. 2020 Sep 25;12(10):2939. doi: 10.3390/nu12102939

Table 1.

Animal models successfully using BET to combat passive thermal stress.

Author	Population	Supplementation	Thermal Stress	Significant Findings (Compared to Identified CON)
Zulkifli et al., 2004	Chickens (N = 150)	Ad libitum intake, water supplemented with 0 (CON) or 50 g·kg⁻¹ BET	Cyclical heat stress (36 °C, 75% RH) for 4 h·day⁻¹, 6 days	BET $↓$ core temperature immediately post-heat stress
Attia et al., 2009	Chickens (N = 300)	Ad libitum intake, feed supplemented with 0 (CON) or 1.0 g·kg⁻¹ BET	Cyclical heat stress (38 °C, 49% RH) for 6 h·day⁻¹, 3 days·week⁻¹, 9 weeks	BET $↓$ core temperature during and after heat stress BET $↑$ Hgb during and after heat stress BET $↓$ blood pH during, but not after heat stress
Khattak et al., 2012	Chickens (N = 250)	Ad libitum intake, feed supplemented with 0 (CON) or 1.2 g·kg⁻¹ BET	Natural daily cyclical heat stress (30–41 °C, 40–93% RH), 35 days	BET $↓$ total leukocyte count BET $↓$ mortality 10-fold
Dangi et al., 2015	Goats (N = 18)	Intramuscular injections of saline (CON) or saline + 0.2 g·kg⁻¹ BET immediately prior to heat stress	Cyclical heat stress (42 °C, 36% RH) for 6 h·day⁻¹, 16 days	BET $↓$ HSP60, HSP70, and HSP90
DiGiacomo et al., 2016	Sheep (N = 36)	Ad libitum intake, feed supplemented with 0 (CON), 2, or 4 g BET daily in morning feed	Cyclical heat stress (43 °C, 49% RH) for 8 h·day⁻¹, 21 days	BET (2 g) + Heat $↓$ core and skin temperature
Sahebi Ala et al., 2017	Chickens (N = 1200)	BET as a replacement for 30% methionine needs according to methyl groups	Cyclical heat stress (32 °C, 40% RH) for 6 h·day⁻¹, 31 days	BET + Heat $\leftrightarrow$ mitochondrial Complex-1 function, whereas Heat alone $↓$ mitochondrial Complex-1 function
Park and Kim, 2017	Ducks (N = 360)	Ad libitum intake, water supplemented with 0 (CON), 700, 1000, or 1300 ppm BET	Cyclical heat stress (33–43 °C, 70% RH) for 8 h·day⁻¹, 20 days	All doses of BET $↑$ RBC count, Hct, and Hgb $↑$ PO₂ and PCO₂ $↓$ blood pH $↑$ Blood electrolyte concentrations (Na⁺, K⁺, Cl⁻)

BET: betaine, Cl⁻: chloride, CON: control group, Hct: hematocrit, Hgb: hemoglobin, HSP: heat shock protein, K⁺: potassium, Na⁺: sodium, PCO₂: partial pressure of carbon dioxide, PO₂: partial pressure of oxygen, ppm: parts per million, RBC: red blood cell, RH: relative humidity.