Effects of Dietary Threonine Levels and Stocking Density on the Performance, Metabolic Status and Immunity of Broiler Chickens

Growth performance, liver and kidney functions, blood hormonal profile, and economic efficiency of broilers fed different levels of threonine supplementation during feed restriction

The objective of the existing investigation was to determine the effect of dietary inclusion of threonine amino acid at different levels during feed restriction on growth indices, liver and kidney function parameters, and some hormonal profiles along with economic indicators in broiler chickens. A total of 1,600 from 2 different breeds (800 Ross 308 and 800 Indian River) at 21-day-old age were incorporated. Chicks were randomly assigned into 2 main groups, control and feed-restricted (8 h/d), during the fourth week of age. Each main group was subdivided into 4 groups. The first group was fed a basal diet without adding extra threonine (100%), the second, third, and fourth groups were fed a basal diet with extra threonine levels of 110, 120, and 130%, respectively. Each subgroup consisted of 10 replicates of 10 birds. We noticed that the dietary inclusion of threonine at extra levels in the basal diets significantly enhanced final body weight, body weight gain, and better feed conversion ratio. This was mainly due to the enhanced levels of growth hormone (GH), insulin-like growth factor (IGF1), triiodothyronine (T3), and thyroxine (T4). Moreover, the lowest feed cost per kilogram body weight gain and improved return parameters were reported in control and feed-restricted birds fed higher levels of threonine than other groups. Also, a significant increase in alanine aminotransferase (ALT), aspartate aminotransferase (AST), and urea levels was observed in feed-restricted birds supplemented with 120 and 130% levels of threonine. Hence, we recommend supplementing threonine at levels of 120 and 130% in the diet of broilers to promote growth and profitability.

Evaluation of Rosmarinic Acid on Broiler Growth Performance, Serum Biochemistry, Liver Antioxidant Activity, and Muscle Tissue Composition

The aim of the present study was to investigate the effects of dietary supplementation with different doses of rosmarinic acid (RA) on the growth performance, serum biochemical indices, liver antioxidant activity, and muscle nutritional component of broiler chickens during 1-20 days of age. A total of 1000 1-day-old Cobb 500 white-feathered broilers were divided into five groups. Each group included four replicates and 50 birds per replicate. The control group was the basic fodder group fed with a basal diet. The experimental groups included four levels of RA (100, 200, 300, and 400 mg/kg RA added to the basal diet, respectively). The results showed that a quadratic increase in final body weight (BW) and average daily gain (ADG) and a quadratic decrease in the feed/gain (F/G) ratio were observed with increasing dietary RA levels. At 200 mg/kg RA supplementation, growth performance was significantly improved. Moreover, under this RA treatment, the highest levels of total protein and globulin were detected in the serum, the activities of total superoxide dismutase and catalase in the liver of broilers were significantly increased, and the malondialdehyde content was significantly decreased, indicating a higher antioxidant capacity of the liver when 200 mg/kg RA was added to the basal diet. The flavor of the muscle meat was improved by dietary supplementation with 200 mg/kg RA. Therefore, adding 200 mg/kg of RA to the diet could significantly improve the growth performance of broilers, improve liver antioxidant capacity, and improve muscle quality, etc. The addition of RA to broiler feed as a natural antioxidant has great prospects.

Influence of in ovo threonine on growth performance, immunocompetence and carcass characteristics in broiler chickens

