bluuebunny/crossref_metadata_2025 huggingface dataset:
Wright’s shifting balance theory of evolution in artificial breeding programmes: empirical testing using the model organism Tribolium castaneum
Authors: Schamber E. M. , Muir W. M.
Published: March 2003

A subdivide/merge breeding system, based on Sewall Wright’s Shifting Balance Theory of Evolution, was modelled using Tribolium castaneum (the red flour beetle). Our objective was to determine the effects of population structure on selection response for increased offspring number, a fitness trait with large nonadditive gene effects. Two different population structures were established: a subdivided population that underwent periodic merging and an undivided control population. The experiment consisted of (1) 150 beetle pairs divided into 10 lines of 15 pairs each, and (2) an undivided control population of 150 beetle pairs. Selection of the subdivided population was performed within lines each generation and in generations 4, 8 and 12, poorer performing lines were eliminated with the remaining lines merged. After merging, selected individuals were randomly paired and re‐subdivided into 10 lines of 15 pairs each. The undivided population was mass selected for increased offspring number each generation using the same selection intensity as the subdivided lines. After 14 generations, selection response in the subdivide/merge system was not significantly different from the control population; however, within each generation, there were lines in the subdivided population that had average larva numbers exceeding those of the undivided population. These results indicate that subdivide/merge systems could be advantageous for shorter‐term breeding objectives. If superior lines are isolated, they can be full‐sib mated or selfed to produce highly inbred lines which can then be crossed – a standard plant breeding practice.
Impact of variation in length of individual testing periods on estimation of (co)variance components of a random regression model for feed intake of growing pigs
Authors: Schnyder  , Hofer  , Künzi
Published: March 2003

A simulation study was conducted to assess the influence of differences in the length of individual testing periods on estimates of (co)variance components of a random regression model for daily feed intake of growing pigs performance tested between 30 and 100 kg live weight. A quadratic polynomial in days on test with fixed regressions for sex, random regressions for additive genetic and permanent environmental effects and a constant residual variance was used for a bivariate simulation of feed intake and daily gain. (Co)variance components were estimated for feed intake only by means of a Bayesian analysis using Gibbs sampling and restricted maximum likelihood (REML). A single trait random regression model analogous to the one used for data simulation was used to analyse two versions of the data: full data sets with 18 weekly means of feed intake per animal and reduced data sets with the individual length of testing periods determined when tested animals reached 100 kg live weight. Only one significant difference between estimates from full and reduced data (REML estimate of genetic covariance between linear and quadratic regression parameters) and two significant differences from expected values (Gibbs estimates of permanent environmental variance of quadratic regression parameters) occurred. These differences are believed to be negligible, as the number lies within the expected range of type I error when testing at the 5% level. The course of test day variances calculated from estimates of additive genetic and permanent environmental covariance matrices also supports the conclusion that no bias in estimates of (co)variance components occurs due to the individual length of testing periods of performance‐tested growing pigs. A lower number of records per tested animal only results in more variation among estimates of (co)variance components from reduced compared with full data sets. Compared with the full data, the effective sample size of Gibbs samples from the reduced data decreased to 18% for residual variance and increased up to five times for other (co)variances. The data structure seems to influence the mixing of Gibbs chains.
Biochemische Polymorphismen und Haupt‐mtDNA‐Haplo‐typen bei Bergschafrassen und Waldschafen als Beitrag zur Abstammung der Hausschafe
Authors: Wassmuth R. , Hiendleder S. , Mendel Ch. , Erhardt G.
Published: March 2003

Morphologische Ähnlichkeiten zwischen Hausschafrassen und bestimmten Subspezies des Ovis ammon L. 1758 können nicht als zwingender Beweis einer Domestikation der betreffenden Unterart gelten, da Einkreuzungen fremder Wildschafformen in Hausschafe anderer genetischer Herkunft gleichfalls als Ursache von Übereinstimmungen anerkannt werden müssen. Das Heranziehen des maternal vererbten mitochondrialen Genoms eröffnet jedoch die Möglichkeit, heutige Schafrassen – trotz domestikationsbedingter morphologischer Veränderungen und Einkreuzungen u. a. m. –über zahlreiche Generationen bis zu domestizierten Wildschafformen zurückzuverfolgen, sofern diese nicht bereits ausgestorben sind. Mittels haplogruppenspezifischen polymorphen HinfI‐Fragmenten von mtDNA und Proteinpolymorphismen bei Tieren verschiedener Bergschafrassen, die maternal als Torfschaf‐Abkömmlinge gelten, sowie auch von zur Gruppe der Zaupel gehörenden Waldschafen, sollte geklärt werden, ob der in Europa vorwiegend auftretende Haupt‐mtDNA‐Haplotyp B mit dem ältesten Hausschaf in Europa, dem Torfschaf (Ovis aries palustris RÜTIMEYER 1862) in Zusammenhang gebracht werden kann. Die Stichproben aus Steinschafbeständen slowenischer und bayerischer Herkunft, weißen und braunen Bergschafen, Brillenschafen aus Bayern und Villnösserschafen weisen einheitlich den Haupt‐mtDNA‐Haplotyp B auf, wie dies auch bei einem zusätzlich untersuchten Bergamaskerbock der Fall ist. Allerdings wurde in der Waldschafgruppe bei mehr als der Hälfte der Tiere dieser Stichprobe der Typ A festgestellt, was zeigt, daß nicht alle Zaupelschaf – Nachkommen auf die gleiche Wildschaf – Unterart wie die Steinschaf – Nachkommen zurückgeführt werden können. Im Hämoglobin (HBB) kommen die Varianten HBBA und HBBB in allen untersuchten Rassen in ausgeglichener Frequenz vor, wobei beim braunen Bergschaf die Frequenz von HBBA (0.857) erhöht ist. Bayerische Steinschafe waren am CA2‐Locus, Waldschafe am GC‐Locus polymorph. Im Transferrin wurden deutliche Unterschiede im Vorkommen und in der Frequenz der einzelnen Allele zwischen den Populationen nachgewiesen. Zusammenhänge zwischen Torfschaf, Kupferschaf, Steinschaf, Zaupelschaf, Bergamasker und ‘europäischem’ Mufflon werden diskutiert. Der Weg zum domestizierten Vorfahren der meisten europäischen Hausschafe führt jedoch über das kleine Torfschaf zu einer noch nicht ermittelten Ovis ammon– Subspezies in Asien.
Selective genotyping with a main trait and a correlated trait
Authors: Medugorac I. , Soller M.
Published: March 2003

