Sire Components Research Articles

GENETIC PARAMETER ESTIMATES FOR EIGHT WEEK BODY WEIGHT IN A FOUNDATION STOCK OF MALE LINE BROILER CHICKENS

The objectives of this study were to estimate heritabilities and genetic correlations for eight week body weight in a foundation stock of male line broiler chickens. A total of 2,086 birds comprising 1500 hens and 586 cocks were used in 3 generations. At hatch, chicks used were wing-banded, weighed and housed on deep litter. Body weights of birds were subsequently taken at 2, 4, 6 and 8 weeks of age. For each generation, data obtained were utilized to estimate heritabilities, genetic and phenotypic correlations from sire component of variance. Selection action (Sel action) statistical software was used to estimate heritability, genetic and phenotypic correlations. Correlations were moderate to high. Heritability estimates for generation 1 ranged from moderate to high 0.34 (CW2) to 0.75 (CW8), low to high for generation 2 (0.17) for CWO and (0.88) for CW8 and positively low for CWO to high for CW8 (0.16 to 0.81) for generation 3. This points to the existence of an appreciable amount of additive genetic variance in the flock and indicates that improvement in the traits can be brought about by intrapopulation selection. The high and positive genetic and phenotypic correlations indicate the pleiotropic action of genes controlling these traits, and that by direct selection for anyone of them; genetic improvement in the others will be realized as correlated responses.

Estimation of genetic parameters as well as trends for growth traits in Harnali sheep

The current study focussed on the growth traits pertaining to Harnali sheep maintained at Sheep Farm, LUVAS, Hisar and data were recorded from pedigree sheets of 1278 animals. Growth traits considered were birth weight (BW), weaning weight (WW), six-month weight (6MW), yearling weight (YW), and pre-weaning average daily gain (PRWDG) and least-squares means for corresponding traits found to be 3.28±0.02 kg, 12.89±0.07 kg, 17.06±0.06 kg, 24.36±0.06 kg, and 106.74±0.61 g, respectively. Effect of different factors like period of birth, sex of animal and dams’ weight at lambing was studied on growth traits. Except YW, significant effect of period of birth was observed on all the growth traits. Sex had significant influence on BW only however, dams’ weight at lambing affected significantly all the considered growth traits except YW. By leveraging the sire component of variance and covariance from mixed model analysis, the paternal half-sib correlation method was used to estimate genetic as well as phenotypic parameters. Estimates of heritability for BW, WW, 6MW, YW and PRWDG were 0.28±0.07, 0.33±0.07, 0.31±0.07, 0.12±0.04 and 0.27±0.06, respectively. Genetic as well as phenotypic trends for WW and PRWDG were found to be positive. Moderate range of genetic variability at weaning weight and its positive genetic and phenotypic correlations with growth traits specially six month’s weight indicated that genetic improvement could be possible through early selection at weaning weight in Harnali sheep.

Effect of genotype and egg weight on hatchability properties and embryonic mortality pattern of native chicken populations

Fertility and hatchability are 2 major parameters that highly influence the reproductive performance of chicken breeds. The objective of this study is to investigate how the genetic background of chickens affects the aspects of fertility, hatchability, and embryonic mortality pattern. Six different native chicken genotypes (black, black-barred, brown, gray, naked neck, and frizzle) kept under similar conditions were evaluated. A total of 1,645 fertile pedigreed eggs from all genetic groups were collected and incubated in forced draft setter. Fertility, hatchability, embryonic mortality, and hatched chick weight were determined. The data were subjected to a one-way analysis of variance with breed (genotype) as a fixed effect. Sire component of variance were used to compute heritability estimates for hatchability traits. The results showed that the fertility and hatchability of the eggs produced from the naked neck or frizzle genotypes exhibited higher values compared to the other genetic groups. An increase in the relative weight of hatched chicks was detected in hatching eggs weighing 44 g or higher. Therefore, attention should be given to the egg size produced by native chicken populations to achieve maximum hatchability performance. Multiple regression analysis revealed that the settable egg weight and the egg weight loss during incubation are the main factors affecting the relative weight of hatched chicks of all genotypes.

