3,246 research outputs found
Effect of variety, growing region and growing season on digestible energy content of wheats grown in Western Australia for weaner pigs
No full textAn 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
Intestinal responses to dehulling and level of inclusion of Australian sweet lupins (Lupinus angustifolius) in weaner pig diets
No full textThe change from sow's milk to solid feed at weaning causes marked alterations in the structure and function of the gastrointestinal tract (GIT), and makes pigs more susceptible to the proliferation of enteric pathogens such as enterotoxigenic Escherichia coli, which can cause post-weaning colibacillosis (PWC). Diet composition and form have major effects on PWC (Pluske et al., 2002), hence it is important to consider the effects of ingredients on nutrient digestibility, since a diet of lower digestibility can result in an increase in the supply of nutrients to pathogenic bacteria in the hind gut. Previous research has demonstrated that a small amount of insoluble fibre ameliorates the incidence of PWC (Kim et al., 2008), while some soluble fibres lead to proliferation of enteric pathogens (Pluske et al. 2002). We hypothesise that increasing concentrations of whole or dehulled Australian sweet lupins in place of milk products in weaner pig diets will alter the GIT responses and plasma metabolites
Factors influencing the total tract apparent digestibility of nutrients from wheat for the weanling pig
No full textThe objectives of the studies conducted in the Part A of this thesis were to quantify the variation of digestible energy (DE) content of wheat and to document the responsible factors for the variation. The general hypothesis tested in Part A of this thesis was that the variety, growing region, growing season, supplementation of xylanase and postharvest grain storage (i.e., six months of storage at ambient temperature) will influence the DE content of wheat when fed to weaner pigs.
Experiment 1 (Chapter 3) examined the variation in the chemical composition of wheats as influenced by variety (Arrino, Westonia and Stiletto were selected), growing region (each wheat was selected from a high, medium and low rainfall region), season (1999 and 2000) and post harvest storage for 6 months. In this experiment, up to a 19% variation in the crude protein (CP) content (mean13.3, SD 2.59), up to a 5% variation in the starch content (mean 65.4, SD 3.56), and a 10-20% variation in the total (mean 9,2, SD 0.86), insoluble (mean 8.1, SD 0.84) and soluble (mean 1.1, SD 0.23) non-starch polysaccharides (NSP) contents were observed. The major experimental findings were:
* Variety of wheat influenced the variation of most carbohydrate components, including fast digestible starch (FDS) (P<0.001), acid detergent fibre (ADF) (P<0.01), total and insoluble NSP (P<0.05), and in vitro extract viscosity (P<0.05);
* The annual precipitation level in each region correlated to bushel weight (P<0.01), protein (P<0.01) and carbohydrate composition, including starch (P<0.05), soluble NSP (P<0.001), lignin (P<0.001) and free sugars (P<0.001), indicating the importance of the growing environment on the DE content of wheat;
* Growing season influenced bushel weight (P<0.001), CP (P<0.01), amylose and amylopectin (components of starch, P<0.05), ADF (P<0.001), lignin (P<0.001), soluble NSP (P<0.001) and free sugars contents (P<0.001), and the in vitro extract viscosity of wheat (P<0.05);
* Storage of wheat decreased ADF (P<0.05), lignin (P<0.01) and soluble NSP contents (P<0.01) and increased the free sugar content (<<0.001).
In Experiment 2 (Chapter 4), the effect of variety, growing region and growing season on the DE content of wheat in 5-week-old male weaner pigs was examined, and Summary III correlations between various chemical composition of wheat and DE content were established. The major findings were:
* The DE content of wheats varied by up to 1.3 MJ/kg (12.5 13.8; mean = 13.3) in 1999 and by up to 1.8 MJ/kg (12.6 14.4; mean = 13.7) in 2000;
* Both the variety and growing region significantly influenced (P<0.05 - P<0.001) the DE content of wheat;
* Generally, the wheat variety Westonia and wheats grown in the low rainfall region contained a higher DE content than other wheats and growing regions;
* In addition, growing season influenced (P<0.001) DE content of wheat;
* The mean DE content determined with weaner pigs in the current study was approximately 1 MJ/kg DM lower when compared to published estimates of the DE content of wheat determined with growing pigs;
* Prediction of in vivo DE content of wheat for weaner pigs using NIRS (Near Infra- Red Spectroscopy) was not successful.
* Significant inverse relationships between the DE content and xylose (P<0.05), NDF (P<0.01), total-P (P<0.01) and phytate-P content (P<0.05) of wheat were seen in 1999. However, such relationships were not significant in 2000, indicating a very strong seasonal influence on both chemical composition and DE content of wheat.
Experiment 3 (Chapter 5) examined the effects of a supplemental enzyme (xylanase) and storage for 6 months on the DE content of wheats. In 1999, use of the enzyme tended to increase the DE content from 13.3 to 13.6 MJ/kg (P=0.065) whereas in 2000, use of the enzyme caused no change in DE content (13.7 to 13.6 MJ/kg). However, the response to enzyme addition was much greater in some wheats grown in some regions than others, suggesting that the DE response to xylanase supplementation was not systematic but appeared to be associated with the grain structure, with the DE content consequently arising from an interaction between variety and growing conditions of the wheat. For wheats harvested in 1999, storage improved the E content from 13.3 to 4.0 MJ/kg (P<0.01), but for the 2000 wheats, storage for 6 months decreased DE content from 13.7 to 13.0 MJ/kg (P<0.001). However, the 2000 data need to be interpreted with caution because some of the wheats were infested with weevils.
