Paternal Half-sib Groups Research Articles

Genetic variation in the humoral immune response in Atlantic salmon ( Salmo salar) against Aeromonas salmonicida A-layer

Antibody responses to Aeromonas salmonicida A-layer were analysed in family material of Atlantic salmon ( Salmo salar), consisting of 791 fish belonging to 34 full-sib groups within 12 paternal half-sib groups. The fish were immunized twice and blood samples were collected three times. Significant increase in antibody titre from first to second, and from second to third sampling, was observed. Genetic variation in antibody titres was observed at the three samplings with estimated heritabilities ranging from 0.16 to 0.20, and a significant heritability estimate was recorded in the antibody response after the second immunization ( h 2=0.16). Moderate to high genetic ( r=0.5–0.72) and phenotypic ( r=0.29–0.57) correlations were found between the titre values at different samplings, and between selected titres and titre increases. Production parameters, such as mean slaughter weight and mean survival rate were obtained for fish which were reared commercially in the sea, and which belonged to the same full-sib groups as those analysed for A. salmonicida A-layer antibodies. No significant correlation between the mean antibody titre to A. salmonicida A-layer in this study and mean slaughter weight and survival rate in full-sib family material in the sea was observed.

Genetic and phenotypic parameter estimates of pelvic measurements and birth weight in beef heifers

Data on 1210 spring-born (1983 to 1988) yearling heifers were analyzed by paternal half-sib procedures to obtain genetic and phenotypic parameter estimates involving birth weight and pelvic measurements. Data included records on 629 Angus, 325 Simmental, and 256 Salers representing 93, 49, and 22 paternal half-sib sire groups, respectively. Heritabilities for birth weight (BW), pelvic height (PH), pelvic width (PW), and pelvic area (PA) for Angus were 0.30, 0.61, 0.28, and 0.43, respectively. Corresponding values for Simmental and Salers heifers were 0.14, 0.34, 0.44, 0.37, and 0.18, 0.02, 0.29, 0.15, respectively. Genetic correlations among pelvic measurements (PH-PW, PH-PA, PW-PA) were positive (0.25 to 1.03) except for the estimate of -0.07 for PH-PW in Simmentals. Genetic correlations between BW and the 3 pelvic measurements (BW-PH, BW-PW, BW-PA) were negative (-0.18 to -0.36) except for the estimates of 0.53 (BW-PW) and 0.26 (BW-PA) in Simmentals and 2.84 (BW-PH) and 0.39 (BW-PA) in Salers. Phenotypic correlations among pelvic measurements ranged from 0.16 to 0.80. Phenotypic correlations between birth weight and the 3 pelvic measurements were consistently lower (-0.02 to 0.09) than the genetic correlations.

Genetic variation in lysozyme activity and spontaneous haemolytic activity in Atlantic salmon ( Salmo salar)

Lysozyme activity and spontaneous haemolytic activity (SH) were analysed in three repeat blood samples of n=960 fish from 34 full-sib groups within 12 paternal half-sib groups of Atlantic salmon, Salmo salar. At the first and second blood-sampling, the fish were vaccinated with a combined fish vaccine. After the third sampling, the fish were challenged with the pathogenic bacterium Vibrio anguillarum. A statistically significant effect of sire on lysozyme activity, SH activity, and survival after vibriosis challenge was found, providing evidence of significant genetic variation in these traits. The estimated heritabilities were low to moderate (0.1–0.3) for the SH activity, and relatively low (<0.1) for the lysozyme activity and survival after vibriosis challenge. The correlations between the three successive samplings were relatively high for the SH activity, but low for the lysozyme activity based on both phenotypic and full-sib records. The full-sib correlations between the lysozyme activity and SH activity were negative, suggesting the existence of negative genetic correlations between these parameters. The correlations between the lytic activities and survival after vibriosis challenge were in general non-significant, except for a negative phenotypic correlation between survival and lysozyme activity at second sampling.

