Stress is often an important consideration for animal welfare. A number of factors can contribute to stress in domestic animals, most notably thoseused in food production. We investigated the effects and heritability of stress in domestic chickens (Gallus gallus). Using a spatial learning paradigm, we tested an early social isolation-stressed group and their offspring against unstressed controls, to determine if this cognitive function was negatively affected by stress. In the parental generation, we found that across sessions control birds improved in performance, indicating a learning trend. Stressed birds showed no difference across sessions, indicating a lack of learning. No effects of the parental treatment were found in the offspring of stress and control birds. Social isolation stress was found to affect spatial memory learning, however, we did not find evidence that the parental stress influenced the spatial abilities of the next generation despite changes in other behaviours.

Raffinose family oligosaccharides (RFO) are major soluble carbohydrates of lentil (Lens culinaris Medik) seeds. When consumed by humans, RFO pass indigested through upper digestive tract as ¦Á-galactosidase enzyme required for RFO breakdown is not produced in humans. Consumption of lentils with high concentrations of RFO result in stomach discomfort, bloating and diarrhea due to bacterial fermentation of RFO in large intestine. This has lead to a relatively low use of lentils for human consumption. RFO are therefore considered anti-nutritional factors and development of lentil cultivars with reduced RFO concentrations is desired to improve lentil quality and consumption. To explore the possibility to develop lentil cultivars for low-RFO concentration, heritability of RFO trait and influence of environmental conditions on RFO must be known. In addition, RFO biosynthesis and accumulation in lentil seeds must be understood. However, very limited information is available on the above mentioned aspects of RFO in general and in lentil in particular. Therefore, the objectives of this study were: (1) to evaluate natural variation in RFO concentration and composition in commonly grown lentil cultivars and to determine the correlation between RFO concentration and other important seed constituents, (2) to investigate heritability and effect of environment on concentration and composition of lentil seed soluble carbohydrates, (3) to assess natural variation and diversity in RFO concentration in the genus Lens, (4) and to evaluate the association between galactinol synthase activity and accumulation of RFO in lentil seeds. Analysis of 22 lentil genotypes revealed significant (P ¡Ü 0.05) variation in total starch, amyolse, protein, total RFO and seed weight and seed colour. Stachyose was the major RFO in all lentil genotypes followed by raffinose and verbascose. A significant (P ¡Ü 0.05) inverse correlation was found between RFO and amylose concentration (r = -0.34); whereas RFO concentration and thousand seed weight correlated positively (r = 0.35). The analyses of variance of eleven cultivars grown at ten different environments showed that cultivar, environment and their interaction had significant effects on sugar concentration in lentil seeds. The high broad sense heritability of RFO (h2= 0.85) indicated that RFO concentration in lentil seeds is highly heritable and thus amenable to genetic improvement. An extensive evaluation of domesticated and wild species and subspecies of the genus Lens revealed significant (P ¡Ü 0.05) variation and diversity in RFO concentration and composition of individual oligosaccharides. Higher Shannon-Weaver diversity indices (SDI) for total RFO, raffinose and verbascose traits were observed in wild lentils compared to domesticated genotypes. Lens ervoides genotypes and some wild genotypes contained almost half the RFO concentration of cultivated lentils and therefore, wild genotypes may be useful for developing low-RFO lines. Higher verbascose and lower stachyose concentration was found in Lens ervoides genotypes, whereas higher raffinose and lower verbascose concentration is found in Lens nigricans genotypes. Study of galactinol synthase activity in developing seeds with varying RFO concentration showed no clear association between galactinol synthase activity and RFO concentration. The sucrose and galactinol concentration of developing seeds were also not associated with total RFO concentration of lentil seeds. This finding suggests a non-regulatory role of galactinol synthase in RFO biosynthetic pathway in lentil seeds. Together, all these findings are not only significant to devise strategies to develop lentil cultivars with reduced RFO concentration but also for understanding RFO biosynthesis in lentil seeds.

