Progeny Differences Research Articles

<b>Estimation of genetic and phenotypic trends for dairy traits of Gyr and Guzerá breeds

Milk production has high economic importance in dairy cattle production systems, which justifies its inclusion in genetic breeding programs. The objective of this study was to evaluate the genetic and phenotypic trends of dairy traits in Gyr (167 lactations) and Guzerá (148 lactations) breeds in the State of Rio Grande do Norte (RN). Milk, fat and protein production obtained from monthly dairy controls were the traits evaluated. The expected differences in progeny (DEPs) for these traits were estimated using an animal model. From the means of phenotypic values and DEPs, we estimated the genetic and phenotypic trends in linear regressions as a function of the year of calving of the animal. Positive genetic and phenotypic trends were observed for Gyr (26.8 and 88.7 kg year-1) and Guzerá (8.44 and 37.68 kg year-1). Gyr breed presented positive genetic trends for fat (1.08 kg year-1) and protein (0.45 kg year-1) production and the Guzerá breed showed positive genetic trends for fat (0.36 kg year-1) and protein (0.25 kg year-1) production. The selection applied in the evaluated herds has produced satisfactory genetic and phenotypic progress for milk, fat and protein production.

Condition‐dependent reproductive tactics in male smallmouth bass: evidence of an inconsistent birthdate effect on early growth and age at first reproduction

AbstractMany animals exhibit alternative forms of reproductive behavior, the expression of which depends on individual condition or status. For instance, male smallmouth bass Micropterus dolomieu that are large early in life often build a nest and spawn for the first time at a young age and small body size, while males that are small early in life delay reproduction, invest in growth and spawn when they are older and larger, tactics referred to as α and β, respectively. The observation that larger males also tend to spawn earlier within a season led to a hypothesis that birthdate – more specifically, dispersal date – may control which tactic is adopted. Here, we examined the individual growth and reproductive histories of 184 male M. dolomieu of three cohorts for evidence of a birthdate effect on early life condition and the subsequent expression of tactics, namely whether a long first‐year growth period tends to induce the α tactic and whether variability in the timing of reproduction by parents within a season contributes to body size differences in progeny at the end of their first‐year growth period. The extent to which male condition early in life influences the expression of tactics was also evaluated. Evidence of a birthdate effect on progeny condition and subsequent tactic choice was observed for only one of the three cohorts and, in another cohort, tactic choice and individual condition were largely unrelated. The seasonal variability in birthdates and growth histories suggest that a broad range of swim‐up dates may be necessary to generate differences in condition early in life that are sufficiently large to control future reproductive decisions. Potential impacts of various physical, environmental and biotic factors that may mediate the seasonal timing of reproduction by parents or individual growth early in life are discussed.

Response of the common cutworm Spodoptera litura to lead stress: Changes in sex ratio, Pb accumulations, midgut cell ultrastructure

When cutworm Spodoptera litura larvae were fed on the diets with different lead (Pb) concentrations for one or five generations, changes in growth and food utilization were recorded; Pb accumulations were detected by Atomic Absorption Spectrophotometer; changes in midgut cell ultrastructure were observed by Transmission Electron Microscopy (TEM). The effects of Pb stress on S. litura growth and food utilization differed significantly between insects of the 1st and 5th generation. The male–female rate of 200mgkg−1 Pb treatment from the 1st generation and 50mgkg−1 Pb treatment from the 5th generation was significantly higher than control. No significant difference of Pb accumulations was found in larvae, pupae and adults between the 1st and 5th generation. No significant difference of Pb accumulations in corresponding tissues of larvae was found between male and female. Compared to fat body, hemolymph, head, foregut and hindgut, the highest Pb accumulation was found in migut of larvae exposed to 200mgkg−1 Pb. TEM showed that expanded intercellular spaces were observed in Pb-treated midgut cells. The nuclei were strongly destroyed by Pb stress, evidenced by chromatin condensation and destroyed nuclear envelope. Mitochondria became swollen with some broken cristae after exposure to Pb. Therefore, neither gender nor progeny difference was present in Pb accumulations of S. litura, although effects of Pb stress on S. litura growth and food utilization differed from different generations and genders. Pb accumulations in midgut caused pathological changes in cells ultrastructure, possibly reflected the growth and food utilization of S. litura.

