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The current study evaluated growth performance and digestion responses of finishing bulls fed diets containing 825 g/kg flint maize [dry matter (DM) basis] ground to medium (1.66 mm; MG) or coarse particle sizes (2.12 mm; CG), with added monensin (26 mg/kg; DM basis; MON) or a blend of essential oils (BEO) + exogenous α-amylase (AM; 90 mg/kg + 560 mg/kg commercial product, respectively, DM basis). In Expt 1, 256 Nellore bulls were blocked by initial body weight (BW) (360 ± 11.7 kg) and assigned to 48 pens in a 2 × 2 factorial arrangement of treatments. Effect of a maize particle size × feed additive interaction was not detected for final BW, DM intake (DMI), average daily gain (ADG) and feed efficiency. The DMI was greater for bulls fed BEO + AM v. MON. Final BW and ADG tended to be greater for bulls fed CG than MG maize. An interaction was detected for hot carcass weight which was 11 kg heavier for bulls fed BEO + AM v. MON in diets containing CG, but not MG particle size. In Expt 2, four ruminally cannulated Nellore steers were offered the same treatments as Expt 1, in a 4 × 4 Latin Square design. Intake of most nutrients was greater for steers fed CG than steers fed MG maize. In summary, feeding bulls CG maize increased growth performance and carcass characteristics compared with MG. The combination of BEO + AM resulted in heavier carcass weights compared with MON supplementation when included in diets containing CG maize.
Schmidt-hammer exposure-age dating (SHD) of boulders on cryoplanation terrace treads and associated bedrock cliff faces revealed Holocene ages ranging from 0 ± 825 to 8890 ± 1185 yr. The cliffs were significantly younger than the inner treads, which tended to be younger than the outer treads. Radiocarbon dates from the regolith of 3854 to 4821 cal yr BP (2σ range) indicated maximum rates of cliff recession of ~0.1 mm/yr, which suggests the onset of terrace formation before the last glacial maximum. Age, angularity, and size of clasts, together with planation across bedrock structures and the seepage of groundwater from the cliff foot, all support a process-based conceptual model of cryoplanation terrace development in which frost weathering leads to parallel cliff recession and, hence, terrace extension. The availability of groundwater during autumn freezeback is viewed as critical for frost wedging and/or the growth of segregation ice during prolonged winter frost penetration. Permafrost promotes cryoplanation by providing an impermeable frost table beneath the active layer, focusing groundwater flow, and supplying water for sediment transport by solifluction across the tread. Snow beds are considered an effect rather than a cause of cryoplanation terraces, and cryoplanation is seen as distinct from nivation.
Around 30% of individuals with schizophrenia remain symptomatic and significantly impaired despite antipsychotic treatment and are considered to be treatment resistant. Clinicians are currently unable to predict which patients are at higher risk of treatment resistance.
To determine whether genetic liability for schizophrenia and/or clinical characteristics measurable at illness onset can prospectively indicate a higher risk of treatment-resistant psychosis (TRP).
In 1070 individuals with schizophrenia or related psychotic disorders, schizophrenia polygenic risk scores (PRS) and large copy number variations (CNVs) were assessed for enrichment in TRP. Regression and machine-learning approaches were used to investigate the association of phenotypes related to demographics, family history, premorbid factors and illness onset with TRP.
Younger age at onset (odds ratio 0.94, P = 7.79 × 10−13) and poor premorbid social adjustment (odds ratio 1.64, P = 2.41 × 10−4) increased risk of TRP in univariate regression analyses. These factors remained associated in multivariate regression analyses, which also found lower premorbid IQ (odds ratio 0.98, P = 7.76 × 10−3), younger father's age at birth (odds ratio 0.97, P = 0.015) and cannabis use (odds ratio 1.60, P = 0.025) increased the risk of TRP. Machine-learning approaches found age at onset to be the most important predictor and also identified premorbid IQ and poor social adjustment as predictors of TRP, mirroring findings from regression analyses. Genetic liability for schizophrenia was not associated with TRP.
People with an earlier age at onset of psychosis and poor premorbid functioning are more likely to be treatment resistant. The genetic architecture of susceptibility to schizophrenia may be distinct from that of treatment outcomes.
