The effect of dl-methionine and betaine on growth performance and carcass characteristics in broilers

Muscle quality traits and oxidative status of Iberian pigs supplemented with zinc and betaine under heat stress

The study analyzed the effect of supplemental zinc and betaine on meat quality and redox status of muscles (longissimus lumborum and gluteus medius) from heat- stressed pigs. Twenty-four pure Iberian pigs were assigned to one of three treatments (n = 8): control diet, Zn supplemented diet (120 mg/kg) and betaine supplemented diet (5 g/kg) that were all exposed to 30 °C during 28 days. No significant differences were observed in chemical composition and fatty acid profile of the muscles. The Zn diet improved the water retention capacity of longissimus, increased the antioxidant properties (ABTS and FRAP) and the glutathione peroxidase activity, and reduced the level of MDA. No significant effects associated to the betaine diet were observed in quality traits and antioxidant markers of muscles. These findings suggest that Zn supplementation may be used as a nutritional strategy to improve the antioxidant properties of meat of Iberian pigs subjected to heat stress conditions.

Conversion of energy and protein rich food waste as an alternative feed ingredient in broiler feed formulation

A series of experiments were performed to find out the impact of food waste on growth attributes and performance of broilers in a tropical climate. Two hundred and fifty-one-day-old broiler chicks were randomly separated into 5 groups, where each group comprised 50 animals. The broilers were fed with five different dietary treatments. Treatment 1 (T1), the diet consisted of food waste ingredients such as sprat heads, fish offal (protein), scraped coconut, and swill cooked rice as energy supplements; dietary treatment II (T2) diet was formulated with protein rich food waste; treatment III (T3) diet formulated with energy-rich food waste; treatment IV (T4) without any food waste materials, but a diet formulated with commercially available feed ingredients; and treatment V (T5), a 100% commercially-available broiler diet. Total feed intake per week and total weight gain were significantly (p < 0.05) higher in the commercial diet (T5) contrary to the formulated diets. The highest feed conversion ratio (FCR) was recorded in T3. The average dressing percentage was not significantly different (p > 0.05) in T1, T3, and T5. Average DM % in litter and DM % in feces were higher in T5, but average nitrogen % in droppings were lower in T4 and T5 compared to other diets. The study shows the potential application of food waste as an alternative feed in the broiler industry and its abundance and easy collection makes it a promising feeding regime in urban and suburban areas.

m6A demethylase FTO regulate CTNNB1 to promote adipogenesis of chicken preadipocyte

BACKGROUND

N6-methyladenosine (m⁶A) is an abundant post-transcriptional RNA modification that affects various biological processes. The fat mass and obesity-associated (FTO) protein, a demethylase encoded by the FTO gene, has been found to regulate adipocyte development in an m⁶A-dependent manner in multiple species. However, the effects of the m⁶A methylation and FTO demethylation functions on chicken adipogenesis remain unclear. This study aims to explore the association between m⁶A modification and chicken adipogenesis and the underlying mechanism by which FTO affects chicken preadipocyte development.

RESULTS

The association between m⁶A modification and chicken lipogenesis was assessed by treating chicken preadipocytes with different doses of methyl donor betaine and methylation inhibitor cycloleucine. The results showed that betaine significantly increased methylation levels and inhibited lipogenesis, and the inverse effect was found in preadipocytes after cycloleucine treatment. Overexpression of FTO significantly inhibited m⁶A levels and promoted proliferation and differentiation of chicken preadipocytes. Silencing FTO showed opposite results. Mechanistically, FTO overexpression increased the expression of catenin beta 1 (CTNNB1) by improving RNA stability in an m⁶A-dependent manner, and we proved that FTO could directly target CTNNB1. Furthermore, CTNNB1 may be a positive regulator of adipogenesis in chicken preadipocytes.

CONCLUSIONS

m⁶A methylation of RNA was negatively associated with adipogenesis of chicken preadipocytes. FTO could regulate CTNNB1 expression in a demethylation manner to promote lipogenesis.

Betaine: A Potential Nutritional Metabolite in the Poultry Industry

Poultry industry has been recognized as a fast-developing sector aiming to produce low-cost and high-nutrient foods for human consumption. This review article aimed to focus on the significant roles of dietary betaine supplementation in the poultry industry. In this respect, different effects of betaine on performance and carcass traits, as well as its osmoregulatory, anticoccidial, immune-modulatory, and heat-stress alleviation activities, were discussed. Different concentrations of betaine supplementation can improve the feed conversion ratio, final body weight, breast muscle yield, egg production ratio, and reduce body fat contents in broiler chicken, turkey, duck, geese, and quail diets. Betaine supplemented with methyl groups can eliminate the need to have some methyl-group donors, including choline and methionine, therefore having positive effects on feed conversion ratio in poultry diets. The osmolytic character of betaine can alleviate heat stress and have a positive impact on tonic immobility, which consequently reduces stress in poultry. By inhibiting distinct developmental stages of Eimeria species, betaine reduces the damaging effects of coccidiosis on broiler chickens and improves intestinal structure and function. The immunological, cardiovascular, neurological, renal, and hepatic metabolic systems benefit from betaine's osmo-protective properties. Therefore, betaine has the potential to be considered as an alternative to feed additives and enhances the health status and productive performance of poultry.

