Effect of variety, growing region and growing season on digestible energy content of wheats grown in Western Australia for weaner pigs

An experiment was conducted to examine the digestible energy (DE) content for weanling pigs in a cohort of wheats grown in Western Australia, and to establish relationships between DE content and their chemical composition. The 3 5 3 5 2 factorial experiment examined the wheat variety (Arrino, Stiletto and Westonia), growing location (high, medium and low rainfall zone) and harvest year (1999 and 2000). Pigs (no. = 5 per diet) aged about 28 days were given a diet at a level of 0.05 5 live weight containing 900 g/kg of the wheat and an acid-insoluble ash marker for 10 days, with samples of faeces collected from each pig for the final 5 days. The average live weight of pigs was 6.6 (s.d. 0.77) kg. The DE content of wheats harvested in 1999 varied by up to 1.3 MJ/kg, while wheats harvested in 2000 varied by up to 1.8 MJ/kg. When the 2 years' data were combined, the DE content ranged from 12.5 to 14.4 MJ/kg. Both the variety and growing region significantly influenced (P 0.05) with the wheats harvested in 2000. In addition, the precipitation level (mm) during the growing season of wheats was strongly correlated (r = -0.821, P < 0.01) to the DE content of wheat in year 1999, but was not correlated in 2000. The results indicate that the genetic and environmental conditions during the growth of wheat have a significant impact on the utilization of plant energy in weaner pigs, and that greater attention needs to be paid to these influences in the assignment of energy values for wheats given to weaner pigs

Efficacy of a reduced protein diet on clinical expression of post-weaning diarrhoea and life-time performance after experimental challenge with an enterotoxigenic strain of Escherichia coli

Previous experiments have shown that feeding a reduced protein diet within the first 2 weeks post-weaning reduces gastrointestinal protein fermentation and clinical expression of post-weaning diarrhoea (PWD). However, growth of young pigs receiving a reduced protein diet without crystalline essential amino acids (CEAA) supplementation is depressed after weaning. It has been argued that the short-term performance reduction caused by feeding a reduced protein diet would be compensated and the lifetime performance of pigs would not be affected. An experiment was therefore conducted to examine PWD and lifetime growth of pigs after feeding a reduced protein diet without and with CEAA supplementation for 2 weeks after weaning. Two hundred individually housed pigs weaned at 21 d of age (Large White×Landrace, castrate:female ratio of 1:1, mean±SEM body weight of 5.5±0.05kg) were stratified to one of four dietary treatments (n=50): High protein+antimicrobial compound diet (HP+AMC, 230g crude protein (CP) with 2.5g lincospectin and 3g zinc oxide per kg feed), High protein diet (HP, 230gCP/kg), Reduced protein+amino acid supplemented diet (RP+AA, 185gCP/kg with added CEAA up to HP level), and Reduced protein diet (RP, 185g CP/kg without CEAA supplementation). Pigs were fed the experimental diet for 2 weeks and then all pigs were fed the same series of commercial diets until slaughter. All pigs were experimentally infected with an enterotoxigenic strain of E. coli (6 and 10mL of 1.9×109cfu/mL, serotype O149:K91:K88) at 72, and 96h after weaning. Infection increased plasma haptoglobin levels (P0.05). Carcass characteristics were not affected (P>0.05) by the treatments. The results indicate that although feeding a RP diet without CEAA supplementation decreased performance after weaning, it did not influence lifetime performance or carcass characteristics and reduced the clinical expression of PWD

Performance and intestinal responses to dehulling and inclusion level of Australian sweet lupins (Lupinus angustifolius L.) in diets for weaner pigs

A total of 180 entire male weaner pigs weighing 6.4 ± 0.1. kg (mean ± SEM) and housed in pairs was used in a completely randomised block design with 9 dietary treatments (n= 10 pens). Pigs were blocked based on weaning weight. The diets were (i) a wheat-based control diet containing 240. g/kg of milk products (whey and skim milk powder), and (ii) 8 diets containing whole or dehulled lupins (cv. Coromup) that substituted the milk products at 60, 120, 180 and 240. g/kg of diet (replace 25%, 50%, 75%, or 100% of the milk products in the control diets). The diets were isoenergetic [15. MJ digestible energy (DE)/kg], and were formulated to contain the same ileal standardised digestible lysine content (0.85. g/MJ DE) and ideal patterns of other essential amino acids. Pigs receiving 240. g/kg of dehulled lupins grew slower (P<0.05) than pigs fed the other diets mainly due to decreased feed intake. Pigs fed diets containing more than 180. g/kg of dehulled lupins had a higher faecal β-haemolytic Escherichia coli score on day 3 after weaning (P<0.05). Moreover, inclusion of 240. g/kg of whole lupin or more than 180. g/kg of dehulled lupins increased (P<0.001) plasma urea nitrogen (PUN) levels. Total tract apparent digestibility (TTAD) of dry matter decreased (P<0.001) in all lupin diets compared with the control diet. These data indicate that inclusion of dehulled lupin immediately after weaning should be limited to less than 180. g/kg whilst whole lupins can be included up to 240. g/kg without deleterious effects on production and intestinal health

Influence of the imperfection direction on the ultimate response of steel frames in advanced analysis

