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Five Karan Swiss crossbred (Sahiwal x Brown Swiss) calves were abruptly switched over from a diet of concentrate and maize fodder to ad libitum air dried Leucaena leucocephala leaves plus twigs. After 17 days on the L. leucocephala diet, 3 of the calves were supplemented with copper sulphate (10 mg/kg DM L. leucocephala) for 12 days. Thereafter all the calves were taken off the L. leucocephala diet and returned to the pre-experimental concentrate and maize fodder diet. While on the L. leucocephala diet, the average DM intake/d of L. leucocephala declined to 497 g within 3 weeks and all calves lost weight. This weight loss was reversed in the 3 calves that received copper sulphate, and all calves gained weight when they resumed the concentrate and maize fodder diet. The toxic effects of L. leucocephala feeding for 24 days were characterised by poor growth, emaciation, alopecia, loss of hair from the tail switch, ear and eye lesions, ulceration of the mouth region, drooling viscid saliva and vomiting of thick green saliva in one of the calves. Mean levels of 3,4 dihydroxypyridone (DHP) (mg/100 ml) were 30.35 +/- 13.52 and 55.57 +/- 13.77 on days 2 and 4 respectively in rumen liquor and up to 136.01 +/- 80.18 in urine. The mean ratios of mimosine: DHP of 3.14, 0.12 and 0.04 in feed, faeces and urine respectively revealed extensive degradation of mimosine to DHP in the calves fed the L. leucocephala diet and it was concluded the calves were unable to tolerate a diet consisting solely of L. leucocephala.

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.

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