Betaine improves growth performance, liver health, antioxidant status, breast meat yield, and quality in broilers fed a mold-contaminated corn-based diet

Betaine has been demonstrated to improve growth performance and antioxidant status of animals under various stress conditions. However, there is no literature on the effects of betaine in animals exposed to mycotoxins, which are among the most prevalent contaminants in feed. Therefore, this study was conducted to evaluate the influence of dietary betaine on broilers fed a diet based on mold-contaminated corn (MCC). A total of 192 Ross 308 male broiler chicks at 1 d of age were randomly divided into 4 groups with 6 replicates and fed an MCC-based diet supplemented with 0, 250, 500, and 1,000 mg/kg betaine, respectively. Betaine increased average daily gain (linear, P = 0.030) and decreased feed conversion ratio (linear, P = 0.027) of broilers during d 1 – 21, and decreased feed conversion ratio during d 22 – 42 (linear, P = 0.012; quadratic, P < 0.001) and d 1 – 42 (linear, P = 0.003; quadratic, P = 0.004), whereas feed intake was not affected. Total cholesterol (linear, P = 0.024), alanine aminotransferase (quadratic, P < 0.001) and alkaline phosphatase (linear, P = 0.007; quadratic, P = 0.025) activities in serum were decreased by betaine. Betaine linearly increased breast muscle yield (P = 0.003) and pH_24 h (P = 0.008), and decreased drip loss (P = 0.022). Betaine increased (linear, P = 0.025; quadratic, P = 0.016) total superoxide dismutase activity in breast muscle and reduced malondialdehyde content in serum (linear, P = 0.006), liver (quadratic, P = 0.006) and breast muscle (linear, P = 0.003). Moreover, the zearalenone concentrations in breast muscle were linearly decreased by betaine (P = 0.006). It was concluded that betaine could improve growth performance, liver health, antioxidant status, and breast meat yield and quality, and reduce zearalenone residue in broilers fed the MCC-based diet, especially at 500 or 1,000 mg/kg.

Serum Lipid, Amino Acid and Acylcarnitine Profiles of Obese Cats Supplemented with Dietary Choline and Fed to Maintenance Energy Requirements

Obesity is a health concern for domestic cats. Obesity and severe energy restriction predispose cats to feline hepatic lipidosis. As choline is linked to lipid metabolism, we hypothesized that dietary choline supplementation would assist in reducing hepatic fat through increased lipoprotein transport and fatty acid oxidation. Twelve obese cats (body condition score [BCS] ≥ 8/9) were split into two groups. Cats were fed a control (n = 6; 4587 mg choline/kg dry matter [DM]) or a high choline diet (n = 6; 18,957 mg choline/kg DM) for 5 weeks, for adult maintenance. On days 0 and 35, fasted blood was collected, and the body composition was assessed. Serum lipoprotein and biochemistry profiles, plasma amino acids and plasma acylcarnitines were analyzed. The body weight, BCS and body composition were unaffected (p > 0.05). Choline increased the serum cholesterol, triacylglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, very low-density lipoprotein cholesterol and plasma methionine (p < 0.05) and decreased the serum blood urea nitrogen and alkaline phosphatase (p < 0.05). Choline also reduced the plasma acylcarnitine to free carnitine ratio (p = 0.006). Choline may assist in eliminating hepatic fat through increased fat mobilization and enhanced methionine recycling.

Effects of Nano Emulsified Vegetable Oil and Betaine on Growth Traits and Meat Characteristics of Broiler Chickens Reared under Cyclic Heat Stress

The effects of nano-emulsified vegetable oil (NEVO) and betaine (BET) supplements on growth performance and meat qualities of broilers reared under cyclic heat stress (HS) were investigated. Two hundred and eighty-eight mixed-sex broilers at 21 d were randomly distributed to a 2 × 3 factorial arrangement of treatments formed by two environmental temperatures (thermoneutral (TN; 24 ± 1 °C) and cyclic high-temperature (HT; 35 ± 1 °C)) and three dietary treatments (control (CON), NEVO, and BET). The cumulative performance (21-35 d) revealed a reduction in average daily gain (ADG) (p < 0.05) in the CON compared to NEVO. NEVO and BET groups had a better feed conversion ratio (FCR) and performance efficiency factor (PEF) compared with the CON (p < 0.001, p < 0.01, respectively). The environmental temperature affected daily feed intake (DFI), ADG, FCR, and PEF. The addition of BET improved breast fillets yield, temperature, pH_15min, and pH_24hr (p < 0.05) in comparison with the CON. Moreover, the TN group had lower fillet temperature and higher pH_15min compared to the HT. Moreover, HT increased shear force (SF), hardness, springiness, cohesiveness, and chewiness of the fillets compared to TN. In conclusion, dietary supplementation with BET and NEVO could effectively improve performance parameters and meat characteristics under HS conditions.

