Dietary Betaine Improves Intestinal Barrier Function and Ameliorates the Impact of Heat Stress in Multiple Vital Organs as Measured by Evans Blue Dye in Broiler Chickens

Abstract

In a 2 × 2 factorial design, 60 male Ross-308 broilers were fed either a control or 1 g/kg betaine diet and housed under thermoneutral (TN) or heat stress (HS) conditions. Broilers were acclimated to diets for 1 week under TN (25 °C), then either kept at TN or HS, where the temperature increased 8 h/day at 33 °C and 16 h/day at 25 °C for up to 10 days. Respiration rate (RR) was measured at four time points, and on each of 1, 2, 3, 7 and 10 days of HS, 12 broilers were injected with 0.5 mg/kg of Evans Blue Dye (EBD) solution to quantify regional changes in tissue damage. Betaine was quantified in tissues, and ileal damage was assessed via morphometry and transepithelial resistance (TER). Heat stress elevated RR (p < 0.001) and resulted in reduced villous height (p = 0.009) and TER (p < 0.001), while dietary betaine lowered RR during HS (p < 0.001), increased betaine distribution into tissues, and improved ileal villous height (p < 0.001) and TER (p = 0.006). Heat stress increased EBD in the muscle and kidney of chickens fed the control diet but not in those receiving betaine. Overall, these data indicate that supplemented betaine is distributed to vital organs and the gastrointestinal tract, where it is associated with improved tolerance of HS. Furthermore, EBD markers help reveal the effects of HS on organs dysfunction.

Betaine and Isoquinoline Alkaloids Protect against Heat Stress and Colonic Permeability in Growing Pigs

“…Reductions in intestinal blood flow during hyperthermia can compromise GIT blood flow, leading to epithelial cell loss and exposure of the lamina propria, which in the ileum has been associated with reduced transepithelial resistance (TER) and increased permeability to macromolecules and bacterial lipopolysaccharide [ 8 , 29 , 30 ]. Consistent with published data, we found that colonic macromolecular permeability was about 60% greater in HS compared to TN pigs.…”

Heat stress on microbiota composition, barrier integrity, and nutrient transport in gut, production performance, and its amelioration in farm animals

“…In chickens, HS (20°C vs. 30°C) increased the activity and expression of apical SGLT1 in intestine by approximately 50%, but no effects on this transporter was noted in the pair-feeding, indicating that increased transported activity was not resulted from decreased feed intake [ 89 ]. In leghorn hens, HS (20°C–22°C, 50°C–60% relative humidity vs. 30°C–33°C, 70%–80% relative humidity) for 28 days decreased calcium binding protein (calbindin) in ileum, cecum, and colon [ 90 ]. In the above discussion, it is apparent that gene or protein expressions of some nutrient transporters are elevated in the intestine under HS, which seems due to adaptive mechanisms to allow proper nutrient absorption by over expressing the transporters compensating HS-induced reduction in absorptive surface area caused by reduced villi height and mucosal damage.…”

Dietary Betaine Reduces the Negative Effects of Cyclic Heat Exposure on Growth Performance, Blood Gas Status and Meat Quality in Broiler Chickens

“…There is also some limited evidence that skeletal muscle from broilers exposed to HS has reduced protein synthesis and proteolysis [2] which may impact on subsequent meat quality. Other possible impacts on chicken meat quality include reduced pH, resulting in paler meat [3], increased level of lipid oxidation [4] and altered muscle fiber structure [5,6]. As a result, there is a high demand for affordable nutritional strategies to ameliorate the adverse effects of HS on meat quality and growth performance in domestic animals [7,8].…”