Initial geometric imperfections are unavoidable in steel members and frames due to erection and manufacturing tolerances. These include frame out-of-plumbness, member out-of-straightness and cross-sectional imperfections, and can have a significant influence on the response and resistance of steel structures. Thus, they need to be accounted for in the analysis and design of steel structures, especially when advanced design procedures are adopted. One of the easiest approaches to introduce geometric imperfections in structural finite element models is through the linear superposition of scaled eigenmodes, which are obtained from a priori elastic buckling analysis. Although the shape and magnitude of frame and member imperfections are specified in international standards, the rules for the combination of different types and directions of imperfections are unclear or impractical, and often require designers to consider many possible combinations to find the critical, or “worst case”, shape of the imperfection including the direction of each eigenmode. This paper investigates the influence of the direction of modes contributing to the imperfection on the ultimate load (i.e., resistance) of steel frames when using advanced analysis. Ultimate loads are estimated from advanced finite element simulations for 20 regular and irregular unbraced frames featuring steel and austenitic stainless steel compact sections, in which initial imperfections are modelled as linear superpositions of six scaled buckling modes considering all possible combinations of direction. The results show that the influence of the imperfection direction on the ultimate frame load is small, and that assuming a combination of all buckling modes with positive amplitudes provides a simple and accurate estimation of the critical imperfection combination.The project leading to this research has received funding from the European Union's Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie Grant Agreement No. 842395.Peer ReviewedPostprint (published version

Reliability of stainless steel frames designed using the Direct Design Method in serviceability limit states

Steel structures can be consistently and efficiently designed using system-based design-by-analysis approaches such as the Direct Design Method. However, since direct design approaches lead to potentially lighter structural configurations, they can also result in larger deformations under service loads. Thus, greater attention may be required to serviceability limit states in structures designed using design-by-analysis approaches than for structures designed elastically at their ultimate limit state following current two-stage approaches, especially for materials showing highly nonlinear stress vs strain responses such as stainless steel alloys. With the aim of investigating the influence of allowing larger deformations in the ultimate limit state design of stainless steel structures, this paper presents an explicit analysis framework for assessing serviceability reliability at system level. Using this framework, the paper investigates the serviceability reliability of cold-formed stainless steel portal frames designed using the Direct Design Method for different load cases, including the gravity load and the combined gravity plus wind load combinations. The study considers six baseline frames covering the most common stainless steel families and international design frameworks (i.e., Eurocode, US and Australian frameworks), for which the reliability of vertical deflection and lateral drift serviceability limit states is investigated using advanced numerical simulations and First-Order Reliability Methods. From the comparison of the calculated average annual reliability indices and the relevant target reliabilities for the different design frameworks, it was found that the reliability of stainless steel frames appears to be adequate for the serviceability limit states investigated for the Eurocode, US and Australian frameworks.Peer ReviewedPostprint (published version

On the system-based design for steel frames using inelastic analysis

Design by inelastic analysis of overall system behaviour is permitted in several steel design specifications worldwide (e.g., the American Specification AISC360-10 and the Australian Specification AS4100-1998). Advanced inelastic analysis is better able to capture the system behavioural characteristics as they currently are understood. This paper presents a case study of the design of three planar steel structures using different design methods, including the Direct Analysis method in AISC360-10, the inelastic design method in AISC360-10, and the inelastic method (“advanced analysis”) in AS4100. The effects of structural ductility (capacity of load redistribution) and failure modes on the design results are discussed

Different fibre sources fed to weaner pigs influence production performance and acute phase protein levels

Dietary fibre is fermented by microbiota in the distal gastrointestinal tract (GIT) to short-chain fatty acids (SCF A). Previous studies (e.g., Pluske et al., 2002) have shown differential effects of SCF A on growth performance and the incidence of disease such as post-weaning diarrhoea (PWD), however more recently the SCF A have become recognised as potential mediators in inflammatory and immune functions in the GIT (Vinolo et al., 2011). This experiment examined the effects of infection with an enterotoxigenic strain of E. coli on pig performance, SCF A production, and biomarkers of inflammation after weaning

Simplified expressions for reliability assessments in code calibration

First Order Reliability Methods (FORM) have been used by specification committees in the reliability analyses required for the calibration of resistance and safety factors for the past 40 years. However, these methods are iterative, require input information that may not be readily available, and make comparisons between different approaches or design frameworks difficult. This paper presents a set of simplified equations to estimate reliability indices , resistance factors and partial safety factors based on simpler First Order Second Moment (FOSM) considerations for the US and Eurocode frameworks, which are particularized for different load cases, and on the semi-probabilistic approach prescribed in the Eurocode 0. The equations provide direct relationships between the reliability calibration results corresponding to different design frameworks, and can be used to estimate resistance factors as simple cross-checks for the US framework based on the partial safety factors derived for the Eurocode (or vice versa) from basic statistical input information and given target reliability, including when the data available in the literature is insufficient to perform FORM analyses. The accuracy of the proposed equations is assessed against reliability results derived using FORM techniques for an extensive database of steel and stainless steel frames subjected to gravity and combined gravity plus wind load cases collected from the literature, and limitations for their applicability are recommended. The results demonstrate that the set of equations proposed in this paper provides accurate estimations of the reliability index, resistance factors and partial safety factors and can assist specification committees in the process of calibrating suitable system factors.Peer ReviewedPostprint (published version

Relationship between the quantity and quality of carbohydrates and the digestible energy content of wheats for weaner pigs

The aim of this study was to establish correlations between the quantity and quality of carbohydrates and the digestible energy (DE) content of wheats fed to weaner pigs