In some instances of quantitative trait loci (QTL) mapping, a correlated trait may be available for which measurement is less costly or more convenient than direct measurement of the trait of main interest. In this paper we consider ways of combining phenotyping for a main trait and a correlated trait to maximize power within the overall framework of a selective genotyping design. Four schemes are compared: (1) Selection for the main trait only (2) Selection for the correlated trait only (3) Two‐stage selection (4) Three‐stage selection. Optimum proportion selected for the two traits were obtained for the various schemes, and power parameters compared, according to the correlation r, between the two traits, and the proportion of the population, Q, phenotyped for the main trait. The schemes were compared under two sets of assumptions: (1) Total population size and proportion that can be phenotyped for the main trait are fixed, and (2) Total costs are fixed, with relative cost, c′, of rearing and phenotyping for the correlated trait as compared to the main trait. Under (1), the multi‐stage schemes are very advantageous when r is high, and Q is low. Under (2), the single‐stage schemes were always superior to the multi‐stage schemes; Scheme 1 being preferred when r2/c′ < 1.0, and Scheme 2 when r2/c′ > 1.0.
Effects of genetic groups on estimates of variance components for a maternally influenced trait in the Spanish Limousine
Authors: Díaz C. , Moreno A. , Carabaño M. J.
Published: March 2003

Residual maximum likelihood (REML) estimates of variance components for standardized 210‐day weights were obtained in the Limousine breed from Spain under different animal models. All models were applied including (Gdm) or not (G00) genetic groups for the direct and the maternal components. Genetic groups were defined according to sex of progenitor and generation in two different approaches depending on whether the full pedigree information or reduced pedigree was used. For the most complex model, which included direct, maternal and permanent environmental variances as well as the direct–maternal covariance, genetic groups were imposed either to the direct (Gd0) or to the maternal (G0m) component treating genetic groups as covariates without the QP transformation. For the Gdm case (genetic groups for both direct and maternal effects) with the full pedigree information, the estimates of the direct genetic variance and the genetic covariance between direct and maternal genetic effects showed the largest reduction, while the estimate of maternal genetic variance was only slightly reduced, with respect to G00, a model without genetic groups. This result might be due to a less important variability among group effects for the maternal component, probably due to a lower selection intensity performed for this component. However, for the Gd0 case, estimates of genetic variances and especially the direct–maternal covariance were largely overestimated with respect to the Gdm case. Inclusion of direct and maternal grouping was deemed necessary for this population. Reduction of pedigree information did not seem to have a large impact on variance component estimation. Nevertheless, deeper pedigree information together with a correct definition of the generation to assign genetic groups is needed to accommodate the effect of selection on direct and maternal components of this trait, in this population.
Estimation of genetic parameters for non‐return rate (NRR) in German herdbook Pietrain and Landrace AI boars
Authors: Steinheuer R. , Hamann H. , Distl O.
Published: March 2003

Between January 1993 and May 2000, 95 136 artificial insemination (AI) records of 445 Bavarian boars were recorded by three Bavarian AI stations. The analysis of the non‐return rate (NRR) was based on AI matings performed by AI technicians. The animal models applied for estimation of variance components for NRR included the fixed effects of AI station, breed of boar, first and subsequent insemination, type of insemination, duration of breeding period of the sow, and AI technician. Herd–year–season and permanent environment of the sow as well as the paternal additive genetic effects were taken into account as random effects. The estimation procedures employed for the described model were both linear and non‐linear. Genetic variances for the NRR (33‐55‐77 days after insemination) were small. Estimates of paternal heritability for NRR were low with (NRR33), (NRR55) as well as (NRR77) using the non‐linear model, and (NRR33), (NRR55) as well as (NRR77) employing the linear model. Due to the low heritabilities genetic progress on mating success for AI boars may be only possible, if sufficiently large numbers of observations are available.
Inheritance of congenital umbilical hernia in German Fleckvieh
Authors: Distl O. , Herrmann R. , Utz J. , Doll K. , Rosenberger E.
Published: March 2003

The frequency of congenital umbilical hernia and its distribution by sires was investigated in German Fleckvieh calves being sold at livestock markets in Miesbach and Traunstein. Data included 53 105 calves from 77 livestock auctions in the years 1996 and 1997. The overall incidence for congenital umbilical hernia was 1.8%. Significant influences were the sex of the calf, the occurrence of multiple births, age of the calf at examination, the market place/market date, the herdmate incidence of congenital umbilical hernia, the sire and the sire line. The inheritance of congenital umbilical hernia could not be explained either by an autosomal recessive or by an autosomal dominant single gene. Testing for oligogenic models revealed that at least three gene loci may be involved. It also seemed likely that dominant alleles can play a role in the mode of inheritance. Congenital umbilical hernias have genetic implications, and thus they should be regarded in the selection of young sires.
Effective size of populations with unequal sex ratio and variation in mating success
Authors: Nomura T.
Published: March 2003