Broiler genetics influences proteome profiles of normal and woody breast muscle

Wooden or woody breast (WB) is a myopathy of the pectoralis major in fast-growing broilers that influences the quality of breast meat and causes an economic loss in the poultry industry. The objective of this study was to evaluate growth and proteome differences between 5 genetic strains of broilers that yield WB and normal breast (NB) meat. Eight-week-old broilers were evaluated for the WB myopathy and divided into NB and WB groups. Differential expression of proteins was analyzed using 2-dimensional gel electrophoresis and LC-MS/MS to elucidate the mechanism behind the breast myopathy because of the genetic backgrounds of the birds. The percentages of birds with WB were 61.3, 68.8, 46.9, 45.2, and 87.5% for strains 1-5, respectively, indicating variability in WB myopathy among broiler strains. Birds from strains 1, 3, and 5 in the WB group were heavier than those in the NB group (P < 0.05). Woody breast meat from all strains were heavier than NB meat (P < 0.05). Within WB, strain 5 had a greater breast yield than strains 1, 3, and 4 (P < 0.0001). Woody breast from strains 2, 3, 4, and 5 had a greater breast yield than NB (P < 0.05). Six proteins were more abundant in NB of strain 5 than those of strains 2, 3, and 4, and these proteins were related to muscle growth, regeneration, contraction, apoptosis, and oxidative stress. Within WB, 14 proteins were differentially expressed between strain 5 and other strains, suggesting high protein synthesis, weak structural integrity, intense contraction, and oxidative stress in strain 5 birds. The differences between WB from strain 3 and strains 1, 2, and 4 were mainly glycolytic. In conclusion, protein profiles of broiler breast differed because of both broiler genetics and the presence of WB myopathy.

Effect of dietary betaine supplementation on egg quality, semen quality, hematology, fertility and hatchability in broiler breeders

An experiment was conducted to establish the growth response, egg quality, semen quality, hematological attributes, fertility and hatchability in broiler breeders supplemented with graded levels of betaine. The broiler breeders (CARIBRO-VISHAL) of about 38 weeks divided into four treatments viz. T1 (basal diet), T2 (T1 + 1 g), T3 (T1 + 2 g) and T4 (T1 + 3 g betaine/kg) consisting of 24 female birds and 6 male birds per treatment with three replicates of 8 female and 2 male birds each in completely randomized design. Hen day egg production (HDEP) was significantly increased in betaine supplemented groups. Semen concentration was found to be significantly improved following betaine supplementation with highest increment in T4 group. Mass motility in T3 group during 4th week of experimental trial was found to be significantly increased. In female birds, a significant difference in RBC count, PCV, MCH and MCHC was observed among the treatments during 2nd week of trial. Fertility and hatchability (TES: total eggs set; FES: fertile eggs set) was increased in betaine supplemented groups with highest increment in T4 treatment group. Total embryonic mortality was lowest for T4 treatment group. Thus, it can be concluded that dietary supplementation of betaine at 3 g/kg was helpful in improving the reproductive performance in broiler breeders.

The effects of betaine supplementation in diets containing different levels of crude protein and methionine on the growth performance, blood components, total tract nutrient digestibility, excreta noxious gas emission, and meat quality of the broiler chickens

The effects of betaine supplementation on growth performance, blood components, nutrient digestibility, excreta noxious gas emission, and meat quality of broiler chickens were examined using different dietary crude protein (CP) and methionine (Met) levels. A total of 768 Ross 308 broiler chickens were allotted to four treatments, with 12 replications of each treatment conducted over 6 wk. Treatments were factorially designed, with 2 levels of CP [Starter: CP 21% (low Met) and 23% (high Met); Finisher: CP 18% (low Met) and 20% (high Met)] and 2 levels of betaine supplementation (0 and 0.12%). Body weight gain and feed conversion improved significantly as dietary levels of protein increased (P < 0.05), but the results for betaine supplementation differed. The concentrations of serum total protein, albumin, and glutathione peroxidase (GPx) were elevated by either the supplementary betaine or the CP (P < 0.05). In addition, serum albumin concentration significantly increased in groups fed low CP amounts and betaine 0.12% compared with groups fed low CP only (P < 0.05). Total tract digestibility of nitrogen in broilers fed high CP amounts or 0.12% betaine, was observed to be greater than that in groups fed low CP amounts or no betaine treatment (P < 0.05). Supplemental betaine affected excreta ammonia gas emission, and hydrogen sulfide concentrations decreased significantly in low CP-fed groups (P < 0.05). Breast meat quality and relative organ weights were not influenced by CP levels or dietary betaine supplementation. These results suggest that betaine does not increase productivity, but may affect serum total protein, albumin, GPx, excreta ammonia emission, and nitrogen digestibility in broiler chickens. In addition, betaine supplementation is more effective in increasing serum albumin concentration when it was added in low CP (low Met) diets.

