Response surface and fixed effects models of non-genetic factors for dairy cows in Saudi Arabia [electronic resource].

Includes references.

Response surface model of statistical analysis was used to quantify the relationship between non-genetic factors (NOF) such as days open (DO). days in milk (DIM), age at calving and milk production. Data included 103.776 records; each one had cow identification, non-genetic traits and production traits such as total milk production, 305-milk yield and peak yield. Least square means of three farms were 10467, 11047 and 10697 liters of milk respectively. Cows calved on fall-winter season produced 10839 liters, compared with 10636 liters for cows calved in spring-summer season. Second lactation cows gave the highest production (11, 105 liters), and sixth lactation cows produced the lowest production (10, 283 liters). Significant parameters (p<.O I) supported the linear and quadratic relationship between age at calving and total yield, 231305-dyield and peak milk production, respectively.

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