To estimate the effective size (Ne) of populations with unequal sex ratio, a well‐known formula, Ne=4NmNf/(Nm + Nf), has been frequently used, where Nm and Nf are the numbers of male and female parents, respectively. In this paper, the formula was examined under typical mating systems in animals. It was shown that the formula holds only when there are no variations in the numbers of mates (mating success) of parents of each sex. More appropriate equations were developed by accounting for the variation in mating success. It was found that for animal populations with harem mating system, an equation Ne=4NmNf/(2Nm+Nf) gives a more accurate estimate than the well‐known formula. The effective population sizes of several wild, experimental and domestic animals are estimated by applying the derived equations to the published demographic and ecological data.
Choice of statistical model for estimating genetic parameters using restricted maximum likelihood in swine
Authors: Satoh M. , Hicks C. , Ishii K. , Furukawa T.
Published: March 2003

Summary Restricted maximum likelihood (REML) was used to determine the choice of statistical model, additive genetic maternal and common litter effects and consequences of ignoring these effects on estimates of variance–covariance components under random and phenotypic selection in swine using computer simulation. Two closed herds of different size and two traits, (i) pre‐weaning average daily gain and (ii) litter size at birth, were considered. Three levels of additive direct and maternal genetic correlations (rdm) were assumed to each trait. Four mixed models (denoted as GRM1 through GRM4) were used to generate data sets. Model GRM1 included only additive direct genetic effects, GRM2 included only additive direct genetic and common litter effects, GRM3 included only additive direct and maternal genetic effects and GRM4 included all the random effects. Four mixed animal models (defined as EPM1 through EPM4) were defined for estimating genetic parameters similar to GRM. Data from each GRM were fitted with EPM1 through EPM4. The largest biased estimates of additive genetic variance were obtained when EPM1 was fitted to data generated assuming the presence of either additive maternal genetic, common litter effects or a combination thereof. The bias of estimated additive direct genetic variance (VAd) increased and those of recidual variance (VE) decreased with an increase in level of rdm when GRM3 was used. EPM1, EPM2 and EPM3 resulted in biased estimation of the direct genetic variances. EPM4 was the most accurate in each GRM. Phenotypic selection substantially increased bias of estimated additive direct genetic effect and its mean square error in trait 1, but decreased those in trait 2 when ignored in the statistical model. For trait 2, estimates under phenotypic selection were more biased than those under random selection. It was concluded that statistical models for estimating variance components should include all random effects considered to avoid bias.
The effect of energy density and the lysine to energy ratio of diets on the performance of piglets
Authors: Roth F. X. , Eder K. , Kirchgessner M.
Published: March 2003

Introduction  The aim in the feeding of piglets is to realize the maximum growth rates, according to the high growth capacity of these animals. In this respect, the supply of energy and essential amino acids is of particular significance. Among the essential amino acids, lysine, as the first growth‐limiting amino acid, plays a predominate role. In the practical feeding of piglets, the recommendation is to start feeding, after weaning at 4 weeks of age, with a diet containing 13.4–13.8 MJ metabolizable energy (ME) per kg and a lysine concentration of 12.1–12.4 g/kg, which represents a ratio between lysine and energy of 0.9 g/MJ ME. After the initial phase, when the live weight is in the range 20–30 kg, it is recommended that the dietary energy is reduced to 13.0–13.4 MJ ME/kg and the lysine concentration to a range of 10.7–11.0 g/kg (representing a lysine : energy ratio of 0.82 g/MJ ME) (DLG 1996). The present study was carried out to investigate whether this recommended phase‐feeding system allows maximum growth performance in piglets, or whether a constant high energy and lysine concentration during the whole rearing period is superior with regard to growth performance of piglets. Therefore, two experiments were carried out with early‐weaned piglets. The first experiment, using a bifactorial design, investigated the effects of the dietary energy density and the ratio between lysine and energy on the growth performance of piglets at constant levels during the whole phase of 8–30 kg live weight. The second experiment, using a similar experimental design, was conducted to investigate the combined effect between those factors in the second phase, at live weights between 20 and 30 kg.
Einfluß technischer Behandlungen von Rapskuchen auf die Abbaubarkeit des Futterrohproteins im Pansen
Authors: Dänner Von E. , Schmidt J. , Kluge H. , Nonn H. , Jeroch H.
Published: March 2003

