Genetic Parameters For Growth Traits Research Articles

Genetic and phenotypic parameters of body weight in West African Dwarf goat and Djallonké sheep

The International Trypanotolerance Centre's small ruminant breeding programme was initiated in 1995. The aim was to increase the efficiency of meat production and the trypanotolerance of the animals (sheep and goat). To achieve that goal, selection was based on estimated breeding values for daily weight gain from 4 to 12 months of age measured on trypanotolerance challenge. The purpose of this study was to estimate genetic parameters for growth traits and to evaluate genetic trends in West African Dwarf goat and Djallonké sheep resulting from the breeding programme under a low input production environment. Data for West African Dwarf goat and Djallonké sheep included birth weight (BW), weaning weight (W120), yearling weight (W360), pre-weaning (GR0–4) and post-weaning (GR4–12) growth rate. The data were analysed using an animal model that accounted for fixed effects of sex, year of birth, season of birth, parity of the dam, type of birth and the interaction year by season of birth. Estimates of heritability for BW, W120, W360, GR0–4 and GR4–12 were 0.5, 0.43, 0.30, 0.32 and 0.11 for goats and 0.39, 0.54, 0.21, 0.54 and 0.23 for sheep, respectively. The genetic correlation between BW and W120 was high for goats (0.74) and moderate for sheep (0.47). Genetic correlations between W120 and GR4–12 were high (0.92) for goats and moderate (0.49) for sheep. Between GR0–4 and BW the correlation was positive but low for sheep (0.26) and moderate for goats (0.60). Positive trends were found in mean estimated breeding values for animals born in the period 1995–2002 which demonstrated the effectiveness of the implemented breeding programs.

DIFFERENT MODELS FOR ESTIMATING GENETIC PARAMETERS FOR GROWTH TRAITS OF HOLSTEIN FRIESIAN UNDER SEMITROPICAL CONDITIONS

SUMMARY Estimates of genetic parameters resulting from three different models for birth weight, weaning weight, yearling weight and total gain were compared. Data consisted of 823 Holstein-Friesian animals progenies of 25 sires and 459 dams in a single herd. The MTDFREML programs were used to estimate heritabilities, predicted transmitting abilities (PTA) and genetic correlations. The three models compared were: Model I, a sire model, included year-season of birth and sex of calf as fixed effects and sire as random effect. Model II, a sire-dam model, included, in addition to the effects in model I, dam as a second random effect. Model III, a full animal model, included, in addition to the fixed effects of model I, animal additive direct genetic effect, maternal genetic effect and permanent environmental effect, as three random effects. The likelihood function showed that the full animal model best fit the data. Heritability estimates and genetic correlations obtained from model III were higher than those obtained from models I and II for all traits. Models I and II resulted in changes in ranking for PTA in contrast with model III. In conclusion, full animal model could be most appropriate for estimating genetic parameters for growth traits than the sire or the sire-dam models.

Estimation of (Co)variance Components and Genetic Parameters of Growth Traits in Beef Cattle

Dadi, H. Schoeman, S.J. and Jordaan, G.F. 2004. Estimation of (co)variance components and genetic parameters of growth traits in beef cattle. J. Appl. Anim. Res., 26: 77–82. Variance components and genetic parameters of birth weight (BW), weaning weight (WW) and average daily gain (ADG) in a multibreed beef cattle population were estimated by Restricted Maximum Likelihood (REML) procedures. Four different unitrait animal models were fitted ranging from a simple model with the animal direct effects as the only random effect to the model allowing for both genetic and permanent maternal environmental effects. The simple model excluding maternal effects most likely inflated direct heritability estimates. The model that included direct genetic and permanent maternal environmental effects generally best described the data analysed. Estimates of permanent maternal environmental effects were 0.15 (BW), 0.24 (WW) and 0.24 (ADG), the effects were the important factor determining WW and ADG. Direct and maternal genetic correlations were 0.61, −0.53 and −0.79 for BW, WW and ADG, respectively under the model accounted both for maternal genetic and permanent maternal environmental effects.

Genetic parameters for growth traits in South African Brahman cattle

Genetic parameters for growth traits in the South African Brahman breed were estimated using ASREML from data records of birth weight (BWT) = 41 509, weaning weight (WWT) = 37 705, yearling weight (YWT) = 22 682 and final weight (FWT) = 13 055 collected between 1985 and 2002. The direct additive contribution to BWT, WWT, YWT and FWT were 0.28, 0.14, 0.14 and 0.18 respectively. The corresponding maternal heritability estimates were 0.11, 0.06, 0.05 and 0.03 respectively. The maternal permanent environmental component due to the dam contributed 3-7% of the total phenotypic variances of the traits under consideration. The corresponding contribution of herd-year-season x sire interaction ranges from 5% to 6%. The genetic correlation between animal effects was -0.36 for BWT. The prospects of improvement of these traits by selection seem possible and contribution of maternal permanent environment due to dam is of considerable importance as maternal effects. South African Journal of Animal Science Supp 2 2004: 44-46

