Dietary nutrient restrictions in the post-weaning period change Santa Inês ewe lamb nutritional metabolic profile

The objective of this study was to evaluate the metabolic profile of Santa Inês ewe lambs fed diets for early or late-maturing diets with or without nutrient restrictions. The experiment consisted of a 2 × 2 completely randomized factorial experiment with either early- or late-maturity feed formulation according to "Nutrient Requirements of Small Ruminants" with or without 15% crude protein (CP) and total digestible nutrients (TDN) restrictions in diets formulated, five replications, and 20 ewe lambs averaging 15.1±2.6 kg. Lambs on early-maturity diets consumed greater (P<0.05) dietary ether extract (EE), non-fibrous carbohydrates, and TDN than those on late-maturity diets. Lambs on early-maturity diets had 7.11% greater dry matter digestibility (DMD) compared to lambs fed late-maturity diets. Lambs fed late-maturity diets, in general, had greater intake (IN), excreted (EN), and retained (RN) N as well as greater RN/IN and EN/IN ratios. There were no differences in blood total protein or albumin among lambs fed for different finishing maturity targets. Diets designed for late-maturing lambs resulted in greater microbial N and CP as well as rumen and metabolizable, degradable, and undegradable rumen and metabolizable CP. The selection of diets for early or late maturity carcasses depends on the production system goals. Diets without restrictions are recommended for early-maturity carcass finishing while diets with 15% CP and TDN restriction are recommend for late-maturity finishing.

Effect of different blend levels of spineless cactus and Mombasa hay as roughage on intake, digestibility, ingestive behavior, and performance of lambs

This study aimed to determine the best level of the blend of spineless cactus (Nopalea cochenillifera) and Mombasa (Panicum maximum) hay as roughage in the diet of lambs based on intake, digestibility, ingestive behavior, and lamb performance. Forty-eight uncastrated crossbred Santa Ines breed lambs with an average age of 4 months old and an average initial BW of 20.5 kg ± 2.8 kg were distributed in two experiments using a completely randomized design: experiment 1: 16 lambs (four treatments and four replicates) for in vivo digestibility trial in metabolic cage; experiment 2: 32 lambs (four treatments and eight replicates) in feedlot to determine intake, ingestive behavior, and performance. As the amount of cactus in the roughage increased, there was a linear reduction (P <0.001) on intake (g/day) of dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), non-fibrous carbohydrates (NFC) digestibility, time spent ruminating, feeding efficiency of NDF (P = 0.0153), NDF rumination efficiency rate (P = 0.032), final BW, TWG, and ADG of lamb. However, there was a linear increase (P <0.001) on the intake of the NFC and TDN, digestibility coefficient of DM, CP, total carbohydrates (TC) and NDF gross energy, metabolizable energy, and time spent idling when spineless cactus increased in the roughage blend. The least amount of cactus in the roughage (112-637 g/kg DM) promoted higher intake of DM and CP, improving lamb performance. However, the blend up to 450-300 g/kg DM improved digestibility and energy production as well as it did not affect the feed efficiency.

Effect of replacing forage sorghum silage with biomass sorghum silage in diets for F1 Holstein × Zebu lactating cows

The objective of this study was to evaluate the replacement of forage sorghum silage (FS silage) with BRS 716 biomass sorghum silage (BRS 716 silage) in diet of F1 ½ Holstein × ½ Zebu cows on their nutrient intake and digestibility, ingestive behavior, nitrogen balance, and milk yield and composition. The experimental design was in two 5 × 5 Latin squares, simultaneous, composed, each, by five animals, five treatments, and five experimental periods. The study included 10 cows with an initial body weight (BW) of 544 ± 12.84 and 88 ± 14 days of lactation at the beginning of the experiment. The treatments were defined by replacement FS silage at levels 0, 25, 50, 75, and 100% with BRS 716 silage. The roughage:concentrate ratio in the total dry matter (DM) of the diets was 75:25. The replacement of FS silage with BRS 716 silage reduced (p < 0.01) the dry matter intake and digestibility of dry matter, but it had not changed average milk yield (12.68 kg/day; p = 0.94), feed efficiency, body weight, the score of body condition, and the average daily gain of the cows. The milk composition was not changed except casein/total protein in milk that decreased and that increased linearly milk urea nitrogen. The inclusion of BRS 716 silage increased the activities of rumination and chewing and decreased the periods of feeding and idleness. The replacement of up to 100% of FS silage with BRS 716 silage in the diet of F1 Holstein × Zebu cows does not alter average milk yield, despite changing diet intake and digestibility.