1 Einleitung und Problemstellung

Mit der Ausdehnung des Rapsanbaues in der Bundesrepublik Deutschland nahm auch das Angebot an entfetteten Nachprodukten der Rapssaat zu. Das im Rahmen der GATT‐Verhandlungen getroffene ‘Blair‐House‐Abkommen’ setzt jedoch einer Steigerung des Absatzpotentials und damit der Anbaufläche von Konsumraps in Europa entschiedene Grenzen. Neben der konventionellen Vermarktung als Konsumraps über die Handelsunternehmen kann auch die Ölgewinnung in dezentralen Anlagen ein zukunftsträchtiger Weg sein. Der beim Abpressen der Ölsaat in diesen Anlagen anfallende Rapskuchen stellt ein hochwertiges Eiweißfuttermittel für die Wiederkäuerfütterung mit einem Restölgehalt je nach Preßverfahren von 5–12% dar (H enkel und M
osenthin 1989). Für eine optimale Einbeziehung von Rapskuchen als Proteinkomponente in Wiederkäuerrationen sind jedoch umfassende Kenntnisse über die Abbaubarkeit des Rohproteins im Pansen sowie Möglichkeiten zu deren Beeinflussung Voraussetzung. Aus diesem Grund wurde am Institut für Tierernährung der Agrarwissenschaftlichen Universität Mosonmagyaróvár (Ungarn) untersucht, welchen Einfluß eine technische Behandlung von Rapskuchen mittels Expander bzw. Extruder auf die Abbaubarkeit des Futterrohproteins in den Vormägen bei wachsenden Rindern hat. Die Untersuchungsbefunde sollen einen Informationsgewinn für den sachgerechten Einsatz von Rapskuchen in der Wiederkäuerfütterung liefern.
Phytase and vitamin E in the feed of growing pigs: 2. Influence on carcass characteristics, meat and fat quality
Authors: Gebert S. , Bee G. , Pfirter H. P. , Wenk C.
Published: March 2003

Lipid oxidation is one of the the major causes of deterioration in the quality of meat and meat products. In addition to its nutrition value, meat has other aesthetic attributes, including its attractive sensory properties and therefore, lipid oxidation in meat and adipose tissue is undesirable. It can be reduced by the addition of antioxidants to feeds.

Vitamin E functions is a lipid‐soluble antioxidant in the cell membranes. One of the most potent forms is α‐tocopherol. It is capable of quenching free radicals and thus protects susceptible cellular structures, especially polyunsaturated fatty acids in cell membranes, against oxidation and subsequent breakdown to potentially harmful, chemically reactive products (Packer and Fuchs 1993). Vitamin E supplementation above the physiological demand enhances the vitamin E concentration in tissue samples, milk and eggs (Leonhardt et al. 1997). Furthermore a positive effect on the various quality criteria of products of animal origin such as shelf life, colour, taste, etc. can be realized to meet the expectations of consumers (Asghar et al. 1991b; King et al. 1995).

In another article it was demonstrated that supplementing diets with phytase had a positive effect on the digestibility of minerals such as phosphorus, calcium, iron and zinc (Gebert et al. 1999). The results indicated that dietary fat digestibility was significantly decreased due to the phytase supplementation. In addition, the α‐tocopherol digestibility had a tendency to be impaired in the phytase‐ or vitamin E (200 p.p.m. α‐tocopheryl acetate)‐supplemented diets, indicating that the released minerals of the phytic acid complex could act as bi‐ and trivalent cations and might damage those nutrients which are susceptible to oxidation (mainly polyunsaturated fatty acids) or could use up the antioxidative vitamins in the digesta.

Therefore it was of interest to investigate the effect of phytase and vitamin E (α‐tocopheryl acetate) supplementation in pig diets on the carcass characteristics as well as meat and fat quality, mainly with respect to stability against oxidative destruction.
Effects of dietary fat type and xylanase supplementation in rye containing diets on energy metabolism in male broilers
Authors: Dänicke S. , Franke E. , Strobel E. , Jeroch H. , Simon O.
Published: March 2003

Xylanase supplementation of rye‐based diets which contained 10% beef tallow was shown to markedly improve the digestibility of fat whereas the enzyme effect in diets containing 10% soya oil was much less pronounced (Dänicke et al. 1997b). Such interactions between fat type and xylanase supplementation have also been reported for wheat–rye‐based diets (Langhout et al. 1997) and wheat‐based diets (Allen et al. 1997) and were attributed mainly to the fatty acid composition of different types of fat and to changes in digesta viscosity caused by soluble pentosan. The apparent metabolizable energy, N‐corrected (AMEN) contents of such diets were affected in a similar manner suggesting that energy metabolism is also influenced by xylanase supplementation and the type of dietary fat. However, changes in the metabolizability of gross energy does not necessarily indicate whether the efficiency of metabolizable energy (ME) for energy gain is changed nor if different proportions of ME are used for maintaining an energy equilibrium, i.e. ME maintenance requirement. In addition, studies suggest that both dietary fat level and fat type might exert effects on the efficiency of utilization of ME for energy retention (Carew and Hill 1964; de Groote et al. 1971; Fuller and Rendon 1979; Brue and Latshaw 1985). Hence, the aim of this study was to investigate the partitioning of ME between maintenance needs and energy retained as protein and as fat when feeding rye‐based diets. The diets contained either soya oil or beef tallow and were either unsupplemented or xylanase‐supplemented.
Distribution of 15N‐Chlorocholine chloride in eggs of laying hens
Authors: SONGSANG A. , CHAKEREDZA S. , THINGGAARD G. , VEARASILP T. , TER MEULEN U.
Published: March 2003

