Optimising between and within family selection for harvest weight in prawns with restricted harvest size.

Manual grading of prawns restricts the number that can be harvested. A restricted harvest size places a limit on the opposing within family and between family sources of selection pressure. A simulation study with inbreeding constrained at 0.5% per generation, a harvest size of 2000, heritability of 0.3, common family environmental effect of 0.1, indicates that maximum response to selection could be achieved with as few as 40 families. Increasing the number of families above 80 may reduce total selection response. It is important to be aware that increasing the number of families may not always yield a greater genetic response.

Temporal genetic structure patterns in tropical maize populations under reciprocal recurrent selection.

In order to investigate the effect of long term recurrent selection on the pattern of gene diversity, thirty randomly-selected individuals from the progenitors (p) and four selection cycles (C0, C3, C6 and C11) were sampled for DNA analysis from the tropical maize (Zea mays L.) breeding populations, Atherton 1 (AT1) and Atherton 2 (AT2). Fifteen polymorphic Simple Sequence Repeat markers amplified a total of 284 and 257 alleles in AT1 and AT2 populations, respectively. Reductions in the number of alleles were observed at advanced selection cycles. About 11 and 12% of the alleles in AT1 and AT2 populations respectively, were near to fixation. However, a higher number of alleles (37% in AT1 and 33% in AT2) were close to extinction. Fisher's exact test and analysis of molecular variance (AMOVA) showed significant population differentiations. Gene diversity estimates and AMOVA revealed increased genetic differentiations at the expense of loss of heterozygosity. Population differentiations were mainly due to fixation of complementary alleles at a locus in the two breeding populations. The estimates of effective population at an advanced selection cycle were close to the population size predicted by the breeding method.

Multi-trait assessment of early-in-life female, male and genomic measures for use in genetic selection to improve female reproductive performance of Brahman cattle

Early-in-life female and male measures with potential to be practical genetic indicators were chosen from earlier analyses and examined together with genomic measures for multi-trait use to improve female reproduction of Brahman cattle. Combinations of measures were evaluated on the genetic gains expected from selection of sires and dams for each of age at puberty (AGECL, i.e. first observation of a corpus luteum), lactation anoestrous interval in 3-year-old cows (LAI), and lifetime annual weaning rate (LAWR, i.e. the weaning rate of cows based on the number of annual matings they experienced over six possible matings). Selection was on an index of comparable records for each combination. Selection intensities were less than theoretically possible but assumed a concerted selection effort was able to be made across the Brahman breed. The results suggested that substantial genetic gains could be possible but need to be confirmed in other data. The estimated increase in LAWR in 10 years, for combinations without or with genomic measures, ranged from 8 to 12 calves weaned per 100 cows from selection of sires, and from 12 to 15 calves weaned per 100 cows from selection of sires and dams. Corresponding reductions in LAI were 60-103 days or 94-136 days, and those for AGECL were 95-125 or 141-176 days, respectively. Coat score (a measure of the sleekness or wooliness of the coat) and hip height in females, and preputial eversion and liveweight in males, were measures that may warrant wider recording for Brahman female reproduction genetic evaluation. Pregnancy-test outcomes from Matings 1 and 2 also should be recorded. Percentage normal sperm may be important to record for reducing LAI and scrotal size and serum insulin-like growth factor-I concentration in heifers at 18 months for reducing AGECL. Use of a genomic estimated breeding value (EBV) in combination with other measures added to genetic gains, especially at genomic EBV accuracies of 40%. Accuracies of genomic EBVs needed to approach 60% for the genomic EBV to be the most important contributor to gains in the combinations of measures studied.

Genetic response to growth rate selection in pigs measured on two feeding levels

From the findings of McPhee et al. (1988), there is an expectation that selection in the growing pig for bodyweight gain measured on restricted feeding will result in favourable responses in the rate and efficiency of growth of lean pork on different levels of feeding. This paper examines this in two lines of Australian Large White pigs which have undergone 3 years of selection for high and for low growth rate over a 6-week period starting at 50 kg liveweight. Over this test period, pigs of both lines are all fed the same total amount of grower food, restricted to an estimated 80% of average ad libitum intake. 'Animal production for a consuming world': proceedings of 9th Congress of the AAAAP Societies and 23rd Biennial Conference of the ASAP and 17th Annual Symposium of the University of Sydney, Dairy Research Foundation, (DRF). Sydney, Australia.

