Growth Response Of Chicks Research Articles

Impacts of Biosynthesized Manganese Dioxide Nanoparticles on Antioxidant Capacity, Hematological Parameters, and Antioxidant Protein Docking in Broilers.

Using green tomato extract, a green approach was used to synthesize manganese oxide nanoparticles (MnO2NPs). The synthesis of MnO2NPs was (20.93-36.85 nm) confirmed by energy-dispersive X-ray (EDX), scanning and transmission electron microscopy (SEM and TEM), Fourier transform infrared spectroscopy (FTIR), and UV-visible spectroscopy (UV-vis) analyses. One hundred fifty-day-old Arbor Acres broiler chicks were randomly divided into five groups. The control group received a diet containing 60 mg Mn/kg (100% NRC broiler recommendation). The other four groups received different levels of Mn from both bulk MnO2 and green synthesized MnO2NPs, ranging from 66 to 72 mg/kg (110% and 120% of the standard level). Each group comprised 30 birds, in three replicates of 10 birds each. Generally, the study's results indicate that incorporating MnO2NPs as a feed additive had no negative effects on broiler chick growth, antioxidant status, and overall physiological responses. The addition of MnO2NPs, whether at 66 or 72 mg/kg, led to enhanced superoxide dismutase (SOD) activity in both serum and liver tissues of the broiler chicks. Notably, the 72 mg MnO2NPs group displayed significantly higher SOD activity compared to the other groups. The study was further justified through docking. High throughput targeted docking was performed for proteins GHS, GST, and SOD with MnO2. SOD showed an effective binding affinity of -2.3 kcal/mol. This research sheds light on the potential of MnO2NPs as a safe and effective feed additive for broiler chicks. Further studies are required to explore the underlying mechanisms and long-term effects of incorporating MnO2NPs into broiler feed, to optimize broiler production and promote its welfare.

Effect of replacing full-fat soybean meal with undefatted cashew reject kernel meal on the growth response, blood parameters, organ weight and abdominal fat weight of broiler chicks

This preliminary feeding trial examined the effects of replacing full-fat soybean meal with undefatted cashew reject kernel meal on the growth response, blood parameters, organ weight and abdominal fat of broiler chicks. Three hundred 1-day-old unsexed Arbor-acre strain broiler chicks stochastically assigned in a completely randomized design to five dietary class of sixty birds each replicated six times in a 21-day feeding trial. The control diet (T1) was a maize- full-fat soybean meal (SBM) based diet. Undefatted cashew reject kernel meal (UCRKM) was used to replace 12.50 %, 25.00 %, 37.50 % and 50.00 % full-fat SBM in the control diet, and were referred to as diets T2, T3, T4 and T5 correspondingly. The chemical composition revealed that UCRKM contained 26.56 % crude protein, 3.30 % crude fibre, 2.99 % ash, 35.05 % ether extract, 23.07 % nitrogen-free extract and 4285.76 kcal kg-1 metabolizable energy. Significant disparities (P ≤ 0.05) were noticed in growth parameters with feed conversion ratio similar to those on T1 up to 50 % substitution. The red blood cell count, mean corpusculars, platelet count, alanine amino transaminase, alkaline phosphatase, creatinine, internal organ weights were influenced (P ≤ 0.05) except the liver and abdominal fat. UCRKM is therefore recommended as a replacement for up to 50.00 % full-fat SBM in broiler starter diets.

