Influence of dietary energy on bird performance, carcase parts yields and nutrient composition of breast meat of heterozygous naked neck broilers reared at natural optimum and summer temperatures

Effects of season, genotype, and rearing system on broiler chickens raised in different semi-intensive systems: performance, mortality, and slaughter results

This study aimed to determine the effects of chicken genotype (fast-growing and slow-growing), various semi-intensive production systems (extensive indoor, free-range, and traditional free-range), and season (spring and summer) on animal performance, mortality, growth curve, and slaughter results under semi-environmentally controlled conditions in a subtropical region. Production systems were applied in conformity with the EU standards. While the summer experiment improved performance during brooding (1st-28th days), hot conditions led to a decline in performance during the growing period. In addition, negative effects were determined for all parameters of Gompertz growth curve in summer (P < 0.05, for all). In spring, fast-growing showed 36% higher final live weights than slow-growing, and this difference decreased in summer (16% for extensive indoor and 25% for free-range) (P < 0.05, for all). Fast-growing in extensive indoor and free-range displayed similar weight gains in the growing period, whereas grazing ones consumed less feed (P < 0.05) and thus showed better (P < 0.05) feed conversion. The same situation was true for slow-growing in spring. The mortality was approximately 1% in all groups in spring, while it was 17.36 and 18.06% for fast-growing in extensive indoor and free-range and 1.39, 2.78, and 4.29 for slow-growing in extensive indoor, free-range, and traditional free-range in summer. It is advantageous to choose fast-growing if short-term (56 days) fattening especially under optimum conditions is to be preferred. If the growing period coincides with summer, slow-growing should definitely be preferred and the fattening period should be extended to 82 days. Grazing improved feed conversion (P < 0.05) by reducing cereal-based diet consumption in both genotypes but did not affect carcass yield. However, grazing had a positive effect on fleshing.

Climate change and heat stress: Impact on production, reproduction and growth performance of poultry and its mitigation using genetic strategies

Heat stress is an important environmental determinant which adversely affects the performance of poultry worldwide. The present communication reviews the impact of heat stress on production, reproduction and growth performance of poultry, and its alleviation using genetic strategies. The adverse effects of high environmental temperature on poultry include decrease in growth rate, body weight, egg production, egg weight, egg quality, meat quality, semen quality, fertility and hatchability, which cause vast financial losses to the poultry industry. High ambient temperature has an antagonistic effect on performance traits of the poultry. Thus, selection of birds for high performance has increased their susceptibility to heat stress. Additionally, heat burden during transportation of birds from one place to another leads to reduced meat quality, increased mortality and welfare issues. Molecular markers are being explored nowadays to recognize the potential candidate genes related to production, reproduction and growth traits for selecting poultry birds to enhance thermo-tolerance and resistance against diseases. In conclusion, there is a critical need of formulating selection strategies based on genetic markers and exploring more genes in addition to HSP25, 70, 90, H1, RB1CC, BAG3, PDK, ID1, Na, F, dw and K responsible for thermoregulation, to improve the overall performance of poultry along with their ability to tolerate heat stress conditions.

Effect of Dietary L-Methionine Supplementation on Growth Performance, Carcass Traits, and Plasma Parameters of Starter Pekin Ducks at Different Dietary Energy Levels

Simple Summary

Tremendous improvements have been made in the duck commercial industry, especially in aspects such as the increase of body weight and shortening of the production cycle. Meat duck production has been increasing annually worldwide. Improvements in precise nutrition were crucial for ducks to improve growth efficiency and reduce diet costs. Currently, L-Met, a new methionine (Met) source, has been commercially available for duck diet formulation. The bioavailability of L-Met is greater than DL-Met for growth performance in duck. The present study estimated the Met requirement of starter Pekin ducks from 1 to 21 days of age by supplementing crystal L-Met to formulate the diets at different ME levels. The results suggested that the Met requirement of starter Pekin ducks was affected by dietary ME levels. The data potentially provide theoretical support for the utilization of crystalline L-Met in duck production.