Effects of rumen-protected betaine supplementation on meat quality and the composition of fatty and amino acids in growing lambs

Rumen-protected betaine (RPB) can enhance betaine absorption in the small intestine of ruminants, while betaine can alter fat distribution and has the potential to affect the meat quality of livestock. Hence, we hypothesized that RPB might also affect the meat quality of lambs. Sixty male Hu sheep of similar weight (30.47 ± 2.04 kg) were selected and randomly subjected to five different treatments. The sheep were fed a control diet (control treatment, CTL); 1.1 g/day unprotected-betaine supplemented diet (UPB); or doses of 1.1 g/day (low RPB treatment; L-PB), 2.2 g/day (middle RPB treatment; M-PB) or 3.3 g/day (high RPB treatment; H-PB) RPB-supplemented diet for 70 days. Slaughter performance, meat quality, fatty acid and amino acid content in the longissimus dorsi (LD) muscle, shoulder muscle (SM) and gluteus muscle (GM) were measured. Compared with CTL, betaine (including UPB and RPB) supplementation increased the average daily weight gain (ADG) (P < 0.05) and average daily feed intake (P < 0.01) of lambs. Rumen-protected betaine increased ADG (P < 0.05) compared with UPB. With increasing RPB doses, the eye muscle area of the lambs linearly increased (P < 0.05). Compared with CTL, betaine supplementation decreased water loss (P < 0.05) in SM and increased pH24 in the SM (P < 0.05) and GM (P < 0.05). Compared with UPB, RPB decreased water loss in the GM (P < 0.01), decreased shear force (P < 0.05) in the LD and SM and increased the pH of the meat 24 h after slaughter (pH24). With increasing RPB doses, the shear force and b* value in the LD linearly decreased (P < 0.05), and the pH24 of the meat quadratically increased (P < 0.05). Compared with CTL, betaine supplementation increased the polyunsaturated fatty acid in the GM (P < 0.05). Compared with UPB, RPB supplementation decreased the saturated fatty acid (SFA) content in the LD (P < 0.05) and increased the unsaturated fatty acids (UFA), mono-unsaturated fatty acids and UFA/SFA ratio in the LD (P < 0.05). Compared with CTL, the content of histidine in the LD increased with betaine supplementation. Compared with UPB, RPB supplementation increased the content of total free amino acids and flavor amino acids in the LD of lambs (P < 0.05). With increasing RPB, the isoleucine and phenylalanine contents in the LD linearly increased (P < 0.05). Overall, the data collected indicated that the meat quality of lambs (especially in the LD) improved as a result of betaine supplementation, and RPB showed better effects than those of UPB.

Thermotolerance of Broiler Chicks Ingesting Dietary Betaine and/or Creatine

The present study aimed to assess the effect of dietary betaine (B) and/or creatine (C) on performance and thermoregulatory responses of broiler chicks. Indian River broiler chicks, fitted with compact thermosensors, were reared to market age (five weeks). The chicks were randomly distributed into four treatment groups, in a 2 × 2 factorial arrangement of treatments-basal control diet (Control group: CONT; B-/C-); 1 g betaine/kg feed (Betaine group: BETA; B+/C-), 1.2 g creatine monohydrate/kg feed (Creatine group: CRET; B-/C+), and combination (Betaine and Creatine group: COMB; B+/C+) of both supplements. At 31 days of age, 20 chicks from each group were exposed to acute heat stress (A-HS) for 3 h (34.45 ± 0.20 °C), and hemogramic profiles were screened before and after. Performance parameters (feed intake, body weight gain, and feed conversion ratio) were reported on a weekly basis, and carcass meat quality was evaluated at the end of experiment. Redness of breast was higher due to B and C treatments separately than the CONT group (B by C interaction; p < 0.05). Compared to the CONT, dietary supplements alleviated hyperthermia responses, with B alone being more efficient than C or COMB treatments. The mitigation of hyperthermia is likely mediated by enhancement of water balance indicators. Although not efficient in improving growth performance, dietary B and/or C are efficient in improving thermophysiological performance and survival of finishing broiler chicks under A-HS.

