STUDY OF CULLING OBJECTIVES IN MODERN DAIRY FARMS

Abstract

Culling refers to the removal oflive cows from herd. Generally culling reflects a negative quality of dairy cows. Culling occur by two features:

FIRST feature is known as "voluntary culling". This means select cows depending on their milk production to improve their genetic potentiality of milk production. SECOND feature is known as "involuntary culling". This refers to exclude cows by force due to health reasons such as reproductive disorders, udder problems, diseases 00000 etc The sense of culling aspects and culling reasons represent importance of economic role in dairy farms. With these reasons in mind, this study has been carried out to investigate the following: 1- Study the culling of dairy cows by estimate the annual culling rate, relative rate of culling reasons, distribution of the culling seasons, parities and final stage of lactation. 2- Confirming or refusing the hypothesis theory which means that "animals of higher milk yield than a certain limit dictated by the adverse environment may be rejected earlier and consequently will have shorter longevity compared to those of medium or lower production" 3- Study the stayability traits measured as [longevity, productive life, number of complete lactation, total life milk production] by: I. Study of some environmental factors affect stayability traits.

II. Heritability estimates for stayability traits to improve it