Effect of various doses of injected selenium on performance and physiological responses of sheep to heat load1

Abstract

The aim of the study was to determine the effects of various doses of injected Se on the physiological responses of sheep to heat load. Fifteen 9-mo-old Australian Merino wethers (mean BW = 27.2 ± 2.1 kg) were randomly assigned to 1 of 3 treatments: 0 (control), 0.5, and 5 mg of Se, which was administered as a subcutaneous sodium selenate injection (5 mg/mL Se) on d 1, 8, and 15 of exposure to heat stress. The animals were housed individually in an environmental chamber and exposed to high temperature from 0700 to 1800 h (maximum = 38°C; minimum = 24°C) and to thermoneutral temperature from 1800 to 0700 h (maximum = 24°C; minimum = 20°C) for 21 d. Rectal temperature (RT) and respiration rate (RR) were measured daily at 0800, 1200, and 1600 h. Feed intake was measured daily, and sheep were weighed on d 1, 8, 15, and 21. Blood samples were collected on d 1 and 21. The 5 mg Se treatment decreased RT by 0.3°C (P = 0.02) and BW loss by 4.5% (P < 0.05) and increased eosinophil count (P < 0.05). There were no differences (P > 0.05) between treatments in RR and DMI, serum concentrations of glucose, total protein, cholesterol, and NEFA or in blood hematology variables. The findings of this study have important implications for the sheep industry. Further studies are warranted to elucidate the dynamics of Se on productivity and health during hot conditions.

A supplement containing multiple types of gluconeogenic substrates alters intake but not productivity of heat-stressed Afshari lambs1

“…Animals on a decreased plane of nutrition mobilize adipose tissue to compensate for energy insufficiency. This observation agrees with our previous sheep study (Mahjoubi et al, 2014) and other ovine reports (Sano et al, 1983;Sevi et al, 2001;Caroprese et al, 2012;Alhidary et al, 2012). Furthermore, the increased NEFA concentration in PFTN controls compared with HS animals replicates findings across species, as similar results have been reported in pigs (Pearce et al, 2013;Sanz Fernandez et al, 2015), steers (O'Brien et al, 2010), and lactating cattle (Wheelock et al, 2010;Baumgard et al, 2011).…”

Blood Haematology, Serum Thyroid Hormones and Glutathione Peroxidase Status in Kacang Goats Fed Inorganic Iodine and Selenium Supplemented Diets

“…However, Juniper et al (2008) and Alhidary et al (2012) showed that dietary supplementation of Se did not affect (p>0.05) the haematological parameters of lambs and sheep, respectively. In line with our findings, the concentrations of Hb and PCV were also unaffected by the iodine supplementation in male goats (Rajendran et al, 2001).…”

Effects of selenium and vitamin E on performance, physiological response, and selenium balance in heat-stressed sheep1

“…The Se and vitamin E requirements of heat stressed sheep are largely unknown because existing recommendations (0.1 and 15 mg/d for Se and vitamin E, respectively; NRC, 1985) were estimated based on prevention of white muscle disease in sheep (McDowell, 1992). Therefore, the concentration of Se used in this study was up to 8 times the NRC (1985) recommendation and was calculated based on results obtained by Alhidary et al (2012) whereas the concentration of vitamin E used in the current study was recommended by Kott et al (1998). It is generally accepted that heat stress exerts adverse effects when the THI exceeds 78 (Fuquay, 1981).…”