Effects of different levels of dietary sulfur and molybdenum on concentrations of copper and other elements in plasma and liver of lambs fed palm kernel cake diets

Abstract

A 6-month experiment with nine dietary treatments was conducted to determine amounts of S plus Mo supplements required to maintain normal hepatic concentrations of Cu and Mo and to prevent chronic Cu toxicity in lambs fed palm kernel cake (PKC) diets. All diets consisted of PKC supplemented with minerals and vitamins, and with appropriate amounts per kg DM of S (level 0 or level 1 ¼ 1 g) as sodium sulfate and/or Mo (level 0; level 1 ¼ 4 mg; level 2 ¼ 8 mg; level 3 ¼ 16 mg; level 4 ¼ 32 mg) as ammonium molybdate to form treatments S0Mo1, S0Mo2, S0Mo3, S0Mo4, S1Mo0, S1Mo1, S1Mo2, S1Mo3 and S1Mo4.There was no effect (P.0·05) of dietary treatments on the growth performance of the lambs. The dietary supplement of 1 g S plus 8 mg Mo per kg dietary DM (treatment S1Mo2) prevented accumulation of Cu in the liver without elevation of the concentration of Mo (P.0·05). The treatments S0Mo1, S0Mo2 and S0Mo3 increased (P,0·05) hepatic Cu concentrations from 376 mg/g DM to between 1090 and 1294 mg/g DM. Also, the treatments S1Mo3 and S1Mo4 resulted in higher (P, 0·05) hepatic Mo concentrations compared with the treatment S1Mo0. It was concluded that the dietary supplement of 1 g S plus 8 mg Mo/kg PKC DM added to the PKC used is sufficient to maintain normal hepatic concentrations of Cu and Mo and to prevent chronic Cu toxicity in sheep fed diets containing any amount of PKC.

Effects of dietary molybdenum, sulfur and zinc on the excretion and tissue accumulation of trace elements in sheep fed palm kernel cake-based diets

“…The plasma Zn concentration was also relatively high for the control diet (2.95 mg/ml), probably due to the relatively high Zn concentration in the presently used PKC (59 mg/kg DM). In comparison, the Zn concentration in the PKC used in another experiment (Alimon et al, 2011) was only 35 mg/kg DM and the plasma Zn concentration was only approximately 1.5 mg/ml. Therefore, considering the present high dietary Zn concentration and its inadequate reduction of the liver Cu accumulation, the dietary Zn supplements appear not to be practical or adequate in preventing chronic Cu toxicity in sheep fed PKC-based diets.…”

“…However, supplemental S resulted in an increased liver Mo concentration (Alimon et al, 2011); therefore, an excessive dietary Mo supplement together with S supplement may result in an excessive accumulation of Mo in the internal organs, mainly liver. This is not desirable to consumers.…”

“…Owing to the fact that the concentration of Fe in PKC is known to range between 800 and 6000 mg/kg DM and was 1512 mg/kg DM in the presently used PKC, and that the excessive dietary concentrations of Fe may result in bent legs of lambs (Hidiroglou et al, 1978) and in decreased productivity in dairy cows (Coup and Campbell, 1964), the use of dietary Fe to reduce the bioavailability of dietary Cu was not considered in the present experiment. It should be pointed out that even though the Fe content in PKC is extremely high, the chronic Cu toxicity in Malaysia in sheep fed diets containing a high proportion of PKC (over 30%) persists and the dietary supplementation with S was not effective in reducing the hepatic Cu accumulation (Alimon et al, 2011). Therefore, only dietary Mo, Mo 1 S and Zn supplements were the subject of the present investigation.…”

“…In a recent experiment (Alimon et al, 2011), graded levels of dietary Mo supplements (without added S) between 0 and 32 mg/kg DM were used in sheep fed a PKC-based diet, but even with the highest level of the supplement the liver Cu concentration increased from the initial 376 mg/g DM to the 6-month final 776 mg/g DM. This is in agreement with the results of the present experiment using 20 mg/kg DM of supplemental Mo.…”

“…However, such reduction in sheep fed a PKC-based diet was not sufficient to prevent chronic Cu toxicity (Ivan et al, 1999). In addition, the Fe concentration in PKC is very high (800 to 6000 mg/kg dry matter (DM)), but the chronic Cu toxicity persists in sheep fed higher concentrations (over 30%) of the dietary PKC, while the supplementation of a PKC diet with S was not effective in reducing the accumulation of Cu in the liver (Alimon et al, 2011). Therefore, the use in sheep of the dietary Fe supplement to reduce the bioavailability of Cu in the dietary PKC appears not to be logical, while treatments with tetrathiomolybdate are no longer appropriate.…”