Selection and characterisation of two attenuated vaccine lines of Eimeria tenella in Australia

Objective To attenuate two strains of Eimeria tenella by selecting for precocious development and evaluate the strains in characterisation trials and by field evaluation, to choose one precocious line for incorporation into an Australian live coccidiosis vaccine for poultry. Design Two strains from non-commercial flocks were passaged through chickens while selecting for precocious development. Each strain was characterised for drug sensitivity, pathogenicity, protection against homologous and heterologous challenge, and oocyst output in replicated experiments in which the experimental unit was a cage of three birds. Oocyst output and/or body weight gain data collected over a 10 to 12 day period following final inoculation were measured. Feed conversion ratios were also calculated where possible. Results Fifteen passages resulted in prepatent periods reduced by 24 h for the Redlands strain (from 144 h to 120 h)and 23 h for the Darryl strain (from 139 h to 116 h). Characterisation trials demonstrated that each precocious line was significantly less pathogenic than its parent strain and each effectively induced immunity that protected chickens against challenge with both the parent strain and other virulent field strains. Both lines had oocyst outputs that, although significantly reduced relative to the parent strains, remained sufficiently high for commercial vaccine production, and both showed susceptibility to coccidiostats. Conclusion Two attenuated lines have been produced that exhibit the appropriate characteristics for use in an Australian live coccidiosis vaccine.

Characterisation and early detection of an offtype from micropropagated Lady Finger bananas

An offtype has been identified from micropropagated Lady Finger bananas (Musa spp., AAB group, Pome subgroup) that is characterised by its slow growth and poor bunch size. Bunch weights were approximately 25% those of normal Lady Finger plants and all of the fruit produced was unmarketable. This particular offtype is the most commonly encountered from micropropagated Lady Finger plants and, in 2 instances, blocks of 3000 and 1500 plants were entirely comprised of this single offtype. Detection of offtype plants was possible during establishment and growth of plants in the glasshouse by the presence of chlorotic streaks in the leaves. In more severe cases the streaks coalesced into chlorotic patches that developed thin, necrotic areas that eventually produced holes or splits in the leaves. Symptom expression was not ameliorated by the addition of fertiliser and even though symptoms were similar to severe Ca and B deficiency, both normal and offtype plants had similar levels of these elements in the leaves. The offtype plants were also slow growing in the glasshouse and produced significantly (P<0.05) smaller pseudostems and leaves than normal plants. Offtype plants could be readily detected after 4 weeks deflasking using the presence of chlorotic streaks in the leaves as the main selection criterion. Maximum discrimination was possible between weeks 5–7 and at the 6-leaf stage when all of the offtypes could be detected.

Towards the development of a Cavendish banana resistant to race 4 of fusarium wilt: gamma irradiation of micropropagated Dwarf Parfitt (Musa spp., AAA group, Cavendish subgroup)

'Dwarf parfitt', an extra-dwarf Cavendish cultivar with resistance to subtropical race 4 fusarium oxysporum f. sp. cubense 9Foc), was gamma irradiated at a dose of 20 Gy and putative mutants were recovered with improved agronomic characteristics. Further screening of putative mutants for improved yield and fruit size, as well as a degree of resistence to fusarium wilt, led to the selection of a line (DPM25) with improved productivity when grown on soils infested with subtropical race 4 Foc. DPM25 was equal to the industry standard, 'Williams', in every agronomic trait measured and it consistently showed a lower incidence of fusarium wilt. Further improvement of field resistance to race 4 Foc is needed in DPM25 and further cycles of mutation induction and selction is an option discussed.

Assessing for genetic and environmental effects on ruminant feed quality in barley ( Hordeum vulgare )

Grain samples from a combined intermediate and advanced stage barley breeding trial series, grown at two sites in two consecutive years were assessed for detailed grain quality and ruminant feed quality. The results indicated that there were significant genetic and environmental effects for “feed” traits as measured using grain hardness, acid detergent fibre (ADF), starch and in-sacco dry matter digestibility (ISDMD) assays. In addition, there was strong genotypic discrimination for the regressed feed performance traits, namely Net Energy (NE) and Average Daily Gain (ADG). There was considerable variation in genetic correlations for all traits based on variance from the cultivars used, sites or laboratory processing effects. There was a high level of heritability ranging from 89% to 88% for retention, 60% to 80% for protein and 56% to 68% for ADF. However, there were only low to moderate levels of heritability for the feed traits, with starch 30–39%, ISDMD 55–63%, ADF 56–68%, particle size 47–73%, 31–48% NE and ADG 44–51%. These results suggest that there were real differences in the feed performance of barleys and that selection for cattle feed quality is potentially a viable option for breeding programs.