Selection for social genetic effects in purebreds increases growth in crossbreds

BackgroundAverage daily gain (ADG) in pigs is affected by both direct and social genetic effects (SGE). However, selection for SGE in purebreds has not conclusively been shown to improve ADG in crossbreds, and it is unknown whether SGE in purebreds are equal to those in crossbreds. Moreover, SGE may reflect dominance related behaviour, which is affected by the variation in body weight within a group. Therefore, we hypothesized that (a) there is a positive effect of parent average SGE estimated in purebred pigs on phenotypic ADG in crossbred offspring, and (b) there is an interaction between SGE on ADG and standard deviation in starting weight of pigs within the group. We also hypothesized that (c) social genetic variance for ADG exists in crossbred pigs, and (d) there is a favourable genetic correlation between SGE on ADG in purebred and crossbred pigs.ResultsWe found a statistically significant interaction between the standard deviation in starting weight and SGE within groups, and conditioning on the mean standard deviation in starting weight, we found a favourable regression coefficient (0.37 ± 0.21) of ADG in crossbreds on SGE in purebreds. Variances for SGE were small in both Landrace (L) and Yorkshire (Y), and higher for SGE in both the dam and sire component of crossbred YL. The genetic correlations between SGE in purebreds and the dam or sire component of SGE in crossbreds were also favourable (0.52 ± 0.48 and 0.34 ± 0.42, respectively), although not significantly different from 0.ConclusionsWe confirmed that there is a positive effect of SGE estimated using purebred information on phenotypic ADG in crossbreds, and that the largest effect is achieved when the within-group variation in starting weight is small. Our results indicate that social genetic variance in crossbreds exists and that there is a favourable genetic correlation between social genetic effects in purebreds and crossbreds. Collectively, our results indicate that selection for SGE on ADG in purebreds in a nucleus farm environment with little competition for resources can improve ADG in crossbreds in a commercial environment.

Inheritance of growth traits and impact of selection on carcass and egg quality traits in Vanashree, an improved indigenous chicken.

The present study was carried out to assess the inheritance of growth traits and to study the effect of selection on carcass characteristics and egg quality traits in Vanashree, an improved indigenous chicken. Estimates of heritability were high for body weights recorded at 4, 5 and 6weeks of age and 8th week shank length, while it was moderate for 8th week body weight. Estimates of heritability on sire component of variance declined as age increased from 4 to 8weeks of age. The genetic and phenotypic correlations among various growth traits were positive and high in magnitude. The body weight continued to increase up to 40weeks of age particularly in male birds, while there was little increase in shank length from 20 to 40weeks of age particularly in hens. There was no significant change in carcass characteristics and egg quality traits except that there was some improvement in dressing percentage over the generations. Sex effect was significant on relative weights of the breast, legs, gizzard, liver and heart and abdominal fat percentage. There was increase in Haugh unit and albumen index, yolk percentage, yolk to albumen ratio and yolk colour in the present generation. The results suggest that there is adequate additive genetic variation for growth traits in the population and that Vanashree chicken could continue to be improved so as to make it a promising dual purpose purebred indigenous chicken for increasing the productivity of free range or semi-intensive systems of production.

Impact of microsatellite based selection on grower and layer economic traits in Rhode Island Red chicken

The present study aimed to assess impact of selection based on microsatellite-genotypes at ADL0176 and the association of microsatellite-genotypes at ADL0176 and MCW0044 located on chromosome number-2 with growth and layer economic traits in RIR chicken could reveal impact when the sire component influenced the growth and layer economic traits of the progeny-birds with different genotypes at ADL0176 and MCW0044 microsatellites. DD, EE and CC/AD-genotypes at ADL0176 microsatellite had corresponding higher BW28, BW40 and EW40 of the progeny than other genotypes, while BB-genotype at MCW0044 had higher BW40. Present findings could suggest the use of microsatellite-marker based selection for faster genetic improvement of economic traits in RIR chicken, provided its validation by taking larger sample sizes.