Digestibility of spineless cactus meals in extruded diets for Nile tilapia (Oreochromis niloticus): energy, protein, amino acids, and carbohydrates

The aim of the present study was to determine the apparent digestibility coefficients (ADCs) of gross energy, dry matter, crude protein, amino acids, and different carbohydrate fractions of spineless cactus meals (SCMs) for Nile tilapia juveniles, fed with extruded diets. Fish were fed a reference diet or one of five test diets, each of which included 70% reference diet and 30% corresponding SCM. Fecal collection was performed in modified Guelph method. The ADCs for dry matter, gross energy, and soluble carbohydrates of the "redonda" spineless cactus meal (RSCM) were higher (P < 0.05) than those of either the "IPA 20" spineless cactus meal (ISCM) or "gigante" spineless cactus meal (GSCM), and the ADCs for crude protein of the RSCM and "Orelha de elefante africana" spineless cactus meal (OEASCM) were higher than those of the other cactus meals (P < 0.05). In addition, the ADCs for dry matter, crude protein, and gross energy of the SCMs were similar to wheat middlings. The digestibility of the less soluble fraction of the evaluated carbohydrates, the non-fibrous carbohydrates, varied between 58.32 and 73.04%, indicating efficiency in the digestion and absorption process. The data obtained in this article can be the basis for growth experiments, with the substitution of traditional ingredients for SCMs. The determination of zootechnical, physiological, metabolic, and health variables can indicate the potential for using SCMs in diets for Nile tilapia.

Bacteria from tropical semiarid temporary ponds promote maize growth under hydric stress

World climate change has triggered soil water stress and imposed limitations on agricultural production. Plant growth-promoting bacteria (PGPBs) have been an efficient strategy to improve the biological supply and growth of plants under distinct abiotic stress conditions. We hypothesized that the soils from a temporary pond may harbor PGPBs with potential strains which increase maize tolerance to water deficit. We studied rhizosphere and bulk soil of Mimosa bimucronata in a temporary pond from semiarid Northeast Brazil to access strains with characteristics to promote plant growth and mitigate abiotic stress for maize crop. We isolated 355 bacterial isolates, from which 96 were selected based on the morphophysiological characterization to assess IAA production (42 % produced over 50 μg mL^-1 of IAA), calcium phosphate solubilization (with one isolate achieving medium IS), biofilm and exopolysaccharides production (66 % and 98 % of isolates, respectively). Based on these mechanisms, the 30 most promising bacterial isolates were selected to assess biological nitrogen fixation (74 % of the isolates showed nitrogenase activity greater than 20 C₂H₄.h^-1.mg^-1), ACC deaminase activity (80 % of isolates) and growth in medium with reduced water activity (8 % of isolates grew in medium with water activity (A_w) of 0.844). We sequenced the 16S rRNA gene from the seven most promising isolates in in vitro and in vivo assays, which were identified as Staphylococcus edaphicus, Bacillus wiedmannii, Micrococcus yunnanensis, Streptomyces alboflavus, Streptomyces alboflavus, Bacillus wiedmanni and Bacillus cereus. In vivo, eleven isolates and three bacterial consortia did not differ from the control with nutrient solution, for total leaf area and root dry mass of maize. S. alboflavus (BS43) had the best in vivo results, not differing from the control with nutrient solution. We highlight the unpublished potential of Staphylococcus edaphicus and Streptomyces alboflavus in promoting the growth of plants under water stress. In addition, it is the first report of bacteria isolated from a temporary pond in the Brazilian semiarid which promoting plant growth attributes and development.

Drought impacts, social organization, and public policies in northeastern Brazil: a case study of the upper Paraíba River basin

The upper Paraíba River basin plays a key role in controlling the flow from the Epitácio Pessoa Reservoir, a major reservoir in the semiarid region of Paraíba state. The objective of this study is to analyze historical droughts and public policies and their impacts on the social organization in the upper Paraíba River basin, which is located in the semiarid region of Brazil. In this study, the following methodological procedures were used: (a) historical survey of drought occurrence and dam construction in the semiarid region of Brazil, (b) data processing of hydrologic records (rainfall and streamflow), and (c) field visits to collect and compare data on the changes in the volume of water stored behind dams. The results showed that state intervention in the semiarid region follows a trend based on the characteristics of each historical moment and the interests of the groups that comprise the state sector. It is also observed that the implementation of several public policies, such as social programs, construction of dams, and the transfer of water from the São Francisco River, has resulted in significant changes in the streamflow behavior in this semiarid region. These changes have differed in magnitude depending on the hydrological characteristics of each period (i.e., dry, rainy, or normal). Finally, the use of dams for water management in the semiarid region was identified as the main factor influencing water security and social organization.

