Milk production parameters of purebred Jersey (J) cows and Fleckvieh × Jersey (F × J) cows in a pasture-based feeding system were compared using standard milk recording procedures. Milk, fat and protein production was adjusted to 305 days per lactation and corrected for age at calving. Effects of breed, parity, month and year were estimated for milk, fat and protein yield as well as fat and protein percentage, using the general linear model procedure. Fixed effects identified as affecting milk production parameters significantly were breed, parity and year. F × J cows produced significantly more milk than J cows (6141 ± 102 and 5398 ± 95 kg milk, respectively). Similarly, fat and protein yields were significantly higher in F × J (272 ± 4 and 201 ± 3 kg, respectively) than in Jersey cows (246 ± 3 and 194 ± 2 kg, respectively). Fat and protein percentages only differed slightly in absolute terms being 4.61 ± 0.04% fat in the Jersey compared to 4.47 ± 0.04% fat in the F × J. Protein levels for J and F × J cows were 3.62 ± 0.03 and 3.51 ± 0.03%, respectively. Despite a lower fat percentage, F × J crossbred cows may be more productive than purebred Jersey cows which may be due to heterotic effects.