The crystal structure of tlapallite has been determined using single-crystal X-ray diffraction and supported by electron probe micro-analysis, powder diffraction and Raman spectroscopy. Tlapallite is trigonal, space group P321, with a = 9.1219(17) Å, c = 11.9320(9) Å and V = 859.8(3) Å3, and was refined to R1 = 0.0296 for 786 reflections with I > 2σ(I). This study resulted from the discovery of well-crystallised tlapallite at the Wildcat prospect, Utah, USA. The chemical formula of tlapallite has been revised to (Ca,Pb)3CaCu6[Te4+3Te6+O12]2(Te4+O3)2(SO4)2·3H2O, or more simply (Ca,Pb)3CaCu6Te4+8Te6+2O30(SO4)2·3H2O, from H6(Ca,Pb)2(Cu,Zn)3(TeO3)4(TeO6)(SO4). The tlapallite structure consists of layers containing distorted Cu2+O6 octahedra, Te6+O6 octahedra and Te4+O4 disphenoids (which together form the new mixed-valence phyllotellurate anion [Te4+3Te6+O12]12−), Te4+O3 trigonal pyramids and CaO8 polyhedra. SO4 tetrahedra, Ca(H2O)3O6 polyhedra and H2O groups fill the space between the layers. Tlapallite is only the second naturally occurring compound containing tellurium in both the 4+ and 6+ oxidation states with a known crystal structure, the other being carlfriesite, CaTe4+2Te6+O8. Carlfriesite is the predominant secondary tellurium mineral at the Wildcat prospect. We also present an updated structure for carlfriesite, which has been refined to R1 = 0.0230 for 874 reflections with I > 2σ(I). This updated structural refinement improves upon the one reported previously by refining all atoms anisotropically and presenting models of bond valence and Te4+ secondary bonding.
Building on the recent advances in next-generation sequencing, the integration of genomics, proteomics, metabolomics, and other approaches hold tremendous promise for precision medicine. The approval and adoption of these rapidly advancing technologies and methods presents several regulatory science considerations that need to be addressed. To better understand and address these regulatory science issues, a Clinical and Translational Science Award Working Group convened the Regulatory Science to Advance Precision Medicine Forum. The Forum identified an initial set of regulatory science gaps. The final set of key findings and recommendations provided here address issues related to the lack of standardization of complex tests, preclinical issues, establishing clinical validity and utility, pharmacogenomics considerations, and knowledge gaps.
Herbicide resistance is ‘wicked’ in nature; therefore, results of the many educational efforts to encourage diversification of weed control practices in the United States have been mixed. It is clear that we do not sufficiently understand the totality of the grassroots obstacles, concerns, challenges, and specific solutions needed for varied crop production systems. Weed management issues and solutions vary with such variables as management styles, regions, cropping systems, and available or affordable technologies. Therefore, to help the weed science community better understand the needs and ideas of those directly dealing with herbicide resistance, seven half-day regional listening sessions were held across the United States between December 2016 and April 2017 with groups of diverse stakeholders on the issues and potential solutions for herbicide resistance management. The major goals of the sessions were to gain an understanding of stakeholders and their goals and concerns related to herbicide resistance management, to become familiar with regional differences, and to identify decision maker needs to address herbicide resistance. The messages shared by listening-session participants could be summarized by six themes: we need new herbicides; there is no need for more regulation; there is a need for more education, especially for others who were not present; diversity is hard; the agricultural economy makes it difficult to make changes; and we are aware of herbicide resistance but are managing it. The authors concluded that more work is needed to bring a community-wide, interdisciplinary approach to understanding the complexity of managing weeds within the context of the whole farm operation and for communicating the need to address herbicide resistance.
Seven half-day regional listening sessions were held between December 2016 and April 2017 with groups of diverse stakeholders on the issues and potential solutions for herbicide-resistance management. The objective of the listening sessions was to connect with stakeholders and hear their challenges and recommendations for addressing herbicide resistance. The coordinating team hired Strategic Conservation Solutions, LLC, to facilitate all the sessions. They and the coordinating team used in-person meetings, teleconferences, and email to communicate and coordinate the activities leading up to each regional listening session. The agenda was the same across all sessions and included small-group discussions followed by reporting to the full group for discussion. The planning process was the same across all the sessions, although the selection of venue, time of day, and stakeholder participants differed to accommodate the differences among regions. The listening-session format required a great deal of work and flexibility on the part of the coordinating team and regional coordinators. Overall, the participant evaluations from the sessions were positive, with participants expressing appreciation that they were asked for their thoughts on the subject of herbicide resistance. This paper details the methods and processes used to conduct these regional listening sessions and provides an assessment of the strengths and limitations of those processes.
