Investigating the effects of wasted onion on dry matter intake, nutrient digestibility, and ruminal fermentation and blood parameters in sheep

In order to investigate the effects of different levels of wasted onion (WO) on nutrient digestibility, volatile fatty acids, protozoa population and blood parameters, four Kermani male sheep (BW, 45±1.5 kg) were assigned to Latin square design with four 21-days period. After determining the chemical composition of WO, different levels of it (DM basis) was replaced with barley grain in diets. The experimental diets were: 1) control (no WO), 2) diet containing 8% WO, 3) diet containing 16% WO, and 4) diet containing 24% WO. The dry matter intake, and dry matter and crude protein digestibility of experimental diets were not affected by the WO. The intake and excretion nitrogen and percentage of retained nitrogen were not affected by experimental diets. Also, ruminal fermentation parameters including pH, NH3-N and protozoa population were not affected by addition of WO in diets, but ruminal valeric acid concentration decreased with increasing WO (p<0.05). Furthermore, blood cholesterol decreased linearly (p<0.05) by adding WO. In general, the use of WO up to 24% of the diet instead of barley grain showed no signs of poisoning or anemia (paleness of the mucous membranes, slight discoloration of urine, weakness and lethargy) in sheep. Therefore, due to the fact that the majority of parameters tested in this study were not significantly affected when using WO in diet, WO can be used up to 24% (DM basis) in sheep's diet.