Genetic variation in lysozyme activity in rainbow trout ( Oncorhynchus mykiss)

Lysozyme activity in blood was analysed in full- and half-sib families of rainbow trout, Oncorhynchus mykiss. 1075 fish from 80 full-sib groups within 30 paternal half-sib groups were sampled. The elapsed time between the initial crowding of fish for blood sampling and the collection of a blood sample from a particular fish, affected the lysozyme activity significantly. Statistically significant effects of sire on the lysozyme activity provide evidence of significant additive genetic variation in lysozyme activity in rainbow trout. The estimated heritabilities of the lysozyme activity were in the order of 0.2–0.3 with a standard error of approximately 0.05–0.15. Production parameters, such as mean weight at slaughter and mean survival during the sea-rearing period, were obtained for fish which were reared commercially and which belonged to the same full-sib groups as those analysed for lysozyme activity. The correlations between least squares means of lysozyme activity and production parameters, based on the full-sib records, were not significant.

Genetic variation in haemolytic activity in Atlantic salmon (Salmo salar L.)

Spontaneous and antibody‐dependent haemolytic activity against sheep red blood cells (SRBC) has been studied in serum from Atlantic salmon, Salmo salar L. Considerable increase in haemolytic activity was detected when SRBC were sensitized with haemolysin produced in Atlantic salmon. Haemolytic activity was sensitive both to divalent cations and to heat treatment. Significant reduction in haemolytic activity was detected after absorption with SRBC, indicating the presence of natural antibody against SRBC in Atlantic salmon serum. Persistent haemolytic activity of unsensitized SRBC in serum absorbed to remove natural antibodies was found, which suggests the activation of the alternative complement pathway, while the observed increased haemolytic activity in the presence of specific antibody against SRBC suggests activation of the classical complement pathway. Spontaneous and antibody‐dependent haemolytic activity were both analysed in absorbed and non‐absorbed sera in a family material of Atlantic salmon. The material consisted of 574 fish belonging to 57 fullsib groups within 20 paternal halfsib groups. Fish with signs of sexual maturity generally showed reduced haemolytic activity. Statistically significant effect of sire on the spontaneous haemolytic activity of both absorbed and nonabsorbed serum, and on antibody‐dependent activity, provides evidence of significant additive genetic variation in both the alternative and the classical complement activation in Atlantic salmon. Neither on a phenotypical nor on a family basis were the two traits statistically correlated. The estimated heritabilities were 0.2–0.3 with a standard error of approximately 0.1.

Genetic variation in susceptibility of Atlantic salmon to furunculosis

The purpose of this experiment was to study the magnitude of genetic variation in mortality due to experimental furunculosis; furunculosis is the most serious salmon disease in Norway at present. Fifty fulisib- and 25 paternal halfsib groups of Atlantic salmon, in total 5000 fish, were infected with Aeromonas salmonicida ssp. salmonicida at Vikan AkvaVet, Namsos. Infection was by means of cohabitation, and all fish were marked and kept in the same tank during the experiment. The death rate averaged 68% with large variation between family groups. Heritability of mortality was high, h 2 = 0.48 ± 0.17 for the sire component and h 2 = 0.32 ± 0.10 for the dam component estimates. It is concluded that resistance to furunculosis can be effectively improved by selective breeding.

Distributional characteristics of phenotypic variation within paternal half sib groups for postweaning average daily gain in two beef cattle populations of different origins

Distributional characteristics of phenotypic variation within paternal half sib groups for postweaning average daily gain in two beef cattle populations of different origins

Paternal Effects on Seed Size in a Population of Crepis tectorum (Asteraceae)

Two crossing experiments were designed to examine if there was a paternal (genetic) effect on three seed size parameters (length, width and weight), in a population of the annual Crepis tectorum. An ANOVA on paternal half-sib groups revealed a significant effect of pollen donor identity on seed width and seed weight. Some of the paternal effect reflected differences among pollen donors in the ability to initiate seed development on the recipient heads (% seed set), which was negatively correlated with seed size. This effect was greatest for seed width reflecting strong lateral compression of the seeds in heads with a high seed set. Increasing the number of pollen donors from one to five had no positive effect on seed size variability within flowering heads, suggesting that the expression of genetic variation is weaker at this level. An additional experiment showed that germinability increased with seed size, while only seed width affected seedling growth. These observations are used to discuss the potential for parent-offspring conflict and selective seed provisioning based on embryo size, in this population.