Abstract

A 2 × 6 factorial experiment was conducted to determine the influences of dietary metabolizable energy (ME) and methionine (Met) levels on growth performance, carcass traits, and plasma biochemical parameters of starter Pekin ducks from 1 to 21 days of age. A total of 600 one-day-old male Pekin ducklings were randomly assigned to 12 groups (six replicates each group and eight ducks per replicate) in a 2 × 6 two-factor arrangement. The basal Met levels of two basal diets (11.54 and 12.52 MJ/kg ME) were 0.31 and 0.29%, respectively. The crystalline L-Met was supplemented to yield six diets according to different supplemental levels (0, 0.05, 0.10, 0.15, 0.20, and 0.25%). The results showed that the body weight (BW) and average daily weight gain (ADG) were increased (p < 0.05) with increasing dietary Met levels. Dietary ME levels changed from 11.54 to 12.52 MJ/kg increased the BW and ADG (p < 0.05) as well as decreased the average daily feed intake and feed to gain ratio (p < 0.05). As the dietary Met level increased, leg muscle yield increased (p < 0.05). Conversely, increasing the dietary ME level decreased the leg muscle yield (p = 0.0024) and increased abdominal fat (p < 0.001). Meanwhile, the concentrations of total cholesterol (TCHO), high-density lipoprotein cholesterol (HDLC), and low-density lipoprotein cholesterol (LDLC) in plasma were decreased (p < 0.05) when the ME levels of diets changed from 11.54 to 12.52 MJ/kg. Meanwhile, the plasma TCHO and HDLC concentrations decreased (p < 0.05) as dietary Met levels increased. Based on the linear-broken line model, the dietary Met requirement of starter Pekin ducks from 1 to 21 days of age for optimal ADG were 0.362% (0.052% supplemental L-Met) at 11.54 MJ ME/kg and 0.468% (0.178% supplemental L-Met) at 12.52 MJ ME/kg, respectively, when crystal L-Met was supplemented to formulate the diets. This suggested that the Met requirement of starter Pekin ducks was affected by dietary ME levels. The data potentially provide theoretical support for the utilization of crystalline L-Met in duck production.

Effects of dietary energy and protein content and lipid source on growth performance and carcass traits in Pekin ducks

The present study was conducted to determine the impact of dietary energy and protein concentrations and lipid sources on growth performance and carcass traits of Pekin ducks. In Exp. 1, 15-day-old ducks (6 replicate pens, 60 ducks/pen) were randomly assigned to 4 dietary treatments with different metabolizable energy (ME) and crude protein (CP) concentrations (2,850 kcal/kg and 16%, 2,950 kcal/kg and 16.5%, 3,050 kcal/kg and 17.0%, and 3,150 kcal/kg and 17.5%) based on body weight (BW). In Exp. 2, 20-day-old ducks (4 replicate pens, 60 ducks/pen) were randomly allotted to 3 dietary fat sources (soybean oil, lard, and palm oil) with or without emulsifier in a 3 × 2 factorial arrangement. In Exp. 1, increasing ME and CP level improved (P < 0.05) body weight gain (BWG) and cost-to-gain ratio linearly, but reduced (P < 0.05) feed intake (FI) and feed-to-gain ratio (F/G) linearly. Breast skin thickness and liver redness (a*) value increased (P < 0.05) linearly with the increasing ME and CP level. In Exp. 2, no interactions between fat sources and emulsifier were observed. Feeding lard and palm oil diets increased (P < 0.05) final BW and BWG compared to soybean oil. Birds fed soybean oil and palm oil diets had lower (P < 0.05) FI compared to those fed lard diet. F/G in soybean oil and lard groups was higher (P < 0.05) compared to palm oil group. Birds in palm oil and lard groups had higher (P < 0.05) European production efficiency factor than those in soybean oil group. The addition of emulsifier increased (P < 0.05) BWG. In summary, the optimal ME and CP level for roasting was 2,950 kcal/kg ME and 16.5% CP and the palm oil was better than soybean oil and lard in Pekin ducks from 15 to 40 D of age.

Effect of dietary energy and protein content on growth and carcass traits of Pekin ducks