The distribution of Chlorocholine chloride (CCC) in the eggs of laying hens was studied using 15N‐CCC. Twelve layers (37 weeks old) were divided into four groups and used in this study consisting of three feeding phases. In phase one (7 days), all the hens received a CCC‐free diet [165 g CP/kg dry matter (DM); 11.58 MJ ME/kg DM]. In phase two (11 days), four levels of 15N‐CCC: 0, 5, 50 and 250 ppm were added to the respective diets, while in phase three (7 days), CCC‐free feed was again offered. Egg samples were taken and the 15N content of egg yolk and albumin were determined. At the end of phase two, there was a significant (p < 0.05) increase in 15N content in egg yolk from hens fed the 50 and 250 ppm CCC diets and in albumin from hens fed the 250 ppm CCC diet. The estimated 15N‐CCC residue was 1.71, 6.64, 28.80 ppm in egg yolk and 1.58, 1.08 and 4.50 ppm in albumin from hens fed 5, 50 and 250 ppm CCC, respectively. The CCC residue, from quantitative analysis ranged from 0.21 to 0.93 and 0.93 to 2.43 ppm in yolk of hens fed 50 and 250 ppm CCC, respectively, whereas a range of 0.40–1.46 ppm, was found in the albumin of hens fed 250 ppm. The difference in measured CCC in yolk and albumin and that estimated from 15N‐CCC could have been due to breakdown products of 15N‐CCC. Seven days after withdrawal of 15N‐CCC, the estimated 15N‐CCC residue in egg yolk decreased to 0.43, 2.45 and 15.59 ppm, on 5, 50 and 250 ppm CCC dietary treatments, respectively, and to 2.46 ppm in albumin from hens fed 250 ppm CCC. The higher increase in 15N content could have been due to a higher incorporation of 15N‐CCC into yolk than albumin during the process of rapid yolk deposition. This experiment showed that consumed CCC is distributed both into yolk and albumin in a dose dependent manner and that CCC is metabolized in laying hens. However, the level of CCC in the diet which could lead to accumulation of detectable CCC levels in eggs as observed in this study, is much higher than the established maximum residual limits in grains.
Effect of dietary conjugated linoleic acids on the distribution of fatty acids in serum lipoprotein fractions and different tissues of growing pigs
Authors: Tischendorf F. , Möckel P. , Schöne F. , Plonné M. , Jahreis G.
Published: March 2003

The effect of conjugated linoleic acid (CLA) on blood lipids [total cholesterol, high‐density lipoprotein (HDL), low‐density lipoprotein (LDL) and triacylglycerols (TAG)] and the fatty acid distribution of the lipoprotein fractions, backfat, muscle fat, and liver lipids were examined in an experiment with two groups of 40 pigs [Pietrain × (Landrace × Large White)] each. The 20 female and 20 male castrated pigs of each group were fed with isoenergetic and isonitrogenous diets supplemented with either 20 g/kg rapeseed oil (control) or 20 g/kg CLA–TAG. The CLA preparation contained 54.2% pure CLA consisting of approximately two‐thirds cis,trans/trans,cis‐isomers and one‐third trans,trans‐isomers. The fatty acids of lipoproteins, backfat, muscle lipids and liver lipids were analysed by gas chromatograph (GC). CLA supplementation did not significantly influence blood lipids and the LDL to HDL ratio. In the CLA‐fed pigs the very low‐density lipoprotein (VLDL) contained higher saturated fatty acid (SFA) concentrations at the cost of the monounsaturated fatty acids (MUFA). The percentage of polyunsaturated fatty acids (PUFA) remained unchanged. The highest CLA content was analysed in VLDL (4.00%) followed by LDL (2.78%) and HDL (1.45%). The ratio of cis,cis to trans,trans isomers increased from VLDL over LDL to HDL. The content of SFA, probably in backfat and muscle lipids, increased whereas the part of MUFA decreased as a result of reduced Δ9‐desaturase activity. The percentage of PUFA (without CLA) was higher in backfat of the control group in accordance with the dietary PUFA supply. This shift in the fatty acid distribution was not observed in the liver lipids. In all the three tissues analysed, the CLA‐fed pigs had a significantly increased CLA content: the highest increase was in the backfat (5.65%), followed by liver lipids (2.41%), and muscle lipids (1.47%). An isomer‐specific accumulation was observed for cis,cis‐CLA isomers in muscle, and for trans,trans‐CLA isomers in backfat.

We conclude that CLA supplementation results in a higher SFA content in backfat and muscle lipids but not in liver lipids. There is a discrimination of the trans‐10, cis‐12 isomer and the trans,trans isomers in the formation of the cell membranes.
Faecal bacterial profile, nitrogen excretion and mineral absorption in healthy dogs fed supplemental oligofructose
Authors: Beynen A. C. , Baas J. C. , Hoekemeijer P. E. , Kappert H. J. , Bakker M. H. , Koopman J. P. , Lemmens A. G.
Published: March 2003

In a cross‐over trial, five healthy dogs were fed a dry food without or with 1% (w/w) oligofructose to assess any oligofructose‐induced effects on the faecal bacterial profile, nitrogen excretion and mineral absorption. The diets were given for a period of 3 weeks. Oligofructose feeding significantly raised the number ofBifidobacteria,StreptococciandClostridiain faeces. The numbers of faecal anaerobic and aerobic bacteria were raised after ingestion of oligofructose. The faecal pH was unchanged. There was no effect of oligofructose feeding on the route of nitrogen excretion which was associated with a lack of effect on faecal ammonium and urinary urea excretion. It is suggested that the absence or presence of an effect of oligofructose on urinary and faecal nitrogen excretion depends on the background composition of the diet, in particular the content of non‐digestible, fermentable carbohydrates. In the diets used, the content of non‐digestible, fermentable carbohydrates was not measured. Both apparent magnesium and calcium absorption were significantly raised by oligofructose feeding, but phosphorus absorption was unaffected. The data presented may contribute to the qualification of the use of oligofructose in dog foods.
Introducing Baculovirus oryctes Huger into Oryctes monoceros Oliv. populations in Tanzania
Authors: Seguni Z. , Lohr B. , Mwaiko W.
Published: March 2003

