ROLE OF BETAINE IN ALLEVIATING THE HEAT STRESS IN THE POULTRY BIRDS & LIVESTOCK
Betaine is a known multifunctional nutrient in poultry nutrition, as an efficient methyl group donor it can replace other methyl group donors such as choline and methionine, which assists birds under heat stress conditions and improves slaughter characteristics (Rao et al., 2011; Shakeri et al., 2018). The major betaine source so far has been betaine anhydrate extracted from sugar beet. Betaine acts as a strong osmolyte, which is important regarding cellular dehydration via minimizing water loss in the intestine (Kettunen et al., 2001). Furthermore, betaine, being involved in the energy metabolism, can reduce the demand for energy-consuming ion pump activity and supports cells to maintain their function during stress periods (Fu et al., 2022). In poultry production, data on betaine indicate a positive impact on performance, improved carcass composition, reduced litter moisture as well as being beneficial to overcome coccidiosis and stress (Kettunen et al., 2001; Fetterer et al., 2003). The effects of betaine on the host are resolved by various mechanisms such as altered protein synthesis by enhancing the availability of methionine and influencing several physiological functions like membrane synthesis and acetylcholine formation by increasing the availability of choline (Eklund et al., 2005). The same authors reported also that betaine upregulates the synthesis of methylated compounds such as carnitine, which is required for fatty acids transport across the inner mitochondrial membrane where their oxidation occurs. Betaine affects intestinal cells by increasing their water-binding capacity, stabilizes the structure of the mucosa and reduces coccidial lesions, and increases cell action as indicated by a higher activity of proteolytic enzymes (Xu and Yu, 2000; Kettunen et al., 2001; Eklund et al., 2005; Amerah and Ravindran, 2015). Furthermore, some studies reported that betaine enhances the digestion and absorption of nutrients, stimulates bacterial fermentation of fiber, improves feed conversion ratios, breast meat yield and meat quality, and reduces carcass fat (Eklund et al., 2005; Metzler-Zebeli et al., 2009; Ratriyanto et al., 2010). Betaine may also reduce digestive disorders and mortality under unfavourable conditions such as infections and heat stress, and thereby improve production efficiency. Several studies showed that dietary betaine supplementation could improve the bird’s performance and reduce the negative impact of heat stress on cell viability and immune response by improving cell osmoregulation (Wang et al., 2004; Attia et al., 2005; dos Santosa et al., 2019). Today, betaine can be supplemented as natural betaine, isolated from natural sources; synthetic anhydrous betaine or synthetic betaine-HCl. Scientific data on the comparison between synthetic betaine-HCl and natural betaine are limited, prompting us to examine whether the 2 forms of betaine have different effects on the intestine. Numerous studies showed that betaine had the ability to improve chicken’s performance as mentioned above; however, how betaine exert this positive effect is not known. Additionally, the mechanism behind this positive effect of betaine on gut function is lacking. Applying the Ussing chambers technique allows the quantitative analyses of flux rates or the uptake of defined molecules (e.g., electrolytes or sugars) across the intestinal epithelium, as indicators for intestinal permeability at given sites (Awad et al., 2018). Despite the numerous reports on the use of betaine in poultry production, nothing is known so far about the effect of betaine on the gut epithelial barrier or gut microbiota in chickens. The growing global livestock production is moving away from antibiotic growth promoters and coccidiostats, means that the industry will therefore face new challenges impacting gut health. As a consequence, gut health management has become a key focus in the livestock production, especially under heat stress conditions.
India being a tropical country, one of the major problems is the heat stress in the summer season which becomes worse by high relative humidity. Poultry is very sensitive to heat stress as it has a high body temperature, lack of sweat glands and body is covered with feathers. High temperature increases the stress mechanism of the birds leading to adverse effect on the production and well-being of the bird.
Heat stress impairs overall production performance of the birds by decreasing feed intake and negatively affecting intestinal development, leading to reduced nutrient digestibility. Apart from inducing high mortality rate, heat stress is known to depress growth rate and reduce meat yield in broiler birds. In layers lower feed intake impairs ovarian function, leading to decreased feed efficiency, egg production and egg quality. In addition, reduced immune functions such as thyroid activity and antibody production are also evident in heat stressed birds. (Ratriyanto et al, 2018)
Across the world, cattle, poultry, and swine producers are faced with the challenge of managing heat stress in their animals when they are exposed to high environmental temperatures and relative humidity levels. For example, pigs often display signs of heat stress when exposed to an ambient temperature of 31°C or more, which makes it a big challenge for production in many countries.