A study was conducted to determine the influence of dietary energy and protein concentrations on growth performance and carcass traits of Pekin ducks from 15 to 35 d of age. In experiment 1, 14-d-old ducks were randomly assigned to 3 dietary metabolizable energy (11.8, 12.8, and 13.8 MJ/kg) and 3 crude protein concentrations (15, 17, and 19%) in a 3 × 3 factorial arrangement (6 replicate pens; 66 ducks/pen). Carcass characteristics were evaluated on d 28, 32, and 35. In Experiment 2, 15-d-old ducks (6 replicate cages; 6 ducks/cage) were randomly allotted to the 9 diets that were remixed with 0.5% chromic oxide. Excreta were collected from d 17 to 19, and ileal digesta was collected on d 19 to determine AME_n and amino acid digestibility. In Experiment 1, there were interactions (P < 0.05) between dietary metabolizable energy and crude protein (CP) on body weight (BW) gain and feed intake, wherein BW gain increased more to increasing dietary CP as dietary metabolizable energy increased. However, feed intake was only influenced by dietary crude protein at 11.8 MJ ME/kg and not 12.8 or 13.8 MJ/kg. As dietary CP increased from 15 to 19%, breast meat yield increased by 10.8% on d 35 (P < 0.01). Conversely, increasing metabolizable energy from 11.8 to 13.8 MJ/kg increased dressing percentage, breast skin, and subcutaneous fat, but decreased breast meat yield (% but not weight) on d 35 (P < 0.01). In Experiment 2, the determined AME_n for diets formulated to contain 11.8, 12.8, or 13.8 MJ ME/kg were 11.66, 12.68, and 13.75 MJ/kg, respectively; determined standardized ileal digestible Lys was 0.95, 1.00, and 1.21% for diets formulated to contain 15, 17, or 19% crude protein, respectively. The best body weight gain and feed conversion ratio was obtained when ducks were fed a high dietary AME_n (13.75 MJ/kg) and high CP (19%, 1.21% SID Lys). These results provide a framework for subsequent modeling of amino acid and energy inputs and the corresponding outputs of growth performance and carcass components.

Effects of decreases in the three most limiting amino acids of low protein diets at two different feeding periods in Japanese quails

1. Diets containing 100 (AA100), 95 (AA95), 90 (AA90) or 85% (AA85) of National Research Council (NRC, 1994) recommendations of methionine, threonine and lysine in a low-protein diet (200 g/kg) were fed to 15-d-old quails. 2. Decreases of up to 15% of NRC recommendations in these three amino acids did not affect feed intake, weight gain and gain:feed intake values in the 15-35- and 15-42-d feeding periods. 3. Compared to control diet, feeding cost per bird was lower in males fed with AA95 and AA85 at 15-35 d and with AA85 diets at 15-42 d. At 15-35 d, feeding cost per 100 g weight gain was lower in both males and females receiving the AA85 diet while at 15-42 d it was lower in males fed with AA85 and females fed with AA90 compared to the control diet. Feeding cost calculated based on 100 g weight gain resulted in more meaningful results than cost calculated for the production of a bird. 4. Dietary amino acid content did not significantly affect carcase, thigh (bone in and skin on) or breast meat (deboned and skin on) yields. Males fed with AA90 diet and females fed with AA90 and AA85 had lower protein contents in their breast meat (without bone and skin) compared to the ones fed with control diet.

The effect of the Naked Neck genotype (Nana), feeding and outdoor rearing on growth and carcass characteristics of free range broilers in a hot climate

Alternative poultry production with special reference to free range broilers has increased significantly since the nineties in many regions of the world. Numerous factors influence the productive performance of this type of broilers: genotype (namely the use of naked neck animals), feeding and access to an outdoor area. The aim of this paper is to study the influence of each of these factors on the productive performance of free range broilers under commercial rearing conditions. A total of 3200, day old chicks of both sexes from naked neck and normally feathered genotypes were used in this trial. After a joint initiation phase, animals were divided into four different treatments with the combination of two concentrates (high vs low energy content) and management (access to outside park or not). Experiment lasted a total of 12 weeks. Live weight date was recorded weekly and a samples of animals from the trial were sacrificed at the age of 8, 10 and 12 weeks, when carcass characteristics were determined. Besides sex, the only factor that seems to affect growth characteristics was genotype as naked neck animals had poorer growth rates than normally feathered. No effect was detected on carcass yields and percentages of carcass components for any of the variables. From the data presented in this trial the practises associated with free range production are of relative inconsequence to the technical animal production parameters and can only be justified by a pressing need to differentiate these products from standard poultry products in what concerns both welfare issues and meat characteristics. The results also indicate that genetic material from alternative poultry production in Europe can be a useful option in poultry production development projects in the tropics.