The growth promoting and immunostimulant effects of levamisole hydrochloride on broiler chicks

ABSTRACT The current study was carried out to investigate the effects of levamisole Hcl. (LMS) supplementation on the performance, immunological response, and various hematological, biochemical, and histopathological changes in broilers. A total of 120 one-day-old Ross (308) broiler chicks were randomly assigned to one of two feeding treatments, each of which has 3 replicates (20 chicks per each replicate). The first (control) group was fed a basal diet with no supplements, whereas the second (LMS) group was given LMS 25 mg/kg live body weight via drinking water every day for 37 days. The results showed that LMS supplementation enhanced final body weight, weight gain, and average FCR, over the entire experimental period, and increased PCV percent, Hb percent, and WBC count. Furthermore, phagocytic activity increased (P < 0.05) by roughly 15.3% at the 5th week of chicken age compared to the control. At 3 and 5 weeks of the experiment, the LMS-treated group’s intestinal villi improved considerably (P < 0.05) in length, width, goblet cell number, and crypt depth compared to the control group. In conclusion, including LMS in the diet increased broiler chick growth, performance, and immunological response. As a result of its growth-promoting and immunostimulant properties, we recommended its usage in chicken farms.

Potential ameliorative role of Spirulina platensis in powdered or extract forms against cyclic heat stress in broiler chickens

Global warming has become intensified and widespread, threatening the world with causing acute heatwaves that adversely affect poultry production and producers' profitability. Spirulina platensis is a precious and promising mitigating strategy to combat the detrimental impacts of heat stress due to its high contents of nutrients and bioactive components. The current study was designed to compare the incorporation impact of S. platensis powder or aqueous extract on the growth and physiological responses of heat-stressed broiler chicks. Six hundred 1-day-old Ross 308 male broiler chicks were allocated into five experimental groups with six replicates of 20 chicks each. The control group fed the basal diet without additives, SPP1 and SPP2 groups fed the basal diet with 1 g/kg and 2 g/kg S. platensis powder, respectively, while SPE1 and SPE2 groups received 1 ml/L and 2 ml/L S. platensis aqueous extract in the drinking water, respectively. All birds were exposed to cyclic heat stress (34 ± 2 °C for 12 h) for three successive days a week from day 10 to day 35. In vitro analysis showed that total phenols, flavonoids, and antioxidant activity of S. platensis were remarkably decreased (P < 0.001) in the aqueous extract compared to the powder form. Body weight, weight gain, and feed conversion ratio were improved (P < 0.001) in all treated groups, while carcass yield and dressing percentage were increased only in SPP1 and SPP2. Feed and water intake and blood biochemical parameters were not affected. Both forms of S. platensis enhanced the lipid profile, redox status, and humoral immune response of heat-stressed chicks superior to the powder form. Conclusively, the powder form of S. platensis was more effective in enhancing the productivity of broilers and alleviating the negative impacts of heat stress than the aqueous extract form.

Response of Japanese quail chicks (Cortunix cortunix japonica) to various dietary energy levels in a tropical environment

A total of one thousand and eighty (1080) unsexed day-old quail chicks with an average initial weight of 7.68±0.39g were used in a feeding trial to determine the growth response of quail chicks fed iso-nitrogenous rations to various dietary energy levels in Nigerian (tropical) environment. Six iso-nitrogenous (26% CP) diets containing 2500, 2600, 2700, 2800, 2900 and 3000 Kcal/kg ME were used in a complete randomized design, respectively for the study. The birds were fed feed and water ad libitum for 6 weeks at the end of which 10 birds from each replicate were randomly selected for carcass analysis. There were significant (P&lt;0.05) differences in the final live weight, weight gain, cost per gain and age at 1 egg across dietary treatments. Feed, intake decreased non-significantly (P&gt;0.05) as the level of energy increased in the diets. Total protein, Haemoglobin, packed cell volume, red blood cell and white blood cell were non significantly (P&gt;0.05) affected by dietary treatments and were within the normal range for quails. The cholesterol level however, increased non-significantly (P&gt;0.05) as the level of dietary energy increased. Except for the carcass weight and abdominal fat, the carcass parameters were not significantly (P&gt;0.05) affected by the dietary treatments. It was concluded that a dietary energy level of 2800 Kcal/kg ME, will be adequate for optimum performance of quail chicks under the condition of this experiment