138 GENETIC PARAMETER ESTIMATION FOR EMBRYO TRANSFER TRAITS

Genetic selection has made tremendous progress on economically important traits in the beef industry. Most of the progress has been from quantitative genetics through use of expected progeny differences (EPD). These values allow prediction of differences in progeny of a sire compared to progeny of other sires. Development of EPD for male and female reproductive traits has largely been ignored because of low heritability of reproductive traits, even though reproduction plays a vital role in the economics of beef operations. Therefore, continued research in the area of genetic selection for fertility is becoming increasingly important. Critical limiting factors for animal breeding programs using MOET nucleus schemes include variability in superovulatory response of donor animals and resulting pregnancy of transferred embryos. Thus, the overall objective of this research was to develop genetic parameters associated with MOET to assist producers in identifying animals with greater genetic merit for these protocols. Records were examined from a large-scale MOET system in beef cattle that contained data only for cows in which at least one transferable embryo was obtained. Data on these animals were extracted and analyzed on 10 425 transferred embryos (2900 collections) from 611 donor animals (Angus, Brangus, and Charolais) utilizing semen from 215 bulls. Phenotypic traits examined included pregnancy status of the recipient following transfer (ET-preg; determined by rectal palpation at 60 days post-transfer and/or confirmed calving date of recipient), number of transferable embryos per collection (ET-trans), and number of unfertilized ova at collection (ET-UFO). Basic statistical analysis and pedigree/trait files were developed using procedures in SAS (SAS Institute, Cary, NC). Genetic parameters were estimated for a single-trait animal model using restricted maximum likelihood (REML) procedures in Wombat (Meyer K 2007 Zhejiang Uni. Science B 8, 815–821). Wombat also computed EPD and standard errors for each trait evaluated. The model included fixed effects of year as well as random animal and residual effects. The EPD for ET-preg ranged from –6.1 to 4.4% (SE = 2.2 to 4.2) for semen sires (sires of the transferred embryos) and –5.3 to 3.8% (SE = 3.2 to 4.2) for donor animals. Additionally, the heritability estimated for ET-preg was 0.03. Heritability estimated for ET-trans was 0.00, indicating minute genetic variation and thus, EPD were not presented. Heritability estimated for ET-UFO was 0.05 with EPD values (deviation of the number of UFO from the mean) ranging from –0.6 to 0.8 (SE = 0.3 to 0.6) for semen sires and –0.4 to 1.1 (SE = 0.5 to 0.6) for donor cows. As previously shown for reproductive traits, heritability of ET-preg, ET-trans, and ET-UFO was low. Genetic improvement in fertility by selection on embryo transfer traits is possible, but progress would be slow. Further studies are underway on a larger dataset to refine these estimates and to examine repeatability.

Development of Pseudacteon nocens (Diptera: Phoridae) on Solenopsis invicta and Solenopsis richteri Fire Ants (Hymenoptera: Formicidae)

We studied the developmental performance of the large morph of Pseudacteon nocens Borgmeier (Diptera: Phoridae), a prospective biological control agent of imported fire ants (Hymenoptera: Formicidae). We measured selected life history traits of this parasitoid as a function of 1) host species (Solenopsis invicta Buren versus Solenopsis richteri Forel), 2) temperature (22 versus 28°C), 3) source population of the fly (Corrientes and Santiago del Estero, Argentina), and 4) varied size distributions of offered host ants. Developmental periods were influenced by host species, although the populations responded in opposing manners. Developmental times, however, were most strongly influenced by temperature with total developmental periods lengthened by 17–32% at 22°C. Pupal mortality was also significantly lower at this temperature. Although numbers of progeny per female were significantly higher for the Corrientes population, we found no significant differences in progeny per female according to host species. Interestingly, we found that females were larger than males, and flies from Corrientes were larger than those from Santiago del Estero, even after statistical adjustments for host size. The modal frequency of host size elected in all treatment combinations tested was identical (0.6 mm), a size that represented the apparent threshold for producing female progeny. These laboratory and additional field observations demonstrate considerable interpopulational variation in P. nocens and lend further support to the applied approach focusing at the population, as opposed to the species level, with respect to both source and target areas for classical biological control introductions of Pseudacteon flies.