Lately the rate of genetic gain in most agronomic crop species has been reduced due to several factors that limit breeding efficiency and genetic gain. New genetic tools and more powerful statistical analyses provide an alternative approach to enhance genetic improvements through the identification of molecular markers linked to genomic regions or QTLs controlling quantitative traits. The main objective of this research was to identify genomic regions associated with enhanced agronomic performance in lines per se and hybrid combination in Sorghum bicolor (L.) Moench. A population composed of 187 F5:6 recombinant inbred lines (RIL) was derived from the cross of restorer lines RTx430 and RTx7000. Also, a testcross hybrid population (TCH) was developed by using each RIL as a pollinator onto ATx2752. A linkage map was constructed using 174 marker loci generated from AFLP and SSR primer combinations. These markers were assigned to 12 different linkage groups. The linkage map covers 1573 cM with marker loci spaced at an averaged 9.04 cM. In this study, 89 QTL that control variation in seven different morphological traits were identified in the recombinant inbred line population, while in the testcross hybrid population, 79 QTL were identified. These traits included grain yield, plant height, days to mid-anthesis, panicle number, panicle length, panicle exsertion and panicle weight. These putative QTL explained from 4 to 42% of the phenotypic variation observed for each trait. Many of the QTL were not consistent across populations and across environments. Nevertheless, a few key QTL were identified and the source of the positive additive genetics isolated. RTx7000 was consistently associated with better agronomic performance in RIL, while in testcrosses, RTx430 was. Some genomic regions from RTx7000 may be utilized to improve RTx430 as a line per se. However, it is very unlikely that such regions will have a positive effect on the combining ability of RTx430 since testcross results did not reveal any transgressive segregants from the RIL population.

Upland cotton (Gossypium hirsutum) is cultivated in many contrasting production environments and is often subjected to a combination of abiotic stresses such as high temperature (heat) and water deficit (drought) stress. In the present dissertation, two recombinant inbred line populations were constructed from heat-tolerant and -susceptible parental lines and evaluated in multiple environments under the presence of two treatments, well-watered (heat stress) and water-limited in the presence of high temperature (combination of heat and drought stresses). We assessed two agronomic traits, seed cotton yield and lint yield, as well as six fiber traits, lint percent, micronaire, length, strength, uniformity, and elongation. Fiber traits had moderate to very high broad-sense heritabilities, while heritabilities of agronomic traits were lower for both populations in each irrigation regime. Correlations between traits were not effected by the irrigation regimes. A stability analysis across the range of environments tested demonstrated that high seed cotton yield performance and greater stability may play a role in tolerance to the combination of heat and drought stresses. Additionally, we constructed linkage maps for both recombinant inbred line populations and mapped QTL controlling variation all eight traits. A total of 138 QTL were identified across populations for the eight traits. Climate change in the form of rising temperatures and reduced water availability will increase the occurrence of the combination of heat and drought stresses in a farmer's field. Thus, current cotton breeding programs will need to focus on the development of cotton varieties tolerant to heat, drought, and the combination of the two.

The heritability of microfibril angle (MFA) in loblolly pine, Pinus taeda L., and its genetic relationships with height, diameter, volume and specific gravity were examined in two progeny tests with known pedigrees. Significant general combining ability (GCA), specific combining ability (SCA), and SCA x block effects indicated that there are both additive and non-additive genetic influences on MFA. Individual-tree narrow-sense heritability estimates were variable, ranging from 0.17 for earlywood (ring) 4 MFA to 0.51 for earlywood (ring) 20 MFA. Genetic correlations between MFA, specific gravity and the growth traits were non-significant due to large estimated standard errors. Multiple-trait selection and breeding in a mainline and elite population tree improvement program were simulated using Excel and Simetar (Richardson 2001). The effects of four selection indices were examined in the mainline population and the effects of seven selection indices and four breeding strategies were examined in the elite population. In the mainline population, selection for increased growth caused decreased wood quality over time. However, it was possible to maintain the overall population mean MFA and mean specific gravity at levels present in the base population by implementing restricted selection indices. Likewise, selection for improved wood quality in the elite population resulted in decreased growth unless restricted selection indices or pulp indices derived from those of Lowe et al. (1999) were used. Correlated phenotypic responses to selection on indices using economic weights and heritabilities were dependent on breeding strategy. When a circular mating system (with parents randomly assigned to controlled-crosses) was used, the index trait with a higher economic weight was more influential in determining correlated responses in non-index traits than the index trait with a lower economic weight. However, when positive assortative mating was used, the index trait with a greater variance was more influential in determining correlated responses in non-index traits than the index trait with a lower variance regardless of economic weight.