The DE response to supplemental xylanase in 1999 was negatively correlated to the total and insoluble arabinose to xylose ratio (P<0.01), in vitro extract viscosity (P<0.01) and lignin (P<0.06), while FDS (P<0.06) and phytate-P (P<0.06) positively correlated to the DE response to xylanase.
The DE response to storage in 1999 was positively correlated to the NDF (P<0.001) and xylose contents (P<0.01) of the wheats, which had negative influences on the DE content of non-stored wheats. The addition of xylanase in stored wheat did not improve the DE content, suggesting changes in chemical composition (eg, activation of xndogenous xylanases) during storage.
In Experiment 4 (Chapter 6), the same wheats were analysed or phosphorus (P) and hytate-P content, as the latter is considered to be anti-nutritive in pig diets. The total P and phytate-P content of all wheat samples ranged 2.6 (s.e. .64) g/kg and 1.8 (s.e. 0.13) /kg DM, respectively. Endogenous phytase activity was highly variable and averaged 63 (s.e. 29.6) FTU/kg between wheats. The variety, rowing region, season and storage of wheat did not influence the variation of P content. However, the precipitation level over two growing seasons was positively correlated to total-P (P<0.05) and hytate-P contents (P<0.05) of wheat. Phytate-P content of wheat can be predicted from total-P content (r=0.974, P<0.001).
In Part B, two experimental designs were generated based n the results of experiments described in Part A. From the previous experiment (Experiment 2, Chapter 4), it was evident that the structure of starch (i.e., amylose: mylopectin ratio) and phytate-P content of wheat were correlated to DE content of wheat. To reinforce the established correlations the following experiments were carried out, with the general hypothesis that the structure of starch (i.e., waxy vs. non-waxy wheat), particle size of ground wheat, and phytate-P content of wheat will influence the digestibility of nutrients (i.e., nitrogen, energy, minerals) in wheat-based weaner pig diets.
In Experiment 5, the same variety (Janz) of a waxy (98% of total starch was amylopectin) isoline and a non-waxy isoline (71% of total starch was amylopectin) wheat were ground through a hammermill fitted either with a 8.5 mm or 4.5 mm screen to achieve average particle sizes of 930 and 560 mcm, respectively. Diets were formulated and then fed to weaner pigs (3-5 weeks of age) with or without xylanase plus beta-glucancase. Digestibilities of starch, nitrogen, energy, and DE content of diets were measured at day 7 and day 21 to examine any age-related improvement of nutrient digestibilities during the first 3 weeks post-weaning. Waxy wheat improved total tract digestibility of starch (P<0.05) and CP (P<0.05), and the reduction of particle size improved total tract starch digestibility (P<0.001) at both 7 and 21 days after weaning.
However, energy digestibility and DE content of the diet were not influenced by either wheat type or particle size. Supplementation of xylanase plus ?-glucanase improved starch digestibility (P<0.01) and DE content (P<0.05) but not other nutrients, and this occurred especially in non-waxy (P=0.03) and larger particle-sized wheat (P=0.01).
Pigs increased ability to digest protein with age (P<0.05). However, the improvement in nutrient digestibilities in waxy and fine particle size wheat diets did not translate to improved pig performance.
In Experiment 6, the hypothesis tested was that the digestibility and pig performance responses to supplemental xylanase, phytase and xylanase plus phytase would differ in weaner pigs according to P content of wheat. To test this hypothesis, two wheats containing high and low levels of total P (2.52g vs. 3.76 g total-P/kg DM) were obtained and fed to weaner pigs. Diets either had no enzyme or were supplemented with xylanase, phytase, or a combination of xylanase plus phytase. The hypothesis was partly supported in this experiment, since P and Ca digestibility were influenced by a wheat content by enzyme ineraction. Overall improvements in macronutrient digestibility and pig performance by supplementation of various enzymes were not significant. Daily growth (P<0.05 - P<0.01) and FCR (P<0.05 - P<0.01) were improved by the supplemental enzyme only in the first week of the feeding trial, mainly due to the increased P and Ca availability induced by the enzymes. Amounts of P and Ca digested were below the recommended requirements by NRC in the first two weeks of the feeding trial. Supplementation of phytase generally improved P and Ca digestibility (P<0.05) in both low-P and high-P wheats. However, xylanase plus phytase supplementation did not produce synergistic effect for macronutrients, and mineral digestibilities, over single supplementation of xylanase or phytase.
