ARTICLE 52 FEED & ADDITIVE MAGAZINE December 2022 mulated lactic acid) increase protein denaturation resulting in more drip and cooking losses. This type of altered quality of meat is known as PSE (pale soft exudative). Betaine can delay the glycolysis of meat after slaughter by affecting energy metabolism and slowing down the decrease in pH (Fu et al., 2021). For the conservation of meat, preventing rancidity and reducing lipid peroxidation by a good antioxidant ability is desired. Betaine improves the antioxidant defense status, by an increased activity of the enzymes glutathione peroxidase (Alirezaei et al., 2012) and superoxide dismutase (Wen et al., 2019). Additionally, reduction of TBARS (thiobarbituric acid reactive substances) and malondialdehyde (MDA) indicate less peroxidation (Alirezaei et al., 2012; Shakeri et al., 2019; Wen et al., 2021) and thus the positive effect of betaine. THE IMPACT OF HEAT STRESS High temperature is one of the most influential factors adversely affecting animal production and is a major problem in tropical and subtropical regions. Heat stress reduces feed intake and growth performance, even in indigenous broiler breeds (Liu et al., 2019). Broilers exposed to high temperatures show a lower breast yield, an increased fat percentage and noticeable differences in some meat quality parameters such as pH and color (Al-Sagan et al., 2021). The impact of betaine on meat quality might therefore especially be visible under heat stress circumstances (Shakeri et al., 2019). As an osmoprotectant, betaine is known to decrease the stress induced by high environmental temperatures and to improve water retention and cellular functions such as enzyme production. This results in a decrease in body temperature and better growth, feed intake and feed conversion ratio. Carcass and breast yield were shown to linearly increase with increasing dosages of betaine (Liu et al., 2019). The negative impact of heat stress on meat quality can also be alleviated by betaine. One gram of betaine/kg diet increased tenderness, water holding capacity and moisture of the meat (Attia et al., 2009). Decreased redness (a* value) of breast muscle in broilers under heat stress was restored by betaine too (Wen et al., 2019). POULTRY For broilers, it’s known that betaine can improve the breast meat yield and growth performance of the birds. Focusing on the impact of betaine on meat quality, the trial of Al-Sagan et al. (2021), with supplementation of 1g/kg betaine, demonstrated a reduction in cooking loss of 14% compared to control. Shear force was also reduced in the group supplemented with 0.75g/kg betaine (Al-Sagan et al., 2021). Dietary betaine linearly decreased cooking loss, decreased drip loss and shear force, and increased pH at 24h according to the study by Yang et al. (2022). Accordingly, Wen et al. (2018) reported that diet supplemented with betaine increased meat redness and tended to decrease drip loss of breast muscle in broilers under heat stress. Not only breast muscle, but also thigh muscle quality improved with additional betaine in the diet, as observed by Chen et al. (2022). A decreased drip loss, higher pH levels and a tendency for decreased cooking loss in thighs were described. Moreover, Chen et al. (2020) concluded that betaine supplementation not only improved growth performance of broilers, but also alleviated meat quality deterioration of transported broilers through altering muscle anaerobic glycolysis and antioxidant capacity. Betaine has the property to improve cellular antioxidant status and to reduce oxidative damage, indicated by decreased TBARS in the meat (Shakeri et al., 2019; Yang et al., 2022). In ducks (Chen et al., 2019), it was observed that
RkJQdWJsaXNoZXIy MTUxNjkxNQ==