Selecting for increased barley grain size

In this study, 120–144 commercial varieties and breeding lines were assessed for grain size attributes including plump grain (>2.8 mm) and retention (>2.5 mm+>2.8 mm). Grain samples were produced from replicated trials at 25 sites across four years. Climatic conditions varied between years as well as between sites. Several of the trial sites were irrigated while the remaining were produced under dryland conditions. A number of the dryland sites suffered severe drought stress. The grain size data was analysed for genetic (G), environmental (E) and genotype by environment (G×E) interactions. All analyses included maturity as a covariate. The genetic effect on grain size was greater than environmental or maturity effects despite some sites suffering terminal moisture stress. The model was used to calculate heritability values for each site used in the study. These values ranged from 89 to 98% for plump grain and 88 to 96% for retention. The results demonstrated that removing the sources of non-heritable variation, such as maturity and field effects, can improve genetic estimates of the retention and plump grain fractions. By partitioning all variance components, and thereby having more robust estimates of genetic differences, plant breeders can have greater confidence in selecting barley genotypes which maintain large, stable grain size across a range of environments.

The genetic effective and adult census size of an Australian population of tiger prawns (Penaeus esculentus)

This study compares estimates of the census size of the spawning population with genetic estimates of effective current and long-term population size for an abundant and commercially important marine invertebrate, the brown tiger prawn (Penaeus esculentus). Our aim was to focus on the relationship between genetic effective and census size that may provide a source of information for viability analyses of naturally occurring populations. Samples were taken in 2001, 2002 and 2003 from a population on the east coast of Australia and temporal allelic variation was measured at eight polymorphic microsatellite loci. Moments-based and maximum-likelihood estimates of current genetic effective population size ranged from 797 to 1304. The mean long-term genetic effective population size was 9968. Although small for a large population, the effective population size estimates were above the threshold where genetic diversity is lost at neutral alleles through drift or inbreeding. Simulation studies correctly predicted that under these experimental conditions the genetic estimates would have non-infinite upper confidence limits and revealed they might be overestimates of the true size. We also show that estimates of mortality and variance in family size may be derived from data on average fecundity, current genetic effective and census spawning population size, assuming effective population size is equivalent to the number of breeders. This work confirms that it is feasible to obtain accurate estimates of current genetic effective population size for abundant Type III species using existing genetic marker technology.

International Society for Applied Ethology. Special issue: a Selection of Papers from the 38th International Congress of the ISAE, Helsinki, Finland, August 2004

Welcome to the latest collection of papers selected from the International Society for Applied Ethology's (ISAE's) annual congress. The ISAE is a multi-faceted scientific society that supports applied research on animals under the influence of humankind. Every year, we aim to invite congress participants who have submitted papers, plenary talks, run workshops, or presented the memorial lecture on theoretical, review or discussion papers of topical interest to contribute to the Special Issue. These papers are peer-reviewed before being published here in Applied Animal Behaviour Science. International Society for Applied Ethology (ISAE) Special Issue 2004.

International Society for Applied Ethology. Special issue: a selection of papers from the 39th International Congress of the International Society for Applied Ethology (ISAE), Tokyo, Japan, August 2005

Welcome to the latest collection of papers selected from the International Society for Applied Ethology's (ISAE's) annual congress. The ISAE is a multi-faceted scientific society that supports applied research on animals that are managed by humans. Every year, we aim to invite congress participants who have submitted papers, plenary talks, run workshops, or presented the memorial lecture on theoretical, review or discussion papers of topical interest to contribute to the Special Issue. These papers are peer-reviewed before being published here in Applied Animal Behaviour Science. This year, we have a variety of papers to bring to your attention. The David Wood-Gush Memorial lecture, the keynote address of the congress, was given by Shigeru Watanabe on animal cognition and welfare. His paper highlights how animal's sensory capabilities relate to their welfare. On the topic of human–animal bonds, Stine Christiansen and Björn Forkman explore how animal welfare is assessed in a veterinary context, and how those assessments might be improved by ethologists. Yoshie Kakuma and co-authors report on the discussions from a workshop on the welfare of working and companion dogs in five different countries. Based on their plenary lectures, Michael Cockram discusses the factors that affect farmed animals during road transport and how these might contribute in making decisions to restrict journey times, while Clive Phillips and co-author Danica Peck examine how personality influences the behaviour and interactions between zoo-housed tigers and their keepers. We hope you enjoy these papers. Our sincere thanks go to both the authors and referees, without whom these special issues would not be possible. A selection of papers from the 39th International Congress of the International Society for Applied Ethology (ISAE), Tokyo, Japan, August 2005.