The experiment was conducted to investigate the effect of in ovo threonine (Thr) injection on 18th embryonation day at the broad end of the egg using 24G needle on growth performance, organs development, immunocompetence and carcass yield in broiler chickens. Fertile eggs (n=500) were randomly distributed to 5 groups, viz. (i) uninjected control, sham control (0.5 mL sterile water), Thr @15 mg/egg, Thr @30 mg/egg, and Thr @45 mg/egg. Hatchability was better in chicks treated with 45 mg Thr/egg compared to other Thr-injected groups. In ovo Thr injection had quadratic effect on weight gain (WG) and production index at the 2nd and 3rd weeks. Chicks fed 45 mg Thr/egg had better feed conversion ratio (FCR) at 2nd week compared to other groups while feed intake (FI) was not affected. Thr injected chicks had higher thymus weight (d0), bursa weight (d3), spleen weight (d3 and d7) whereas quadratic effect were observed on weights of bursa, thymus and spleen at d21. In ovo Thr administration improved (group-wise, linear or quadratic) the relative weights of gizzard, intestine, and liver at hatch, proventriculus at d7, as well as intestine and liver at d21. No significant difference was recorded for humoral and cell mediated immune response following in ovo Thr injection. Carcass traits of broiler chickens were not influenced by in ovo Thr administration, except breast meat which slightly differs, among the treatment groups. The results of this study suggested that in ovo Thr can improve growth performance, digestive and immune organs development at the early age.

Growth performance and small intestinal morphology of native chickens after feed supplementation with tryptophan and threonine during the starter phase

Background and Aim:

The amino acid content of feed can affect growth performance of poultry during the first 6 weeks of life or the starter phase. Unlike for broiler and layer chickens, there is no information concerning standard requirements for tryptophan and threonine during the starter phase. This study aimed to determine the amount of threonine and tryptophan that should be supplemented in chicken feed to maximize growth performance and small intestinal morphology of native chickens during the starter phase.

Materials and Methods:

A total of 128 day-old native chickens were divided into four treatment groups with four replications based on a completely randomized design. The treatment diets were as follows: T₀ (control feed); T₁ (T₀+0.10% L-tryptophan+0.35% L-threonine); T₂ (T₀+0.17% L-tryptophan+0.68% L-threonine); and T₃ (T₀+0.25% L-tryptophan+1.00% L-threonine).

Results:

The feed intake was highest for the T₂ and T₃ groups (123.06 and 124.18 g/bird/week, respectively). The T₃ group had the highest body weight gain (49.35 g/bird/week) and carcass weight (201.44 g/bird) relative to the other groups, while the T₂ and T₃ groups showed similar, significant (p<0.05) increases in feed conversion ratio (2.57 and 2.51, respectively) and carcass percentage (60.88 and 60.99%/bird, respectively) compared to the other groups. This study showed villi height, crypt depth, and villi width of duodenum, the highest jejunum and ileum of T3 (1109.00±27.26, 1325.50±75.00, 1229.50±101.68, 225.50±17.52, 236.00±24.81, 219.75±17.25, 192.25±14.41, 191.75±4.79, and 184.75±6.40, respectively) compare to other treatment.

Conclusion:

These results indicate that supplementation of feed with 0.17% L-tryptophan and 0.68% L-threonine positively affected the growth performance and small intestinal morphology of native chickens during the starter phase.

Nutritional significance of amino acids, vitamins and minerals as nutraceuticals in poultry production and health - a comprehensive review

Nutraceuticals have gained immense importance in poultry science recently considering the nutritional and beneficial health effects of their constituents. Besides providing nutritional requirements to birds, nutraceuticals have beneficial pharmacological effects, for example, they help in establishing normal physiological health status, prevent diseases and thereby improve production performance. Nutraceuticals include amino acids, vitamins, minerals, enzymes, etc. which are important for preventing oxidative stress, regulating the immune response and maintaining normal physiological, biochemical and homeostatic mechanisms. Nutraceuticals help in supplying nutrients in balanced amounts for supporting the optimal growth performance in modern poultry flocks, and as a dietary supplement can reduce the use of antibiotics. The application of antibiotic growth enhancers in poultry leads to the propagation of antibiotic-resistant microbes and drug residues; therefore, they have been restricted in many countries. Thus, there is a demand for natural feed additives that lead to the same growth enhancement without affecting the health. Nutraceuticals substances have an essential role in the development of the animals' normal physiological functions and in protecting them against infectious diseases. In this review, the uses of amino acids, vitamins and minerals as well as their mode of action in growth promotion and elevation of immune system are discussed.