Effect of sire, diet and week of spawning on volume of eggs retained by artificially spawned rainbow trout

Based on the performance of 223 mature, artificially spawned, 2-year-old rainbow trout females, consisting of progeny from 26 sires and 52 dams, the average volume of eggs retained in the ovary and the body cavity (35.9 ml) represented 14.7% of the average of 244.2 ml of eggs spawned per female. Although not specifically measured, it was observed that the majority of the retained eggs were held in the ovary. The variability among females was very large; the standard deviation was 18.7 ml with a coefficient of variation of 52.1%. In terms of number of eggs, an average of 357.4 eggs (14.5%) out of a total of 2453.8 were retained by the female. Diet had a significant effect on eggs retained. Fish reared on a high-protein, high-energy diet retained an average of 41.5 ml which was significantly higher than the 29.4 ml retained by females reared on a low-protein, low-energy diet. The volume of eggs retained by females reared on a commercial control diet (intermediate levels of protein and energy) was intermediate (36.5 ml). Differences in volume of eggs retained among weeks of the spawning season were not significant. The distribution of genetic effects for volume of eggs retained was evaluated by estimating breeding values for daughters from each sire, using data corrected for diet effects. The estimated breeding values ranged from a low of 23.9 ml to a high of 62.2 ml. The average values for paternal half-sib groups ranged from 26.8 to 45.4 ml, with a mean of 35.5 and standard deviation of 5.1 ml. The estimated heritability of volume of eggs retained was 0.34±0.22.

Efficiency of MOET nucleus breeding schemes in selecting for traits with low heritability in dairy cattle

ABSTRACTTheoretical rates of genetic response are calculated for adult multiple ovulation and embryo transfer (MOET) nucleus breeding schemes and conventional breeding systems in dairy cattle. For a single trait breeding objective, the relative responses with MOET schemes decline as the heritability falls and the number of progeny in the progeny test scheme increases. Selection for an aggregate breeding objective of milk yield and another trait, for different values of heritability, correlation and relative economic importance, is also examined. Generally, the overall response of efficient MOET schemes exceeds the progress of an efficient conventional breeding scheme with 50 to 100 daughters per bull. Only if the relative economic weight for the lowly heritable trait exceeds 0·60 and the progeny test is on 200 offspring are conventional systems superior. Testing additional paternal half-sib groups from a MOET scheme gives a considerable extra response, especially when lowly heritable traits have a dominating economic importance.

The genetic influence on serum haemolytic activity in rainbow trout

Haemolytic activity was analysed in sera from 202 rainbow trout ( Salmo gairdneri). The material consisted of 20 full-sib groups within nine paternal half-sib groups. The fish were blood-sampled and individually carlin-tagged. Repeat blood-samples were taken 2 and 8 weeks after the first sampling. An increase in the antibody-dependent haemolytic activity and decrease in the non-specific haemolytic activity, from the first to the second sampling, indicated different activation patterns associated with these responses in rainbow trout. Both the antibody-dependent and the non-specific haemolytic activity showed statistically significant variation between families. The magnitude of the estimated heritabilities ranged from medium to relatively high.

Relationships between breeding values for growth of beef sires in purebreeding and crossbreeding

The studies confirmed that genetic variability for various growth traits, recorded in commercial crossbred and purebred progeny of beef sires, is slightly higher in purebred beef cattle. Breeding values were estimated according to the performance of paternal half-sib groups either purebred or commercially crossbred. Their correlation coefficients ranged from r = −0.007 to r = +0.46. The reason for these relatively low correlations may be, among other effects, due to sire × maternal breed interactions. The presence of these interactions indicates, by analogy to studies in poultry breeding, evidence of specific combining ability which should be taken into account in the selection of beef sires. The studies provide confirmatory evidence that recurrent selection of beef bulls to be used in commercial crossbreeding may be accomplished on the basis of fattening crossbred performance.

