Francois-Xavier Oury

Relationships between digestibilities of food components and characteristics of wheats ( Triticum aestivum ) introduced as the only cereal source in a broiler chicken diet

1. The aim of the experiment was to establish relationships between chemical or physical characteristics of wheats ( Triticum aestivum ) and digestibilities of food components in broiler chickens fed on wheat-based diets. Twenty-two wheat samples, each differing by their cultivar origin, were included at 550 g/kg in diets offered to male Ross broiler chicks. The other main ingredients were soya bean meal (340 g/kg) and rapeseed oil (68.5 g/kg). Diets were given as pellets. 2. In vitro viscosities of wheats measured as potential applied viscosity (PAV) or real applied viscosity (RAV) varied between 1.91 and 6.03, or between 0.95 and 3.81 ml/g (dry matter basis), respectively. Hardness of wheats varied between 17 (soft) and 95 (very hard), and lipase activity of wheats varied from 1 to 13.6 (relative scale). 3. PAV and RAV values were not significantly correlated with hardness. PAV and RAV values were correlated with (80:20) ethanol:water insoluble.961, 0.932, respectively), with the amount of water retained by cell walls ( r .656, 0.492, respectively), and with lipase activity ( r = 0.600, 0.532, respectively. 4. Hardness was correlated with ash ( r = -0.484), nitrogen ( r = 0.534), mean particle size of wheat flours ( r = 0.631), and specific energy of pelleting ( r = -0.574). 5. Wheat diets were evaluated in two assays with 3-week-old chicks, with 11 diets per assay. In each assay, a balance experiment was carried out using the total collection method. Growth performance was also measured during the balance experiment. 6. In vitro viscosity parameters were negatively correlated with diet AME n .05), lipid digestibility ( P < 0.05) and, to a lesser extent, protein digestibility ( P < 0.05). In vitro viscosity data were positively correlated with food:gain ratio ( P < 0.05) and water loss parameters ( P < 0.05), and were not significantly ( P > 0.05) correlated with starch digestibility. 7. Wheat hardness-related parameters were correlated ( P < 0.01) wi.273, -0.305, 0.212, respectively). 8. Wheat lipase activity was negatively c.179; P < 0.05) and starch ( r = -0.225; P < 0.01) digestibilities and with individual diet AME n ( r = -0.266; P < 0.001). Individual diet AME n .175) with the values calculated by the EU AME n prediction equation (Fisher and McNab, 1987). Among the correlations observed between the individual measured AME n :EU predicted AMEn ratio and wheat parameters ( P .05), the correlation obtained with wheat lipase was the highest ( r = -0.195). The correlations with lipase could be explained in part by strong correlations between lipase and in vitro viscosity parameters.

Effects of food deprivation and particle size of ground wheat on digestibility of food components in broilers fed on a pelleted diet

1. The first aim of the experiment was to study the effect of wheat (Triticum aestivum) particle size on the digestibility of starch in a pelleted diet given to broilers. The second aim was to study the consequences of food deprivation before the excreta collection period (from 21 to 24 d). Wheat from a strong hardness cultivar was incorporated at 546·1 g/kg in diets. The other main ingredients were soybean meal (353·5 g/kg) and rapeseed oil (55·0 g/kg). Diets were given as pellets. The experimental design was a 2 × 2 factorial design testing two particle sizes of wheat flour and two procedures of a balance experiment (with or without food deprivation). 2. Birds given diet C (wheat coarse grinding before pelleting) had significantly greater gizzard weight than birds fed on diet F (wheat fine grinding before pelleting). 3. Starch digestibility value was significantly increased when birds were fed on diet F. This effect was halved by food deprivation. No significant effect of grain particle size was observed for protein and lipid digestibility values. However, food deprivation decreased apparent protein digestibility, with an effect which was more pronounced for fine than for coarse grinding. 4. AMEN of the diet was significantly improved by fine grinding of wheat and decreased by food deprivation. However, no significant differences in growth performance were induced by differences in wheat grinding. 5. No significant effect of grinding was observed on the water excretion:feed intake ratio. No significant difference was observed for vent score between treatments. 6. There was over-excretion of starch in the first hours of refeeding following food deprivation.

