Twelve lactating Sahiwal cows were divided into three equal groups on the basis of milk yield (mean 8.39 L/day), parity and body weight. All the animals were fed concentrate mixture along with wheat straw and green oats (Concentrate mixture and roughages as 50:50; green oat and wheat straw as 60:40) as total mixed ration for 126 days. While group T1 was fed ration consisting of concentrate mixture without any additional mineral mixture and common salt, group T2 had 2 % mineral mixture and 1 % salt in their concentrate mixture and group T3 had 20 % seaweed (Sargassum wightii) in their concentrate mixture without additional mineral mixture and salt. A metabolism trial of 7 days collection period was conducted on all the experimental animals after 56 days of experiment. The results showed that there were no significant changes in nutrient intake and digestibility of dry matter, organic matter, crude protein, crude fibre and ether extract. Similarly, there were no significant changes in milk composition (protein, fat, lactose, solid-not-fat) in different treatment groups. However, seaweed supplemented group had significantly (P \ 0.05) higher milk yield and 4 % fat corrected milk yield than the other groups. Thus, incorporation of brown seaweed in the diet of lactating Sahiwal cows to the extent of 20 % in concentrate mixture increased their milk yield.