Spatial variation and availability of nutrients at an oyster reef in relation to submarine groundwater discharge

Submarine groundwater discharge (SGD) is often an overlooked component of the solute budgets in coastal embayments and is not considered in oyster restoration, conservation, and management plans. A combination of spatial and temporal geochemistry (nutrients, trace metals, alkalinity components, stable isotopes, and major ions) of porewater and surface water combined with SGD-derived solute fluxes and turnover times was used to examine the significance of SGD in delivering nutrients to paleovalley systems in coastal embayments, thus sustaining the health and productivity of oyster reefs. A 1-km² area encompassing a paleovalley system, in Copano Bay, Texas, exhibited significant differences in the spatial and temporal hydrogeochemical characteristics (major ions, stable isotopes and nutrients) along the reef when compared to the other environments (i.e., paleovalley, estuary-wide). Solute fluxes (i.e., dissolved organic carbon (DOC), dissolved inorganic nitrogen (DIN), total alkalinity, DIC, etc.) are slightly larger at the reef, followed by the margin and shoreline. During dry conditions, SGD from the 1-km² area was estimated to supply anywhere between two-fold to one order of magnitude more nitrogen (in the form of DIN) than the riverine inputs to Copano Bay. During a wet year SGD equates the river input in the form of DIN. In addition, SGD-based turnover times, averaging <11 days for all nutrients, are significantly shorter than the average estuary flushing time (i.e., 38 days). Results from this study suggest that SGD within a paleovalley system is an important component in the estuarine nutrient budget through significant inputs and cycling processes between the subsurface and water column, particularly during low surface flows. Thus, estuarine environments such as paleovalley margins and interfluves provide favorable conditions to oysters through preferably enhanced SGD solute fluxes and should be considered in oyster restoration efforts.

Nitrogen and phosphorus retention budgets of a semiarid plain basin under different human activity intensity

Excessive nitrogen (N) and phosphorus (P) runoff from human activities results in degraded water quality. It is, therefore, crucial to quantitatively assess nutrient inputs over time and their impact on riverine nutrient exports. In this study, we estimated the long-term (1995-2015) nutrient inputs at the county scale by integrating Net Anthropogenic Nitrogen Input (NANI) and Net Anthropogenic Phosphorus Input (NAPI) methods, and nutrient exports into rivers by the Export Coefficient Model (ECM) for a semiarid plain basin, the Baiyangdian (BYD) Basin, China. The results showed that N and P input intensities in the year 2015 reached 18852 kg N km² yr^-1 and 2073 kg P km^-2 yr^-1, showing a 35% and 11% increase in comparison with 1995, respectively. About 60% of these nutrients were derived from fertilizer application. The multi-year averaged N and P exported to rivers was 548 kg N km^-2 yr^-1 and 79 kg P km^-2 yr^-1, respectively. Hotspots for nutrient budgets were found in the southeastern counties. Hotspots covered about 12% of the total land, but contributed by 38-52% of total nutrient budgets. The nutrient export ratios showed no significantly temporal variations, and only about 2.15-2.89% of NANI and NAPI were exported into rivers. The low nutrient export ratio was due to the low water discharge that limited the nutrient transportation in the semi-arid plain basin. As most of anthropogenic nutrient inputs were retained in the basin, their impacts on the pollution of soils and aquifers need to be considered and adequately addressed in the future. This study constructs the spatial quantitative nutrient budgets, which can provide effective information for region policy formulation.

Diets containing cunhã (Clitoria ternatea L.) hay and forage cactus (Opuntia sp.) meal on production and meat quality of Boer crossbred goat

The aim of this study was to evaluate the effect of association of forage cactus meal (CM) and cunhã hay (CH) on carcass traits, meat quality, and fatty acid (FA) profile of goats. Twenty-four goats were finished on diets composed with the association of CM and CH (83% CH + 17% CM, 67% CH + 33% CM, or 50% CH + 50% CM), corresponding to 60% of the total diet; the remainder was composed of 10% elephant grass and 30% concentrate. The control treatment consisted of 70% elephant grass and 30% concentrate. Carcass yield and commercial cut weight were higher in the animals fed CH and CM at any concentration (P < 0.05). Animals fed with intermediate and high CM content resulted in meat with better proportions of unsaturated FA (P = 0.0281), desirable FA (P = 0.0024), omega 6/omega 3 ratio (P = 0.0340), and hypo-/hypercholesterolemic index (P = 0.0140). The inclusion of CH and CM provided carcass yield and FA profile more favorable for consumer market and human health.

How does Spix's yellow-toothed cavy (Galea spixii Wagler, 1831) face the thermal challenges of the Brazilian tropical dry forest?

The aim of this work was to investigate the thermal biology of the Spix's yellow-toothed cavy (Galea spixii) from the hot and dry environment of the Brazilian Caatinga by infrared thermography and biophysical equations. We monitored the rectal temperature, as well as the non-evaporative (radiative and convective pathways) and evaporative heat exchanges of males and females. The mean rectal temperature of females and males was 37.58 ± 0.02 and 37.47 ± 0.02 °C, respectively. We identified thermal windows by infrared thermography. The surface temperatures and the long-wave radiation heat exchanges were higher in the periocular, preocular, pinnae and vibrissae regions, in that order. The surface temperature of the periocular and preocular regions correlated positively with rectal temperature. Convective heat exchange was insignificant for thermoregulation by G. spixii. Evaporative heat loss increased when the thermal environment inhibited the radiative pathway. Females showed higher evaporative thermolysis than males at times of greater thermal challenge, suggesting a lower tolerance to heat stress. Therefore, infrared thermography identified the thermal windows, which represented the first line of defense against overheating in G. spixii. The periocular and preocular surface temperatures could be used as predictors of the thermal state of G. spixii.