Grain characterization and milling behaviour of near-isogenic lines differing by hardness

Wheat grain hardness is a major factor affecting the milling behaviour and end-product quality although its exact structural and biochemical basis is still not understood. This study describes the development of new near-isogenic lines selected on hardness. Hard and soft sister lines were characterised by near infrared reflectance (NIR) and particle size index (PSI) hardness index, grain protein content, thousand kernel weight and vitreousness. The milling behaviour of these wheat lines was evaluated on an instrumented micromill which also measures the grinding energy and flour particle size distribution was investigated by laser diffraction. Endosperm mechanical properties were measured using compression tests. Results pointed out the respective effect of hardness and vitreousness on those characteristics. Hardness was shown to influence both the mode of fracture and the mechanical properties of the whole grain and endosperm. Thus, this parameter also acts on milling behaviour. On the other hand, vitreousness was found to mainly play a role on the energy required to break the grain. This study allows us to distinguish between consequences of hardness and vitreousness. Hardness is suggested to influence the adhesion forces between starch granules and protein matrix whereas vitreousness would rather be related to the endosperm microstructure.

Soft wheat instead of hard wheat in pelleted diets results in high starch digestibility in broiler chickens

1. The aim of the experiment was to re-examine variations in digestibilities of food components in 3-week-old broiler chickens fed on pelleted diets based on wheats differing in lipase activity and hardness. Fourteen wheat (Triticum aestivum) samples, each from a different cultivar, were included at 550 g /kg in 14 different diets given to male Ross broiler chicks from 7 d of age. The other main ingredients consisted of soyabean meal (353 g /kg) and rapeseed oil (55 g /kg). A 15th diet containing durum wheat (Triticum durum) was also tested. 2. Hardness of wheats (Triticum aestivum) varied between 14 (very soft) and 88 (very hard), and lipase activity of wheats varied from 1 to 13·1 (relative scale). No significant correlation was found between in vitro viscosities and other parameters such as hardness, particle size of wheat flours and lipase. Hardness was correlated with the mean particle size of wheat flours and durability of pellets. 3. Individual lipid digestibilities were negatively correlated with in vitro viscosities of wheats. 4. Individual starch digestibilities were negatively correlated with wheat hardness, particle size of wheat flour before pelleting, and pellet durability. The ratio of measured AMEN to predicted AMEN was also negatively correlated with wheat hardness. Simple regression calculation showed that a 100-point increase in wheat hardness resulted in a 3% decrease in the AMEN value of diets. Multiple regression calculation showed the food/gain ratio (d 10 to d 21) to be positively related to wheat hardness and negatively related to pellet durability. 5. Wheat lipase activity was positively correlated with individual starch digestibility, which was the reverse of a result obtained in a previous experiment. Thus, wheat lipase activity did not seem consistent for predicting starch digestibility and AMEN values. 6. Among all wheat samples, durum wheat showed the highest protein content and the lowest content of water-insoluble cell-wall. Starch digestibility of durum wheat tended to be lower than that of other wheats (0·916 vs 0·936). However, no significant difference in AMEN was observed between the durum wheat sample and other wheats. 7. Gut morphometric data measured at d 24 did not show significant differences between dietary treatments.

Predicting hybrid value in bread wheat: biometric modelling based on a "top-cross" design.

Abstract Multi-environmental experimentation made it possible to compare 311 hybrids and their 59 parental lines for five characters: yield, two yield components (number of grains per m2 and 1000-grain weight), height and date of heading. At all three sites, average high-parent heterosis exceeded 6%, and our results confirm that hybrids in general head as early as the earlier parent does and are as high as the taller parent. For the five characters studied ecovalences were significantly lower in the F1 than in the parents, indicating a higher level of homeostasis for hybrids. The experimental model, based on a ”top-cross” design comprised of 55 lines used as females and four testers, made it possible to implement different hybrid-value prediction models. For yield, by far the most important character to predict, the predictor based on the general combining ability and the per se value of the parents, appears to be the most interesting. The prediction remains, however, imperfect as specific combining ability (SCA) has a strong impact for this character. Attempting to take account of SCA in the prediction, by using a multiplicative model for ”male×female” interaction modelling, did not prove convincing.

Relationships between wheat grain physical characteristics studied through near-isogenic lines with distinct puroindoline-b allele

Key messageGenetic (different forms of puroindoline-b) and environment (through variations in vitreousness), have important effects on wheat grain mechanical properties. The two methods of hardness measurements (NIRS, SKCS) do not give the same information.AbstractBread wheat near-isogenic lines differing in hardness, due to distinct puroindoline-b alleles (the wild type, Pinb-D1a, or the mutated forms, Pinb-D1b or Pinb-D1d), were grown for three years in seven sites and under two nitrogen fertilization levels, to study genetic and environmental effects on grain mechanical properties. Two methods, Near-Infrared Reflectance Spectroscopy (NIRS) and Single Kernel Characterization System (SKCS), currently used for grain hardness characterization, were carried out. Grain vitreousness, which is known to affect the grain mechanical behavior but is generally not studied, was also measured, as well as three other characters (Thousand Grain Weight, Test Weight and protein content). The relationships between the different characters were studied. Results revealed a clear effect of the different Pinb-D1 alleles on NIRS hardness, and a marked impact of the environmental conditions on vitreousness. SKCS hardness was influenced by both Pinb-D1 alleles and environmental conditions. The relationship between SKCS and NIRS hardness was strong when considering together soft and hard genotypes, but moderate within a class of genetical hardness. Vitreousness had only a weak effect on NIRS hardness, whereas vitreousness and SKCS values were strongly correlated, with two distinct regressions for soft and hard genotypes. Vitreousness was positively related to protein content, especially in the case of hard genotypes, which were able to reach high vitreousness values never observed for soft genotypes.