Genetic Studies on Growth Traits in Rajasri Variety of Backyard Chicken

Background: Rajasri, a synthetic dual purpose variety suitable for backyard rearing. The current study was aimed to study the inheritance of Rajasri birds. Methods: This study was carried out during April 2019 to August 2019 at poultry research station, Hyderabad. Data collected on 6980 chicks produced from 220 sires and 660 dams in half sib mating in 4 hatches were utilized to estimate the genetic parameters. Result: Highly significant (P≤0.01) influence of hatch and sex on body weights and average daily gains and shank length was observed. The overall least-squares means of body weights at birth, 2, 4, 6, 8, 10, 12, 14, 16, 18 and 20 weeks of age were 32.35±0.4, 80.87±0.17, 184.29 ±0.44, 351.49±0.76, 576.16±1.10, 741.31±0.97, 878.03±0.91, 1038.9±0.91, 1160.61±0.99, 1271.59±1.27 and 1370.64±1.72g and shank length at 4 and 6 weeks of age were 47.49±0.05 and 62.18±0.06 mm, respectively. The overall least-square means of average daily gain peaks at 6-8 weeks age. Heritability estimates of body weights through sire component ranged from 0.04±0.016 (BW20) to 0.44±0.05 (BW0). Genetic and phenotypic correlations among body weights were ranged from 0.02±0.14 (BW6-BW14) to 0.98±0.01 (BW16-BW18) and 0.003±0.01 (BW2-BW20) to 0.93±0.01 (BW18-BW20), respectively.

Estimation of heritability and repeatability for pre-weaning body weights of domestic rabbits raised in the humid tropics

Heritability and repeatability estimates are needed for the genetic evaluation of livestock populations and consequently for the purpose of upgrading or improvement. Pooled data on 302 progenies from three consecutive parities of purebred rabbit breeds (Chinchilla, Dutch and New Zealand white) raised in Derived Savanna Zone of Nigeria were used to estimate heritability and repeatability for pre-weaning body weights between 1st and 8th week of age. The experiment was carried out at the Rabbitry Unit of the Teaching and Research Farm of the Ebonyi State University, Abakaliki. Traits studied include: Kit Weight at birth (KWB), 2nd week (K2W), 4th week (K4W), 6th week (K6W) and 8th week (K8W). Nested random effects analysis of (Co) variance as described by Statistical Analysis system (SAS) were employed in the estimations. Respective heritability estimates from the sire component (h2S ) and repeatability (R) as intra-class correlations of repeated measurements from the three parities for KWB, K2W, K4W and K8W were 0.59±0.24, 0.55±0.24, 0.93±0.31, 0.28±0.17, 0.64±0.26 and 0.12±0.14, 0.05±0.14, 0.58±0.02, 0.60±0.11, 0.20±0.14. Heritability and repeatability (except R for KWB and K2W) estimates are moderate to high. In conclusion, since pre-weaning body weights in the present study tended to be moderately to highly heritable and repeatable, hence, improvement of rabbits raised in derived savanna zone can be realized through genetic selection criterions.

Estimation of genetic parameters for production and reproduction traits in Kashmir Merino sheep

Data pertaining to 6,300 birth records spread over 21 years of Kashmir Merino sheep maintained at Government Sheep Breeding Farm Kralapathri and Government Sheep Breeding Farm Goabal Kashmir and Fleece Testing Laboratory were used to estimate the genetic parameters. The genetic parameters for birth weight (BWT), 6 months body weight (6-MWT), yearling body weight (12 MWT), greasy fleece yield of first clip (GFY-1), greasy fleece yield of second clip (GFY-2), fiber diameter (FD), staple length (SL), age at first lambing (AFL) and inter-lambing period (ILP) were estimated by paternal half-sib correlation method using sire components of variance and covariance. The heritability estimates for BWT, 6-MWT, 12-MWT, SL, GFY-1, GFY-2 were moderately high whereas the estimates of heritability for FD, SL, AFL and ILP were low respectively. The genetic correlation between different traits ranged from - 0.73±0.10 to 0.87±0.04 while as phenotypic correlation different traits ranged from - 0.66±0.07 to 0.54±0.01. Keeping in view its high heritability of SMW and favorable correlations with birth weight, yearling body weight, wool traits and age at first lambing, it is concluded that selection on basis of 6-MWT would be effective to improve growth, quality wool production and age at first lambing in Kashmir Merino sheep.

