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Using Statistical Models in Genetic Evaluation on Shami Goats | General Commission for Scientific Agricultural Research

Using Statistical Models in Genetic Evaluation on Shami Goats

Kamel Fattal
General Commission for Scientific Agricultural Research, Aleppo Research Center
Aleppo University, Faculty of Agriculture
2009

abstract

This study was carried out at Hamemeh Research Station to improve Shami goats (Aleppo) in north of Syria. The overall objective is to study the genetic evaluation of Shami goats herd and to define the genetic improvement. Data was derived for all years from 2001 till 2006 on 1068 records for kids and 2273 records for test day milk yield, fat% and protein% traits. This data was used to estimate phenotypic, additive genetic, permanent environment, genetic parameters (Heritability, genetic correlations), variance covariance structure, and to predict breeding values and permanent environmental values for each animal within each studied traits. Results were summarized as following:
1. Kids weights traits:Data was statistically analyzed using least square mean and maximum likelihood function, (Harvey, 1990) program.The results showed that least square means of birth weight, weaning weight and weight at 6 months age were 3.66 ± 0.17,13.10 ± 0.44, 27.83 ± 0.95 kg respectively. Least square means of growth rates to weaning, and from weaning to 6 months old were 158±0.01, 123±0.01 g/day respectively. The least square means at birth weight of male, female and intersexes kids were 3.89, 3.50 and 3.60 kg respectively. The kids sex effect of had high significant.On birth weight, weaning and 6 months weights also the gender was high significant. Growth rate to weaning and from weaning to 6 months old trait. The least square means at weaning weight of male, female and intersexes kids were 14.01, 12.30 and 13.00 kg respectively. The kids sex effect of was insignificant for weaning weight trait. The least square means at 6 months age of male, female and intersexes kids were 29.75, 26.57 and 27.15 kg respectively. The values of growth rates to weaning for male, female, and intersexes were 169, 147, 158 g/day respectively. The values growth rates from weaning to 6 month for male, female, intersexes were 132, 120, 118 g/day respectively.
The least square means at birth weights of single, twin and triplet kids were 4.28, 3.68 and 3.03 kg respectively. The least square means at weaning weight of single, twin and triplet kids were 13.74, 13.10 and 1249 kg respectively. The least square means at 6 months age of single, twin and triplet kids were 28.40, 27.65 and 27.43 kg respectively. The effect of type had high significant on weight traits at birth. Least square means of growth rates to weaning for mal, female and intersexes were 169, 147, 158, g/day respectively. Growth rates from weaning to 6 month old for male, female and intersexes were 132, 120, 118 g/day respectively.  Estimation of heritability was 0.31± 0.03, 0.08 ± 0.04 and 0.16±0.06 of birth weight, weaning weight and 6 months age respectively. Growth rates to weaning and from weaning to 6 month old were 0.09 and 0.12 respectively. Genetic correlation between birth weight and weaning weight was 0.19 ± 0.01, while between birth weight and 6 month age was 0.46 ± 0.07. Also genetic correlation between weaning weight and weight at 6 month age was 0.75 ±0.33 repeatedly. Estimation of birth weight and weaning weight were 0.28, 0.22 respectively.
2. Test day Milk, fat% and protein% traits:Animal mixed model was used with multiple traits technique to obtain the results by program specialized in data analysis of genetic animal production (M,T,D,F,RE,ML) multi, trait, divertive, free, restriction, maximum likelihood. The values means were 1.66±0.74, 3.29±0.90, and 3.31±0.54 kg for TDMY, F%, and P% respectively. A mean weight goat at kidding was 62.14±14.94 kg. The additive genetic variance was 7.88, 5.62, and 0.60 for F%, TDMY, and P%, respectively. The permanent environmental variance was 1.10, 0.92, and 0.86 for TDMY, F%, and P% respectively. The residual variance was 2.05, 0.68, and 0.26 for F%, TDMY, and P% respectively. The phenotypic variance was 10.84, 7.40, and 1.72 for F%, TDMY, and P% respectively. The heritability was 0.76, 0.73, and 0.35 for TDMY, F%, and P%, respectively. The genetic correlations were 0.12 and 0.75 between TDMY and F% and P% respectively. While the genetic correlation between F% and P% was 0.35. The ranges of breeding values were from -1.84 to 1.77, from -1.77 to 1.57, and from -0.54 to 0.46 for TDMY, F%, and P% respectively. The rank correlation between breeding values for TDMY and each F%, and P% were -0.41 and 0.76 respectively, while rank correlation between values for F%, and P% was 0.48. This indicated that possible genetic improvement for TDMY with P% in milk, but the opposite of that was founded for F% in milk.
3. Annual genetic, environmental and phenotypic changes of test day of milk:
Annual genetic change was -0.005±0.001 kg/year, while estimates of environmental, phenotypic change were 0.049±0.016, 0.086±0.012 kg/year respectively.
4. Estimation of Lactation Curve Function Parameters: – The intercept of lactation curve: The least square mean of parameter a [intercept] was 0.52±0.03 kg. Dam, kidding weight, year, month kidding were highly significant affected parameter a. – The increasing of lactation curve: The least square mean of parameter b [the increasing to the peak of lactation curve] was 0.70±0.03 kg.

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