Effects of Fish Oil, Safflower Oil and Monensin Supplementation onPerformance, Rumen Fermentation Parameters and PlasmaMetabolites in Chall Sheep

Thirty-two lactating chall ewes were assigned to eight groups and received one of eightdietary treatments for ten weeks as follows: control diet (con); a fish oil-supplemented diet (20g/kg dry matter intake (dmi); fo); a safflower oil-supplemented diet (20 g/kg dmi; so); amonensin-supplemented diet (15 mg/kg dmi; mo); a diet supplemented with fish oil (20 g/kgdmi) and safflower oil (20 g/kg dmi; fs); a diet supplemented with fish oil (20 g/kg dmi) andmonensin (15 mg/kg dm;i fm); a diet that contained safflower oil (20 g/kg dmi) and monensin(15 mg/kg dmi; sm); and a diet that contained fish oil (20 g/kg dmi), safflower oil (20 g/kgdmi) and monensin (15 mg/kg dmi; fsm). during the experimental period, ewes were kept inindividual pens and the amounts of feed that were offered to individual ewes were recordeddaily. milk samples were collected weekly and analyzed for their composition. rumen fluid andplasma samples were obtained from each ewe on the final day of the trial and stored at -20˚cbefore analysis. results showed that the so diet had no significant effect (p< 0.05) on dmi,however, other diets reduced thedmisignificantly. milk yield was significantly lower for ewesthat were fed diets supplemented with monensin compared to the other groups (p<0.05). themilk fat percentage was relatively low for all treatments, although only fs, fm and fsmtreatments were significantly different from the control group. the yield of milk fat wassignificantly reduced in the mo, fs, fm, sm and fsm groups. the percentage of protein inmilk was significantly reduced in the fs and fsm diets. however, the milk protein yield wasreduced significantly as a direct result of the decreased milk yield in ewes that were fed the mo,fs, fm, sm and fsm diets. the mo diet increased significantly the concentration of ureanitrogen in milk. fish oil and safflower oil-supplemented diets with or without monensinresulted in decreased numbers of infective protozoa, and a decreased acetate-to-propionate ratioin rumen fluid when compared to the con group. the concentrations of plasma glucose andurea were not affected by any of the treatments, but the plasma concentrations of triglycerides,total cholesterol, and hdl-cholesterol were higher in ewes that consumed the oil-containingdiets than the other groups. it was concluded that dietary supplementation with a combination offish oil, safflower oil and monensin could alter the composition of milk from ewes and, inparticular, cause a reduction in the percentage of fat in the milk. this may make this milk moresuitable for human consumption.