Effect of threonine and potassium carbonate on broiler chicken performance, immunity, carcass traits, and small intestine morphology

This study aimed to investigate the interactive effect of dietary threonine (i.e., 100, 110, and 120%) and low and high dietary potassium (i.e., 0.85 and 0.94% of diet) on the performance, immune response, blood metabolites, carcass traits, and jejunum morphology of broiler chickens in Iran. In a completely randomized design, 300 1-day-old broiler chicks (Ross 308) were assigned to one of six dietary treatments with a 3 × 2 factorial arrangement. Broiler chicken growth performance, blood metabolite concentration, jejunum morphology, and antibody titter against Newcastle disease and influenza viruses were not affected by dietary treatments (P > 0.05). High level of dietary potassium led to lower toe web thickness index at 4 h post injection while compared to control group, threonine supplementation significantly decreased toe web thickness of broiler chickens at 24 and 48 h post injection (P < 0.05). Dietary treatments had no significant effects on carcass, abdominal fat, and breast and thigh percentages while higher dietary potassium increased serum glucose concentration (P < 0.05). Broilers fed diet supplemented with 20% supplemented threonine and higher potassium level had lower breast meat fat percentage while those fed diet supplemented with 20% threonine and low potassium had higher thigh meat protein percentage (P < 0.05). It can be concluded that although threonine supplementation improved toe web thickness index as cell-mediated immune response and lowered breast meat fat percentage in broiler chickens, there was no interaction between potassium with threonine in broiler chicken nutrition.

Estimates for digestible threonine: lysine for 21 - 35-day-old female meat-type quails

ABSTRACT Two assays were performed to estimate digestible threonine-lysine (Threo-Lys) ratio for female meat-type quails between 21 and 28 days old and between 28 and 35 days old. Experimental design was totally randomized. The first assay comprised 440 quails distributed into 5 treatments, 8 replications and 11 fowls per cage. The second assay comprised 280 quails distributed into 5 treatments, 8 replications and 7 fowls per cage. Five digestible Threo: Lys ratios were evaluated (0.66, 0.71, 0.76, 0.81 and 0.86). Performance, carcass and cut yield, chemical composition of carcass and nitrogen balance were evaluated. There was an improvement (P<0.05) in feed conversion and increase in feed intake due to ratios of digestible Threo: Lys between 21 and 28 and between 29 and 35 days olds, respectively. At 35 days old, there was a better (P<0.05) carcass yield and a negative nitrogen balance for Threo: Lys analyzed. A ratio of 0.86 may be recommended for digestible Threo: Lys as the best for feed conversion and carcass yield for female meat-type quails between 21 and 28 and between 28 and 35 days.

Threonine Requirements in Dietary Low Crude Protein for Laying Hens under High-Temperature Environmental Climate

Simple Summary

The threonine (Thr) requirement of laying hens in a high-temperature climate is scarcely referred in the review of literature. Therefore, our aim was to estimate the dietary Thr requirement in low CP diets in a high-temperature environmental climate. Based on our findings, the optimal dietary Thr requirements to optimize egg production, serum uric acid, and serum CuZn-SOD were 0.58%, 0.59%, and 0.56%, respectively, by regression analysis.

