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Three each of 3-year-old Angus and Simmental heifers, surgically modified to collect bile, were used to measure the effects of pregnancy and breed on bile flow, biliary copper and zinc excretion and plasma copper and zinc concentrations. Bile copper excretion was significantly higher at 7-mo of pregnancy when samples from both breeds were pooled. From then onwards it declined to its lowest, one week post-partum. During pregnancy, plasma copper concentration increased slightly, reaching its highest level at 7-mo of pregnancy and then decreased slightly until full term. In pooled samples from both breeds, the correlation between increase in bile copper excretion and plasma copper concentration from 0 to 7-mo of pregnancy was high (r = 0.85) and significant (p < 0.05). Plasma zinc concentration decreased to the lowest level around 6-mo of pregnancy but increased thereafter until full term. In cows that were dried off one week after parturition, major shifts in bile and plasma copper and zinc parameters occurred at one week following and these coincided with a marked decline of bile flow and bile copper and zinc excretion. By 3-mo post-partum, biliary copper and zinc excretion and plasma copper and zinc concentrations had reached levels observed prior to pregnancy. When the data from all samples were pooled, the bile flow and bile copper excretion were significantly (p < 0.05) higher in Simmental, and plasma copper and zinc concentration higher in the Angus.

A grazing experiment was conducted to determine the production potential of buffaloes as a function of supplementation and pasture production during different seasons. Six groups of two cross-bred Murrah buffalo heifers of 16 ± 3 months of age mean live weight of 127 ± 10 kg were randomized into 0.6ha of coconut land to remain and continuously graze the herbage from Jan 2004 to Jan 2005. The treatments were: (T1) Natural herbage; (T2) T1+ supplement (rice bran/molasses/urea/mineral mixture) + Gliricia sepium (3-5kg / day). Dry matter (DM) yields were not only influenced by the seasons, but were also related linearly to the seasonal rainfall. The DM yield and CP content increased towards the end of the experiment in T2 as compared to T1. The average daily gain and total gain of both treatments were linearly related to the DM yield and ranged from 297 kg/head/ha for T1 and 446 kg /head/ ha for T2. It is concluded that season had a significant influence on ruminant production under natural grazing conditions. Supplementation could compensate the seasonal fluctuations in grazed herbage

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