Parameters from in vitro gas production techniques could have potential as predictors of dry-matter intake (DMI) and digestibility. Fermentation is usually carried out under conditions where nitrogen (N) is not limiting. Therefore where N supply is a constraint to intake and digestibility, prediction equations may be inaccurate. This study compared the use of N-free and N-rich media in an in vitro fermentation method (Theodorou et al., 1994) and studied the relationships between in vitro and in vivo parameters obtained using both media.
In the Central Kenyan Highlands, dairy cattle ownership is a crucial element in poverty alleviation. For example, in Kiambu district just north of Nairobi, out of the population of 744010, 48% of 189709 households stall feed dairy cattle. Farm sizes average 1.1 to 2.0 ha per household. Producing sufficient forage for dairy cattle is difficult and low dry matter intake constrains dairy production and there is a positive correlation between stover intake and milk yield.. Napier grass comprised 40% of the total dry matter fed to cattle and maize forage 24% according to the project’s Rapid Rural Appraisal, maize thinnings and stover being routinely fed to livestock. In another survey, dry maize stover accounted for nearly 65% of dry matter intake of dairy cattle during October.
While livestock sector is the back-bone of Ethiopian economy, production levels are low due to a variety of causes. It is characterized by low milk production, poor growth rates, extended calving or lambing intervals and a relatively late age at maturity. The major constrain for this is seasonality of feed quality and poor availability during the dry season, with nitrogen supply especially limiting. However legume forages such as cowpea offer the possibility to enhance dietary N levels and improve livestock production (Abule et al., 1995). With its quick growth, drought resistance and rapid ground cover cowpea has become an essential component of sustainable subsistence agriculture in marginal lands and drier regions of the tropics. This study was conducted to examine the ability of cowpea forages, offered as a supplement to low quality maize stover, to enhance intake and production performance in growing Ethiopian highland sheep.
Several techniques involving enzymes as alternatives to rumen fluid in in vitro studies have been proposed. However, high cost, ill-defined characterisation and high variation among enzyme preparations and batches have discouraged their use. In addition, most studies have aimed at determining dry matter degradability (DMD) at a fixed time, commonly 48 h. Consequently little information has been published concerning the DM degradation dynamics of forages incubated with enzymes. Therefore the objective of the present study was to compare the ability of a commercial enzyme mixture to describe the fermentation dynamics of two contrasting forages, using the ANKOM in vitro fermentation system (Daisy II, ANKOM Co, USA).
Non-additivity occurs when the nutritive value of a mixture of feedstuffs differs from that of the sum of its components. It is most commonly observed when one dietary constituent influences, either positively or negatively, the apparent digestibility of another under conditions where components such as nitrogen and sulphur are non-limiting. In general negative effects occur due to the depression of rumen pH or substrate competition, while positive effects have been identified when readily fermentable fibre sources such as sugar beet pulp have been included in rations containing poorly fermented forages such as cereal straw. With the increasing use of in vitro systems, not just to examine feed degradation characteristics but to derive parameters such as microbial protein yield, the following study was conducted to determine whether such interactions could be identified in vitro.
A number of fibrolytic enzyme preparations have been shown to increase the rate and extent of fermentation of alfalfa fractions (Colombatto et al., 2000a). However, responses to enzyme addition have been mixed and several factors are believed to be involved. Among these, specific enzyme activities and application rates are very important. The present study examined a commercial enzyme preparation already established as effective, for its ability to increase the rate and extent of in vitro fermentation of alfalfa stems, when applied at different levels.