222 Sire influence on hatchability and heritability estimates of quails in a humid tropical environment

Abstract Study on Japanese quail was undertaken to determine sire influence on hatchability and estimation of heritability values among three strains of the birds in a humid tropical environment in Nigeria. Fertility and hatchability traits; body weight (BW), shank length (SL), thigh length (TL), breast length (BL), keel length (KL), and wing length (WL) at 2nd, 6th, 10th weeks of age were measured on 300 crossbred progeny from 270 Cinnamon brown dam mated with three different strains of sire namely; Cinnamon brown (CB), Panda White (PW), and Silver Brown (SB) in the mating ratio of 1: 4. The data were subjected to analysis of variance appropriate for completely randomised block design (CRBD) and significant means separated with Duncan’s multiple range tests. Heritability estimate was done using the sire component equation. The average percent fertility (71.64 - 75.76 %), hatchability (50.41 -57.17%), percent dead in germ (55.00 - 69.08%),dead in shell (11.20 - 18.25%) were significantly (P < 0.05) better in PW - sired progeny, while piped (13.06 - 20.11%), brooding (3.00 - 4.67%) and rearing mortality showed no significant difference (P > 0,05) among the three sired - progeny. The analysis showed that at weeks two, six, and ten, SB - sired progeny had superior heritabity estimates in most of the linear traits and recorded lower indeterminate values as compared with other sired - progeny. Moderate to high heritability estimate (42 - 83%) obtained for body weight at six and 10 weeks among the three progenies suggests that selection for body weight or growth rate in Japanese quail should be carried out at 6 and 10 weeks of age and that PW - sired progeny be selected for better hatchability for enhanced breeding program for both egg and meat production in the strains.

Meta-analysis of seminal traits affecting bull fertility.

The pedigree information on bulls was collected from Frozen Semen Bank (FSB). Male reproductive data on seminal characters (semen volume (SV), sperm concentration (SC), initial progressive motility (IPM), post-thaw motility (PTM), and total spermatozoa (TS)) were analyzed to calculate their repeatability, heritability, genetic correlation, phenotypic correlation, and environmental correlation values. The principal component analysis revealed SV and SC were the two most important characters among the five seminal characters that can be further used. The repeatability value for seminal characters was very low (0.02-0.2). The sire component of heritability value varied from very low to low (0.0001 to - 0.24). The dam component of heritability value varied from very low to high (0.01 to 0.64). The genetic correlation value calculated from the sire component indicated a slightly antagonistic relationship between SV and SC (- 0.007) and SV and PTM (- 0.049). The environmental correlation value was found to be negative for all the traits except the value calculated from the dam component between SC and IPM (0.027). The phenotypic correlation values between the seminal traits were low and mostly negative except between SC and IPM (0.107) and PTM and TS (0.109). Statistically significant correlation was observed between PTM and SV (- 0.157), PTM and IPM (- 0.145), PTM and TS (0.109), and SC and IPM (0.107). Since the estimated heritability, repeatability, and the correlation values were found low, individual selection method cannot be applied on these bulls.

