الفهرس 
Introduction
Factors affecting birth weightOnly 14 pages are availabe for public view
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Abstract
This study was carried out to estimate the productive and reproductive performance for a herd of Egyptian Nubian (Zaraibi goat). Total number of 4080 kids and 789 Zaraibi does sired by 96 bucks used in this study. The records were collected form ElSerw Experimental Station, belonging to Institute of the Animal Production Research, Ministry of Agriculture, Egypt.
The records of the does on total milk yield, lactation length, daily milk yield, litter size and litter weight at birth and weaning through years from 1988 to 2000 were studied in the present study.
The results obtained from the analysis of the data could be summarized as follows:
1-The means values of total milk yield and daily milk yield produced through 258.84day lactation period were 275.89 and 1.08 kg, respectively.
2-The coefficients of variation of total milk yield, lactation length and daily milk yield were 53.90, 27.07 and 52.27%, respectively.
3-Year of kidding had a highly significant effect (P<0.01) on total milk yield, average daily milk yield and lactation length.
4-The effect of season of kidding on milk yield and daily milk yield of goats was significant (P<0.01). While lactation length did not affect by season of kidding.
5-The litter size at birth had not significant effect on total milk yield, lactation length and daily milk yield.
6-The effect of age at first kidding on all milk yield traits were significant for quadratic regression and it were not significant for linear regression.
7-The number and weight of kids at born were 1.93 kids and 3.5 kg, respectively. Also, total number and weight of kids at weaning were 1.66 kids and 17.44kg, respectively.
8-The influence of year of kidding on litter size and weight at born and weaning were significant (P<0.01).
9-Season of kidding had significant effect (P<0.01) litter size at born. While no significant effect for season of kidding on litter weight at born, litter size and weight at weaning.
10-The results showed positive linear regression coefficients of litter size and litter weight at born at and weaning with highly significant effect (P<0.01) on litter size at born and only significant on litter weight at born and litter size at weaning. However, no significant effect for litter weight at weaning. Negative quadratic regression coefficients of litter size at weaned and litter weight at born and weaning on age at first kidding and the effect was not significant.
11-The mean values for total lifetime total milk yield, lifetime milk yield / day of lactation length and milk yield per day of productive life were 744.24, 618.39 and 1.24 kg, respectively.
12-Overall means (BSE for lifetime total milk yield, lifetime lactation period and lifetime average milk yield / day were 859.62 (R+ (B32.43, 624,44 (R+ (B22.04 and 1.28 (R+ (B0.02, respectively. 13Year of kidding had a highly significantly effect (P<0.01) on lifetime total milk yield, lifetime lactation period and lifetime average milk yield / day. Also milk production effects on lifetime total milk yeild and lifetime average milk yield / day was significant (P<0.01) and was not significant on lifetime lactation period. All lifetime milk yield traits did not affect by season of kidding and number of kids at born. 14The present results indicated that positive linear and quadratic regression coefficients of lifetime total milk yield, lifetime lactation period and lifetime average milk yield /day. All lifetime milk yield traits did not affect by age at first kidding. 15The mean values of total litter size at birth and at weaning were 4.95 and 3.90 kids. While total litter weight at birth and at weaning were 9.36 and 42.97kg, respectively 16Year of kidding had highly significantly effect (P<0.01) on least squares means of total litter size at birth, total litter weight at birth and weaning and milk yield /day. 17Both litter size at birth and total litter weight at weaned were affected (P<0.01) by litter size born. Also, litter size at birth had significant effect (P<0.05) total weight at birth. While milk yield /day did not affect by litter size at birth. 18Milk production had highly significant effect (P<0.01) on milk yield /day. While total litter size at birth and total litter weight at birth and at weaning did not affected by milk yield. 19It could be noticed that positive linear and quadratic regression coefficients of total litter size at birth, total litter weight at birth and at weaning and milk yield. All lifetime kids production traits and milk yield / day did not affected by age at first kidding. 20The mean values for weights of kids at birth, 30, 60 and 90 day (weaning) were 2.11, 5.33, 7.85 and 10.61 kg, respectively. Average daily gain for kids during the period from birth to 90 day (weaning) was 0.09 kg. 21Overall mean (R+ (BSE for weight at birth, 30, 60, and 90 day (weaning) were being 2.01 (R+ (B0.03, 5.19 (R+ (B0.10, 7.78 (R+ (B0.13 and 10.51 (R+ (B0.11, respectively. Also, overall mean (R+ (BSE for daily gain from birth to 90 day (weaning) was 0.09 (R+ (B0.001. 22All weight traits for kids were affected (P<0.01) by sire, year of kidding, sex and type of birth. While season of kidding had a highly significant effect on weight at birth and 90 day. Daily gain for kids was affected (P< 0.05) by all studied factors except season of kidding. 23The variations for weight of kids due to sire trends decreased with increase of age from birth to weaning at 90 day and it ranged from 0.05 to 0.09. Also, variations in weight of kids resulting from environmental components increased by increase of age and it ranged from 0.92 to 0.95. The heritability estimates for weight at birth, 30, 60 and 90day were 0.31, 032, 0.30 and 0.18, respectively. 24The heritability estimates for daily gain of kids due to sire and environment were 0.05 and 0.95, respectively. 25Heritability estimates for weight at birth, 30, 60, 90day (weaning) and daily gain were 0.31 (R+ (B0.05, 0.32 (R+ (B0.05, 0.30 (R+ (B0.05, 0.18 (R+ (B0.04 and 0.18 (R+ (B0.04, respectively 26Genetic correlation between all weights of kids traits ranged from 0.27 (between weight at birth and 30 day) to 0.52 (between weight at 60 and 90 day). The trend in genetic correlation for all weights showed a tendency to increase with increase of age. 27Phenotypic correlation between all weights of kids traits were positive and it ranged from 0.28(between weight at birth and 90 day) to 0.72 (between weight 30 and 60 day). Also, Phenotypic correlation for all weights traits showed a tendency to decrease with increase age. 28Genetic and phenotypic correlations between daily gain and all weight traits tended to increase with increase of age and it ranged from 0.02 to 0.95 and from 0.05 to 0.97, respectively. 29Blup estimates for weight at birth, 30, 60, 90 day (weaning) and daily gain from birth to weaning were ranged from 0.19 to 0.17, 0.74 to 089, 0.050 to 1.04, 0.54 to 0.49 and 0.004 to 0.006, respectively. The corresponding values of rank estimates were ranged from 3 to 62, 1 to 55, 1 to 55, 4 to 63 and 4 to 63, respectively. 30Blup estimates for all weights as minimum, maximum and ranged from 0.993 to 0.304, 0.008 to 1.042 and 0.52 to 2.04, respectively. The range of Blup estimated for weight increase by increase of age up to 60day (from 0.52 to 2.09) and then decrease to (1.70) at 90 day. 31The present results showed that rank correlation among them, all weights increased by increase in age and it ranged from 0.001 to 0999. The same trend observed for rank correlations between daily gain and all weight traits and increased by increase of age from 0.001 to 0.999. 32The values of were genetic trend and linear regression coefficients for all weights and daily gain change from negative to positive. Genetic trend had nonsignificant effect on all weight traits and daily gain. While phenotypic trend and quadratic coefficients were positive. All weight traits and daily gain for kids were affected (P<0.01) by phenotypic trend.