الفهرس 
Effect of year of calvingOnly 14 pages are availabe for public view
 |  | from | 206 |  |  |
| | | from | 206 | | |
Abstract
This i n v e s t i g a t i o n waa c a r r i e d out to s t u d y the non genetic effect and genetic parameters affect in!; I nctation curve ( i n i t i a l milk y i e l d , maximum m i l k y i e l d , and persistency of l a c t a t i o n . This study wac also carried out to construct a s e t of s e l e c t i o n indexes to be used f o r the improvement of milk production in the Friesian cows under l o c a l conditions. The influence of variouo nongenetic factoro such as season and year of calving , p a r i t y and farm on the l a c t a t i o n t r a i t s was also studied in order to adjuat the data f o r their e f f e c t . The data used Fn t h i s study comprised 2531 normal l a c t a t i o n record6 of F’riesians prod~lcing for 210 days or more covering the period of 1967 to 1979, end representing all available records In two farms . These farms are located a t Sakha and El-Karada in the Northern p a r t of the Delta. Records were hbp0 c l a s s i f i e d tjy season of cdvFng into four seasons : Winter,Spring ,Sumrr,er and Autumn; Four indexes of persio tericy were computed f o r each record (PI, P2, Pj , and P4) in PI , the first s i x months of the l a c t a t i o n period were d i v i d e d into equal i n t e r v a l s each of three montha. Persietency hdex of an Individual records waa calculated as the r a t i o of production.