EFFECT OF PROTEASE SUPPLEMENTATION ON THE PERFORMANCE AND DIGESTIBILITY OF BROILERS

Premise of the study was to validate the growth promoting eff ect of protease on the performance and to explore its digestion enhancer eff ect in broiler chicks. For this purpose 4 commercial diets were divided into two types (low and high density) and were enriched with protease using a completely randomized design with 4 replicates per diet having 10 chicks each having totaled 200 poultry broiler chickens (day-old). Until 14 days, no eff ects were observed on chicks however at day 14; little variations were observed on weight gain, feed intake and FCR (feed conversion ratio) among the enzyme enriched diets. At day 28, prominent response of protease supplementation in low protein was procured. The chicks gained 10.06 and 8.0 % more weight on CFP1 than CFG1 and CFG2, respectively. Similar response in FCR was observed and was found to be 0.20 and 0.15 points better on CFP1 than on CFG1 and CFG2, respectively. However, CFP2 failed to show protease effi cacy declining the weight gain by 23.01 % while the FCR by 0.49 points as compared with CFP1. This suggested that the nature of feed ingredients in the diets is important for obtaining maximum benefi t of protease supplementation. The overall performance indicated signifi cant response to enzyme supplemented diets. Among the low protein diets CP digestibility remained unchanged but they were diff erent in sparing AME (apparent metabolizable energy) for chicks. The CFP2 spared 98.21 kcal/Kg more AME than CFP1. However, this increased AME values did not help to boost the performance and was attributed to the widening ratio between CP and AME. These results demonstrated that the overall growth response of chicks was improved on low protein diet enriched with protease. It showed higher CP digestibility and AME values than good quality diets. However, the inconsistent results observed within the two types of diets revealed that the nature of diets might have infl uenced the effi cacy of protease. Key words: Broilers, digestibility, protease, FCR, Feed intake.

Feed storage conditions influenced the growth response, blood profile, intestinal morphology and microflora of broiler chicks

Feed storage conditions influenced the growth response, blood profile, intestinal morphology and microflora of broiler chicks

Effect of Homeopathic Medicine (Alfalfa), Methionine and Lysine Supplementation in Low Protein Based Diets on the Performance of Broiler Chicken

An experiment was conducted, with objective to determine the feed consumption, final live weight, weight gain, feed efficiency and economy in broiler chicken fed with locally available low protein based diets (20 percent CP in starter and 18 percent CP in finisher) supplemented with methionine, lysine and homeopathic medicine alfalfa. For this hundred fifty day-old birds of commercial broiler (Vencobb) were randomly assigned to five dietary treatments(10 chicks/treatment) and replicated three times in CRD with treatments composition of low protein based diets (LPB) (T0), LPB+ 100g/100 met + 300g/100 lysine (T1), LPB + 200g/100 met +300g/100lysine (T2), LPB + Alfalfa 5ml/100 chicks 2 day in week with drinking water (T3) and LPB + Alfalfa 5ml/100 chicks 3 day in week with drinking water (T4). Synthetic methionine and lysine was used for supplementation of deficient amino acid. Same condition was applied in finisher diets of broiler chicken. The result showed that chicks fed with LPB in both starter and finisher diet had significantly (P&lt;0.05) lower feed intake, final live weight , total weight gain, feed efficiency and income over feed and chicks cost (IOFCC) with compromising chicks fed with LPB with addition of methionine and lysine each and also homeopathic medicine alfalfa in starter and finisher period. Highest feed intake, final live weight, weight gain, feed efficiency was obtained with treatment (T1) followed by treatment (T2). However, positive growth response and better health status of chicks was also observed from supplementation of homeopathic medicine alfalfa with LPB and non-significant difference on Income Over Feed and Chicks Cost was obtained with treatment (T1). So, it was concluded that with supplemental methionine, lysine and alfalfa, the CP level of broiler chicks could be reduced up to 20 percent in starter and 18 percent in finisher diets without adverse effect on feed intake, final live weight, weight gain, feed efficiency and Income overfeed and chicks cost, provided under locally based feed ingredients.Int. J. Appl. Sci. Biotechnol. Vol 6(2): 174-180