Genetic analysis of body weight in a selected line of Rhode Island Red grower chicken

A total of 1207 pedigreed progenies of 50 sires and 177 dams of a selected line of Rhode Island Red chicken were investigated in two hatches at ICAR-Central Avian Research Institute for genetic analysis of their body weights. The genetic and non-genetic parameters of chick weight at day-old age and body weight at different ages were estimated using least squares analysis of variance. The heritability and correlation coefficients were estimated for different traits using paternal half-sibs. The mean sum of squares for sex component of variance was significant for body weights at third week of age onwards, males being heavier throughout the ages. Sire component of variance was also significant for chick weight and different body weights except the estimates at 6th and 16th week of age. Hatch component of variance was highly significant for chick weight and body weights upto 12th week of age. Regression effect of chick weight on subsequent body weights was found significant specifically for body weights from 1st week onwards to 20th week of age. The heritability estimates were 0.775±0.151 for chick weight, 0.303±0.09 to 0.44±0.142 for body weights from 1st week to 12th week of age, and 0.258 to 0.248 for body weights from 16th week to 20th week of age. The estimates at lower age could be used in selection programme based on the flock's own performance to improve those traits. The genetic and phenotypic correlation coefficients were positive and highly significant in most of the cases. The corresponding estimates ranged from 0.044 to 0.990 and 0.020 to 0.788, and these coefficients could be combined in construct of standard selection indices for optimum growth in body weight that might be adopted in future breeding strategy for this RIR chicken genotype.

Estimation of genetic parameters for production traits in Munjal sheep

Astudy was carried out to estimate the genetic parameters of production traits in Munjal sheep using 16 years (2001–2016) data of 462 sheep maintained at Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar Mixed model analysis included the sire as a random effect and effects of period of birth, sex, dam's age at lambing as fixed effects. Heritability estimates and genetic correlations for different traits were calculated by paternal half-sib correlation method using sire components of variance and covariance. Period of birth and sex of lamb had significant effect (P<0.05) on all traits except greasy fleece weight (GFW). Dam's age at lambing had significant (P<0.05) effect only on birth weight. The overall least squares means of production traits recorded for birth weight (BW), weaning weight (WW), six months body weight (SMW), yearling body weight (YBW) and annual GFW were 4.1±0.07, 15.57±0.22, 20.79±0.53, 26.40±0.41 and 1.84±0.04 kg, respectively and the corresponding heritability estimates were 0.35±0.18, 0.48±0.20, 0.57±0.24, 0.48±0.25 and 0.52±0.22, respectively. Genetic correlations among production traits were positive and low to high in magnitude (0.10±0.05 to 0.76±0.05) and the highest genetic correlation of 0.76±0.05 was found between SMW and YBW. Phenotypic correlations among various production traits were found to be positive and significant ranging from 0.17±0.04 to 0.81±0.03. It was concluded that selection on the basis of SMW would be the best approach to improve growth performance in Munjal sheep as the trait has high heritability and positive genetic correlation with other body weights.

Genetic evaluation of egg quality traits in Uttara fowl using MMLSML

External and internal egg quality traits of Uttara fowl reared at instructional poultry farm were measured in 125 eggs selected from 25 sires. The heritability estimates of traits were estimated from sire component of variances and covariances using mixed model least- squares and maximum likelihood (MMLSML). Heritability estimates for external egg quality traits ranged from 0.34 to 0.83 and for internal egg quality traits from 0.19 to 0.81. Genetic correlation between egg weight and eggshell thickness (EST) was positive (0.43) and EST showed high genetic correlations with eggshell weight (0.79) also. Internal egg quality traits like albumen height showed high positive genetic correlations with albumen weight (0.63), albumen index (0.84), yolk height (0.71) and yolk index (0.65). In conclusion, higher albumen height tends to have better internal egg quality and it is feasible to improve egg quality through selection.

