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The Effect of Copper and Cobalt Supplementation on the Digestibility of Fibrous Feeds in Sheep

ZELENAK I, JALC D, PLACHA I, SVIATKO P, VENDRAK T, SIROKA P, GYULAI F
Veterinarni Medicina 37, 1992, 221-229

The effects of an addition of copper, cobalt, and copper + cobalt on the in vitro digestibility of hay, treated beech sawdust and cellulose by the rumen fluid of sheep fed a complete food ration, complete food ration with 15 % treated beech sawdust and a diet consisting of 80 % hay and 20 % barley were investigated, respectively. The rumen fluid obtained from animals fed a complete food ration showed the significantly higher digestibility of hay [Tab. I] when Cu [P < 0.05], Co, or Cu + Co [P < < 0.001] had been added into the rumen. The cellulose digestibility increased only after Co application [P < 0,05]. The microelements supplementation in all three forms had a very significant effect on the digestibility of treated beech sawdust by the rumen fluid of sheep fed a diet with 15 % sawdust content, although the initial digestibility by the rumen fluid in the control animals [without microelements] was only 44.9 %. A similar trend was also observed in the cellulose digestibility, but after Co application this increase was not significant. The rumen fluid of animals fed hay [80 %] and barley [20 %] showed the highest digestibility. The digestibility of sawdust reached 60 % and the of cellulose 95.9 % without microelements sopplementation [control]. In this case the effect of microelement supplementation on the sawdust digestibility was manifested only in the case of cobalt by the digestibility decrease [P < 0.001]. The cellulose digestibility also decreased after administration of Cu [P < 0.01] and Co [P < 0.05]. The Cu + Co supplementation did not influence its digestibility. It follows from our results that Cu and Co supplementation had a positive effect on the digestibility of hay, treated beech sawdust and cellulose provided the animals were fed complete food rations when the rumen fluid showed the lower fermentation acitivity. At the diet with the high fermentation acitivity [hay + barley] of the rumen fluid, the mineral supplementation did not increase the digestibility of sawdust or cellulose. The effect of microelements on the production and composition of volatile fatty acids was variable [Figs. 1, 2, 3 and 4]. The application of Cu and Co into the rumen of sheep fed a complete food ration with 15 % treated beech sawdust increased the number of protozoa of the Isotricha and Dasytricha genus, whereas the total number of protozoa did not change [Tab. II]. At the diet consisting of hay and barley the total number of protozoa decreased significantly only after Cu administration [Tab. III]


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