Abstract

Lohmann Brown hens (n = 420), at 28 weeks of age, were divided into five dietary treatments, and each treatment included six replicates of 14 laying hens. Dietary crude protein (14%) was presented as the control diet. Dietary L-Thr was added to the control diet for 12 weeks. Dietary Thr levels are 0.43%, 0.49%, 0.57%, 0.66%, and 0.74%, based on digestible base. From 28 to 40 weeks, hen-day egg production presented a quadratic trend to supplementing dietary Thr (R² = 0.96, p = 0.02), and reached a maximum level at 0.58%. Serum uric acid demonstrated a quadratic trend (R² = 0.62, p = 0.02) at 0.59%. Both serum total cholesterol and 3-hydroxy-3-methylglutaryl (HMG-CoA) reductase showed lower levels (p < 0.05) at 0.66% Thr. Serum CuZn-SOD elevated (p < 0.05) at 0.49%, 0.57%, and 0.66% Thr, as compared to the control group, and showed a quadratic trend (R² = 0.87, p = 0.003) at 0.56%. Supplemental L-Thr decreased (p < 0.05) the expression of ileal HSP70 at 0.66% Thr. In summary, the optimal dietary Thr requirements to optimize egg production, serum uric acid, and serum CuZn-SOD were 0.58%, 0.59%, and 0.56%, respectively, by regression analysis.

The effects of supplemental threonine on performance, carcass characteristics, immune response and gut health of broilers in subtropics during pre-starter and starter period

Three hundred thirty-day-old unsexed commercial broiler chicks (Vencobb-400) with initial average body weight of 44.04 ± 0.42 g were allocated into five experimental groups, in a completely randomized design (CRD) with 21-day experiment. Groups were formed according to dose of supplemental L-threonine in various rations i.e., 100% NRC specification, 100% threonine of Vencobb-400 strain specification, 110% threonine of Vencobb-400 strain specification, 120% of threonine of Vencobb-400 strain specification and 130% threonine of Vencobb-400 strain specification. Average daily feed intake (ADFI), average daily body weight gain (ADG), cumulative feed conversion ratio (CFCR), carcass characteristics, immune response, intestinal morphometry and biochemical profile were studied. The ADFI and ADG increased linearly and quadratically as dietary threonine levels were increased. However, the CFCR did not differ (p ˃ 0.05) among the groups. Though the carcass weight and drumstick yield did not differ (p ˃ 0.05) among the groups, the relative breast yield increased linearly (p = 0.007). The relative dressing yield and relative thigh weight increased linearly (p = 0.05 and p = 0.03, respectively). The relative weight of immune organs like bursa and thymus increased linearly. The mean total serum immunoglobulin, ND-ELISA titre and the mean lymphocyte proliferation response index increased linearly, whereas mean phagocytic activity index of neutrophil increased linearly (p < 0.001) and quadratically (p = 0.001). The mean villus height (VH), crypt depth (CD), villus surface area and mean goblet cell number/villus increased linearly and quadratically, whereas the villus width (VW) and goblet cell density increased quadratically. The serum glucose increased linearly (p = 0.001), whereas serum total protein concentration and serum globulin level increased both linearly and quadratically. The albumin: globulin ratio tended to decrease linearly. There was a significant decrease (p < 0.05) in serum cholesterol and VLDL cholesterol level. However, a linear increment (p = 0.04) in the blood serum HDL cholesterol level with a linear reduction (p = 0.01) in the blood serum LDL cholesterol was noticed.

Threonine in broiler diets: an updated review

Threonine (Thr) is the third limiting essential amino acid after methionine and lysine in cornsoybean based diets of broilers. Dietary imbalance of Thr, therefore, results in a poor growth performance in broilers. This review summarizes literature data on the known effects of dietary levels of Thr on growth performance, gut morphology, immunity and carcass characteristics in broilers. Due to continuous improvement in genetic potential and management practices for poultry production, dietary Thr requirements are changing. A number of studies have shown that supplementation of Thr in broiler diet at a higher level than the current NRC recommendation (0.74-0.81%), increases body weight gain, feed conversion ratio, and improves gut morphology, carcass quality and immune status, mainly by enhancing the functional capability of digestive system and immune organs (spleen, bursa, and thymus). According to the literature data discussed in this review, the minimal and maximal total dietary Thr levels for healthy birds reared in normal conditions were 0.67 and 0.90% for growth performance, 0.77 and 1.1% for a better gut health, 0.60 and 1.02% for immunity and 0.62 and 0.97% for better carcass characteristics. This background provides impetus to further investigate the exact level of Thr and its effects on growth performance, gut morphology, immunity and carcass characteristics in broilers.