Development of <I>Pseudacteon nocens</I> (Diptera: Phoridae) on <I>Solenopsis invicta</I> and <I>Solenopsis richteri</I> Fire Ants (Hymenoptera: Formicidae)

We studied the developmental performance of the large morph of Pseudacteon nocens Borgmeier (Diptera: Phoridae), a prospective biological control agent of imported fire ants (Hymenoptera: Formicidae). We measured selected life history traits of this parasitoid as a function of 1) host species (Solenopsis invicta Buren versus Solenopsis richteri Forel), 2) temperature (22 versus 28 degrees C), 3) source population of the fly (Corrientes and Santiago del Estero, Argentina), and 4) varied size distributions of offered host ants. Developmental periods were influenced by host species, although the populations responded in opposing manners. Developmental times, however, were most strongly influenced by temperature with total developmental periods lengthened by 17-32% at 22 degrees C. Pupal mortality was also significantly lower at this temperature. Although numbers of progeny per female were significantly higher for the Corrientes population, we found no significant differences in progeny per female according to host species. Interestingly, we found that females were larger than males, and flies from Corrientes were larger than those from Santiago del Estero, even after statistical adjustments for host size. The modal frequency of host size elected in all treatment combinations tested was identical (0.6 mm), a size that represented the apparent threshold for producing female progeny. These laboratory and additional field observations demonstrate considerable interpopulational variation in P. nocens and lend further support to the applied approach focusing at the population, as opposed to the species level, with respect to both source and target areas for classical biological control introductions of Pseudacteon flies.

Climatic adaptation in Picea abies progenies is affected by the temperature during zygotic embryogenesis and seed maturation

ABSTRACTThe temperature during maternal reproduction affects adaptive traits in progenies of Norway spruce (Picea abies (L) Karst.). Seed production in a cold environment advances bud set and cold acclimation in the autumn and dehardening and flushing in spring, whereas a warm reproductive environment delays timing of these traits. We repeated crosses between the same parents and produced seeds under contrasting temperatures. Elevated temperatures were applied at different time points from female meiosis to embryogenesis, followed by full‐sib progeny tests in common environments. We measured timing of terminal bud formation, cold acclimation in the autumn and transcription levels of conifer phytochromes PhyO, PhyN, PhyP, and the class IV chitinase PaChi4 in these tests. No progeny differences were found that could be related to temperature differences during prezygotic stages and fertilization. In contrast, progeny performance was strongly associated with the degree‐days from proembryo to mature seeds. Progenies with a warm embryonic history formed terminal buds later, were less hardy and expressed lower transcription levels of the Phy and PaChi4 genes. We hypothesize that temperature during zygotic embryogenesis and seed maturation regulates an ‘epigenetic memory’ in the progeny, involving differential expression of genes that may regulate bud phenology, cold acclimation and embryogenesis in Norway spruce.

The development ofPhytophthora canker on different cocoa genotypes infected and uninfected withcocoa swollen shoot virus

Cocoa trees previously infected with the swollen shoot virus were more predisposed to Phytophthora palmivora canker than those uninfected. Progeny differences and time of inoculation significantly affected the size of canker lesions. Copyright © 2005 Whurr Publishers Ltd.