The growth response of ostrich (Struthio camelus var. domesticus) chicks fed on diets with three different dietary protein and amino acid concentrations

1. Feeding costs are the largest expense in an ostrich production system, and protein is one of the more expensive components of the diet. This study evaluated the growth response of ostrich chicks on diets containing different concentrations of protein (amino acids). The diets were formulated to contain three concentrations of protein (one diet with 20% less protein than the conventional concentration, L; one diet with the conventional concentration of protein, M and one diet with 20% more protein than the conventional concentration, H) for each of the phase diets. The phase diets were pre-starter, starter, grower and finisher.2. This study includes the analysis of ostrich body weight (BW) by modelling growth with linear polynomial and non-linear functions for all the data not separated for treatments. In total, 3378 BW recordings of 90 animals were collected weekly from hatch (d 0) to 287 d (41 weeks) of age.3. Seven non-linear growth models and three linear polynomial models were fitted to the data. The growth functions were compared by using Akaike’s information criterion (AIC). For the non-linear models, the Bridges and Janoschek models had the lowest AIC values for the H treatment, while the Richards curve had the lowest value for M and the von Bertalanffy for the L treatment.4. For the linear polynomial models, the linear polynomial of the third degree had the lowest AIC values for all three treatments, thus making it the most suitable model for the data; therefore, the predictions of this model were used to interpret the growth data. Significant differences were found between treatments for growth data.5. The results from this study can aid in describing the growth of ostriches subjected to optimum feeding conditions. This information can also be used in research when modelling the nutrient requirements of growing birds.

Prospects ofin ovofeeding and nutrient supplementation for poultry: the science and commercial applications—a review

In ovo supplementation of poultry embryos was first reported several decades ago, but it is only recently that concerted research has been directed at developing the technology for this process to be routinely used by the poultry industry. Although the technology of in ovo feeding was patented more than 10 years ago, it has not been widely adopted by the poultry industry. This review examines the early development of the enteric system of the poultry embryo; defines and distinguishes between in ovo feeding and in ovo nutrient administration; highlights the importance of early feeding of the chick; and discusses the development of in ovo feeding technology and its effects on hatchability, growth, gut health and immune response of chicks. The range of possible nutrients that can be administered is also explored. The limitations associated with embryo development and nutrient metabolism are highlighted, leading to the prediction of the future role of in ovo feeding in the poultry industry.

Dietary guanidino acetic acid is an efficacious replacement for arginine for young chicks

Guanidino acetic acid (GAA) is synthesized in the liver and kidney from Arg and Gly and subsequently methylated by S-adenosylmethionine to form creatine. Four bioassays were carried out to determine the capacity of GAA to serve as a dietary replacement for Arg for growing chicks. Broiler chicks were fed Arg-deficient dextrose-casein (0.88% Arg) or corn-corn coproduct-soybean meal (1.0% Arg) basal diets during 9-d battery feeding trials involving 5 pens of 4 chicks per treatment. The dextrose-casein diet was shown to be markedly deficient in Arg as both weight gain and G:F increased (P < 0.01) due to addition of Arg, GAA, or creatine. The optimal level of added GAA was 0.12% of the diet, but this level of GAA or 1.0% creatine-H(2)O did not improve growth performance when added to an Arg-adequate diet. A second assay confirmed this level of optimal Arg in a 2 × 2 factorial arrangement of l-Arg and GAA supplementation. Using a practical-type diet based on corn, corn gluten meal, distillers dried grains with solubles, and soybean meal, similar improvements (P < 0.05) in G:F resulted from addition of 0.25% Arg, 0.12% GAA, or 0.15% creatine·H(2)O. These results demonstrate that 0.12% supplemental GAA, like creatine, produces consistent growth responses in young chicks fed Arg-deficient diets. To provide further evidence of the capacity for GAA to serve as a dietary Arg replacement, the dextrose-casein diet was supplemented with 7 graded doses of Arg in the absence or presence of 0.12% GAA (14 total diets). Quadratic (P < 0.01) responses in weight gain and G:F responses to supplemental Arg were observed. Similar supplemental Arg requirements were estimated in the absence and presence of 0.12% GAA, but GAA elicited a greater improvement (P < 0.05) in G:F when added to Arg-deficient, compared with Arg-adequate, diets. Collectively, these data indicate that GAA can be used as an efficacious replacement for dietary Arg for young chicks.

