Heat stress is a major issue in developing nations with tropical climates, particularly for broiler chickens because of their rapid growth and conventional open-shed housing. The most cost-effective and efficacious method for reducing heat stress for marginal farmers is nutritional management as opposed to housing management or automation. Because of its osmo-protectant, methyl donor, and amino acid sparing effects, the current investigation confirms that supplementing with 1g/kg of betaine can be the best strategy to control heat stress losses. Because of its effectiveness and low cost, our results can assist broiler farmers, industry, and even small-scale farmers.
Ameliorating heat stress is the major challenge to the broiler industry especially in tropical regions. Among livestock, poultry is particularly sensitive to temperature associated environmental challenges especially heat stress. High ambient temperature has deleterious effect on productive performance in poultry which often results in economic losses. Heat stress is a result of disequilibrium between production and loss of body heat, where the former exceeds later. The major effects due to heat stress might be increased osmotic disturbances and elevated production of free radicals causing oxidative injuries at cellular level to ultimately imposing stress. In order to maintain homeostasis, physiological and behavioral responses are exhibited by birds, which compromises the performance, immunity and meat quality (Shakeri et al. 2018) Combating heat stress without compromising production performance is a difficult task. Efforts are under way to ameliorate the negative effects of heat stress through dietary interventions to achieve optimum performance. As a by-product of sugar beet processing, betaine is commercially available as a feed additive. Betaine is a trimethyl derivative of the amino acid glycine, a metabolite of plant and animal tissues which may provide a strategic solution for these challenges (Akhavan-Salamat and Ghasemi 2016). Protection of cells against osmotic inactivation is a principal biological function of betaine in living beings. Plants and bacteria also produce and accumulate betaine to cope with salt imbalances and thermal stress. Natural betaine has two roles in nutrition as protection of cells against osmotic inactivation and as a methyl donation via. Transmethylation (Alahgholi et al. 2014)
As an osmo-protective agent, betaine accumulates inside the cell without and maintaining normal functions. As an osmolyte agent it protects the intestinal cell proteins and enzymes from high ambient temperature. Betaine keeps cells hydrated and maintains ion balance to improve thermotolerance (Abudabos et al. 2016). Betaine involves in transmethylation process, wherein methyl groups (–CH3) containing a single carbon atom is donated, to synthesize critical metabolites and regulate gene expression through DNA methylation (Chand et al. 2017). Transmethylation helps in nucleic acid, protein and choline synthesis. From nutritional aspect, betaine can replace other methyl donors such as methionine up to 15–20%, total sulphur containing amino acids up to 10% of and almost all of choline. By decreasing the requirement of these essential and costly nutrients, betaine effectively minimizes feed cost. Besides, betaine has also been shown to improve embryonic and post-birth survival rate of piglets (Van Wettere et al., 2012).
Betaine also offers several other beneficial effects such as to improve hatchability and chick weight; spare choline and methionine; improve gut health and function; alleviate heat stress; increases carcass and breast meat yield; reduces coccidiosis lesions (additive effect in combo with ionophores); reduce wet litter condition; improve immune response etc. High blood homocysteine level increases risk of chick mortality, betaine significantly counters homocysteine (Sakomura et al. 2013; He et al. 2015). Betaine as a methyl donor provides its labile methyl groups for the synthesis of several metabolically active substances such as creatine and carnitine. Enhanced methionine availability after dietary supplementation of betaine resulting in improved animal performance (Rao et al., 2011). To address the complex challenges posed by heat stress in broiler chickens, particularly in tropical regions, a comprehensive understanding of the physiological responses and nutritional interventions is imperative. High ambient temperatures disrupt the delicate balance between heat production and dissipation, leading to adverse effects on poultry performance and economic losses. The intricate interplay of osmotic disturbances and heightened free radical production at the cellular level exacerbates the stress imposed by heat. Efforts to counteract heat stress without compromising production performance are underway, with a focus on dietary interventions. Betaine, derived from sugar beet processing, emerges as a promising solution due to its multifaceted roles as an osmo-protectant, methyl donor, and amino acid sparing agent. Within cells, betaine accumulates, preserving normal functions and safeguarding proteins and enzymes in intestinal cells from the impact of high ambient temperatures. Its involvement in the transmethylation process contributes to the synthesis of critical metabolites and the regulation of gene expression through DNA methylation.
From a nutritional standpoint, betaine proves to be a versatile substitute for other costly methyl donors, effectively reducing the requirements for essential nutrients such as methionine, sulphur-containing amino acids, and choline. The economic benefits extend beyond feed cost reduction, as betaine demonstrates positive effects on embryonic and post-birth survival rates in piglets. The study emphasizes the multifaceted benefits of betaine supplementation, including improvements in hatchability, chick weight, gut health, immune response, carcass and breast meat yield, and the reduction of coccidiosis lesions. Additionally, betaine counters the detrimental effects of high blood homocysteine levels, mitigating the risk of chick mortality. As a methyl donor, betaine contributes labile methyl groups for the synthesis of metabolically active substances, further enhancing animal performance.
Against this backdrop, the present study evaluates the efficacy of post-hatch betaine supplementation on broiler performances reared under higher environmental temperatures, providing valuable insights for the sustainable management of heat stress in poultry farming.