مشخصات پژوهش

The effects of selenium-methionine (Se-Met) and chromium-methionine (Cr-Met) supplementation on performance and response to transportation stress were studied on 24 Baluchi ewe lambs (18–20 weeks of age) for 9 weeks. The lambs were randomly assigned to four dietary treatments: (1) control; (2) 1.5 mg supplemental Se-Met/kg dry matter (DM) of diet; (3) 0.8 mg supplemental Cr-Met/kg DM of diet; and (4) 1.5 mg Se-Met plus 0.8 mg Cr-Met/kg DM of diet (Se-CrMet). At the commencement of week 8, a road transportation stress (TS) was carried out for 30 min. Lambs fed Cr-Met and Se-Cr-Met diets had higher feed intake than the control and Se-Met animals (P<0.0001). Lambs on Cr-Met diet showed higher average daily gain (ADG) compared to the control group (P=0.007). Se-Met and Cr-Met supplementation alone or in combination significantly (P<0.05) reduced feed conversion ratio (FCR). The animals that received Se-Met (P= 0.014), Cr-Met (P=0.005), and Se-Cr-Met (P=0.003) supplemented diets had lower glucose concentration than the control. Lambs on Cr-Met had higher blood T concentration than control animals (P=0.040), while Cr-Met (P=0.039) and Se- 3 Cr-Met (P=0.032) supplementation increased triiodothyronine (T 3 )tothyroxin(T ) ratio. Animals fed Se-Met and/or Cr-Met supplements had lower blood malondialdehyde (MDA) in week 9 of the experiment (P<0.05). Blood ferric-reducing antioxidant power (FRAP) tended to be higher in the Se-Met- and Se-Cr-Met-supplemented groups (P<0.1).TS reduced feed intake in lambs fed the control diet in week 8 of the experiment (P=0.003). The lambs given with supplemental Cr-Met exhibited lower glucose concentration before transportation (BT) (P=0.029) and after transportation (AT) (P= 0.016) compared to the control. Lambs fed Se-Cr-Met had the lowest cortisol concentration BT (P<0.05). It was concluded that feeding Se-Met and/or Cr-Met supplements could improve growth performance and be beneficial in attenuating the adverse effects of transportation st