Heat stress activates strain responses in livestock such as reduced feed intake and increased blood flow to the skin as the animals attempt to dissipate the heat. These responses impair gut health and growth as well as increasing mortality, in turn impacting farm animal welfare and productivity. The potentially significant reduction in performance and profitability means that animal production industries are always on the lookout for innovative ways to alleviate the issue.
The role of betaine and its physiological functions
Over the last years, the use of betaine in animal feed diets has moved from selective utilization, to that of a core ingredient in key feed formulations for poultry and even ruminants. The increased use of betaine in animal diets has been driven by producer demands, to counter performance challenges under heat stress conditions especially in poultry as a methionine and choline sparing tool. But the truth is, that betaine is more than a methionine and choline sparing tool. The benefits are the result of betaine’s role in two main physiological functions: its osmolyte property and acting as a methyl group donor.
Both functions of betaine play a key role, particularly when animals are under challenging conditions, which include dietary changes, heat stress, temperature stress (fluctuation between the day and night temperatures) and pathogenic challenges, mainly coccidiosis often with wet litter as a consequence. This in turn can lead to further severe complications like respiratory disease, or pododermatitis. The fact is, that the higher the challenges, the higher the demand is on methyl groups. In such conditions, the mineral and water balance might be disturbed and the cell wall integrity potentially damaged.
Energy is one of the major dietary cost factors in poultry production and osmoregulatory responses are highly energy consuming processes. Betaine, being involved in the energy metabolism, can reduce the energy required for the osmoregulation. Under normal conditions, the energy saved can be used for increased performance and improved carcass quality. Whilst in challenged conditions, it can reduce digestive disorders and lower mortality, thereby better production efficiency.
Additionally, has further potential benefits like lowering carcass fat content and increasing breast meat yield, has a significant role in hepatic protection and it is a source of glycine, relevant in low protein diets-nitrogen reduced feeding.
As a multi-functional nutrient, betaine is a trusted nutritional aid in managing gut health under thermoneutral or hot climatic conditions and for optimizing the feed efficiency in poultry production. In challenging conditions, there is no single product able to serve as the optimum solution.
The functions of natural betaine – A naturally-occurring osmolyte and methyl donor, natural betaine is an effective means of helping cells stay hydrated. It works by interacting with cellular water to maintain water balance. At the same time, it protects cellular organelles, enzymes and proteins and so enables these components to maintain normal functions despite the stresses caused. f A strong body of evidence demonstrates a range of positive responses to Betafin natural betaine during heat stress among livestock. For example, studies on swine have found that natural betaine mitigates heat stress-related changes in intestinal permeability as measured by ileal transepithelial electrical resistance (TEER expressed as AU) and ileal fluorescein isothiocyanate-labelled dextran permeability (APP; Figure 1). This is particularly important in the context of heat stress, when the gut becomes more leaky due in part to shifts in blood flow away from the core towards the skin. f Furthermore, natural betaine has been shown to increase heat shock protein synthesis as part of thermal tolerance development. f Elsewhere, research also suggests a wider role for betaine supplementation during times of stress in terms of supporting gut microbial communities, improving respiration rate and rectal temperature, including noted effects in swine on supporting larger litters and shorter breeding intervals. f Multiple functions of natural betaine -The dual action of Betafin makes it a highly effective means of alleviating heat stress in animals. As an osmolyte, it helps to protect cells against water loss and dehydration. While its function as a methyl donor promotes regeneration of methionine in the liver, which allows optimized dietary addition of choline and/or methionine in livestock diets. Overall,the multiple functions of natural betaine make it a valuable addition to nutrition strategies designed to optimize livestock performance during these challenging conditions.
Hydration is more than a cellular issue. With 98% of all the molecules in the body affected by water, maintaining optimum hydration challenges the whole animal in terms of energy demands. When heat stress occurs, the energy needed to maintain cellular water balance goes up at the same time as the animal is also having to work hard to maintain productivity and survive the stress.
So how can the multiple functions of natural betaine help producers improve efficiency?
