الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
The objectives of the present study are: 1) to estimate some genetic and non-genetic factors affecting productive, reproductive and longevity traits, 2) to estimate genetic and phenotypic parameters for these traits, 3) to study the length of longevity of Friesian cows and to link it to milk yield and reproductive performances and 4) to estimate breeding values for studied traits.
Material and Methods:
Data used in this investigation were collected from 4370 records relevant to 874 purebred Friesian cows, which belong to Shobratana animal production society, located in the north part of Delta region near Tanta city in Egypt. These cows were daughters of 43 sires. The records used covered the period from 1985 to 2003. The following six productive and reproductive traits on first lactation were:
First lactation of total milk yield (TMY1, kg), First dry period (DP1, day), First lactation length (LL1, day), First days open (DO1, day), First calving interval (CI1, month) and Age at first calving (AFC, month).
The longevity traits were:
1- Total milk yield during productive life (TMYPL, kg), 2- Number of days of lactation during productive life (NDLPL day), 3- Number of days of total life (NDTL day), 4- Number of days of productive life (NDPL day), 5- Milk yield per days of lactation (MYDL, kg), 6- Milk yield per days of total life (MYDTL, kg), 7- Milk yield per days of total productive life (MYDPL, kg), 8- Number of lactation completed (NLC lact.).
Data were analyzed using Linear Mixed Model Least Squares and Maximum Likelihood (LSMLMW) computer program of Harvey (1990).
RESULTS:
-The least squares means of TMY1, DP1, LL1, CI, DO1 and AFC were 6309 kg, 70.7 day, 330.4 day 13.4 months, 121.2 day and 27.5 month, respectively. The least squares mean of TMYPL, NDLPL, NDTL, NDPL, NLC, MYDL, MYDTL and MYDPL are 21627 kg, 1113 days, 2246 days, 1400 days, 3.38 lact., 19.9 kg, 9.43 kg and 15.8 kg,
-The heritability for TMY1, DP1, LL1, CI1, DO1 and AFC are 0.141, 0.109, 0.040, 0.104, 0.202 and 0.217, respectively. The heritability for TMYPL, NDLPL, NDTL, NDPL, NLC, MYDL and MYDTL are 0.268, 0.365, o.401, 0.403, 0.401, 0.024 and 0.049, respectively.
-The breeding values of sires for TMY1, DP1, LL1, DO1, CI1, TMYPL, NDLPL, NDTL, NDPL, NLC, MYDL and MYDTL were 685 kg, 18.0 day, 8.15 day, 48.19 day, 1.05 month, 4624 kg, 388 day, 556 day, 558 day, 1.33 lact., 0.272 kg and 0.642 kg , respectively.
Objectives:
The objectives of the present study are: 1) to estimate some genetic and non-genetic factors affecting productive, reproductive and longevity traits, 2) to estimate genetic and phenotypic parameters for these traits, 3) to study the length of longevity of Friesian cows and to link it to milk yield and reproductive performances and 4) to estimate breeding values for studied traits.
Material and Methods:
Data used in this investigation were collected from 4370 records relevant to 874 purebred Friesian cows, which belong to Shobratana animal production society, located in the north part of Delta region near Tanta city in Egypt. These cows were daughters of 43 sires. The records used covered the period from 1985 to 2003. The following six productive and reproductive traits on first lactation were:
First lactation of total milk yield (TMY1, kg), First dry period (DP1, day), First lactation length (LL1, day), First days open (DO1, day), First calving interval (CI1, month) and Age at first calving (AFC, month).
The longevity traits were:
1- Total milk yield during productive life (TMYPL, kg), 2- Number of days of lactation during productive life (NDLPL day), 3- Number of days of total life (NDTL day), 4- Number of days of productive life (NDPL day), 5- Milk yield per days of lactation (MYDL, kg), 6- Milk yield per days of total life (MYDTL, kg), 7- Milk yield per days of total productive life (MYDPL, kg), 8- Number of lactation completed (NLC lact.).
Data were analyzed using Linear Mixed Model Least Squares and Maximum Likelihood (LSMLMW) computer program of Harvey (1990).
RESULTS:
-The least squares means of TMY1, DP1, LL1, CI, DO1 and AFC were 6309 kg, 70.7 day, 330.4 day 13.4 months, 121.2 day and 27.5 month, respectively. The least squares mean of TMYPL, NDLPL, NDTL, NDPL, NLC, MYDL, MYDTL and MYDPL are 21627 kg, 1113 days, 2246 days, 1400 days, 3.38 lact., 19.9 kg, 9.43 kg and 15.8 kg,
-The heritability for TMY1, DP1, LL1, CI1, DO1 and AFC are 0.141, 0.109, 0.040, 0.104, 0.202 and 0.217, respectively. The heritability for TMYPL, NDLPL, NDTL, NDPL, NLC, MYDL and MYDTL are 0.268, 0.365, o.401, 0.403, 0.401, 0.024 and 0.049, respectively.
-The breeding values of sires for TMY1, DP1, LL1, DO1, CI1, TMYPL, NDLPL, NDTL, NDPL, NLC, MYDL and MYDTL were 685 kg, 18.0 day, 8.15 day, 48.19 day, 1.05 month, 4624 kg, 388 day, 556 day, 558 day, 1.33 lact., 0.272 kg and 0.642 kg , respectively.