Corticosterone administration and dietary glucose supplementation enhance fat accumulation in broiler chickens

1. The effects of exogenous corticosterone administration and glucose supplementation on energy intake, lipid metabolism and fat deposition of broiler chickens were investigated. 2. A total of 144 three-d-old male chickens were randomly assigned to one of the following 4 treatments for 7 d: a low energy diet (10.9 MJ ME/kg, 200 g/kg CP) with or without corticosterone (30 mg/kg diet) and drinking water supplemented with glucose (80 g/l) or saccharine (2 g/l, control). 3. Body weight (BW) gain and breast and thigh muscle yields (% body mass) were all significantly decreased by corticosterone treatment. The relative cumulative feed intake (RCFI) and relative ME intake (RMEI), rather than the feed (FI) or ME intake (MEI) were increased by corticosterone administration. Both feed efficiency (FE) and caloric efficiency (CE) were decreased by corticosterone administration. Corticosterone administration had no obvious effect on water consumption. 4. Glucose supplementation had no influence on BW gain and breast and thigh muscle yield (as % of body mass). FI or RCFI was decreased while MEI or RMEI was increased by glucose supplementation. FE was improved by glucose treatment, whereas CE was reduced. 5. Liver weight and abdominal, cervical and thigh fat deposits were all significantly increased by either corticosterone or glucose treatment. 6. Plasma concentrations of glucose, urate, triglyceride, non-esterified fatty acids (NEFA), very low density lipoprotein and insulin were all significantly increased by corticosterone treatment. Glucose supplementation had no obvious influence on any of the measured plasma parameters except for NEFA, which were significantly increased. 7. Lipoprotein lipase activities in either cervical or abdominal adipose tissues, rather than in thigh fat tissue, were significantly elevated by either glucose or corticosterone treatment.

The effect of date fibre supplemented with an exogenous enzyme on the performance and meat quality of broiler chickens

1. Two experiments were conducted to evaluate the use of date fibre as a partial replacement of maize as a source of energy for growing broiler chicken. In experiment 1, date fibre was given alone to determine apparent metabolisable energy (AME) and apparent ileal digestibility of amino acids and crude fibre. 2. Date fibre had lower AME content (8.7 vs 13.6 MJ/kg) and apparent ileal digestibility coefficients for dry matter (0.35 vs 0.83), crude fibre (0.20 vs 0.54) and amino acids. 3. Based on the results of experiment 1, a growth study was conducted to test the effect of exogenous enzymes on the nutritive value of date fibre (experiment 2). 4. Three date fibre contents (5, 10 and 15%) with and without enzyme supplementation were evaluated. Daily feed intake, body weight gain and feed conversion ratio were measured. At the end of experiment 2, 160 birds were randomly selected and slaughtered to evaluate carcase and meat quality traits as well as measuring ileal viscosity. 5. Substitution of maize by 10 and 15% date fibre significantly depressed AME. Enzyme supplementation did not improve crude fibre digestibility. The inclusion of date fibre in the diets except at 5% decreased average daily gains, feed intake and feed conversion ratio. 6. Addition of date fibre caused a significant increase in the weights of total digestive tract, pancreas and caecum. Addition of date fibre or the exogenous enzyme had no significant effect on carcase or meat quality characteristics. 7. Date fibre increased ileal digesta viscosity compared to the control. Addition of the exogenous enzyme decreased the viscosity of the basal diets but had no effect on the date fibre diets.8. This study indicated that date fibre can be included at levels of 5% in broiler diets without affecting performance.

Response of naked neck (Nana) and normal (nana) broiler chickens to dietary energy levels in a subtropical climate

1. The comparative response of naked neck (Nana) broiler chickens and their normally feathered (nana) full sibs to varied dietary energy levels was assessed under natural ambient conditions in a subtropical climate in two separate trials, one in winter (19.0 to 26.0 degrees C) and the other in summer (28.1 to 37.4 degrees C). 2. The chickens were fed on diets with 10.9, 11.5 or 12.1 MJ ME/kg and with a constant protein content of 200 g/kg from 1 to 42 d of age. 3. Both genotypes showed similar body weight, food intake and food conversion efficiency at 42 d of age. Body weight and food conversion efficiency improved on the diet with the highest energy content. 4. Apparent retention (AR) of crude protein (CP) was higher in nana chickens than in their Nana sibs in the winter trial, while no differences were observed for AR of dry matter (DM), crude fibre (CF), ether extract (EE) or calcium. In the summer trial, no difference in nutrient retention was seen between the genotypes. Increasing dietary energy had a positive influence on AR of DM, CP and EE. 5. The relative weights of feathers and skin were lower in Nana chickens than in their normal counterparts. Ready-to-cook yields were greater at the high dietary energy content, while abdominal fat increased with increasing energy content. Nana chickens had more skin protein and less fat in breast muscle and skin than their normal sibs in the summer trial. 6. It was concluded that the Nana broiler chickens showed similar performance and did not differ in dietary energy requirements in comparison to their nana sibs under natural ambient conditions in a subtropical climate.