Water Regulation
Cells have no direct way to hold or control water movement, so water can move according to the concentration gradient prevailing at the time. However, because water is a crucial cellular component, nature has devised ways of manipulating its movement. The most commonly recognised method is through the use of ion pumps, such as sodium-potassium ATPase. They act to increase electrolyte levels (mainly potassium) in the cell to a level which is more concentrated than its hyperosmotic environment, and so minimises water movement. However, these pumps are mainly effective against short term stresses, rather than sustained pressure from dehydration. This is because high accumulation of potassium destabilises cellular enzymes, proteins and organelles; leading to a drop in cellular energy output at a rate that increases the longer the stress persists. This is when the functional benefits of Betafin natural betaine, come into play; providing a safe way to minimise cellular water loss at minimum energy cost.
The Functions of Natural Betaine
A naturally-occurring osmolyte and methyl donor, natural betaine is an effective means of helping cells stay hydrated. It works by interacting with cellular water to maintain water balance. At the same time, it protects cellular organelles, enzymes and proteins and so enables these components to maintain normal functions despite the stresses caused by, for example, high environmental temperatures. By helping cells “cope” with dehydration in this way, natural betaine helps to prevent valuable energy being diverted away from growth and lean gain and so helps to maintain animal performance, despite the challenging conditions. Indeed, the presence of natural betaine has been shown to reduce the activity of ion pumps like Na/K ATPase and Ca2+ ATPase by 64% and 73% respectively. A significant energy saving given that these ion pumps can require up to 2 ATP to ultimately move one molecule of potassium into a cell.
Far Reaching Benefits
A strong body of evidence demonstrates a range of positive responses to Betafin natural betaine during heat stress among livestock. For example, studies on swine have found that natural betaine mitigates heat stress-related changes in intestinal permeability as measured by ileal transepithelial electrical resistance (TEER expressed as AU) and ileal fluorescein isothiocyanate-labelled dextran permeability (APP; Figure 1). This is particularly important in the context of heat stress, when the gut becomes more leaky due in part to shifts in blood flow away from the core towards the skin. In poultry, a series of trials (Table 1) illustrate the beneficial effects of natural betaine against key performance parameters including water retention, survival and feed conversion ratio (FCR). While a further study on broilers given natural betaine reported higher levels of water retention compared to nontreated birds exposed to cycling heat stress and/or coccidian challenge as stressors. Equally significant is the effect of natural betaine on the milk yield of lactating dairy cows on pasture. One study reported an improvement of 6% with betaine supplementation at 2g/kg concentrate under ambient summer temperatures (Figure 2). Plus, milk protein and fat yields (g/day) also increased with betaine addition. Furthermore, natural betaine has been shown to increase heat shock protein synthesis as part of thermal tolerance development. One study noted that heat stressed bovine mammary epithelial cells treated with betaine showed higher levels of heat shock proteins (HSP) 27 and 70 compared to non-supplemented controls. At the whole animal level, supplementation of 114 ng betaine/kg lactating cow weight was shown to increase blood leukocyte HSP 70 with no change in HSP 27. Elsewhere, research also suggests a wider role for betaine supplementation during times of stress in terms of supporting gut microbial communities, improving respiration rate and rectal temperature, including noted effects in swine on supporting larger litters and shorter breeding intervals.
Multiple Functions of Natural Betaine
The dual action of Betafin makes it a highly effective means of alleviating heat stress in animals. As an osmolyte, it helps to protect cells against water loss and dehydration. While its function as a methyl donor promotes regeneration of methionine in the liver, which allows optimised dietary addition of choline and/or methionine in livestock diets. Overall, the multiple functions of natural betaine make it a valuable addition to nutrition strategies designed to optimise livestock performance during these challenging conditions.
Controlling heat stress by way of good infrastructural facilities like providing an insulated house, air conditioners, more space to the birds is really very expensive. Also, the period of summer season is very long in various parts of the country, so only a cheap and efficient alternative can reduce the production cost.
Nutritional therapy is one of the cheapest ways to tackle this problem. Using feed additive having positive effects for resisting thermal stress may be a viable solution. Betaine is an example of such a feed additive. It is a multi-nutritional agent that may help the birds to resist the heat stress. It has many important functions in the health and performance of broiler chickens, especially under the conditions of heat stress because it reduces the body temperature of the birds. The chief physiological role of betaine is to function as a methyl donor and an osmolyte. Betaine supplementation in feed improves growth performance and feed intake under heat stressed condition.