Short communication: Responses of Black Neck ostrich chicks to L-carnitine dietary supplementation during the pre-starter growth period

The objective was to determine the growth responses of Black Neck ostrich chicks to different dietary levels of L-carnitine in pre-starter diets. Thirty-two day-old ostrich chicks were randomly divided into four treatments with four replicates, each containing two chicks. All birds received the same basal diet supplemented with 0 (T0, control), 125 (T125), 250 (T250) or 600 (T600) mg L-carnitine per kg. Responses were monitored over three growth phases, 0 - 15, 16 - 30 and 31 - 60 days, the total period being 60 days. T600 had the lowest live weight (LW) and live weight gain (LWG) over the 60-day treatment period. Live weight and LWG values of T125 and T250 did not differ from those of T0. T600 had the worst feed conversion ratio (FCR) during the different stages (0 - 15, 16 - 30 and 31 - 60 days) and over the total 60-day period. Feed intake (FI) was reduced significantly in the T125 and T600 treatments compared to T0 and T250 treatments over the total period. The treatment, T125, showed the lowest FI and FCR responses over the total period, whereas there was no difference between T0 and T250. The results suggest that supplementing the pre-starter diet with 125 mg/kg of L-carnitine can improve the performance of ostrich chicks by decreasing the FCR. In contrast, the suppressive effect of a high inclusion level (T600) might indicate that ostrich chicks are sensitive to a high level of inclusion that could cause adverse effects.Keywords: Struthio camelus, carnitine, performance, adverse effects, feed conversion ratio

Interactive effects of feed form and dietary lysine on growth responses of commercial broiler chicks

SUMMARY It has been shown in previous studies that older broilers can be affected by feed form, particularly as it relates to the pellet quality not allowing these birds to express their full growth potential. In this study, the interactive effects of dietary lys concentration and feed form were evaluated in broiler chicks. Broilers were given 1 of 3 possible feed forms [mash (Ma), mash exposed to conditioner steam (CM), and pellets in the form of crumbles (PC)] and 1 of 5 possible graded levels of true digestible lys (0.85, 0.95, 1.05, 1.15, and 1.25%) from hatch until 18 d of age. the study comprised a 3 × 5 factorial arrangement of treatments in which feed form and dietary lys were the factors evaluated, with 15 treatment combinations being represented by 8 replicate floor pens, for a total of 120 floor pens. lysine and feed form interacted for effects on BW gain and feed conversion, resulting in birds fed Ma attaining BW gain and feed conversion values similar to those in chicks fed CM and PC, but only when lys was fed at the highest level. Based on regression analysis, BW gain and feed consumption of chicks fed the PC diets responded much quicker to increasing dietary lys levels than did BW gain and feed consumption of chicks fed the Ma and CM diets, and chicks achieved greater BW gain and feed consumption at similar lys concentrations. Furthermore, chicks fed the PC diets achieved their optimal response with less dietary lys. In addition, chicks fed the PC diets quickly reached a maximum response for BW and feed consumption, and they obtained a greater accretion of projected BW gain and feed consumption. Blood plasma analysis of total protein and albumin further corroborated the response observed in chicks fed the Ma diets. overall, there is a need to achieve optimal pellet quality as a way to avoid excessive dietary lys concentration, in turn allowing broiler chicks to express their full growth potential.

