grazing were closely balanced for all groups despite a two‐fold difference between slow‐ and fast‐growing groups. On Campbell Plateau, where HNLC conditions were alleviated, the balance was disrupted, mainly by the preferential growth of diatoms and green algae, which was stimulated beyond grazing. Our results expand the recognized ability of diatoms to escape grazing control to picoplanktonic green algae that also avoid grazing and contribute significantly to phytoplankton productivity and biomass accumulation.