Effect of close-up fat supplementation and body condition score on first 90 days milk production was evaluated in high producing lactating Holstein cows. Data of 6 herds with average 112 milking cows were used. Body condition scores were recorded 50 days before and 45 days after the calving. All cows in each herd were dried off 50-70 days before expected calving and moved to a far-off dry herd with dry matter intake of 3 kg alfalfa, 5 kg corn silage, 1.5 kg wheat straw and 3 kg far-off concentrate (CP: 162 g/kg; ME:12.4 MJ/kg). The cows were moved to the close-up dry herd around 25 days before calving. Close-up dry ration (DM basis) was consisted of 2.2 kg alfalfa, 6.1 kg corn silage, 1.9 kg wheat straw, 5.2 kg concentrate (CP: 176 g/kg; ME: 13.2 MJ/kg), and 300 g of anionic salts. In 3 herds, the close-up ration was supplemented with 0.25 kg palm fat prills (99.5% fat). After parturition, all cows were fed a total mixed ration (as DM) based on 24% alfalfa, 14% corn silage and 60% concentrate. This ration met the requirements of high producing cows (CP: 180 g/kg; ME: 12.2 MJ ME/kg DM). Cows were inseminated around 60-85 days in milk after a presynch-ovsynch estrous synchronization program. During the first 90 days of lactation, weekly milk production was recorded. Data were analyzed using GLM procedure of SAS. Retained placenta, metrits and endometrits were lower in cows fed fat supplemented close-up ration compared with the non-supplemented cows. First 90 days milk yield was significantly influenced by close-up fat supplementation (P< 0.05). Milk yield of fat supplemented and non-supplemented cows was 41.3.8 and 39.6 kg/d/head, respectively. Milk yield appeared to be depressed in postpartum thin cows (BCS= 2.4) compared with normal cows (BCS= 2.9). Results of the present study indicated that fat cows (BCS more than 4.6 before dry off) resulting in lower milk production. It was concluded that relationship between close-up period fat supplementation and milk production in the first 90 days was a critical point.

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