MECHANISM OF ACTION OF BETAINE
Natural betaine is found in several plants and organisms and it is commonly extracted and purified from beetroot. It is a trimethyl derivative of amino acid glycine. It is a bipolar compound that has 3 hydrophobic methyl groups and a hydrophilic carboxyl group.
Betaine plays two main roles in metabolism
It donates the methyl radicals for remethylation of homocysteine to methionine in chicken and to formulate useful compounds such as carnitine, creatine and phosphatidyl choline through the S-adenosyl methionine pathway.
Choline also acts as a methyl donor but only when it is oxidized to betaine in two-step conversion in the liver mitochondria.
Due to its zwitterionic characteristics it acts as an osmolyte which helps to maintain cell water metabolism without affecting cell division.
ADVANTAGES OF USING BETAINE IN POULTRY
- It increases growth rate of poultry birds as it saves the energy used in Na+/ K+ pump at high temperature and allows this energy to be used for growth.
- It improves the dry matter, crude protein, crude fiber, ether extract and non-nitrogen fiber extract digestibility as it helps in the expansion of intestinal mucosa which improves absorption and utilization of nutrients.
- It improves the concentration of short chain fatty acids such as acetic acid and propionic acid which are beneficial to host bacteria i.e., lactobacillus and Bifidobacterium in poultry so that they can inhabit sufficiently in the caecum and can inhibit the intestinal colonization by harmful bacteria.
- It increases the daily egg mass, serum estradiol and melatonin concentration in the laying hens.
- It attenuates the detrimental effects of coccidiosis, partially inhibiting coccidiosis development and improving intestinal structure and functions. Betaine is more effective than DL-Methionine especially for broilers under coccidiosis challenge. (Virtanen and Rosi ,1995)
- Betaine has been shown to interact with lipid metabolism by stimulating the oxidative catabolism of fatty acid via its role in carnitine synthesis and thus can be used as a mean to increase lean and decrease fat in poultry carcass.
- The problem of wet droppings and consequent damp litter can be reduced by betaine supplementation in the drinking water as it promotes high water retention in the birds exposed to cyclic heat stress.
- Significant improvement in hematological parameters such as RBC and platelet count. Also, it reduces the heterophil number and increases the lymphocytes number. The reduction of lymphocytes during heat stress is due to the increase of inflammatory cytokines which stimulate the hypothalamic production of corticotrophin releasing hormones under heat stress.
- Betaine supplementation significantly improves FCR at the rate of 1.5 to 2.0 g per kg feed.
- It improves carcass weight, dressing percentage, thigh, breast and giblets percentage at a level of 0.1 to 0.2% in the feed.
- It increases antibody titer in the birds vaccinated against New Castle disease.
All these effects are directly or indirectly related to methionine biosynthesis and osmoregulatory action of betaine.
INCLUSION OF BETAINE IN POULTRY DIET
The concentration of betaine required to supplement a broilers diet largely depends on the concentration of other labile methyl groups, environmental conditions and the health condition of the birds. Typically, betaine can be added at the rate of 0.05-0.08% in broiler diet. Benefits on coccidiosis lesion scores have been noted at 0.05% but osmolyte activity increases as dose of betaine increases. During diarrhoea, when the osmotic balance is disturbed, the effective dose to control diarrhoea ranged from 0.15-1.5 / kg body weight. Generally, the recommended concentration of betaine in the feed is 500-750 g / tonne. Utilization of betaine may be reduced at higher concentrations. (Panda et al ,2009).
According to Floroupaneri et. al 30-80% of supplemental methionine can be substituted by betaine without any negative effects on the performance of the birds.
CONCLUSION
It is very important to produce the poultry products in a cost -effective and sustainable manner. The use of betaine to combat heat stress in the poultry birds is one of the most effective and the cheapest way. The birds fed with betaine have improved production performance during the time of heat stress. Moreover, it is more rapidly absorbed than methionine and choline. The use of betaine as feed additive in poultry diet has no harmful effects. Also, there is not any kind of public health hazard unlike some other feed additives such as antibiotics which are used in the poultry diet. Still the literature about the methionine sparing effect of betaine is scarce. There is a need to broaden our knowledge regarding betaine and its importance in the poultry industry to cope up with the heat stress problem in poultry.
Compiled & Shared by- Team, LITD (Livestock Institute of Training & Development)
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