Factors affecting energy metabolism and evaluating net energy of poultry feed

Optimizing broiler growth performance through balanced net energy, standard ileal digestible lysine, and amylose/amylopectin ratios: a Box-Behnken response surface approach

This study investigated the effects of net energy (NE), standard ileal digestible lysine (SID Lys), and amylose/amylopectin (AM/AP) ratios on broiler growth performance using a Box-Behnken design. A total of 936 male Arbor Acres Plus broilers (15-35 days post-hatch) were allocated to thirteen treatments with three factors at three levels including NE (2,000, 2,250, 2,500 kcal/kg), SID Lys (1.00 %, 1.20 %, 1.40 %), and AM/AP ratios (0.17, 0.22, 0.27, composed of different ratios of pea starch and waxy corn starch). Growth performance was measured weekly. At the growth stage of 15-20 d, quadratic relationships between dietary NE (P = 0.038), SID Lys (P = 0.010), AM/AP ratios (P = 0.021), and broiler 20 d body weight (BW), with optimization occurring at 2,303 kcal/kg NE, 1.24 % SID Lys, and an AM/AP ratio of 0.22. The 15-25 d feed-to-gain ratio (F/G) decreased linearly with increasing dietary NE (P = 0.038) and SID Lys (P = 0.010). At the growth stage of 21-27 d, linear increases in broiler 27 d BW (P = 0.007) and 21-27 d body weight gain (BWG) (P = 0.013) were observed with higher dietary SID Lys levels, reaching a peak at 2,500 kcal/kg NE, 1.40 % SID Lys, and an AM/AP ratio of 0.17. The 21-27 d F/G decreased linearly with increasing dietary NE (P < 0.001) and SID Lys (P < 0.001) levels. At the 28-35 d growth stage, a significant interaction between NE and SID Lys levels was observed for 35 d BW (P = 0.016) and 28-35 d BWG (P = 0.007). At 2,500 kcal/kg NE, both 35 d BW and 28-35 d BWG increased with higher SID Lys, whereas at 2,000 kcal/kg NE, they initially increased and then decreased as SID Lys levels rose. There was a significant interaction effect of NE and AM/AP ratio on broiler 28-35 d BWG (P = 0.017). Further quadratic curve fitting of 28-35 d BWG and 15-35 d BWG against dietary SID Lys/NE ratio revealed that 28-35 d BWG and 15-35 d BWG were optimized at dietary SID Lys/NE of 5.68 and 5.80 mg/kcal, respectively. These data indicate balancing dietary NE and SID Lys can optimize broiler growth, while lowering the dietary AM/AP ratio further enhances growth performance, likely due to improved starch digestibility and energy release dynamics. This study provides actionable insights for precision nutrition strategies in broiler production.

- Invited Review - Challenges and constraints to the sustainability of poultry farming in Thailand

The poultry farming industry in Thailand plays a crucial role in the nation's economy and food security. However, its long-term sustainability is challenged by disease outbreaks, environmental concerns, rising feed costs, market fluctuations, and shifting consumer preferences. This review examines the current state of poultry farming in Thailand, focusing on broilers, layers, and ducks. Disease control requires strict biosecurity measures and government interventions. Additionally, the industry must address environmental concerns by reducing greenhouse gas emissions and optimizing resource efficiency to align with Thailand's net-zero targets. The rising demand for organic and ethically produced poultry products presents both market opportunities and production challenges, necessitating significant adjustments in farming practices. Regulatory compliance, particularly in export markets, adds another layer of complexity, requiring Thai poultry producers to meet increasingly stringent international standards. The adoption of new technologies, such as precision farming and artificial intelligence-driven systems, presents both opportunities and challenges, especially for smaller producers who may struggle to keep pace with advancements. Rising feed costs, driven by global supply chain disruptions and dependence on imported raw materials, pose a significant economic burden, emphasizing the need for alternative protein sources such as insect-based feed and agro-industrial by-products. Furthermore, regulatory compliance with international standards and consumer-driven trends toward antibiotic-free and organic poultry products further shape the industry's transformation. To ensure sustainable development, Thailand's poultry sector must integrate innovative technologies, adopt environmentally friendly practices, and strengthen collaboration between the government, industry stakeholders, and researchers. The industry can maintain its global competitiveness by addressing these challenges while contributing to sustainable food production and environmental conservation.

Dietary Calcium and Protein Levels Influence Growth Performance, Intestinal Development, and Nutrient Utilization in Goslings

This study evaluated the effects of dietary calcium (Ca) and crude protein (CP) levels on growth performance, nutrient utilization, intestinal morphology, and digestive enzyme activities in goslings during the brooding period. A total of 972 one-day-old Jiangnan White goslings were assigned to a 3 × 3 factorial design with three levels of Ca (0.32%, 0.96%, and 2.88%) and three levels of CP (14.5%, 18.5%, and 22.5%). Results showed that moderate Ca (0.96%) and CP (14.5-18.5%) levels optimized growth performance, with higher body weight (BW), average daily gain (ADG), and average daily feed intake (ADFI), while excessive Ca (2.88%) impaired growth and the feed conversion ratio (FCR). Intestinal morphology was enhanced by 0.96% Ca and moderate CP levels, as reflected by greater villus height and crypt depth. Digestive enzyme activities in the duodenum, jejunum, and ileum were significantly influenced by dietary treatments, with moderate nutrient levels supporting optimal enzymatic efficiency. Nutrient utilization analyses revealed that Ca and CP levels interacted to optimize calcium, phosphorus, and protein metabolism, with the highest utilization rates observed at 0.96% Ca and 14.5% CP. These findings emphasize the importance of balanced dietary formulations to enhance growth performance, nutrient absorption, and metabolic efficiency in goslings, providing practical insights for improving poultry production.