Dietary L-Homoserine Spares Threonine in Chicks ,

Four chick bioassays were conducted to evaluate the threonine (Thr) replacement value of L-homoserine (HS). Growth rate was increased (P < 0.05) by dietary addition of 800 mg L-HS/kg diet to a purified diet severely deficient in Thr or by the addition of 800 or 1000 mg of L-HS/kg diet to a corn-peanut meal diet distinctly deficient in Thr. The addition of an isomolar level of α-ketobutyrate, a catabolic product of both Thr and HS, did not elicit a response. Standard-curve methodology predicted a Thr replacement value of 38 ± 9% for HS. Interactions (P < 0.01) were observed in assays 2 and 4 between dietary Thr adequacy and 800 or 1000 mg L-HS/kg supplementation. Thus, HS improved growth performance when added to a Thr-deficient diet (0.46 g Thr/100 g diet), but it decreased growth performance when added to the same diet containing surfeit Thr (0.80 g Thr/100 g diet). The results indicate that low levels of HS elicit a growth response in young chicks fed Thr-deficient diets.

Is putrescine an essential nutrient for avians?

Putrescine addition to a complete crystalline amino acid diet elicited a growth response in young chicks, suggesting that putrescine may be an essential nutrient in avians. However, high dietary putrescine levels can depress weight gain.

Effect of in ovo threonine supplementation on early growth, immunological responses and digestive enzyme activities in broiler chickens

1. The effects of injecting threonine in ovo on early growth, some immunological responses and the activity of digestive enzymes of broiler chicks were investigated. Fertile eggs were distributed into 6 groups, each of 60. These were: untreated control, sham control, 10, 20, 30 or 40 mg threonine. Threonine was dissolved in 0·5 ml sterile saline and inoculated into the yolk sac of the 14-d-old embryo through the narrow end of the egg. 2. The ratio of chick to egg weight was 1·6% higher in the group given 30 mg threonine and at 28 d of age chicks receiving threonine were 29 to 79 g heavier than untreated controls. 3. Food conversion ratio until 7 d after hatching was improved in those chicks receiving 10, 20 or 40 mg threonine but there was no significant effect on the activities of amylase, pepsin or trypsin. 4. The humoral response to sheep red blood cells was significantly greater in those groups receiving 10, 20 or 30 mg threonine supplementation than in untreated controls. 5. The response to phytohaemagglutinin-P, a measure of the cell-mediated immune response, was not affected, however. 6. It is concluded that injections of 20 to 30 mg threonine into yolk sac can improve post-hatching growth and humoral responses of broiler chicks.

Apparent Metabolizable Energy Needs of Broiler Chicks Subjected to Diverse Ambient Temperature Regimens

SUMMARY Early chick performance is adversely affected by inadequate ambient temperatures. Increasing AMEn may help alleviate poor performance with chicks subjected to low brooding temperatures. This study examined the effects on subsequent growth and meat yield responses in broiler chicks provided diets formulated to either 3,040 or 3,140 kcal of AMEn/kg when subjected to diverse ambient temperatures from 0 to 15 d. Two experiments were conducted. In experiment 1, ambient temperature was considered optimum and was held constant, with set points of 34°C from placement (0 d) to 4 d, 32°C from 5 to 9 d, and 29°C from 10 to 15 d. In experiment 2, suboptimal ambient temperatures (held constant) were 29°C from placement to 3 d, 28°C from 4 to 6 d, 26°C from 7 to 11 d, and 25°C from 12 to 15 d. In both experiments, diet and temperature were common from 16 to 40 d. Energy consumption per unit of gain from 0 to 15 d was improved with chicks fed the moderate AMEn (3,040 kcal of AMEn/kg; 1,553 kcal of AMEn intake) diet compared with chicks fed the high AMEn (3,140 kcal of AMEn/kg; 1,614 kcal of AMEn intake) diet in experiment 1. From 0 to 15 d, feed conversion was improved with chicks provided the high AMEn diet (3,140 kcal of AMEn/kg; 1,689 kcal of AMEn intake) over that of chicks fed the moderate AMEn diet (3,040 kcal of AMEn/kg; 1,678 kcal of AMEn intake) in experiment 2. In both experiments, dietary treatments did not influence final BW gain, cumulative feed conversion, or breast meat yield. Providing chicks with a diet containing moderate AMEn (3,040 kcal of AMEn/kg) when subjected to diverse brooding temperatures was adequate to support cumulative growth responses.