A follow‐up of a Baculovirus oryctes release into the population of Oryctes monoceros in coconut plantations in Tanzania has been made to clarify important points which were not fully considered in an earlier publication. The low recovery of virus‐infected field‐collected beetles (29%) suggested that the release of B. oryctes virus was not a suitable method for the control of O. monoceros. The relatively dry conditions in the coconut growing areas were partly contributory since the virus is non‐occluded. No significant and sustainable reduction in frond damage was obtained after the virus had established itself in the natural O. monoceros population. The status of O. monoceros as a serious pest of coconut is also revised since the beetle affects young plantations more than older plantations and control methods can be directed at picking up feeding insects by hooking and disposal of breeding sites.
Evaluation of natural resistance of winter triticale cultivars to grain aphid using food coefficients
Authors: Ciepiela A. P. , Sempruch C. , Chrzanowski G.
Published: March 2003

Five food coefficients were used to evaluate resistance of winter triticale cultivars against grain aphid Sitobion avenae (Fabr.). On the basis of the results of biochemical analysis the following coefficients were calculated: soluble carbohydrates–total nitrogen, soluble carbohydrates–free amino acids, soluble carbohydrates–protein amino acids, nonprotein amino acids–protein amino acids, nonprotein amino acids–free protein amino acids. The results showed that the values of all coefficients for the ‘Lasko’ cultivar, which is resistant to S. avenae, were higher than those of the susceptible ‘Grado’ cultivar. Applied tests of natural resistance of winter triticale, based on biochemical properties of the plants, revealed considerable variability of resistance of both cultivars to grain aphid. Thus, the tests may be very useful for preliminary selection of newly introduced strains and cultivars of winter triticale in respect of their resistance to grain aphid. The method may be also applied for a quick evaluation of new genetically engineered products and the culture of highly aphid‐resistant plants.
Influence de l’alternance d’hôtes sur le développement de Tetranychus urticae Koch (Acari, Tetranychidae): conséquences sur l’infestation des agrumes au champ
Authors: Allam L. , Hmimina M. , Ouahbi A.
Published: March 2003

Influence of host plant changing on the development of Tetranychus urticas Koch (Acari, Tetranychidae): consequence of mite infestation in Citrus fields. Changes of hosts in T. urticae is associated with notorious lost of reproduction potentialities. At 25°C, the fecundity of females which are always reared on Solanum nigram (75.7 eggs) fell to 1.07 eggs when they were reared on Citrus. It is the same for the longevity of females in this mite. The females permanently feeding on Citrus have a longevity of 16.9 days compared with only 9 days in females from Solanum nigrum that were transferred to Citrus. Similar changes operated at 20°C produce the same results. The practical consequences of these experiences on the swarming of mites in the field of Citrus were analysed.
Temporal and spatial analysis of greenhouse whitefly and its parasitoid Encarsia formosa in two types of greenhouse ecosystems
Authors: Jiang N. , Xu R. , Van Lenteren J. C. , Van Roermund H. J. W.
Published: March 2003

Temporal and spatial relationships between greenhouse whitefly and its parasitoid Encarsia formosa were analysed at different levels by using Rook’s neighbourhood model, and for two types of greenhouses: a small greenhouse in China (15.1 m2) and a large greenhouse in the Netherlands (6480 m2). For whitefly eggs and larvae, there was no difference in their spatial relationship occurring within‐ and between‐plot in the two types of greenhouses. Eggs and larvae occurrence aggregated with no special directional distributions. Whitefly adults exhibited nonlinear spatial density dependence within‐plot, and moved randomly between‐plot. Whitefly adults preferred to fly away in a N–S directions and to settle down at a NW–SE directions with an increase in the number of their neighbouring infected plants within‐plot. The parasitoid E. formosa showed a strong relationship with the temporal and spatial distribution of the host, but influenced the spatial distribution of whitefly.
Effect of gamma irradiation on sperm utilization in twice‐mated female Phthorimaea operculella Zeller (Lep., Gelechiidae)
Authors: Saour G. , Makee H.
Published: March 2003

The effects of the second mating on fecundity and fertility of potato tuber moth (PTM) Phthorimaea operculella (Zeller), when females were mated with 450 Gy‐irradiated and normal males or vice versa, were studied. The percentage of eggs fertilized by sperm of the second mating (P2 value) was 0.99, indicating that sperm transferred during the last mating were predominantly utilized in egg fertilization. Females, mated first with irradiated males, remated after 2 days, whereas those mated with normal males, remated after 3.3 days. Fecundity of twice‐mated females was higher than those mated only once. Females started to lay their eggs 1.9 days after the first mating, regardless of the type of male. However, virgin females did not lay eggs at all. Duration of copulation varied from 102 to 117 min for normal and irradiated males, respectively. The present study elucidated important aspects of mating behaviour of PTM which could improve the efficiency of its control by the sterile insect technique.
Polymorphic diversity in salivary and haemolymph proteins and digestive physiology of assassin bug Rhynocoris marginatus (Fab.) (Het., Reduviidae)
Authors: Ambrose D. P. , Maran S. P. M.
Published: March 2003