After prolonged exposure to tanniniferous diets, it has been reported that some rumen microorganisms acquire defensive mechanisms against tannins (Brooker et al., 2000) or produce tannin-degrading enzymes. Such rumen microorganisms are said to be “tannin resistant” as their fermentation activity is less inhibited by the presence of tannins in the host’s diet. As acacia pods contain tannins their use as protein supplements for goats in the dry season may require that they be first detannified e.g. by using polyethylene glycol (PEG). However, goats with prior exposure to tanniniferous diets may have developed adaptive mechanisms to deal with tannins. This study, therefore, investigated the need for tannin inactivation in feeds given to ‘adapted’ animals by comparing the effect on the in vitro fermentation of tree pods incubated with and without PEG using rumen fluid from adapted and unadapted goats.
In a previous study in Reading (altitude 66 m) (Mauricio et al., 1997) the lag phase was greater when cow faeces was used as a source of microorganisms in the in vitro gas production technique instead of rumen liquor when twelve temperate forages were fermented for 96 h. In the Reading study faeces and rumen liquor were obtained from a cow fed grass silage and concentrate (60:40). The present study was done in Piracicaba, Brazil-BR (altitude 780 m) which has a tropical climate. Using the same forages as in Mauricio et al. (1998), the study examined whether the same differences between faeces and rumen liquor would occur in a tropical environment. In addition, the opportunity was taken to develop an equation relating pressure and volume for the semi-automated pressure transducer technique and compare it with the equation developed in UK by Mauricio et al. (1998).
Treatment of forage with enzyme mixtures can increase rate of degradation in vitro (Colombatto et al., 2000a). However, the complexity of natural forage makes it difficult to determine what fractions are most affected by enzyme treatment. The use of pure substrates (e.g. cellulose and xylan), provides a way of evaluating enzyme mode of action. Therefore, the present study examined the effects of pre-treating avicel and xylan with an enzyme mixture (EM) on a) the reducing sugars produced during treatment before rumen fermentation and b) the gas production profiles during in vitro rumen fermentation using the Reading Pressure Technique (RPT) (Mauricio et al., 1999).
The use of small ruminants, such as sheep, in metabolism studies is more convenient as handling problems are reduced and their maintenance costs are lower, in comparison with cattle. However in vivo digestibility estimates obtained at maintenance are known to differ between these two species. With the increased use of in vitro gas production techniques, to evaluate ruminant feedingstuffs, it is of great importance to identify whether the species from which the rumen fluid inoculum is obtained has a significant influence on the results obtained.
Rumen fluid samples were obtained from a non-lactating Holstein cow (C) and six wether sheep (S) offered the same diet (80 % tropical grass and 20 % dairy concentrate) and prepared so as to have similar dry matter (DM) contents and therefore potentially the microbial mass. Nine substrates (two tropical grasses 1-2, tropical alfalfa 3, barley straw 4, and five temperate grasses 5-9) were examined.
Feed enzymes for ruminants have received considerable attention recently, because of their potential to improve animal performance. However, the commercial preparations available are generally mixtures and are poorly characterised. Furthermore, their role in improving the nutritive value of ruminant feeds is not well understood. Previous work with a commercial enzyme applied at ensiling of maize stover showed a significant decrease in cell wall contents (Altaf et al., 1997). The present study evaluated the enzyme used by Altaf et al. (1997) in terms of a) main enzyme activities; b) ability to hydrolyse feeds at three different pHs and c) HPLC analysis of the products released.
Modern feeding practices often lead to ruminal conditions being sub-optimal for fibre digestion. It has been speculated that fibrolytic enzymes, which usually show optimum activity at pH values below 6.0, may be of benefit when applied to diets of high producing animals. This study used a commercial enzyme mixture (EM), already identified as effective; to investigate its optimum pH range with respect to activity and its impact on the fermentation profiles of pure substrates, under differing pH conditions.
Selected fibrolytic enzyme preparations applied at ensiling have been shown to reduce the fibre contents and to increase the initial rate of in vitro organic matter degradation (OMD) of maize silage (Colombatto et al., 2001). However, there is little information on changes in the fibre content of maize forage during the ensiling process, as affected by enzyme addition. The present study examined the effects of characterised enzyme preparations (Colombatto et al., 2000), derived from mesophilic and thermophilic fungal sources applied at ensiling, on the quality and in vitro rumen degradation characteristics of maize silage, as assessed using the Reading Pressure Technique (RPT, Mauricio et al., 1999).