This thesis is an investigation of several aspects of diapause in the swede midge, Contarinia nasturtii (Kieffer). After developing methodology for induction and quantification of diapause entry in the laboratory, heritability of diapause entry was assessed for sibling larvae reared under diapause-inducing conditions. The diapause-quantification technique was efficient, but diapause frequencies were highly variable across studies employing similar diapause-inducing conditions. The diapause entry trait may be weakly heritable. A field study was conducted on diapause entry and emergence patterns. Diapause frequency was inversely correlated with photoperiod and absolute maximum air temperature. Photoperiod did not influence emergence timing. Two emergence phenotypes were observed before mid-July and a third minor emergence phenotype may exist in mid-to-late August. Approximately one third of emergence in the field was attributed to larvae in diapause for two or more years. Avenues of future research on diapause regulation in both the laboratory and field are discussed. / Natural Science and Engineering Research Council (CGS-M), Ontario Ministry of Agriculture, Food, and Rural Affairs (University of Guelph Sustainable Production Program)

This thesis is an investigation into the possible genetic background underlying the liability of Standardbred racehorses (Std) to atrial fibrillation (AF). Pedigrees of 204 affected Std admitted to the Ontario Veterinary College Teaching Hospital (OVCTH) for treatment of AF born from 1978 to 2007 and of 1,017 randomly selected racing contemporaries (5 for each Std admitted). Estimates of heritability of AF were obtained using a linear threshold animal model. Marginal genetic contributions of ancestors to affected and control cohorts were determined and differences were tested. The estimate of heritability of AF in the Std was 14% on the observed scale. Eleven ancestors had significantly higher contributions to affected cohorts than to controls. Many of these ancestors appeared multiple times in the five-generation pedigrees of affected horses. Results strongly indicate a genetic predisposition to AF in the Std, with the arrhythmia particularly prevalent in one popular sire line.

One of the principle factors that limits the areas to which seeded bermudagrass can be adapted is low temperature. Therefore, increasing the winter tolerance of seeded bermudagrass cultivars has been a goal of turfgrass breeders for many years. Design of an efficient breeding method for developing cultivars with increased tolerance to cool and freezing temperatures could be enhanced by having heritability estimates for cold tolerance traits. Additionally, the identification of correlated traits can be useful in improvement of cultivar development. Heritability estimates for winter tolerance can be obtained from cold treatments imposed artificially or from observations made in the field. Parental clones and their respective polycross half-sib families were established in a randomized complete block design with four replications in 2004 in Lexington, KY. Differences in spring green up and fall dormancy measured in 2006 were detected between genotypes within the progeny and parental groups. These same lines were subjected to 15 replications of a freezing treatment in a freeze chamber. Differences in spring green up and fall dormancy were detected between genotypes within the progeny and parental groups. Differences in freeze response were also detected using the artificial freeze treatment. Broad-sense heritabilities were estimated to be 0.895 and 0.573 for spring green-up and fall dormancy respectively. Narrow-sense heritability estimates were found to be 0.885 and 0.265 for these same traits. These results indicate that this population could be improved for cold tolerance using phenotypic recurrent selection. Freeze response was found to be positively correlated to winter hardiness and seed yield in the parent group.