From waste to resource: Cost-benefit analysis of reservoir sediment reuse for soil fertilization in a semiarid catchment

Reservoir networks have been established worldwide to ensure water supply, but water availability is endangered quantitatively and qualitatively by sedimentation. Reuse of sediment silted in reservoirs as fertilizer has been proposed, thus transforming nutrient-enriched sediments from waste into resource. The aim of this study is to assess the potential of reusing sediment as a nutrient source for agriculture a semiarid basin in Brazil, where 1029 reservoirs were identified. Sedimentation was modelled for the entire reservoir network, accounting for 7 × 10⁵ tons y^-1 of sediment deposition. Nutrients contents in reservoir sediments was analysed and compared to nutrients contents of agricultural soils in the catchment. The potential of reusing sediment as fertilizer was assessed for maize crops (Zea mays L.) and the sediment mass required to fertilize the soil was computed considering that the crop nitrogen requirement would be fully provided by the sediment. Economic feasibility was analysed by comparing the costs of the proposed practice to those obtained if the area was fertilized by traditional means. Results showed that, where reservoirs fall dry frequently and sediments can be removed by excavation, soil fertilization with sediment presents lower costs than those observed for application of commercial chemical fertilizers. Compared to conventional fertilization, when using sediments with high nutrient content, 25% of costs could be saved, while when using sediments with low nutrient content costs are 9% higher. According to the local conditions, sediments with nitrogen content above 1.5 g kg^-1 are cost efficient as nitrogen source. However, physical and chemical analyses are recommended to define the sediment mass to be used and to identify any constraint to the application of the practice, like the high sodium adsorption ratio observed in one of the studied reservoirs, which can contribute to soil salinization.

Nutritional and performance viability of cactus Opuntia-based diets added to concentrate levels for Girolando lactating dairy cows

Objective

The aim of this research was to evaluate the effect of different concentrate levels in diets based on cactus Opuntia Stricta (Haw.) Haw cladodes on the performance of lactating Girolando cows.

Methods

The experiment involved 10 Girolando multiparous dairy cows at 512.6 kg of body weight (BW) and producing 13.2 kg milk/d, allocated into two 5×5 Latin squares. The experimental treatments consisted of control diet composed by cactus Nopalea cochenillifera. Salm-Dyck. cladodes (Nopalea), forage sorghum silage and concentrate at 20% on dry matter (DM) basis, and four concentrate levels diets (20%, 24%, 28%, and 32%) plus cactus Opuntia stricta (Haw.) Haw. cladodes (Opuntia) and forage sorghum silage.

Results

Regarding cows fed control diet, the nutrients intake were greater than for cows fed with cactus Opuntia and concentrate. Regarding concentrate levels, intakes of DM, organic matter (OM), crude protein (CP), non-fiber carbohydrates (NFC), and total digestible nutrients of cows increased linearly. Organic matter, CP, and NDF digestibilities were similar in between to control diet and cactus Opuntia-based diets. The digestibility of NFC increased linearly when the concentrate was inserted. The N balance was the same for control diet and cactus Opuntia-based diets, irrespective the concentrate levels.

Conclusion

For cows producing 14 kg/d with 3.5% of fat, it is recommended 32% of concentrate to be included in cactus Opuntia-based diets, and the increase in concentrate level promotes a linear increase in milk yield.

The impacts of porous rock check dams on a semiarid alluvial fan

Low-tech rock check dams are widely used to address land degradation; however, assessments of their impacts on runoff and sediment are lacking and are often limited to the first few years after construction. In 2008, two small (4.0 and 3.1 ha) instrumented watersheds located 300 m apart on an alluvial fan on the Santa Rita Experimental Range in southern Arizona were treated with 37 porous, loose rock check dams. Ten years after construction, the watersheds are experiencing contrasting responses to treatment. The ratio of runoff to precipitation was higher after check dam construction on one watershed and lower on the other, but not significantly in either case. Statistically significant changes in peak runoff rate are not detectable 10 years after construction at either watershed. However, a statistically significant reduction in sediment concentration was found on one watershed and no change was found at the other. The check dams have altered channel grades. However, backfilling of the dams is nearly complete on one watershed and the other has remaining capacity. The alluvial fan setting poses a complex restoration environment due to high sediment loads that deposit in response to vegetated areas of accumulated sediment creating conditions for channel avulsion and new incising concentrated flow paths. Check dams have a lesser impact on watershed outlet runoff and sediment than on internal watershed channel morphology and vegetation establishment. With monitoring and maintenance, check dams can be an effective tool for grade stabilization, but watershed restoration requires additional practices to address degraded interfluve areas.