Betaine improves the growth performance and muscle growth of partridge shank broiler chickens via altering myogenic gene expression and insulin-like growth factor-1 signaling pathway

This study was conducted to investigate the effect of betaine on growth performance, carcass characteristics, myogenic gene expression, and insulin-like growth factor-1 (IGF-1) signaling pathway in partridge shank broiler chickens. A total of 192 one-day-old partridge shank broiler chickens were randomly divided into 4 groups with 6 replicates of 8 chickens for a 52-d feeding trial. Broilers were fed a basal diet supplemented with 0 (control), 250 (B250), 500 (B500), or 1,000 (B1000) mg/kg betaine. Compared with the control group, the B500 and B1000 groups had higher (P < 0.05) body weight gain (BWG), and the B500 group had a lower (P < 0.05) feed/gain ratio (F:G) during the whole trial period. Moreover, the B1000 group increased (P < 0.05) the breast muscle yield and decreased (P < 0.05) relative abdominal fat weight. The mRNA expression of myocyte enhancer factor 2B (MEF2B) and mechanistic target of rapamycin (mTOR) and mTOR phosporylation were higher (P < 0.05) in both breast and thigh muscles in the B500 and B1000 groups than those in the control group. The higher (P < 0.05) concentration and mRNA expression of IGF-1 were also observed in breast muscle in the B500 and B1000 groups. Additionally, the B1000 group up-regulated (P < 0.05) the mRNA level of myogenic differentiation factor 1 (MyoD1) in breast muscle and myogenin (MyoG) in thigh muscle. In conclusion, diets supplemented with 500 or 1,000 mg/kg betaine improved the growth performance of partridge shank broiler chickens during the whole trial period, and the B1000 group significantly improved the breast muscle growth. These improvements might result from increased mRNA expression of MyoD1 and MEF2B in breast muscle and MyoG and MEF2B in thigh muscle, and through alterations in IGF-1/mTOR signaling pathway.

Transcriptome analysis of hepatic gene expression and DNA methylation in methionine- and betaine-supplemented geese (Anser cygnoides domesticus)

Dietary methionine (Met) restriction produces a coordinated series of transcriptional responses in the liver that limits growth performance and amino acid metabolism. Methyl donor supplementation with betaine (Bet) may protect against this disturbance and affect the molecular basis of gene regulation. However, a lack of genetic information remains an obstacle to understand the mechanisms underlying the relationship between Met and Bet supplementation and its effects on genetic mechanisms. The goal of this study was to identify the effects of dietary supplementation of Met and Bet on growth performance, transcriptomic gene expression, and epigenetic mechanisms in geese on a Met-deficient diet. One hundred and fifty 21-day-old healthy male Yangzhou geese of similar body weight were randomly distributed into 3 groups with 5 replicates per treatment and 10 geese per replicate: Met-deficient diet (Control), Control+1.2 g/kg of Met (Met), and Control+0.6 g/kg of Bet (Bet). All geese had free access to the diet and water throughout rearing. Our results indicated that supplementation of 1.2 g/kg of Met in Met-deficient feed increased growth performance and plasma homocysteine (HCY) levels, indicating increased transsulfuration flux in the liver. Supplementation of 0.6 g/kg Bet had no apparent sparing effect on Met needs for growth performance in growing geese. The expression of many genes critical for Met metabolism is increased in Met supplementation group. In the Bet-supplemented group, genes involved in energy production and conversion were up-regulated. Dietary supplementation with Bet and Met also altered DNA methylation. We observed changes in the methylation of the LOC106032502 promoter and corresponding changes in mRNA expression. In conclusion, Met and Bet supplementation in geese affects the transcriptional regulatory network and alters the hepatic DNA methylation of LOC106032502.

Effects of dietary methionine on growth performance, meat quality and oxidative status of breast muscle in fast- and slow-growing broilers

This experiment was conducted to investigate the effects of dietary methionine (Met) on growth performance, carcass traits, meat quality and oxidative status of breast muscle in fast- (Arbor Acres, AA) and slow- (Partridge Shank, PS) growing broilers from 1 to 42 d of age. The broilers were divided into a 2 × 3 factorial design with 6 replicates per treatment. Diets were formulated to contain low (LM, 0.35 and 0.31% during 1 to 21 and 22 to 42 d), adequate (AM, 0.50 and 0.44%) and high (HM, 0.65 and 0.57%) Met, respectively. The main effects showed that the AA broilers had superior (P < 0.05) growth performance and carcass traits compared with those of the PS broilers. The breast muscle of the AA broilers had lower (P < 0.05) drip loss and malondialdehyde (MDA) content but higher (P < 0.05) cooking loss and glutathione peroxidase (GPX) activity than that of the PS broilers. Compared with the LM diets, the AM and HM diets increased (P < 0.05) 42-d BW, ADG, eviscerated yield and breast muscle yield only in the AA broilers. The AA broilers fed the HM diets had higher (P < 0.05) pH but lower (P < 0.05) L*, cooking loss and ether extract content in breast muscle than those fed the LM diets. Compared with the LM diets, the HM diets resulted in strain-dependent changes (P < 0.05) in muscle oxidative status, with total antioxidant capacity (T-AOC) increased in the AA broilers, GPX activity increased and MDA content decreased in the PS broilers, and superoxide dismutase (SOD) activity increased in both strains of broilers. No differences were observed between the AM and HM diets except for T-AOC in breast muscle. In conclusion, the LM treatment negatively affected broiler growth performance, carcass traits, meat quality and oxidative status of breast muscle in a strain-dependent manner, particularly in the AA broilers, whereas the HM treatment had limited effects compared to the AM treatment.