Effect of changes in hook pattern and size on catch rate, hooking location, injury and bleeding for a number of tropical reef fish species

The Queensland Great Barrier Reef line fishery in Australia is regulated via a range of input and output controls including minimum size limits, daily catch limits and commercial catch quotas. As a result of these measures a substantial proportion of the catch is released or discarded. The fate of these released fish is uncertain, but hook-related mortality can potentially be decreased by using hooks that reduce the rates of injury, bleeding and deep hooking. There is also the potential to reduce the capture of non-target species though gear selectivity. A total of 1053 individual fish representing five target species and three non-target species were caught using six hook types including three hook patterns (non-offset circle, J and offset circle), each in two sizes (small 4/0 or 5/0 and large 8/0). Catch rates for each of the hook patterns and sizes varied between species with no consistent results for target or non-target species. When data for all of the fish species were aggregated there was a trend for larger hooks, J hooks and offset circle hooks to cause a greater number of injuries. Using larger hooks was more likely to result in bleeding, although this trend was not statistically significant. Larger hooks were also more likely to foul-hook fish or hook fish in the eye. There was a reduction in the rates of injuries and bleeding for both target and non-target species when using the smaller hook sizes. For a number of species included in our study the incidence of deep hooking decreased when using non-offset circle hooks, however, these results were not consistent for all species. Our results highlight the variability in hook performance across a range of tropical demersal finfish species. The most obvious conservation benefits for both target and non-target species arise from using smaller sized hooks and non-offset circle hooks. Fishers should be encouraged to use these hook configurations to reduce the potential for post-release mortality of released fish.

The accuracy of varietal selection using factor analytic models for multi-environment plant breeding trials

Modeling of cultivar x trial effects for multienvironment trials (METs) within a mixed model framework is now common practice in many plant breeding programs. The factor analytic (FA) model is a parsimonious form used to approximate the fully unstructured form of the genetic variance-covariance matrix in the model for MET data. In this study, we demonstrate that the FA model is generally the model of best fit across a range of data sets taken from early generation trials in a breeding program. In addition, we demonstrate the superiority of the FA model in achieving the most common aim of METs, namely the selection of superior genotypes. Selection is achieved using best linear unbiased predictions (BLUPs) of cultivar effects at each environment, considered either individually or as a weighted average across environments. In practice, empirical BLUPs (E-BLUPs) of cultivar effects must be used instead of BLUPs since variance parameters in the model must be estimated rather than assumed known. While the optimal properties of minimum mean squared error of prediction (MSEP) and maximum correlation between true and predicted effects possessed by BLUPs do not hold for E-BLUPs, a simulation study shows that E-BLUPs perform well in terms of MSEP.

Simple sequence repeat markers associated with three quantitative trait loci for black point resistance can be used to enrich selection populations in bread wheat

Black point in wheat has the potential to cost the Australian industry $A30.4 million a year. It is difficult and expensive to screen for resistance, so the aim of this study was to validate 3 previously identified quantitative trait loci (QTLs) for black point resistance on chromosomes 2B, 4A, and 3D of the wheat variety Sunco. Black point resistance data and simple sequence repeat (SSR) markers, linked to the resistance QTLs and suited to high-throughput assay, were analysed in the doubled haploid population, Batavia (susceptible) × Pelsart (resistant). Sunco and Pelsart both have Cook in their pedigree and both have the Triticum timopheevii translocation on 2B. SSR markers identified for the 3 genetic regions were gwm319 (2B, T. timopheevii translocation), wmc048 (4AS), and gwm341 (3DS). Gwm319 and wmc048 were associated with black point resistance in the validation population. Gwm341 may have an epistatic influence on the trait because when resistance alleles were present at both gwm319 and wmc048, the Batavia-derived allele at gwm341 was associated with a higher proportion of resistant lines. Data are presented showing the level of enrichment achieved for black point resistance, using 1, 2, or 3 of these molecular markers, and the number of associated discarded resistant lines. The level of population enrichment was found to be 1.83-fold with 6 of 17 resistant lines discarded when gwm319 and wmc048 were both used for selection. Interactions among the 3 QTLs appear complex and other genetic and epigenetic factors influence susceptibility to black point. Polymorphism was assessed for these markers within potential breeding material. This indicated that alternative markers to wmc048 may be required for some parental combinations. Based on these results, marker-assisted selection for the major black point resistance QTLs can increase the rate of genetic gain by improving the selection efficiency and may facilitate stacking of black point resistances from different sources.