When drought meets forest management: Effects on the soil microbial community of a Holm oak forest ecosystem

The growth and survival of plants in semiarid Mediterranean forests can be improved through the benefits conferred by thinning, a forest management practice that removes trees and reduces the competition between the remaining ones. Here, we evaluate the impacts of induced drought (the exclusion of 25% of the natural rainfall for 5 years) and thinning, and their interaction, with the objective of determining whether the thinning of Holm oak (Quercus ilex L.) modulates the resistance of the soil microbial community to drought. Sequencing of 16S rRNA and ITS amplicons revealed that drought, thinning, and their interaction influenced the composition of the bacterial community, while the fungal community was exclusively affected by thinning. Thinning consisted of the removal of the aboveground parts of the Holm oak trees, which were thereafter left in forest stand. Thinning contributed to the C and N contents, with parallel increases in microbial biomass, particularly in summer. Drought increased the amounts of total organic C and total N, likely due to the reduced enzyme activities. Indeed, the composition of the bacterial community was modulated primarily by the indirect and long-term effects of drought - the accumulation of soil organic matter - rather than by the direct effect of the lower water content imposed by the drought treatments. Thinning under drought conditions did not increase soil organic C (SOC) content. However, the resistance of the soil microbial community to drought was fostered by thinning, particularly at the functional level, as indicated by the enzyme activities related to C, N and P cycles. These responses were associated to variations in the composition of the microbial communities in thinned, drought-exposed plots, in comparison to unthinned, drought-exposed plots. In conclusion, the interaction between forest management and drought influenced the soil microbial community of a Holm oak-dominated Mediterranean ecosystem.

Investigation of ozone deposition to vegetation under warm and dry conditions near the Eastern Mediterranean coast

Dry deposition of ozone (O₃) to vegetation is an important removal pathway for tropospheric O₃, while O₃ uptake through plant stomata negatively affects vegetation and leads to climate change. Both processes are controlled by vegetation characteristics and ambient conditions via complex mechanisms. Recent studies have revealed that these processes can be fundamentally impacted by coastal effects, and by dry and warm conditions in ways that have not been fully characterized, largely due to lack of measurements under such conditions. Hence, we hypothesized that measuring dry deposition of O₃ to vegetation along a sharp spatial climate gradient, and at different distances from the coast, can offer new insights into the characterization of these effects on O₃ deposition to vegetation and stomatal uptake, providing important information for afforestation management and for climate and air-quality model improvement. To address these hypotheses, several measurement campaigns were performed at different sites, including pine, oak, and mixed Mediterranean forests, at distances of 20-59 km from the Eastern Mediterranean coast, under semiarid, Mediterranean and humid Mediterranean climate conditions. The eddy covariance technique was used to quantify vertical O₃ flux (F_tot) and its partitioning to stomatal flux (F_st) and non-stomatal flux (F_ns). Whereas F_st tended to peak around noon under humid Mediterranean and Mediterranean conditions in summer, it was strongly limited by drought under semiarid conditions from spring to early winter, with minimum average F_st/F_tot of 8-11% during the summer. F_ns in the area was predominantly controlled by relative humidity (RH), whereas increasing F_ns with RH for RH < 70% indicated enhancement of F_ns by aerosols, via surface wetness stimulation. At night, efficient turbulence due to sea and land breezes, together with increased RH, resulted in strong enhancement of F_tot. Extreme dry surface events, some induced by dry intrusion from the upper troposphere, resulted in positive F_ns events.

Nutritional evaluation and productivity of supplemented sheep grazing in semiarid rangeland of northeastern Brazil

Sheep production systems in Brazilian caatinga rangelands require supplementation adapted to changes in floristic and chemical composition as dry seasons progress. Meeting sheep nutritional needs in extensive semiarid systems is challenging because of sheep dietary preferences and habits. The objective of this trial was to evaluate the substitutive effect of concentrate supplementation on grazing sheep in the Brazilian caatinga rangeland and its consequences on performance in different seasons. The trial was conducted from March to August 2013 at Embrapa Goat and Sheep in Sobral, Ceará State, Brazil. Thirty-two Brazilian Somali multiparous ewes were submitted to estrus synchronization and controlled breeding. At the start of the trial, ewes averaged 30.45 + 2.60 kg body weight (BW). Ewes were divided into four groups and individually offered 0, 200, 350, or 500 g supplement head^-1 day^-1. Intake prediction and digestibility trials were evaluated at three periods: rainy season (April), transition rainy-dry (June), and dry season (August). Sheep weights were taken every 14 days to measure their performance from late gestation until weaning. Ewe BW and body condition score changes were determined too. Lamb BW changes were also measured every 14 days from birth through weaning. A completely randomized design with split plot arrangement using eight replications was used for intake and digestibility measurements. The differences between supplement offered (0, 200, 350, and 500 g sheep-1) and season (rainy, transition rainy-dry, and dry) were submitted to analyses of variance and multiple means were separated, where differences were detected, using the Tukey's test. During lactation up through weaning, ewes supplemented at 500 g day^-1 had greater BW than ewes without supplement. Ewes supplemented with 200 g concentrate head^-1 day^-1 had 9.1% greater (P ≤ 0.05) BW at weaning and their lambs had 19.7% greater birth and 16.6% heavier wean BW despite lower dry matter intake compared to unsupplemented animals. Supplementation with 200 g concentrate increased carrying capacity by 28.8% during the dry season and by 20.5% during the rainy season. This study confirmed that in the dry season, when quality of rangeland forages decreases, supplementation contributes to greater DMI, improves postpartum and lactation BW recovery of ewes, and contributes to greater lamb birth and wean weights. Moreover, supplementation leads to feed substitution effects that may increase rangeland resilience by mitigating overgrazing. Supplementation with 200 g concentrate can also prevent negative energy balance for grazing animals, improving longer postnatal recovery, longer intervals between parturitions, fewer double and is necessary to ensure a better BW at birth to lambs.

