Table 2
Milk production (kg./305d lactation; mean ± SE)

Farm ID	Number of cows	Black	Black: white	White
Farm A	211	11,535.0 ± 253	11,121.0 ± 330	11,830 ± 187
Farm B	690	9,612.7 ± 207	9,920.0 ± 234	9,928 ± 214