From the results obtained in this thesis I propose that:
1) The DE content of wheat for weaner pigs is variable due mainly to the change of chemical composition mediated by variety, growing environment and storage after harvest, and efficacy of supplemental xylanase is dependent on the chemical structure of NSP present in cell walls of wheat;
2) Structure of starch, particle size, age after weaning, and P content of wheat are factors influencing nutrient digestibility in weaner pigs fed a wheat-based diet, and the efficacy of phytase on P and Ca digestibilities is dependent on the phytate-P content of wheat
Piglets suckling anterior teats during lactation grow faster but then show a reduced rate of growth
No full textThe anterior teats of sows contain more protein and DNA (Kim et al., 2000) and produce up to 200% more milk than the posterior teats (Algers et al., 1990). As a consequence, piglets suckling from anterior teats drink more milk and are generally heavier at weaning (Pluske et al., 1996; Kim et al., 2000). However, the subsequent post-weaning performance of piglets tl1at suckled anterior or posterior teats has not been reported. The purpose of this study was to determine the performance of pigs before and after weaning based on their teat (suckling) order during lactation
Addition of oat hulls to an extruded rice-based diet for weaner pigs ameliorates the incidence of diarrhoea and reduces indices of protein fermentation in the gastrointestinal tract
No full textAn experiment was conducted to determine whether adding oat hulls to weaner pig diets based on extruded rice or unprocessed wheat influenced post-weaning diarrhoea (PWD) and protein fermentation in the large intestine. Ninety-six male piglets (5.16 (SEM 0.08) kg) were allocated to (i) extruded rice plus animal proteins (RAP); (ii) RAP with added oat hulls (20 g/kg); (iii) wheat plus animal proteins (WAP); (iv) WAP with added oat hulls (20 g/kg). Blood and faecal samples were collected on days 7 and 14 after weaning at about age 21 d. Pigs fed RAP had more PWD than pigs fed WAP (P < 0.05). Oat hull supplementation to diet RAP decreased the incidence of PWD (P < 0.05). The total-tract digestibility of DM, starch and energy was higher in rice-based diets than in wheat-based diets (P < 0.001); however, oat hulls decreased digestibility of DM and gross energy (P < 0.001). Pigs fed RAP had higher plasma creatinine concentrations (P < 0.01), which were positively correlated to cumulative β-haemolytic Escherichia coli scores after weaning (R2 0.928; P = 0.015). Addition of oat hulls decreased plasma urea concentrations only in pigs fed RAP (interaction; P < 0.05). Pigs fed RAP had lower faecal total biogenic amine concentrations than pigs fed WAP (P < 0.001). Oat hull supplementation tended to decrease total biogenic amine concentrations (P = 0.103). These data indirectly suggest that a mostly insoluble dietary fibre source such as oat hulls can decrease PWD in dietary situations where there may be a misbalance of carbohydrate to protein entering the hindgut
Different fibre sources fed to weaner pigs influence production performance and acute phase protein levels
No full textDietary 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
Nutritional influences on some major enteric bacterial diseases of pig
No full textThere are several enteric bacterial diseases and conditions of pigs that require control to prevent overt disease, to reduce morbidity and mortality, and to improve the efficiency of production. Traditionally, veterinarians, feed manufacturers and producers have relied upon antibiotics and minerals (for example, ZnO, CUSO4) in diets for a large part of this control. However, recent trends, particularly in Europe, are to reduce antimicrobial use and seek alternative or replacement strategies for controlling enteric bacterial diseases. The majority of these strategies rely on 'nutrition', taken in its broadest sense, to reduce the susceptibility of pigs to these diseases. Evidence to date suggests that specific dietary interventions, for example feeding very highly-digestible diets based on cooked white rice, can reduce the proliferation of a number of specific enteric bacterial infections, such as post-weaning colibacillosis. No simple and universal way to reduce susceptibility to pathogens in the gastrointestinal tract has been identified, and the underlying basis for many of the reported positive effects of 'nutrition' on controlling enteric infections lacks robust, scientific understanding. This makes it difficult to recommend dietary guidelines to prevent or reduce enteric bacterial diseases. Furthermore, some diseases, such as porcine intestinal spirochaetosis caused by Brachyspira pilosicoli, are sometimes associated with other pathogens (co-infections). In such cases, each pathogen might have different nutrient requirements, ecological niches and patterns of metabolism for which a variety of dietary interventions are needed to ameliorate the disease. Greater understanding of how 'nutrition' influences gut epithelial biology and immunobiology, and their interactions with both commensal and pathogenic bacteria, holds promise as a means of tackling enteric disease without antimicrobial. agents. In addition, it is important to consider the overall system (i.e. management, housing, welfare) of pig production in the context of controlling enteric bacterial diseases
Intermittent suckling influences the performance of pigs before and after weaning
No full textThe simultaneous and abrupt changes at weaning cause a growth check characterised by sub-optimal performance, marked changes to the gastrointestinal tract, and increased susceptibility to enteric diseases (Pluske et al., 1997). Intermittent suckling (IS) is a regimen in which the sow is removed from her piglets for a period of time each day before weaning. Previous studies have shown that IS reduces the postweaning growth check by stimulating feed intake in lactation (Kuller et al., 2004), but the impacts of duration and length of separation have not been fully evaluated. The hypothesis tested in this study was that piglets separated from their dam for eight hours per day for seven d in the week before weaning would perform better after weaning compared to piglets in conventional weaning regimens
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