Genetic parameter estimates in Sabi sheep

Genetic parameters for growth traits in Sabi sheep were estimated using asreml from data records of 4123 lambs from 130 sires and 1131 dams collected between 1984 and 1994. Reproduction traits and lamb survival to weaning were analysed fitting a sire threshold model. The direct additive contribution to birth weight, 30-day weight, 60-day weight, weaning weight (WW), preweaning average daily gain (ADG), 12-months weight, 18-months weight and Kleiber ratio (KL=ADG to weaning/WW 0.75) was 0.25, 0.11, 0.13, 0.13, 0.17, 0.26, 0.37 and 0.08, respectively. The direct heritability for slaughter, hot and cold carcass weight, total litter weight weaned, mating and postpartum weight and ewe weight at weaning of lamb was 0.27, 0.18, 0.18, 0.12, 0.58, 0.53 and 0.67, respectively. Maternal heritabilty declined from 0.12 at birth to 0.06 at 60 days of age and was negligible thereafter. The maternal permanent environmental component due to the dam contributed 3–15% of the total phenotypic variances for all the traits under consideration. Genetic progress is possible for all the growth, carcass and ewe traits considered in this study. The heritabilty estimates for reproduction traits were low, viz 0.02, 0.06, 0.04, 0.02 and 0.04 for fertility (whether a ewe lamb or not; 0 or 1); reproductive rate (number of lambs born to a ewe mated; 0, 1 or 2); number of lambs weaned to a ewe lambing (0, 1 or 2); number of lambs weaned to a ewe exposed (0, 1 or 2), and lamb survival rate (whether a lamb born alive, was dead or alive at weaning). Though slow genetic progress is possible with all reproduction and survival traits, it would be more efficient to select for prolificacy (number of lambs born to a ewe that lambed; 1 or 2) ( h 2=0.26) but guarding against a higher lamb mortality.

Effets du milieu et génétiques sur la croissance des agneaux Timahdite et croisés au Maroc

La connaissance des paramètres génétiques pour les caractères de croissance d’intérêt économique est nécessaire à l’évolution des populations ovines au Maroc. Les données sur 544 agneaux de race Timahdite (T) et 756 agneaux D’man x Timahdite (DT), tous nés de 1992 à 1998, ont été utilisées pour estimer les paramètres génétiques des poids des agneaux à la naissance, à 30, 70 et 90 jours, ainsi que des gains de poids journaliers de 10 à 30, 30 à 70 et 30 à 90 jours, pour chaque caractère. Les variances-covariances ont été estimées séparément par la méthode du REML, utilisant un modèle animal qui incluait les effets fixes de l’année de naissance, du sexe, de l’âge de la brebis, du type de naissance ou du mode d’allaitement et de l’interaction année de naissance x sexe, effet génétique direct et effet génétique maternel. Les corrélations génétiques et phénotypiques entre les caractères ont été estimées avec des modèles comportant tous les mêmes effets fixes et seulement les effets génétiques directs additifs. Tous les effets fixes ont eu une influence sur les caractères de croissance. Les estimations des héritabilités directes pour les différents caractères poids et gains de poids journaliers ont été faibles à modérées et ont varié de 0,07 à 0,25 chez les T, et de 0,02 à 0,18 chez les DT. Les héritabilités maternelles ont été de 0,20 à 0,36 chez les DT et de 0,01 à 0,10 chez les T, à l’exception du poids à la naissance (0,53). Pour tous les caractères, les corrélations génétiques directes et maternelles ont été élevées et négatives chez les DT (-0,80 et -1,00) et chez les T (-0,90 et -1,00). Cependant, la précision de telles estimations est faible étant donné la petite taille du fichier des données utilisé dans cette étude. Les estimations des corrélations génétiques et phénotypiques ont été positives pour tous les caractères et particulièrement élevées pour les corrélations génétiques entre les poids et les gains de poids après la naissance à la fois chez les agneaux DT et T montrant l’absence d’antagonismes génétiques entre les différents caractères étudiés.

Genetic parameters for growth traits in Suffolk and Polypay sheep

Genetic parameters for growth traits in Suffolk and Polypay sheep were estimated using U.S. National Sheep Improvement Program data. Records on 12,814 Suffolks from 65 flocks and 9,028 Polypays from 39 flocks were used. Heritability ( h 2) estimates for weaning weights (WW) at 30, 60, 90, and 120 d in Suffolks were 0.16, 0.14, 0.21, and 0.55, respectively; h 2 for WW at 30, 60, and 90 d in Polypay were 0.07, 0.08, and 0.07. For postweaning gain (PWG), h 2 for models with and without maternal effects were 0.14 and 0.21, respectively, in Suffolk and 0.13 and 0.22, respectively, in Polypay. Maternal effects (additive+permanent environmental) accounted for 16 to 23% of variation in WW through 90 d of age but for 6% or less of the variation in 120-d WW and PWG. Correlations between WW at different ages were uniformly high. Postweaning gain had significant additive genetic correlations with WW at 30 d (1.00) and 60 d (0.69) in Suffolks but was not significantly correlated with 60 d WW in Polypay (0.41). Residual correlations between WW and PWG were small and not significant. Evidence for a modest antagonistic relationship between additive direct and maternal effects on WW was observed in both breeds.