Effects of interchanging hyperopic defocus and form deprivation stimuli in normal and optic nerve-sectioned chicks

To test the hypothesis that the same mechanisms mediate form deprivation and lens-induced myopia, the ocular growth responses of chicks alternately exposed to lenses and diffusers at regular intervals (3 h) were compared to those of chicks exposed to either negative lenses or diffusers alone. In total, there were four experiments: (1) −15 D lenses and/or diffusers on normal birds, (2) −15 D lenses and/or diffusers on optic nerve-sectioned (ONS) birds, (3) −5/−10/−15 D lenses (sequentially applied) and/or diffusers on normal birds and (4) −5/−10/−15 D lenses and/or diffusers on ONS birds. All treatments were monocular. In all experiments, optical axial lengths (cornea-to-retina distances) in treated eyes were greater than in fellow eyes, irrespective of the optical device (diffuser, lens or switch), lens power (fixed or incremented) and optic nerve condition (intact or severed). In normal chicks, optical axial length responses in the switch group were significantly reduced relative to those of the diffuser but not to those of the −15 D lens group. For both groups of ONS birds, diffusers exaggerated the optical axial length changes. For all groups, the responses to the switch and lens groups were most similar. These results together suggest that the mechanisms mediating form deprivation- and lens-induced myopia are different.

Dietary tryptophan effects on growth and stress responses of male broiler chicks

1. Three experiments were conducted to determine growth of broiler chicks fed on test diets formulated to be deficient or adequate in tryptophan (Trp) using gelatin by-product as a means of generating a Trp deficiency. Growth response estimates of broiler chicks to graduations of Trp were determined by dose–response criteria and regression analyses. Experiments were conducted using broiler chicks from 1 to 20 d of age. 2. Broiler chicks fed Trp-deficient diets had poor body weight gain, feed intake and feed conversion. Recommended total Trp needs were 2·0, 2·1 and 2·2 g/kg for feed intake, body weight gain and feed conversion, respectively. 3. Blood plasma Trp exhibited a sigmoidal trend while blood plasma glucose increased in a linear manner to supplemental Trp. Physiological stress variables measured were unaffected by dietary Trp.

Economically optimal dietary crude protein and lysine levels for starting broiler chicks

An experiment was conducted to quantify the growth response of broiler chicks to cumulative dietary lysine and CP intakes. From d 7 to 17, chicks were fed one combination of dietary lysine and CP (17, 20, 23, and 26% CP and 3.5, 4.0, 4.5, and 5.0 g lysine per 100 g of CP) in a diet containing 3,200 kcal/kg ME. There were significant linear and quadratic effects of dietary CP intake and quadratic effects of dietary lysine intake on body weight gain (BWG), confirming that a diminishing response (marginal BWG decreased as intake of dietary lysine increased) existed (R2 = 0.92 and 0.95, respectively). A significant interaction between dietary CP and lysine for BWG complicates economic modeling because responses must be considered together. A quadratic growth response equation describing BWG as a function of dietary lysine and CP intake was used to develop and demonstrate a quadratic programming model. In general, increasing the price of soybean meal (SBM) decreased the dietary CP concentrations that gave maximum BWG and the concentration of dietary lysine decreased proportionally. In SBM-based diets, the concentration of dietary lysine that maximized BWG was less than or equal to the concentration reached by the proportions of corn and SBM needed to meet dietary CP constraints. Savings from using maximum-profit vs. least-cost formulation models could approach 637,000 dollars per year for a single model poultry complex under some economic situations for the starter diet alone.