Barley is the second largest grain crop produced in Australia and has two primary end uses. The first use is the premium market for malt and beer production. The second use is animal consumption. The quality of barley for the range of end uses is influenced by the cultivar itself as well as the growing environment. A detailed understanding of these factors at the genetic and biochemical levels was required to enable breeding program to select for quality improvement. A number of grain and end product quality traits were assessed for genetic and environmental affects as well as their interaction.Grain size has an important impact on quality and large plump grain is desirable for malt and feed quality. The results from the research conducted in this study clearly show that grain size was affected by cultivar and environmental conditions. Using screenings (< 2.2 mm) and retention (> 2.5mm) data provided information on how cultivars performed under a range of environmental conditions, which included irrigated (water unlimited) to terminal moisture stress (no in crop rain). The results showed a strong genetic component in the variation in grain size and it would be possible to select for increased grain size but also stable grain size when considering cultivars grown under adverse environmental conditions.The husk content in barley impacts on malt and feed quality. The results in this studied showed there were significant genetic effects as well as environments effects on the level of husk. In addition, it was identified that the genetic regions controlled husk expression were associated with two other quality traits, namely, resistance to kernel discolouration and resistance to pre-harvest sprouting (dormancy). These regions on chromosome 4H and 6H are also associated with previously identified dormancy genes.Hardness is a trait not usually considered when assessing barley quality but the results from this study showed there are differences in the level of barley hardness, as measured by three methods, as well as differences in the hardness gene sequence. The three hardness methods used showed that barley hardness could be measured independently of the method used, but also that there were significant genetic and environmental effects on hardness. However, the results from sequencing for allelic variation in the hardness genes showed that while there was polymorphism, and hance the transcribed protein had little effect on variation in quality. The cultivars used were malting and feed cultivars and a set of iv breeding lines targeted at malt quality. It may be possible to identify diverse haplotypes from the use of wild relatives or landraces.This study also investigated the variation in barley for cattle feed quality. Feed quality was determined using an in-sacco dry matter digestibility (ISDMD) assay in fistulated cows as well as three other laboratory assays, namely acid detergent fibre, starch and particle size. These four traits are then used to calculate Net Energy (NE) and Average Daily Gain (ADG). The results show that there were genetic and environmental effects on feed quality. The key trait was the ISDMD assay and there were significant differences between the cultivars tested. The data suggested feed quality was a measurable and definable attribute that could be used in breeding selection.The final aspect of this study compared the feed data obtained with routine malt quality traits, of friability and hot water extract. There were strong genetic and environmental effects. The malting cultivars generally had the highest level of ADG and NE. The results also showed that there were negative correlations between extract and husk, ISDMD and ADG. Positive correlations were shown between friability and hardness, extract and test weight, and there was only a slight correlation between average daily gain and extract.An important aspect of this study was the calculation of the genetic component for each trait. This was carried using spatial analysis of mixed models. It was necessary to use this approach so a true estimation of the genetic component could be calculated which would then allow for the calculation of heritability. In plant breeding, the cultivar is not a fixed effect but rather a random variable, hence it was not possible to use normal analysis of variation (ANOVA) models. Rather models were written with cultivars, like environment and field position, as random effects which will allow the effect of each random variable to be accounted for in the analysis. Best Linear Unbiased Predictions (BLUPs) are calculated and presented for all traits.For all the traits measured in this study, heritability values were calculated to ascertain the level of success in improving these traits through breeding. The range in heritability for grain size was 40 to 90%, husk 30 to 60%, hardness, 40 to 90%, feed quality traits 20 to 80% and malt quality traits 40 to 90%. Generally most traits exhibited a moderate to high level of heritability which indicated genetic improvement was possible through the use of appropriate genetic material.

Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniv., 2003. / Härtill 7 uppsatser.