A Study of Puroindoline b Gene Involvement in the Milling Behavior of Hard-Type Common Wheats

ABSTRACT Differences in milling behavior among hard-type common wheat (Triticum aestivum) cultivars are well known to millers. Among them, the French cultivar Soissons, which contains the Pinb-D1d allelic form of the puroindoline b gene, is particularly distinguished for its high milling value. Near-isogenic lines (NILs) differing by the allelic forms of the puroindoline b gene, Pinb-D1d or Pinb-D1b (one of the most frequent alleles found in the European wheat population), were constructed. Grain characteristics obtained after wheat cultivation in distinct environmental conditions were compared between NILs and the cultivar Soissons, as was their fractionation behavior. Results showed that NILs containing the Pinb-D1d allele displayed lower values of grain hardness and vitreousness than did the corresponding lines containing the Pinb-D1b allelic form under the same cultivation conditions. Both genetic background and environmental conditions appeared to affect grain texture. Measured single-kernel characte...

AN INTEGRATED APPROACH TO IMPROVE BREAD NUTRITIONAL QUALITY

ABSTRACT A post-genomic program was initiated to study the potential improvement of the micronutrient content of wheat and their bioavailability in derived food products. To do so we chose an integrated approach most adapted to the European market and consumers. We were interested in increasing the overall nutritional value of wheat and wheat-based products by a synergy between plant breeding, production schemes and adapted transformation processes. The originality was to take each and every step within the cereal chain into consideration. The aimed targets were the vitamin (B especially) and mineral concentration (Mg) and bioaccessibility. The first objective of this inter-disciplinary project was to explore the genetic basis of targeted nutritional wheat traits. Despite the impact of growing conditions on micronutrient content we showed there is a strong potential for nutritional trait improvement in European wheat by traditional breeding. Rare alleles have been identified by systematic study of germplasm diversity. They are now used in the genetic identification of relevant molecular markers, necessary for efficient introduction of nutritionally correlated chromosome segments in a genetic base of good agronomic and end-use criteria. Wheat is rarely consumed as whole grain products and most of the time goes through fractionation steps (e.g. milling) and transformation processes (e.g. bread-making) Variability in cereal raw material micro-nutrients impact on the nutritional density of final products. A strong interaction between process and variety was observed. New fractionation processes, based on the mechanical properties of the aleurone layer, and product concepts have been derived from this understanding.

Bread wheat milling behavior: effects of genetic and environmental factors, and modeling using grain mechanical resistance traits

Key messageGenetic (Pinb-D1 alleles) and environment (through vitreousness) have important effects on bread wheat milling behavior. SKCS optimal values corresponding to soft vitreous or hard mealy grains were defined to obtain the highest total flour yield.AbstractNear-isogenic lines of bread wheat that differ in hardness, due to distinct puroindoline-b alleles (the wild type, Pinb-D1a, or the mutated forms, Pinb-D1b or Pinb-D1d), were grown in different environments and under two nitrogen fertilization levels, to study genetic and environmental effects on milling behavior. Milling tests used a prototype mill, equipped with two break steps, one sizing step, and two reduction steps, and this enabled 21 individual or aggregated milling fractions to be collected. Four current grain characters, thousand grain weight, test weight, grain diameter, and protein content, were measured, and three characters known to influence grain mechanical resistance, NIRS hardness, SKCS hardness index, and grain vitreousness (a character affecting the grain mechanical behavior but generally not studied). As expected, the wild type or mutated forms of Pinb-D1 alleles led to contrasted milling behavior: soft genotypes produced high quantities of break flour and low quantities of reduction flour, whereas reverse quantities were observed for hard genotypes. This different milling behavior had only a moderate influence on total flour production. NIRS hardness and vitreousness were, respectively, the most important and the second most important grain characters to explain milling behavior. However, contrary to NIRS hardness, vitreousness was only involved in endosperm reduction and not in the separation between the starchy endosperm and the outer layers. The highest flour yields were obtained for SKCS values comprised between 30 and 50, which corresponded either to soft vitreous or hard mealy grains. Prediction equations were defined and showed a good accuracy estimating break and reduction flours portions, but should be used more cautiously for total flour.