Estimation of Genetic Parameters for Reproduction Traits in Munjal Sheep

Estimates of genetic parameters are important to determine the selection criterion and future breeding strategies. Munjal is one of the heaviest breed of sheep and is popular among farmers for faster growth rate and efficient reproduction. The data of reproduction traits of 287 Munjal sheep maintained at Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar for 16 years (2001-2016) were utilized to estimate the genetic parameters. The mixed linear model used for analysis included the sire as a random effect and period of birth and dam’s age at lambing as fixed effects. Heritability and genetic correlations for different traits were estimated by paternal half-sib correlation method using sire components of variance and covariance. All the reproduction traits under study viz., Age at first service (AFS), weight at first service (WFS), age at first lambing (AFL), weight at first lambing (WFL) and first lambing interval (FLI) were significantly affected by period of birth. However, effect of dam’s age at lambing was non-significant on all traits. The overall least squares mean for AFS, WFS, AFL, WFL and FLI were estimated as 563.08±14.43days, 29.06±0.16 kg, 713.48±14.02 days, 31.30±0.16 kg and 351.82±1.12 days, respectively. Heritability estimates for AFS, WFS, AFL, WFL and FLI were obtained 0.19±0.12, 0.24±0.15, 0.17±0.10, 0.27±0.15 and 0.05±0.01, respectively. The genetic correlation of AFS with AFL (0.96±0.01) and WFS with WFL (0.94±0.03) was high and positive indicating that ewes in good body condition at service maintaining it after lambing. Low estimates of heritability for reproduction traits indicated that these traits have low additive genetic variance and mostly influenced by environment. So, these traits can be improved by better managemental practices.

Out crosses between seasonally different segments of a Pacific salmon population reveal local adaptation

In salmon populations, local adaptation to seasonally varying incubation temperature is characterized by temperature-adjusted development times [measured in degree days – accumulated temperature units (ATUs)] that differ between control and F1 hybrid crosses that were made between temporally separated population segments, a contrast not expected in a panmictic population. We examined adaptation of embryo development time to seasonally cooling temperature in a population of pink salmon by estimating genetic components of variation in control and hybrid F1 crosses made between members of early- and late-spawning subpopulations, and replicated our observations in independent odd- and even-year brood lines. In each brood line, both sire and dam components of variation of development time were significant and accounted for a substantially larger portion of variation than their interactions, which suggested that natural selection has acted primarily on additive genetic variation. The implications of these results are that (1) spatially or temporally proximate salmon populations may be structured by distinct adaptations; (2) artificial relaxation of local geneflow barriers may lead to depression of fitness; and (3) populations of salmon genetically structured by local adaptation may carry variation that enhances their persistence during rapid climate change.

Genetic characterization of layer germplasm evolved by AICRP on poultry breeding

The study was carried out to evaluate White Leghorn lines (IWH, IWI, IWK and layer control-LC) and to genetically characterize IWH and LC lines for production traits. Body weight at 20 weeks was significantly higher in LC, IWH and IWK lines as compared to IWI. Similarly, body weight at 40 weeks of age was also significantly higher in LC as compared to IWK, IWH and IWI. Among selected lines, it was significantly higher in IWK than that in IWH and IWI. The ASM was significantly lesser in IWH followed by IWI, IWK and LC. Egg weight at 28 weeks was significantly higher in LC followed by IWK, IWI and IWH. However, egg weight at 40 weeks was significantly higher in IWK followed by LC, IWI and IWH. Similarly, egg weight at 52 weeks of age was significantly higher in IWK followed by LC, IWH and IWI. Egg mass at 40 weeks of age was significantly higher in IWH, IWI and IWK as compared to LC. Egg mass at 52 weeks of age was also significantly higher in IWH as compared to IWK, IWI and LC. However, this trait was significantly higher in IWK and IWI as compared to LC. Heritability estimates on sire component of variance were high for all the traits except for ASM (moderate) in IWH while, they were high for all the traits except for body weight at 40 weeks of age (moderate) in LC.The study concluded that despite the continuous selection, these lines differ for many of the production traits and considerable genetic variation exists for many of the traits in IWH and LC, and IWH line could continue to be improved for production traits.