Factors affecting adipose tissue development in chickens: A review

The intense genetic selection for rapid growth in broilers has resulted in an increase in voluntary feed intake and growth rate, accompanied by increased fat deposition in adipose tissue depots throughout the body. Adipose tissue expansion is a result of the formation of adipocytes (several processes collectively referred to as adipogenesis) and cellular accumulation of triacylglycerols inside lipid droplets. In mammals, different anatomical depots are metabolically distinct. The molecular and cellular mechanisms underlying adipose tissue development have been characterized in mammalian models, whereas information in avian species is scarce. The purpose of this review is to describe factors regulating adipogenesis in chickens, with an emphasis on dietary factors and the broiler. Results from many studies have demonstrated effects of dietary nutrient composition on adipose tissue development and lipid metabolism. Transcription factors, such as peroxisome proliferator-activated receptor γ, CCAAT/enhancer-binding proteins α and β, and sterol regulatory element binding proteins orchestrate a series of cellular events that lead to an increase in activity of fatty acid transport proteins and enzymes that are responsible for triacylglycerol synthesis. Understanding the mechanisms underlying adipose tissue development may provide a practical strategy to affect body composition of the commercial broiler while providing insights on diets that maximize conversion into muscle rather than fat and affect depot-dependent deposition of lipids. Because of the propensity to overeat and become obese, the broiler chicken also represents an attractive biomedical model for eating disorders and obesity in humans.

Effect of dietary betaine on growth performance, antioxidant capacity and lipid metabolism in blunt snout bream fed a high-fat diet

An 8-week feeding experiment was conducted to determine the effect of dietary betaine levels on the growth performance, antioxidant capacity, and lipid metabolism in high-fat diet-fed blunt snout bream (Megalobrama amblycephala) with initial body weight 4.3 ± 0.1 g [mean ± SEM]. Five practical diets were formulated to contain normal-fat diet (NFD), high-fat diet (HFD), and high-fat diet with betaine addition (HFB) at difference levels (0.6, 1.2, 1.8%), respectively. The results showed that the highest final body weight (FBW), weight gain ratio (WGR), specific growth rate (SGR), condition factor (CF), and feed intake (FI) (P < 0.05) were obtained in fish fed 1.2% betaine supplementation, whereas feed conversion ratio (FCR) was significantly lower in the same group compared to others. Hepatosomatic index (HSI) and abdominal fat rate (AFR) were significantly high in fat group compared to the lowest in NDF and 1.2% betaine supplementation, while VSI and survival rate (SR) were not affected by dietary betaine supplementation. Significantly higher (P < 0.05), plasma total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), aspartate transaminase (AST), alanine transaminase (ALT), cortisol, and lower high-density lipoprotein (HDL) content were observed in HFD but were improved when supplemented with 1.2% betaine. In addition, increase in superoxide dismutase (SOD), catalase (CAT), and reduced glutathione (GSH) in 1.2% betaine inclusion could reverse the increasing malondialdehyde (MDA) level induced by HFD. Based on the second-order polynomial analysis, the optimum growth of blunt snout bream was observed in fish fed HFD supplemented with 1.2% betaine. HFD upregulated fatty acid synthase messenger RNA (mRNA) expression and downregulated carnitine palmitoyltransferase 1, peroxisome proliferator-activated receptor α, and microsomal triglyceride transfer protein mRNA expression; nevertheless, 1.2% betaine supplementation significantly reversed these HFD-induced effects, implying suppression of fatty acid synthesis, β-oxidation, and lipid transport. This present study indicated that inclusion of betaine (1.2%) can significantly improve growth performance and antioxidant defenses, as well as reduce fatty acid synthesis and enhance mitochondrial β-oxidation and lipid transportation in high-fat diet-fed blunt snout bream, thus effectively alleviating fat accumulation in the liver by changing lipid metabolism.