Abstract: Rhynocoris marginatus (Fab.) occurs in three morphs viz. (i) niger (black connexivum) (ii) sanguineous (red connexivum) and (iii) nigrosanguineous (black and red banded connexivum). The salivary protein (μg/mg wet weight of salivary gland complex), and haemolymph protein (μg/100 μl) were higher in niger morph than in nigrosanguineous and sanguineous morphs. Endopeptidase (trypsin) activity of homogenate of salivary gland complex (SGC) of niger morph was also higher. It was significantly lower in the sanguineous morph. Endopeptidase activity was found to be uniformly meagre in the anterior midgut (AMG) and in the posterior midgut (PMG) in all the three morphs. The exopeptidase (aminopeptidase) activity was also found to be negligible in SGC in all the three morphs. Niger morph showed a significantly higher activity of exopeptidase in AMG and PMG than the other two morphs.
The effect of integrated pest management practices in an apple orchard on Heteroptera community structure and population dynamics
Authors: Kinkorová J. , Kocourek F.
Published: March 2003

Abstract: The community structure and population dynamics of Heteroptera was studied in an apple orchard in the Czech Republic, between 1992 and 1995. The study investigated the changes which occurred after introduction of integrated pest management (IPM) practices into an intensive apple orchard. The IPM consisted of establishing grass ground cover or planting six selected herb species in two wide belts along the rows of trees. The IPM areas were compared with areas where chemical control was continued. Seventy Heteroptera species were captured (22 predatory and 48 phytophagous). The diversity of heteropteran communities was always higher on IPM plots and six predatory species and 24 phytophagous species were only captured on the IPM plots. Annual variation of abundance of predatory species on IPM plots was smaller than in phytophagous species. Orius spp. were abundant on the chemical control areas due to abundant Tetranychus urticae C.L. Koch populations, which were probably a consequence of the application of pyrethroid insecticides. Other predatory species were more abundant in IPM areas due to higher prey availability. The abundance of phytophagous species was favoured by the herbaceous undergrowth of the IPM plots. The number of predatory Heteroptera species increased after the introduction of IPM practices. Vegetation cover diversity is enhanced due to cultivation of the plots with IPM regime and has not resulted in any additional increase in the abundance of predatory Heteroptera species.
Inactivation or removal of the budded particles of a nuclear polyhedrosis virus of a silkworm, Bombyx mori L. (Lep., Bombycidae)
Authors: Arakawa  , Kamimura  , Miyazawa  , Kiuchi
Published: March 2003

Effective methods to inactivate or remove budded particles of a nuclear polyhedrosis virus of Bombyx mori (BmNPV) from a cell‐cultured media or from host haemolymph that is infected by this virus have been developed. Two types of suspensions containing BmNPV budded virus particles, TC‐100 media that cultured BmN4 cells infected by this virus and haemolymph of B. mori larvae infected by this virus, were treated by 6% (w/v) polyethylene glycol (PEG), 0.01% (w/v) chitosan, 0.05% (v/v) linoleic acid (an emulsion), and/or diethylether. Treatment by linoleic acid followed by PEG‐precipitation and treatment by diethylether followed by PEG‐precipitation were so effective that these treatments suppressed the viral titre of BmNPV‐infected larval haemolymph from an original titre (> 109 TCID50 units/ml) to below a detectable limit. These methods are suggested as being potentially useful in an insect factory system; that is, a protein production system utilizing a baculovirus vector and its insect host or cultured cells on a large scale.
How do wind velocity and light intensity influence host‐location success in Cotesia glomerata (Hym., Braconidae)?
Authors: Gu  , Dorn
Published: March 2003

Wind and light are major climatic factors which affect host‐location process in parasitoids, but these environmental effects have not been studied thoroughly. Wind‐tunnel experiments were designed to dissect how changes in wind velocity and light intensity influence flight initiation, flight orientation and host‐searching efficiency in Cotesia glomerata. This study uncovers the influences of changes in wind velocity and light intensity on different phases of host‐location process in the parasitoid. These results suggest that a cloudy and/or windy weather may reduce the success of host location by C. glomerata because such conditions suppress flight initiation, cause failure to orientate flights to the herbivore‐infested plant and hamper host‐searching activity on the plant.
Biochemical characterization of three nucleopolyhedrovirus isolates of Spodoptera exigua and Mamestra brassicae
Authors: Murillo  , Muñoz  , Lipa  , Caballero
Published: March 2003

Three nucleopolyhedroviruses (NPVs), of different geographical origins, were biochemically characterized and compared. Two that were isolated from Spodoptera exigua (Se‐UZB and Se‐SP3) in Uzbekistan and Spain were SeMNPV type, and the third which was isolated from Mamestra brassicae (Mb‐PL) in Poland was MbMNPV type. The Spanish isolate Se‐SP3 showed restriction endonuclease (REN) profiles that were closely related to two previously described Spanish strains Se‐SP1 and Se‐SP2, but had some unique and characteristic REN fragments. On the other hand, comparison between the Uzbekian (Se‐UZB) and the Spanish (Se‐SP1, Se‐SP2, and Se‐SP3) isolates from S. exigua showed unrelated REN profiles. However, the PstI and BglII profiles of Se‐UZB and Mb‐PL were identical, and very similar to the REN profiles of the MbMNPV strain, which constitutes the active component of Mamestrin® (NPP, Nagueres, France), a commercial bioinsecticide. It is therefore very likely that the Se‐UZB samples were cross‐infected by the Polish strain (Mb‐PL). This work presents two new strains of SeMNPV and MbMNPV, called Se‐SP3 and Mb‐PL, respectively, which were surveyed in two distant areas.
Characterization ofBemisia(Hom., Aleyrodidae) from the Lesser Antilles by electrophoresis
Authors: Ryckewaert  , Alauzet
Published: March 2003