Influence of Soybean Lines Isogenic for Pubescence Type on Twospotted Spider Mite (Acarina: Tetranychidae) Development and Feeding Damage

Soybean lines isogenic for glabrous, normal, and dense pubescence developed from the genotypes ‘Davis’, ‘Tracy-M’, and D75-10169 were used in studies of the impact of pubescence on twospotted spider mite, Tetranychus urticae Koch, development and feeding damage under controlled environmental conditions and a known infestation rate. Significant differences in progeny and feeding damage of the twospotted spider mite between genotypes were observed. There were no significant differences between isolines within genotypes for number of progeny. Glabrous isolines had significantly more adult mites leave the excised plant leaf and significantly less feeding damage than the normal or dense isolines. Results suggest that leaf pubescence, or in this case lack of, could be a potential factor in the control of the twospotted spider mite on soybean. This study also demonstrates a reliable and uniform laboratory procedure, under controlled conditions, for rearing the twospotted spider mite, screening soybean germplasm, and determining resistance mechanisms.

Drought tolerance, abscisic acid and electrolyte leakage in fast‐and slow‐growing black spruce (Picea mariana) progenies

To investigate the role that drought tolerance plays in growth, abscisic acid (ABA) accumulation and electrolyte leakage during water stress were compared in fast‐ and slow‐growing black spruce (Picea mariana [Mill.] B. S. P.) progenies. Changes in the ABA content of the needles were quantified using an indirect enzyme‐linked immuno‐sorbent assay validated by gas chromatography electron capture detection. Needle electrolyte leakage was estimated using a conductivity bridge. Seedlings were stressed using (1) osmotic stress, induced by a stepwise increase in concentrations of polyethylene glycol 3 350 (PEG) for ABA study and (2) air drying for electrolyte leakage study. Progenies did not differ in ABA levels under unstressed conditions, but progeny differences were observed under osmotic stress. Needle ABA content increased up to 500% under osmotic stress. Slow‐growing black spruce progenies (25 and 46) accumulated more ABA under moderate (18% PEG), but not severe (25% PEG), osmotic stress. The slow‐growing progenies also leaked more electrolytes under moderate to severe water stress and lost 50% electrolytes at a higher xylem tension, suggesting they suffered more injury and were less dehydration tolerant. Our previously‐published results showed that slow‐growing progenies lost their photosynthesis and stomatal conductance more quickly during osmotic stress and recovered more slowly after rehydration. Therefore, tolerance of dehydration leading to a maintenance of physiological integrity during drought stress could explain the fast growth rates of more vigorous black spruce progenies.

Inheritancee of Tolerance or Resistance to Manganese Toxicity in Soybeans

AbstractSoybeans (Glycine max L. Merr.) differ in their tolerance to Mn. The objective of this study was to determine the nature or mode of inheritance of Mn tolerance in soybeans. Test plants were Forrest (Mn‐intolerant, Fe‐inefficient), T203 (Mn‐tolerant, Fe‐inefficient) and their F2 progeny Forrest × T203 (F×T) and T203 × Forrest (T×F); and Bragg (Mn‐intolerant, Fe‐efficient), Lee (Mn‐tolerant, mod. Fe efficient) and their F2 progeny, Bragg × Lee (B×L), and Lee × Bragg (L×B). The plants were grown in Mn‐toxic soil and in nutrient solutions containing 0.35 and 0.65 mg Mn/liter. Only T203 did not develop some Mn‐toxicity symptoms under conditions of relatively high Mn. The order of symptom severity was Forrest ≥ Bragg > Lee > T203. Manganese toxicity symptoms also varied among the F2 progeny of reciprocal crosses. The leaves of both parents and progenies contained about 500 mg Mn/g dry matter. Some factor(s) other than Mn concentration in the plants appeared to cause the Mn‐toxicity symptoms. The Fe concentration in plant tops was related somewhat to Mn‐toxicity symptoms in that the Fe concentrations were usually greater in Mn‐intolerant than in Mn‐tolerant genotypes. Control of tolerance to excess Mn appeared to be multgenic rather than controlled by a single gene locus. Reciprocal differences in progeny suggested that cytoplasmic inheritance influenced Mn tolerance. Crop failure can be avoided by selecting a Mn‐tolerant soybean to be grown in a soil relatively high in available Mn.

