Document Type : Original Article
Authors
1
Animal Welfare and Wealth Development Department, Faculty of Veterinary Medicine, 21526, Alexandria University, Egypt
2
Animal Wealth Development Department, Faculty of Veterinary Medicine, 44511, Zagazig University, Egypt
Abstract
The purpose of this study was to evaluate the significance of the effect of some reproductive traits (Days open, calving interval, and dry period) on the productivity of some dairy farms by applying some statistical measures. From the period extended from the summer of 2017 to the winter of 2020, a field survey was conducted on random samples of dairy-producing sectors in several locations in Egypt, Including Menofia, Al-Qalyubia, Beheira, and Giza governorates. There were three sectors: agricultural, private, and government. This study included dairy breeds: crossbred (Balady X Friesian), exotic Holstein-Friesian, Brown Swiss and native Balady. A longitudinal and cross-sectional field survey yielded the results. During data collection, the researcher maintained close touch with dairy owners and management. The dairy farms were visited at least twice, once in the summer and again in the winter. The researcher collected the data by two methods: Based on accurate records obtained from dairy farms in the research locations, and the researcher developed a structured questionnaire procedure based on the study's goals and administered it to dairy owners and managers during the interview. The acquired data was analyzed using correlation and regression techniques. The results indicated that the longest days open value was observed in Holstein Friesian cattle as it reached 200.96 days, followed by Brown Swiss as it reached 190.44 days and the higher dry period length was observed in Balady breed cattle as it reached (131.07 days), followed by crossbred cattle (Balady X Friesian) as it reached (115.70 days). Our results concerned with the calving interval period length showed that the longest calving interval period level was observed for Holstein Friesian (474.11 days), followed by Brown Swiss cattle as it reached 460.30 days. The regression equations results indicated that the changes in the calving interval by about 10% increased milk production by 5.50%. An augmentation of approximately 10% in the duration of days open led to a corresponding rise in milk yield of 2.1%. Additionally, extending the length of the dry period by around 10% resulted in an increased milk production of 3.1%. Our results concluded that the calving interval, days open and dry period are the main reproductive efficiency parameters that affecting positively milk production yield and efficiency and the statistical measures that include regression analysis, correlation analysis with the help of t-test, analysis of variance test is the main statistical a parameter that can be used for determining the factors affecting milk yields and production efficiency.
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