For several years, whiteflies of the genusBemisia(Hom., Aleyrodidae) have caused major damage to vegetable crops in the Lesser Antilles, and have revealed new symptoms. The genetic characterization of the populations involved was attempted using esterases polyacrylamide gel electrophoresis. Most of the individuals analysed showed an identical enzymatic profile, which also appears to be similar to the profile ofBemisia argentifolii(Bellows and Perring) described in the United‐States. However, the individuals collected onJatropha gossypifolia(L.) were different, and matched the N biotype ofBemisia tabaci(Gennadius) known in Puerto Rico.
Effet de l’application d’un mélange lambda‐cyhalothrin (pesticide chimique) et de spores de Metarhizium anisopliae (flavoviride) var. acridum Driver and Milner (biopesticide) appliqué sur les larves de sauteriaux au Mali
Authors: Douro Kpindou  , Lomer  , Langewald  , Togo  , Sagara
Published: March 2003

A mixture of lambda‐cyhalothrin (lambda‐cyhalothrin: chemical insecticide) and Metarhizium anisopliae (flavoviride) var. acridum Driver and Milner, an entomopathogenic fungus (bioinsecticide) was used for grasshopper control in Mali. An oil‐based formulation of Metarhizium anisopliae (flavoviride) var. acridum Driver and Milner has been developed by LUBILOSA a collaborative project for locust and grasshoppers control. It takes 6 to 10 days for the biopesticide to kill the hosts, which is not a problem for larvae in fallows because they will die before reaching the farmers’ fields. However, if crops are infested by adults, the farmers can not wait for 6 to 10 days. An experiment was conducted in Mali using a mixture of a biopesticide and chemical pesticide. The mixture of lambda‐cyhalothrin (chemical insecticide) and Metarhizium anisopliae (flavoviride) var. acridum (biopesticide: oil‐based entomopathogenic fungus spore suspension) was applied to nymphs of Sahelian grasshoppers, using ultra low volume (ULV) sprayers. Both the mixture and lambda‐cyhalothrin alone gave quick mortality, with slightly higher mortality for the mixture. Mortality due to the Metarhizium treatments began 2 days after application and subsequently reached similar levels of mortality to the lambda‐cyhalothrin mixture treatments. The efficacy of the mixture was greater than Metarhizium alone. The efficacy of lambda‐cyhalothrin reached 80% on the day following application, but declined after 10 days, due probably to immigration of untreated grasshoppers.
Field evaluation of Medfly (Dipt., Tephritidae) female attractants in a Mediterranean agrosystem (Balearic Islands, Spain)
Authors: Miranda M. A. , Alonso R. , Alemany A.
Published: March 2003

Field evaluation of female‐targeted trapping systems for the Mediterranean fruit fly Ceratitis capitata (Wied.) was carried out in a Citrus orchard in Majorca (Spain). Traps and lures included: IPMT and Tephri traps, both baited with a three‐component food‐based synthetic attractant 3FA (composed of putrescine, ammonium acetate and Trimethylamine) as well as IPMT‐baited with Nu‐Lure, and Delta traps baited with Trimedlure. The 3FA food‐based synthetic attractant was set up either wet (containing water) or dry (without water) in IPMT and Tephri traps. Two experiments were conducted, the first during autumn/winter conditions and high Medfly population levels, and the second during spring conditions and low population levels. The results obtained show that the 3FA was very effective at capturing females at high and low population levels. In the first experiment the best performance was shown by the Tephri trap baited with 3FA in combination with water, and in the second the best was also the Tephri trap but with dry treatment. The high number of non‐targeted insects captured by the first treatment together with servicing difficulties would indicate that the 3FA/dry‐baited Tephri trap is the best choice in the area of the study. On the other hand the 3FA captured a percentage of mated females equivalent to those obtained with Nu‐Lure. The Trimedlure proved to be an adequate tool to detect the earliest Medfly males in increasing spring population. The implications and advantages of using the 3FA female attractants in sterile insect technique programmes and mass trapping approaches, are discussed.
Effect of temperature on development and activity periods of the leek moth Acrolepiopsis assectella Zell. (Lep., Acrolepiidae)
Authors: Åsman K.
Published: March 2003

Effects of temperature on egg, larval and pupal developmental times of the leek moth were examined at five constant temperatures ranging from 12 to 20°C. Using this data, a linear degree‐day model for the leek moth was developed. The model gave the threshold temperature of Th=6°C, and 630 degree‐days were required above the threshold temperature, to complete the development of the leek moth. To validate the model in the field, flight activity during the summers of 1998 and 1999 was studied using pheromone traps. If the summer is warm the leek moth can have two generations per year in Sweden, but the probability of completing two generations within leek plantations is very limited. The likelihood of the leek moth becoming a pest is highly dependent on access to alternative host plants for the first generation of leek moths.
Factors affecting the response of Ceutorhynchus assimilis Payk. (Col., Curculionidae) males to conspecific odour
Authors: Nazzi F. , Bartlet E. , Watts N. , Wadhams L. J.
Published: March 2003

The effect of post‐emergence feeding on the response of Ceutorhynchus assimilis males to conspecific odour was studied using both laboratory‐overwintered and field‐collected weevils. The response of males to females at different times in the season was also investigated using field‐collected weevils. Males did not respond to the odour of virgin females that were newly emerged from diapause. However, they showed a significant response to the odour of overwintered virgin females that had spent some days on flowering rape. The response of males to females appeared to decline as the season progressed.