Genetic analysis of layer performances in a selected line of Rhode Island Red chicken

The study aimed to estimate genetic parameters of layer performance traits in a selected line of Rhode Island Red (RIR) chicken maintained at this institute. The performance traits were recorded on 433 pedigreed pullet progenies, offsprings of 48 sires and 113 dams; and data were analyzed by least squares analysis of variance. Heritability and correlations were estimated using full-sib correlation method. The least squares means of age at first egg (AFE), body weights (BW20, BW40), egg weights (EW28, EW40) and egg production up to 40 weeks of age (EP40) were estimated. Almost all the traits were significantly affected by sires and hatch, whereas dam within sire could not affect any trait. Birds’ housing weight demonstrated significant regression effect on the above traits. The heritability estimates from sire component of variance ranged from 0.003 to 0.241 in different traits. The heritability estimates from dam component and sire plus dam component ranged from 0.011 to 0.670 and 0.061 to 0.379, respectively. The ranges of genetic and phenotypic correlations among the traits were 0.130 to 0.918 and 0.015 to 0.542, respectively. The varied direction of correlations revealed that selection for earlier age at first egg would favour moderately lower body weights and egg production. Again selection for heavier EW28 would favour late AFE and lower egg production. Present findings would serve as the pre-requisites for chalking out the breeding strategies for genetic improvement of RIR chicken.

GENETIC ANALYSIS OF PRODUCTON AND REPRODUCTION TRAITS IN SURTI BUFFALO ON AN ORGANIZED FARM

Normal 0 false false false EN-US X-NONE GU Estimation of genetic parameters for production traits is important to know the genetic basis for production performance as well as help the breeder in planning of breeding programs for genetic improvement. The data pertaining to milk production and other records of Surti buffalo for the present study were collected from breeding and production records of Livestock Research Station, Navsari from 1988 – 2002. Total there were daily milk production records (morning and evening) for 298 lactations from 130 buffaloes were collected under 15 sires. Maximum data up to four lactations were collected of each animal. Other records i.e. Age at First Calving (AFC), lactation length, Service period (SP), Dry Period (DP), Gestation Period (GP), Calving Interval (CI) were collected for animals under study. The records were analyzed using least squares analysis procedures. The Harvey (1990) programme was used to estimate the genetic parameters i.e. heritability (h 2 ), genetic and phenotypic correlations by Paternal Half sib method. The h 2 estimates for first lactation yield, AFC, first gestation period and first calving interval were found to be high. h 2 estimates for other traits i.e. first lactation length, first service period and first dry period could not be calculated on account of negative sire component of variance. The first lactation yield and age at first calving, and age at first calving and first gestation period were found to be negatively correlated. st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:Table Normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:Calibri,sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:Times New Roman; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;}

Genetic parameters of some layer performance traits in a control line of Rhode Island Red chicken

The study aimed to assess genetics of some layer performance traits in a control line of Rhode Island Red (RIR) chicken maintained at Central Avian Research Institute, Izatnagar. A total of 193 pedigreed pullet progenies of 30 sires mated with 41 dams in two hatches were investigated. Data were analyzed by least squares analysis of variance, and heritability and correlation parameters of different traits were estimated using full-sib correlation method. The least squares means of age at first egg, body weights at 20th and 40th week, egg weights at 28th and 40th week and part period egg production upto 40 weeks of age were estimated. Sires significantly (P<0.05) affected the estimates of body weights, but dam within sire could not affect (P<0.05) any estimate. Hatch influenced (P<0.05) the estimates of age at first egg and body weight at 40th week of age. Birds’ housing weight demonstrated significant regression effect on the estimates of age at first egg, body weight and egg weight at 40th week of age. The heritability estimates from sire component of variance of the traits ranged from 0.018 to 0.438. Corresponding estimates from dam component and sire plus dam component ranged from 0.060 to 0.643 and 0.102 to 0.355. The genetic and phenotypic correlations among the traits were low to high in magnitude when estimated from sire plus dam component. The investigation generated some valuable genetic information of layer performances which might be used as the pre-requisites for chalking out of breeding strategies for its genetic improvement.