Effects of dietary threonine and immune stress on growth performance, carcass trait, serum immune parameters, and intestinal muc2 and NF-κb gene expression in Pekin ducks from hatch to 21 days

An experiment was conducted to investigate the effects of different dietary threonine (Thr) levels and immune stress on Pekin ducklings' growth performance, carcass traits, serum immune parameters, and intestinal mucin 2 (MUC2) and nuclear factor kB (NF-κB) gene expressions. A total of 320 Pekin ducklings was randomly assigned to a 5 × 2 factorial arrangement of treatments. Each treatment group consisted of 4 replicate pens with 8 ducks per pen. Ducklings were fed 5 graded levels of Thr: 0.49, 0.56, 0.60, 0.65, and 0.76% from hatch to 21 d of age. At 11 d of age, ducks in the stressed groups were challenged with bovine serum albumin (BSA), and ducks in the unstressed groups were injected with normal saline water. The results showed that increasing Thr supplementation from 0.49 to 0.56% in the diet can improve BWG; feed consumption; weight and relative weight of breast and leg; weight of liver, bursa of Fabricius, spleen, and thymus; serum natural immune globulin A (IgA) concentration; and MUC2 gene expression in the ileum of 21-day-old Pekin ducks, significantly (P < 0.05). Immune stress with BSA had a significant effect on 21-day-old Pekin ducklings' BWG, feed consumption, and weight and relative weight of breast and thymus (P < 0.05), but no interaction between BSA and dietary Thr content was noticed in our experiment in 21-day-old Pekin ducks (P < 0.05). Dietary Thr requirements of the unstressed groups and stressed groups based on broken-line model analyses for ducks' BWG were 0.705 and 0.603%, respectively, and for ducks' feed consumption were 0.724 and 0.705%, respectively.

Effect of dietary threonine on laying performance and intestinal immunity of laying hens fed low-crude-protein diets during the peak production period

Threonine (Thr) may be a limiting amino acid for laying hens fed diets with lowered protein level. An experiment was conducted to examine laying performance, and the intestinal immune function of laying hens provided diets varying in digestible Thr levels. Lohmann Brown laying hens (n = 480), 28 weeks of age, were allocated to six dietary treatments, each of which included five replicates of 16 hens. Dietary crude protein (CP) 16.18% diet was offered as the positive control diet. L-Thr was added to the negative diet (14.16% CP) by 0, 1.0, 2.0, 3.0 and 4.0 g/kg, corresponding 0.44%, 0.43%, 0.49%, 0.57%, 0.66% and 0.74% digestible Thr. At 40 weeks, a reduction in CP level decreased laying performance (p < 0.05). In the low CP, increasing dietary Thr increased (p < 0.05) egg production and egg mass and rose to a plateau between 0.57% and 0.66%. The hens fed 0.66% Thr showed the lowest value (p < 0.05) of feed conversion ratio (FCR). Serum level of uric acid showed the lowest values (p < 0.05) at 0.57-0.66%. In addition, serum-free Thr maximized (p < 0.05) between 0.66% and 0.74%. Digestive trypsin activity decreased (p < 0.05) when hens fed the low-CP diet compared with hens fed CP (16.18%) and hens fed 0.57-0.66%. Expressions of ileal MUC2 mRNA maximized (p < 0.05) at 0.66% Thr. Occludin mRNA increased with increasing Thr level (p < 0.05). sIgA mRNA reached to the maximum level (p < 0.05) at 0.66% and 0.74% Thr. INF-γ mRNA reached to the lowest level (p < 0.05) at 0.65%. Expressions of ileal IL-2, IL-6, IL-1β mRNA decreased with increasing Thr level (p < 0.05). In conclusion, Thr supplementation resulting in optimal laying performance and stimulated the mucosal immune system, suggesting that it is a limiting amino acid in the low-crude-protein diet of laying hens during the peak production period.