Heidari Jahan Abadi et al. Iranian Journal of Applied Animal Science (2023) 13(1), 43-55 43 The Comparison Effect of Liquid Feeds and Sources of Dietary Selenium on Performance, Blood Metabolites and Anti‐Oxidant Status of Holstein Neonatal Female Calves INTRODUCTION Se (Se) plays important role in several metabolic processes including antioxidant defense systems, thyroid hormone metabolism and immune function (Brown and Arthur, 2001). Because calves are always born with Se deficiency, feeding Se after birth is an important practice for promoting the development of their own immune system and thereby promoting their healthy growth. Se deficiency in calves leads to several economic problems, the most important of which are lack of immunity, low of growth and fertility, abortions, low birth rates and low milk production . So that, an adequate dietary Se intake helps to prevent calves’ dis- ease caused by its deficiency, prevents the accumulation of lipid hydroperoxides in organs and tissues and thus protects them from damage by reactive oxygen species (ROS) (Bickhardt et al. 1999; Hodgson et al. 2006). Selenium is added to ruminant diets in the inorganic or organic form. The objective of this study was to determine the effect of two sources of liquid feed and two sources of dietary selenium (Se) on the performance, blood metabolites and anti-oxidant status of Holstein neonatal female calves Thirty Holstein neonatal female calves were allocated to their treatments, including the colos- trum and milk as liquid feeds with adding 0.3 ppm of either sodium selenite (SS) or Se yeast (SY) as sources of Se and were compared in a 2 × 3 factorial design. Body weight, feed intake and skeletal growth parameters were measured by each calf at birth and at the end of the experiment (day 60). Blood samples were collected by jugular venipuncture into evacuated tubes containing EDTA and stored for further analy- sis. Data were subjected to analyze of variance with GLM using SAS (2004) and mean of parameters were comprised with Tukey test. The results of this experiment showed that although there was no significant effect of both liquid feeds and dietary Se on feed intake, the body weight gain and feed conversion ratio were significantly increased in calves fed by organic Se (P<0.05). Moreover, only body length and stomach size significantly increased o calves fed by organic Se (P<0.05). The results also showed no significant difference in plasma glucose and urea, while the mean of plasma Se, globulin and total protein concentra- tion significantly increased in calves fed by organic Se (P<0.05). In addition, dietary Se not only had a sig- nificant effect on both glutathione peroxidase (GPX) and superoxide dismutase (SOD) activity but also had a significant effect on both growth hormone (GH) and insulin like growth factor (IGF-1), too (P<0.05). The results of the present study implied that adding 0.3 ppm of organic Se to milk or colostrum had a significant effect on performance, blood metabolites and anti-oxidant status of Holstein neonatal female calves.

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