Genetic Relationships and Additive Genetic Variation of Productive and Reproductive Traits in Guernsey Dairy Cattle ,

Data were first lactation production and reproduction records initiated from 1958 to 1981 in two experiment station Guernsey herds. Heritability estimates using paternal half sib groups were .24±.12 for milk yield, .27±.12 for fat yield, and .77±.15 for fat percentage. Heritability estimates for reproductive traits ranged from .01 to .04 for number of services, service period, conception rate, and days open, but were higher for days in milk at first breeding (.12) and age at first calving (.13). Except for age at first calving, coefficients of additive genetic variation were larger for reproductive traits than for productive traits. Genetic correlations between measures of production and reproduction were moderate to large and antagonistic, except that the relationship between production and age at first calving was favorable. Breeding value estimates for milk yield and reproduction were negatively correlated for sires with above average breeding values for milk yield. Huge phenotypic variances for reproductive traits masked substantial additive genetic variation for these traits. When all things are considered it seems unwise to ignore reproductive performance in selection programs for dairy cattle.

Genetic linkage between loci for a red cell alloantigen (U) and serum protease inhibitor (Pi) in the horse.

Preliminary evidence for the fifth autosomal linkage group in the horse, comprised of the loci for a red cell alloantigen (U) and serum protease inhibitor (Pi), was demonstrated by means of paternal half-sib groups in thoroughbred, standardbred and Arabian breeds. Recombination frequency in males was estimated to be 0.125 +/- 0.019.

Factors affecting birth weight of Santa Gertrudis calves

SUMMARYBirth weights of 568 Santa Gertrudis calves by 15 sires out of 111 different dams over a 14-year period were obtained from a herd in Cuba. Year of birth, season of birth, sex of calf, sire and dam all had highly significant influences upon birth weight but there was no effect of dam age or parity. Calf inbreeding ranged from 0 to 25% and led to a decrease of 012 kg in weight for each 1% increase in inbreeding. Calves surviving to weaning or dying between birth and weaning were of similar mean weight. Calves dying at birth were some 4·53 kg above the overall average of 38·59 kg. Sire effects covered a range of some 9·85 kg in birth weight. Heritability of birth weight estimated from an intra-class correlation between paternal half-sib groups was 0·67. Repeatability estimates were of the order of 0·22 from intra-class correlation and 0-24 on the basis of regression of later on earlier records. The overall least squares mean weight of 38-59 kg was several kg higher than previous estimates in the literature.

Variation in postweaning weight gains of steers independent of appetite.

A total of 87 Hereford steers, including 18 paternal half-sib groups, were individually fed a standard ground ration in eight trials. Each trial lasted 32 weeks. Daily feed allotments were restricted to the expected minimum consumption of any contemporary steer. The mean weekly feed consumption was 47.2 kg when a phenotypic CV of 1.7%. The mean weekly weight gain was 5.1 kg with a phenotypic CV of 9%. Since variation in feed consumption among contemporary steers was essentially eliminated by the experimental feeding procedure, variation in weight gain provided direct evidence of differences in intrinsic efficiency of feed utilization for growth and maintenance. Variation among paternal half-sib groups for average weekly gain was significant (P<.05), suggesting that additive genetic variation existed for efficiency of feed utilization.

Variation in Conception Rates of Guernsey Cattle

Summaary Data from 42 Guernesy herds served by one A.I. stud, and 37 Guernsey herds served by another were analyzed to determine heritability of conception rate. The data included records of 2,470 daughters of bulls in these studs, and breedings occurred during the period of 1950 to 1959. Heritability estimates from intrasire correlations of paternal half-sib groups were 0.08 and 0.02 based on an average of from one to four records per daughter, while those based on heifer records only were 0.06 and zero, respectively. Regression of daughters on dams yielded heritability estimates of 0.03 and 0.10 for the two studs.

Hereditary Variation in Conception Rate of Holstein-Friesian Cattle

Summary Variation in conception rates (based on birth of a live calf from first insemination to a high-fertility service sire) of 1,406 Holstein females was studied at one or two service periods (1,824 records) in 41 artificially inseminated herds. Fertility did not vary significantly between herds. Conception rates ranged from 43 to 94% in 27 paternal half-sib groups of heifers (P The heritability of conception rate was estimated from intrasire correlations of paternal half-sib groups to be approximately 8.5%. A comparison of the records of daughters at both service periods from 22 sires showed a trend toward an interaction between sire and parity of daughters (P ≠ 0.07). The value of selection in improving conception rate is discussed.