Feeding management, production and performance of 13 pasture-based dairy farms in a Mediterranean environment

Physical performance data from 13 dairy farms in Western Australia, six feeding all concentrate in the milking parlour and seven feeding a portion of concentrate in a partial mixed ration (PMR) with forage, were collected between March 2012 and June 2013. Each farm was visited 13 times at intervals of 4-6 weeks, and feed intake and milk production was recorded on each visit. Four farms had access to fresh pasture all year round via irrigation. Milk yield (MY) and composition data was calculated daily from milk processor records. Pasture dry matter intake (DMI) was estimated based on metabolisable energy supply and requirements according to published feeding standards. All milk and feed-related measures were significantly affected by visit date (P < 0.01). Mean annual concentrate intake and MY was 2082 +/- 344 kg/cow and 7679 +/- 684 kg/cow, respectively. Daily concentrate DMI was greatest in May 2012 (8.9 +/- 2.2 kg/cow), near the end of the non-grazing season, and lowest in August 2012 (5.1 +/- 1.5 kg/cow). On an average annual basis, PMR farms provided 22 +/- 15% of total concentrate fed as part of a PMR, and 28 +/- 11% of total concentrates and by-products fed as part of a PMR. Daily grazed pasture DMI was highest on all farms in September 2012 (12.9 +/- 2.4 kg/cow), and averaged 6.6 kg/cow on the four irrigated farms between January and May. Daily yield of energy-corrected milk was highest in September 2012 (26.9 kg/cow) and lowest in January 2013 (21.9 kg/cow). Milk fat content was highest in summer and lowest in winter; the reverse was true of milk protein. Feed conversion efficiency was significantly affected by visit date, but mean feed conversion efficiency was the same (1.37) for in-parlour and PMR farms. Overall there was some evidence that PMR feeding systems on Western Australian dairy farms are not optimised to their full potential, but a high degree of variability in performance between all farms was also apparent.