Markov chains and cellular automata to predict environments subject to desertification

The foremost objective of this study was to analyze the performance of a Markov chain/cellular automata model for predicting land use/land cover changes in environments predisposed to desertification. The study area is the Vieira river basin, located in Montes Claros (MG, Brazil). Land use/land cover prognosis was performed for the year 2005 so that this result could be compared with the ranked image for the same year, taken as ground truth. Kappa indices were used to evaluate the change level that occurred between these two cases. Results from cellular automata were evaluated from those of the Markov chain model. The latter proved to be efficient in the quantitative prediction of changes in land use/land cover. Regarding the cellular automata, an average performance was noted in the spatial distribution of classes. Specifically, with regard to desertification, the use of the CA-Markov model was effective at estimating the total area of the most susceptible class to this process, Bare Soil; however, it was inefficient in its spatialization. Even with the caveats related to the performance of cellular automata, the overall prediction capacity of CA-Markov models can be considered as good.

Transference of bioactive compounds from support plants to the termites Constrictotermes cyphergaster (Isoptera)

This study aims to investigate the microbiological potential of the termite species Constrictotermes cyphergaster (Silvestri, 1901) and its support plants. We collected five C. cyphergaster nests from three different support plant species. Microbiological assays were performed on these extracts using the serial microdilution method in triplicate to measure the minimum inhibitory concentration (MIC) of each microorganism for the analysed extract. The ethanol extracts of the termite C. cyphergaster showed no significant activity against strains of Staphylococcus aureus and Escherichia coli, with an MIC >1000 μg mL-1. Only the extracts of the nests and termites with the nest had the same MICs. These results were in contrast to the extracts of Spondias tuberosa (Umbuzeiro), Poincianella pyramidalis (Catingueira), and Amburana cearensis (Cumaru), which demonstrated significant activity against S. aureus with MICs <1000 μg mL-1. The modulating activity of the extracts tested in the present study demonstrated potentiation of most antibiotics across the bacterial strains tested when combined with the extracts for both S. aureus and E. coli. These results indicate that the extracts tested in the present study may be composed of animal and vegetable origins with the potential to modify the activity of antibiotics and thus may aid in antimicrobial therapy.

Prevalence of subclinical hypocalcemia in dairy cows in the Sousa city micro-region, Paraíba state

Subclinical hypocalcemia is a metabolic disorder characterised by a decrease in serum calcium (Ca) levels, with no clinical symptoms. The aim of this study was to determine the punctual prevalence of subclinical hypocalcemia in dairy cows, in the Sousa city micro-region, Paraíba state. Samples were collected from 29 dairy farms, consisting of 153 and 296 blood samples in the pre- and postpartum period respectively. In relation to the mineral supplementation profile, 89.25% of the properties use a commercial supplement. On average, 40.53% of lactating cows presented total serum Ca levels under the lower limit of 8.0 mg/dL, with an exclusive supplement of NaCl resulting in a higher percentage of cows, 61.11%, with the condition of subclinical hypocalcemia. For ionized Ca, the average prevalence of subclinical hypocalcemia was 21.16%. The prevalence of subclinical hypocalcemia for total serum Ca was 37.25 and 42.23% of cows in the pre- and postpartum period respectively. The type of mineral supplement did not influence (P > .05) total and ionized serum Ca levels in lactating cows. There was no significant difference (P > .05) for total and ionized serum Ca levels as a function of the reproductive period in lactating cows. Subclinical hypocalcemia was evident in the dairy cows under evaluation and occurred with an average punctual prevalence of 40.34%. Commercial supplement is the most common form of mineral mixture used; however, it was not able to promote an increase in the levels of total and ionized serum Ca levels due to errors in managing the supply.