PROGENY TEST OF FINNISH AND CANADIAN AYRSHIRE BULLS FOR VEAL AND BEEF PRODUCTION

An experiment was conducted to obtain progeny test comparisons of Finnish and Canadian Ayrshire bulls for veal and beef production. A total of 83 male calves from four Canadian and four Finnish sires was tested. Best linear unbiased estimates of differences between veal calf progeny of Finnish and Canadian bulls for time on test, average daily gain and feed conversion were 4.00 ± 5.63 days, −.044 ±.038 kg/day and.062 ±.067 kg dry matter intake/kg gain, respectively. For veal carcass traits, progeny differences between Finnish and Canadian bulls for dressing percent and carcass grade, quality, finish and color scores (scores ranged from 1 to 3, except for color score which ranged from 1 to 2, with high score desirable) were.25 ± 1.13%, −.085 ±.232,.146 ±.303,.122 ±.302 and.104 ±.192, respectively. When raised for beef, differences between Finnish and Canadian sired steers were.015 ±.019 kg/day for feedlot average daily gain and.21 ±.66% for dressing percent. None of these differences were significant (P >.05). Based on these results, the importation of Finnish semen would not be expected to materially change the veal and beef performance of Ayrshires in Canada.

Effect of Seed Source on Soybean Strain Performance for Two Successive Generations1

We evaluated the performance of 10 soybean [Glycine max (L.) Merr.] strains by planting seed produced at each of 14 diverse locations in 1967. Significant differences among sources were observed for all characters evaluated. The importance of the range among sources for yield (176 kg/ha), maturity (1.5 days), lodging (0.16 score), height (2.1 cm), seed size (0.59 g/100 seed), field emergence (46.7%), protein percentage (0.50%), and oil percentage (0.23%) will depend on the desired accuracy of strain comparisons. The strains ✕ sources interaction was significant only for maturity and field emergence percentage, indicating that relative performance of strains was consistent across sources.Significant differences among seed sources were detectable for one crop season only, except for maturity and seed size. The range among sources in the second crop season was 0.3 days for maturity and 0.21 g/100 seeds for seed size.Geographical distance between sources was not a reliable indication of potential first‐generation differences among sources. Germination percentage and seed size were not useful as direct indices of differences among sources. However, seed lots of a particular genotype that differ appreciably for either character are likely to have differences in progeny performance.Differences due to seed source may be minimized by growing all test strains, including checks, in the same environment immediately before testing. The persistence test indicated that one common environment immediately before testing is adequate to minimize differences of practical importance.

Relationships Between Type and Performance of Daughters of Artificial Insemination Sires

Progeny group means of Predicted Difference milk yield, Predicted Difference fat yield, per cent of daughters with incomplete first lactations, and Descriptive Type were studied for 417 Holstein active artificial insemination (AI) sires which were production summarized in 1969-70. Three multiple regression analyses were : (1) regression of percent incomplete first lactations on Predicted Difference milk, Predicted Difference fat, and Descriptive Type; (2) regression of Predicted Difference milk on Descriptive Type, and (3) regression of per cent of sire's daughters exceeding breed-age average on Descriptive Type.Progeny average type was nearly independent of progeny average milk yield. Udder traits, with the exception of teats, appeared to be most related to utility of a sire's daughters as measured by yield and staying-ability in first lactation. Rear udder was the most consistently useful type trait for predictive purposes. In all cases, increased progeny average rear udder type was associated with increased merit for milk yield and proportion of daughters completing a first lactation. The regression of Predicted Difference milk yield on progeny average udder support and floor was significant but negative. The multiple R2 for predicting per cent incomplete first lactations, from production and type, was 15.0%. The R2 for predicting breeding value for milk from progeny type was only 8.1%.Differences among progeny means for per cent of breed-age average final type score were associated with progeny differences in stature, fore udder, rump, udder support and floor, rear udder, and front end. The R2 for predicting per cent of breed-age average type from Descriptive Type was 70.9%Descriptive Type generally had only a small association with progeny merit for production and staying-ability in first lactations.