Genetic parameters for growth traits in pigs estimated using third degree polynomial functions

A total of 8745 purebred Yorkshire and Landrace pigs extracted from Finnish progeny test station data was analysed. The pigs were weighed weekly during the test. A third degree polynomial function, age = f(weight), was fitted separately for each pig and was used to describe the growth patterns of individual pigs. Their live weight at the inflection point (LWip) was 72 kg, age at the inflection point (AGEip) 126 d, and maximum daily gain (DGmax) 1111 g/d, on average. The average daily gain from 30 to 90 kg (ADG30-90) was 957 g/d and in the smaller weight ranges (30 to 50, 50 to 70 and 70 to 90 kg) the average daily gains were 829, 1042 and 1046 g/d, respectively. Genetic parameters for growth and carcass traits were estimated using REML with an animal model. The heritability estimates (h2) for LWip , AGEip and ADG30-90 were 0.08, 0.33 and 0.23, respectively, and for smaller weight ranges from 0.14 to 0.21. Fast growing and lean animals had higher LWip than others and the rg between LWip and ADG30-90 DGmax and M% was 0.58, 0.73 and 0.57, respectively. The rg between ADG30-90 and M% was close to zero.

Genetic parameters for growth traits of Australian beef cattle from a multibreed selection experiment.

Estimates of covariance components and genetic parameters were obtained for birth, weaning, 200-d, and 400-d weight for a herd of Polled Herefords and a herd of a multibreed synthetics, the so-called Wokalups. Data originated from an experiment in Western Australia selecting for preweaning growth rate. Analyses were carried out by REML fitting an animal model including genetic and permanent environmental maternal effects. Wokalups showed consistently more phenotypic variation, partly due to a scale effect, and higher direct and lower maternal heritabilities than Herefords. Maternal environmental effects were more than twice as important in Herefords than in Wokalups. Estimates of both genetic and environmental correlations among weaning and subsequent weights were essentially unity, identifying maternal effects found for postweaning weights as a "carry over" of those on weaning weight.

Phenotypic and genetic parameters for growth traits in Red Chittagong Cattle of Bangladesh

The present study was carried out to estimate phenotypic and genetic parameters of Red Chittagong Cattle (RCC) for growth traits. Means of birth weight (BW), three month weight (3MW), six month weight (6MW), weaning weight (WW), nine month weight (9MW) and yearling weight (YW) were 15.74, 31.48, 45.33, 57.00, 60.91 and 76.18 kg respectively. Sex significantly (p<0.001) differed BW of calves but did not differ (p>0.05) 3MW, 6MW, WW, 9MW and YW. BW, 6MW, WW, 9MW and YW did not vary significantly (p>0.05) on year of birth but varied significantly (p<0.01) on 3MW. Season of birth had significant difference on 3MW (p<0.001), 6MW (p<0.01) and WW (p<0.01) but had no significant difference (p>0.05) on BW, 9MW and YW. The growth rates at zero to six month (6MGR) and six to twelve month (12MGR) were 0.17 and 0.17 kg /d respectively. Growth rate in both stages had no significant effect (p>0.05) on sex and year of birth. 6MGR had no significant effect (p>0.05) on season of birth but had significant (p<0.05) effect on 12MGR. From single trait analyses heritability (h2) of BW, 3MW, 6MW, WW, 9MW, YW, 6MGR and 12MGR were 0.497, 0.468, 0.475, 0.467, 0.447, 0.478, 0.499 and 0.65, respectively, whereas from multi-trait analysis heritability (h2) of first four traits were 0.498, 0.456, 0.500 and 0.490, respectively. Genetic correlations of BW with 3MW, 6MW and WW were 0.23, 0.38, and 0.53, respectively, 3MW with 6MW and WW were 0.78 and 0.69, respectively and 6MW with WW was 0.76. Estimated heritability values were rather high in magnitude and indicate that these traits would likely respond to selection. Estimates of phenotypic correlations among the traits studied were very low to moderate with values ranging from -0.40 to 0.81, whereas magnitude of genetic correlation ranged from 0.23 to 0.78. It was concluded that these estimated parameters would help to understand the biology of the traits and in designing breeding programme for other indigenous cattle in general. Keywords: Phenotypic and Genetic parameters; Growth traits; Red Chittagong cattle DOI: 10.3329/jbau.v7i2.4733 J. Bangladesh Agril. Univ. 7(2): 265-271, 2009