An overview of nitrate sources and operating processes in arid and semiarid aquifer systems

Nitrate concentration in most aquifers in arid and semi-arid areas has increased in the past several decades as a result of human activities. Under the predominantly oxic conditions of these aquifers, denitrification is inhibited, allowing nitrate, a soluble and stable form of nitrogen (N), to accumulate. Because of its close association with municipal and agricultural wastes, nitrate is commonly used as an indicator of anthropogenic contamination. Aquifers affected by agricultural waste may contain salts from irrigation returns and herbicides in addition to nitrates. Preventing leakage from soil to deeper parts of the aquifer is thus a priority in the sustainable management of aquifers in arid and semiarid areas. Studies report a wide range of nitrate concentrations distributed non-uniformly within the aquifer, with roughly 40% and 20% of sampled wells exceeding 50mg/L nitrate in shallow and deep parts of the aquifer respectively. In aquifers at risk of becoming contaminated, nitrate isotopes (δ¹⁵N, δ¹⁸O, Δ¹⁷O) can be used to identify the source of nitrogen as mineral or organic fertilizer, sewage, or atmospheric deposition. A variety of mathematical models (crop, hydrological, geochemical, or a combination of them) have been successful in identifying best practices that minimize N leakage without negatively affecting crop yield. In addition, field research in crop management, e.g., conservation agriculture, has yielded promising results in determining the adequate dosage and time of application of fertilizers to reduce N losses. Examples of key dryland aquifers impacted by nitrate are discussed, and some of the most pressing challenges to achieve sustainability are presented.

Radionuclides as natural tracers of the interaction between groundwater and surface water in the River Andarax, Spain

The identification of specific aquifers that supply water to river systems is fundamental to understanding the dynamics of the rivers' hydrochemistry, particularly in arid and semiarid environments where river flow may be discontinuous. There are multiple methods to identify the source of river water. In this study of the River Andarax, in the Southeast of Spain, an analysis of natural tracers (physico-chemical parameters, uranium, radium and radon) in surface water and groundwater indicates that chemical parameters and uranium clearly identify the areas where there is groundwater-surface water interaction. The concentration of uranium found in the river defines two areas: the headwaters with U concentrations of 2 μg L^-1 and the lower reaches, with U of 6 μg L^-1. Furthermore, variation in the ²³⁴U/²³⁸U isotopic ratio allowed us to detect the influence that groundwater from the carbonate aquifer has on surface water in the headwaters of the river, where the saline content is lower and the water has a calcium bicarbonate facies. The concentration of ²²⁶Ra and ²²²Rn are low in the surface waters: <1.6 × 10^-6 μg L^-1 and <5.1 × 10^-12 μg L^-1, respectively. There is a slight increase in the lower reaches where the water has a permanent flow, greater salinity and a calcium-magnesium-sulphate facies. All this is favoured by the influence of groundwater from the detritic aquifer on the surface waters. The results of this study indicate the utility in the use of physico-chemical and radiological data conjointly as tracers of groundwater-surface water interaction in semiarid areas where the lithology of aquifers is diverse (carbonate and detritic) and where evaporitic rocks are present.

Spectral reflectance characteristics of soils in northeastern Brazil as influenced by salinity levels

In northeastern Brazil, large swaths of once-productive soils have been severely degraded by soil salinization, but the true extent of the damage has not been assessed. Emerging remote sensing technology based on hyperspectral analysis offers one possibility for large-scale assessment, but it has been unclear to what extent the spectral properties of soils are related to salinity characteristics. The purpose of this study was to characterize the spectral properties of degraded (saline) and non-degraded agricultural soils in northeastern Brazil and determine the extent to which these properties correspond to soil salinity. We took soil samples from 78 locations within a 45,000-km² site in Pernambuco State. We used cluster analysis to group the soil samples on the basis of similarities in salinity and sodicity levels, and then obtained spectral data for each group. The physical properties analysis indicated a predominance of the coarse sand fraction in almost all the soil groups, and total porosity was similar for all the groups. The chemical analysis revealed different levels of degradation among the groups, ranging from non-degraded to strongly degraded conditions, as defined by the degree of salinity and sodicity. The soil properties showing the highest correlation with spectral reflectance were the exchangeable sodium percentage followed by fine sand. Differences in the reflectance curves for the various soil groups were relatively small and were not significant. These results suggest that, where soil crusts are not present, significant challenges remain for using hyperspectral remote sensing to assess soil salinity in northeastern Brazil.

