الفهرس 
Determination of the prevalence and risk factors of lameness in some dairy cattle herdsOnly 14 pages are availabe for public view
 |  | from | 105 |  |  |
| | | from | 105 | | |
Abstract
Lameness is one of the most important welfare, health, and productivity problems in intensive dairy farming worldwide. The disorder is considered the third major health problem (after mastitis and reproductive problems), and is the third most important reason for culling. Nowadays, this issue is selected as the highest research priority. The overall aims of this thesis were the following:
- To investigate lameness prevalence in four dairy cattle herds containing Holstein Friesian
- To determine and gain insights into the risk factors associated with the frequency of lameness incidence including farm, frequency of mastitis, and number of lactations.
- To determine the effect of the frequency of lameness injury on longevity, lifetime milk yield and some reproductive traits including averages of days open, dry period and calving interval.
Four dairy farms in near Alexandria Governorate were involved in this study, Alamia (ALM), Dima (DIM), FARMKEY and Talaat Mostafa (TAL) farms. All farms had pure Holstein cattle. Standard data describing the dairy herd include frequency of lameness injury, frequency of mastitis injury, number of lactations, life-time milk production, longevity, means of days open, dry period and calving interval along the productive life of the cow, as well as cow, sire and dam identifications. Records collected covered the period from 1987 to 2011. Data of this study were analyzed through three steps, as follows:
Determination of the association between frequency of lameness injury and the explanatory variables.
Adoption of survival functions for analyzing lameness data.
94
2. Determination of the effect of farm, frequency of lameness injury and other factors on the life-time milk yield and some reproduction traits.
The main results were:
The prevalence range of lameness across all herds involved in the entire study period was estimated to be between 0 and 19%.
Concerning the lameness prevalence values, it could be mentioned that the values varied widely among farms (range, between 0 to 19%).
Strong and significant (P<0.01) association between lameness incidence and these risk factors was observed.
The results obtained in the present study indicated that lame cows injured three times had the longest longevity and the highest amount of milk yield across their lifetime period, while non-lame cows had the shortest mean of longevity, and those injured twice had the lowest amount of milk produced across their productive life, and the differences were significant.
The results of the present study indicated that lame cows injured three times or more had longer days open and dry period and prolonged calving interval, in comparison with non-lame cows or those injured once or twice.