Partial Replacement of Dietary Methionine with Betaine and Choline in Heat-Stressed Broiler Chickens

We conducted two trials to evaluate the methionine-sparing effects of choline (Chol) and betaine (Bet), and their effects on growth performance and blood antioxidative potential in heat-stressed broiler chickens fed methionine (Met)-deficient diets. We used 360 1-day-old broiler chicks (Ross 308) in a completely randomized study with 5 replicate pens of 12 birds each. After Day 21, we raised the temperature to 35±3°C using an automated air-forced heater for 12 hours/day from 8 am to 8 pm to expose the birds to heat stress. In Trial 1, the treatments comprised a negative control (control-; 1200 mg/kg Met-deficient), a positive control (control+; recommended level of Met), 280Chol (control- plus 280 mg/kg Chol), 560Chol (control- plus 560 mg/kg Chol), 320Bet (control- plus 320 mg/kg Bet), and 640Bet (control- plus 640 mg/kg Bet); and in Trial 2, the treatments comprised a negative control (control-), a positive control (control+), 140Chol+160Bet (control- plus 140 mg/kg Chol and 160 mg/kg Bet), 280Chol+160Bet (controlplus 280 mg/kg Chol and 160 mg/kg Bet), 140Chol+320Bet (control- plus 140 mg/kg Chol and 320 mg/kg Bet), and 280Chol+320Bet (control- plus 280 mg/kg Chol and 320 mg/kg Bet). Compared with the other treatments, the feed conversion ratio (FCR) was improved in the 280Chol and control+ groups in Trials 1 and 2 (P<0.05). In Trial 2, the cost of meat production for the entire experimental period (1-42 days) was higher in the 140Cho+320Bet-fed birds than in the other birds (P<0.05), except the control- birds. Supplementing diets with 280 mg/kg of Chol significantly reduced the serum concentration of uric acid compared with the control+ group (P<0.05). Our results indicate that the Met requirements of heat-stressed broiler chickens can be reduced by 20% (1200 mg/kg) if the diet is supplemented with 280 mg/kg of Chol.

Increased fatty acid β-oxidation as a possible mechanism for fat-reducing effect of betaine in broilers

Two hundred and forty 1-day-old male Arbor Acres broiler chickens were randomly assigned to five dietary treatments with six replicates of eight chickens per replicate cage for a 42-day feeding trial. Broiler chickens were fed a basal diet supplemented with 0 (control), 250, 500, 750 or 1000 mg/kg betaine, respectively. Growth performance was not affected by betaine. Incremental levels of betaine decreased the absolute and relative weight of abdominal fat (linear P < 0.05, quadratic P < 0.01), low-density lipoprotein cholesterol (LDL-C), triglyceride (TG) and total cholesterol (TC) (linear P < 0.05), and increased concentration of nonesterified fatty acid (NEFA) (linear P = 0.038, quadratic P = 0.003) in serum of broilers. Moreover, incremental levels of betaine increased linearly (P < 0.05) the proliferator-activated receptor alpha (PPARα), the carnitine palmitoyl transferase-I (CPT-I) and 3-hydroxyacyl-coenzyme A dehydrogenase (HADH) messenger RNA (mRNA) expression, but decreased linearly (P < 0.05) the fatty acid synthase (FAS) and 3-hydroxyl-3-methylglutaryl-CoA (HMGR) mRNA expression in liver of broilers. In conclusion, this study indicated that betaine supplementation did not affect growth performance of broilers, but was effective in reducing abdominal fat deposition in a dose-dependent manner, which was probably caused by combinations of a decrease in fatty acid synthesis and an increase in β-oxidation.

Potential nutritional and physiological functions of betaine in livestock

The present review summarises the potential nutritional and physiological functions of betaine as a feed additive in relation to performance criteria in livestock production. Betaine, the trimethyl derivative of the amino acid glycine, is a metabolite of plant and animal tissues. In plants, betaine is particularly synthesised and accumulated as an osmoprotectant against salt and temperature stress. In animals, betaine is the product of choline oxidation or it originates from nutritional sources. Over the past decades, numerous studies have been carried out to investigate the potential effects of betaine supplementation on animal performance. Due to its chemical structure, betaine shows the characteristics of a dipolar zwitterion resulting in osmoprotective properties. Promoting effects on the intestinal tract against osmotic stress occurring during diarrhoea or coccidiosis have been reported following betaine supplementation in pigs and poultry. There is also some evidence that dietary betaine may improve the digestibility of specific nutrients. As a product of choline oxidation, betaine is involved in transmethylation reactions of the organism. Betaine as a methyl donor provides its labile methyl groups for the synthesis of several metabolically active substances such as creatine and carnitine. Supplementation with betaine may decrease the requirement for other methyl donors such as methionine and choline. There is also some evidence for enhanced methionine availability after dietary supplementation of betaine resulting in improved animal performance. Alterations in the distribution pattern of protein and fat in the body have been reported following betaine supplementation. A more efficient use of dietary protein may result from a methionine-sparing effect of betaine, but also direct interactions of betaine with metabolism-regulating factors have to be considered. Though the mode of action of betaine as a carcass modifier remains open, there is, however, growing evidence that betaine could have a positive impact both on animal performance and carcass quality.