In vitro and in vivo action of Piptadenia viridiflora (Kunth) Benth against Haemonchus contortus in sheep

Anthelminthic resistant populations of Haemonchus contortus are a major problem in sheep rearing, but plant extracts may offer viable alternative treatments. In our preliminary studies, Piptadenia viridiflora was frequently selected by sheep grazing in the Cerrado. The present research evaluated its in vitro and in vivo anthelmintic activity. The HPLC chromatograms of P. viridiflora aqueous extract (AE) and ethanolic extract (EE) showed the presence of flavonoids. The total condensed tannin (proanthocyanidin) was 0.2 and 1.01% in AE and EE, respectively. In an egg hatching inhibition (EHI) test, the LC90 of AE was 2.4mg/mL, and, of EE, was 2.1mg/mL. After tannin extraction, higher EHI and lower LC90 were observed. In a larval development inhibition test, the LC90 of AE was 13.66mg/g of fecal culture. The highest dose of AE administered to mice (203.0mg/kg bw) was well tolerated, suggesting low toxicity. In vivo, AE was orally administered to lambs at 283mg/kg bw, and, at weeks one, two, and three post-treatment, the mean fecal egg count (FEC) was significantly lower than in untreated lambs (P<0.05). Blood parameters were normal and similar in untreated and treated sheep. For all lamb groups, the mean total serum protein was significantly higher at week two post-treatment than at other evaluated periods (P<0.05). Piptadenia viridiflora extracts had low condensed tannin content and exhibited high anthelminthic efficacy in vitro and significantly reduced FEC. Tannins were not shown to be the principal components affecting EHI, hence it is necessary to isolate and characterize the principal active P. viridiflora compounds, and to assess their possible synergism.

Thinning effects on litterfall remaining after 8 years and improved stand resilience in Aleppo pine afforestation (SE Spain)

Monthly litterfall was monitored over a 3-year period in afforested Aleppo pines in the Mediterranean semiarid SE Spain with the aim of determining the long-term response of pines to reductions in tree competition and how this forest practice might influence stand resilience. Three thinning intensities applied 5 years earlier were evaluated (T75 = 75% of the basal area removed, T60 = 60% and T48 = 48%), both at the stand and at the tree level. On average, the total annual litterfall varied between 1.30 Mg ha(-1) yr(-1) (±0.24 SE) in T75 and 3.28 Mg ha(-1) yr(-1) (±0.78 SE) in the unthinned control. At the stand level, monthly differences among the treatments were found over time in the needles (F = 11.09, df = 3, P = 0.0009) and woody fraction (F = 4.36, df = 3, P = 0.0269) following the thinning gradient: T0 (control)>T48 > T60 > T75, and for the total amount of needles (χ(2) = 9.33, P = 0.025) and twigs (χ(2) = 9.11, P = 0.027) recorded at the end of the study period. High amounts of twig and needle fall were recorded during summer and beginning of autumn, whereas the main miscellanea inputs were registered during the spring, coinciding with the fall of nests and frass from caterpillar outbreaks. At the tree level, the total litterfall fluctuated between 1.5 kg tree yr(-1) in T0 (2nd yr) and 7.0 kg tree yr(-1) in T75 (3rd yr), although mean annual statistical differences among the treatments were found only for the first year of monitoring. However, needle fall was higher for larger pines (T75) than for the smaller ones in control (T0) when the data were analysed over the 3-year-period (F = 3.64, df = 3, P = 0.0247), and the same happened for the woody fraction (F = 3.63, df = 3, P = 0.0250). By contrast, pine trees in the unthinned control registered needle-fall rates (measured as kg m(-2) tree(-1)) that were similar to or higher than those of pine trees in thinned stands, suggesting that defoliation processes took place at high tree densities, especially after a severely dry period. We propose thinning as a measure to adapt high-density plantations to alterations due to climate change, in order to prevent forest decline and mortality.

Net requirements of calcium, phosphorus, magnesium, and sulphur for growth of non-descript breed hair lambs of different sex classes in the Brazilian semiarid conditions

The aim of this study was to determine the net requirements of calcium (Ca), phosphorus (P), magnesium (Mg), and sulphur (S) for weight gain of non-descript breed hair lambs (NDBL) of different sex classes reared under Brazilian semiarid conditions. Sixty NDBL (20 intact males, 20 castrated males, and 20 females), with an average initial body weight of 18.1 ± 0.4 kg and average age of 5 months were used. The macromineral requirements were determined by the differences in body composition through comparative slaughter direct method. The animals were confined for 58 days, and the average fasting body weight (FBW) and average daily gain (ADG) of lambs fed ad libitum were 29.2 ± 0.6 and 0.19 ± 0.01 kg, respectively. The net requirements of macrominerals for gain of NDBL did not differ between sex classes (P > 0.05), and ranged from 1.83 to 1.46 g/day of Ca, 1.21 to 1.01 g/day of P, 37 to 30 mg/day of Mg, and 0.31 to 0.28 g/day of S, for lambs with an ADG of 0.200 kg and 15 or 30 kg of FBW, respectively (P < 0.05). The N to S net ratio reduced and increased, respectively, as the body weight and ADG increase. The net requirements of Ca, P, Mg, and S for gain of NDBL slaughtered young and at the same age did not differ between sex classes and decreased as the body weight increased. The net requirements for gain of Ca and P were similar to those recommended by NRC (2007).