Effects of methionine and betaine supplementation on growth performance, carcase composition and metabolism of lipids in male broilers

1. This study was conducted to investigate the effects of methionine and betaine supplementation on growth performance, carcase composition and lipid metabolism in growing broilers. 2. A total of 450 commercial broilers, 22 d of age, were randomly allocated to three groups, each of which included three replicates (50 birds per replicate). The groups received the same methionine-deficient diet supplemented with 0 or 1 g/kg methionine, or 0.5 g/kg betaine, respectively. 3. Methionine and betaine supplementation significantly improved weight gain and feed conversion. Supplemental methionine and betaine also significantly increased breast muscle yield and decreased abdominal fat content. Meanwhile, addition of methionine and betaine significantly increased the contents of creatine and free carnitine in liver, the activity of hormone-sensitive lipase in abdominal fat and the concentration of free fatty acid in serum, whereas uric acid concentration in serum was significantly decreased. 4. The results of this study suggest that betaine can spare methionine in its function as an essential amino acid and is as effective as methionine in improving performance and carcase quality of growing broilers if the diet is moderately deficient in methionine. The decrease in abdominal fat may be due to the increased carnitine synthesis in liver and hormone-sensitive lipase activity in abdominal fat.

Homocysteine Remethylation in Broilers Fed Surfeit Choline or Betaine and Varying Levels and Sources of Methionine from Eight to Twenty-Two Days of Age

Experiments were conducted to assess the effect of surfeit choline (CHOL) or betaine (BET) on growth performance and homocysteine (HCY) remethylation of young broilers fed graded levels of DL-Met (DLM) or 2-hydroxy-4-(methylthio) butanoic acid (HMB). In Experiment 1, a corn-peanut meal diet deficient in Met (0.25% digestible) and Cys (0.28% digestible) was fed; treatments were formulated to contain graded levels (0, 0.04, or 0.08%) of Met from DLM or 0.04% HMB (adjusted for 88% purity) that were fed in the presence or absence of surfeit isomethyl CHOL (0.25%) or BET (0.28%). In Experiment 2, identical treatments were used, but an additional level of HMB (0.08%) was fed, and the basal diet was adequate in Cys (0.43% digestible). There was no overall effect of CHOL or BET on growth performance in Experiments 1 and 2 (P > 0.05); a significant improvement (P < 0.05) in weight gain and feed efficiency did occur with CHOL and BET addition to the basal diet in Experiment 2. In both experiments, weight gain increased linearly (P < 0.05) with the addition of DLM or HMB. Slope ratio methodology was used to assess HMB efficacy in Experiment 2. In the presence of adequate Cys, HMB efficacy was 81.3%; addition of surfeit BET or CHOL had minimal effect on efficacy. The stable isotope study revealed that CHOL and BET addition to diets deficient in Met and Cys or Met alone increased HCY remethylation. It also showed that CHOL and BET have greater influence on folate-dependent remethylation of HCY (via Met synthase) than on BET-dependent remethylation (via BET-HCY methyltransferase) and that levels of CHOL and BET and type of S amino acid deficiency effect remethylation and HMB efficacy.

Methionine Requirements of Male White Peking Ducks from Twenty-One to Forty-Nine Days of Age

A dose-response experiment with 6 dietary methionine levels (0.20, 0.275, 0.35, 0.425, 0.50, and 0.575%) was conducted with male White Peking ducklings to estimate the methionine requirement of growing ducks from 21 to 49 d of age. One-day-old male White Peking ducklings were fed common starter diets from hatching to 21 d of age and then fed the experimental diets from 21 to 49 d of age. Three hundred thirty-six 21-d-old birds were allotted to 24 pens with 14 birds per pen according to similar pen weight. There were 6 dietary treatments, each containing 4 replicate pens. At 49 d of age, weight gain, feed intake, and feed/gain of ducks from each pen were measured, and 2 ducks selected randomly from each pen were slaughtered to evaluate the yields of abdominal fat, breast meat (including pectoralis major and pectoralis minor), and leg meat (including thigh and drum stick). Significant effects of dietary methionine on weight gain, breast meat, and abdominal fat were observed. Both weight gain and breast meat yield showed significant quadratic response to increasing dietary methionine, and abdominal fat decreased linearly (P < 0.05). According to the quadratic model, the optimal methionine requirement of male White Peking ducks from 21 to 49 d of age for maximum weight gain and breast meat yield were 0.377 and 0.379%, respectively.