Metabolizable and net energy evaluation of corn, soybean meal, and wheat bran in growing male pheasants

The apparent metabolizable energy(AME), AME corrected to zero-nitrogen retention(AMEn) and net energy (NE) values of corn, soybean meal and wheat bran were determined in growing male pheasants with reference diet substitution method. Reference diet was formulated according to standard Pheasants requirement, and test diets contained 40 % of corn, 20 % of soybean meal and 30 % of the wheat bran samples of thereference diet. Ninety male pheasants at the age of 12 wk with similar body weights were randomly divided into four groups. The heat production and energy metabolism of birds were measured in open-circuit respiratory chambers with 6 replicates (4 birds per replicate) per diet in a randomized design. Birds were fed experimental diets for 6 D in the chamber as adaptation. During the following 3 D, feed intake, metabolizable energy value, nitrogen balance, energy balance, O2 consumption, CO2 production, and energy efficiency were determined. Pheasants were allowed free access to feed under controlled environmental conditions. Feces were collected using respiratory calorimetry. The AME values of corn, soybean meal and wheat bran were 14.62 MJ/kg, 10.62 MJ/kg and 7.57 MJ/kg DM, respectively. The corresponding AMEn values were 14.71 MJ/kg, 10.64 MJ/kg and 7.25 MJ/kg DM, respectively. The NE values were 11.20 MJ/kg, 7.02 MJ/kg, and 6.19 MJ/kg DM, respectively. The NE:AME ratios of corn, soybean meal and wheat bran were 77.61 %, 65.68 % and 85.17 %, respectively. The NE:AMEn ratios of corn, soybean meal and wheat bran were77.22 % and 66.89 % and 84.76 %, respectively. The AME, AMEn and NE values of corn were higher than the other two samples.

Climate-smart livestock nutrition in semi-arid Southern African agricultural systems

Climate change is disrupting the semi-arid agricultural systems in Southern Africa, where livestock is crucial to food security and livelihoods. This review evaluates the bioenergetic and agroecological scope for climate-adaptive livestock nutrition in the region. An analysis of the literature on climate change implications on livestock nutrition and thermal welfare in the regional agroecological context was conducted. The information gathered was systematically synthesized into tabular summaries of the fundamentals of climate-smart bioenergetics, thermoregulation, livestock heat stress defence mechanisms, the thermo-bioactive feed components, and potentially climate-smart feed resources in the region. The analysis supports the adoption of climate-smart livestock nutrition when conceptualized as precision feeding combined with dietary strategies that enhance thermal resilience in livestock, and the adaptation of production systems to the decline in availability of conventional feedstuffs by incorporating climate-smart alternatives. The keystone potential climate-smart alternative feedstuffs are identified to be the small cereal grains, such as sorghum (Sorghum bicolor) and pearl millet (Pennisetum glaucum) as dietary energy sources, the native legumes, such as the cowpea (Vigna unguiculata) and the marama bean (Tylosema esculentum) as protein sources, wild browse Fabaceae trees such as Vachellia spp. and Colophospermum mopane, which provide dry season and drought supplementary protein, minerals, and antioxidants, the non-fabaceous tree species such as the marula tree (Sclerocarya birrea), from which animals consume the energy and electrolyte-rich fresh fruit or processed pulp. Feedstuffs for potential circular feeding systems include the oilseed cakes from the macadamia (Macadamia integrifolia) nut, the castor (Ricinus communis), and Jatropha (Jatropha curcas) beans, which are rich in protein and energy, insect feed protein and energy, primarily the black soldier fly larvae (Hermetia illucens), and microbial protein from phototrophic algae (Spirulina, Chlorella), and yeasts (Saccharomyces cerevisiae). Additives for thermo-functionally enhanced diets include synthetic and natural anti-oxidants, phytogenics, biotic agents (prebiotics, probiotics, synbiotics, postbiotics), and electrolytes. The review presents a conceptual framework for climate-smart feeding strategies that enhance system resilience across the livestock-energy-water-food nexus, to inform broader, in-depth research, promote climate-smart farm practices and support governmental policies which are tailored to the agroecology of the region.

Leverage of lysozyme dietary supplementation on gut health, hematological, antioxidant, and immune parameters in different plumage-colors Japanese quails

The current study was conducted on two different feather-colored Japanese quail varieties (brown and white) to examine the impact of lysozyme (LZ) dietary supplementation on growth performance, hematological profile, serum lysozyme, phagocytic and antioxidant activities, along with the gut status and the relative expression of some antioxidant- and immune-related genes. Two forms of LZ; extracted from egg white (natural LZ (NLZ)), and the commercial LZ (CLZ) were included in this experiment. For each quail variety, 240 birds were randomly allocated into four groups with four replicates per group. The first group (control) ate the basal diet (BD) only. The other groups ate the BD supplemented with commercial lysozyme (CLZ, at 100 mg/kg diet), NLZ at 100 (NLZ1) and 200 (NLZ2) mg/kg diet. Different LZ treatments differentially modulated the quail's growth performance with significant increases in the final body weight of white-feathered quails fed the NLZ1 compared to other treatments. The NLZ2 and CLZ noticeably increased the total antioxidant activity (TA) in the white- and brown-feathered quails, respectively. Also, all LZ groups displayed distinct increases in the serum lysozyme and phagocytic activities. For gut status, both varieties exhibited increases in intestinal villi length and goblet cell count with significant reductions in the total lactobacillus, total coliform, and total bacterial counts. These effects were linked with marked modulations of SOD, CAT, GPX, andIL-1βgene expression levels in both quail varieties. Therefore, the LZ could differentially impact quail growth, immune and antioxidant status as well as gut health.

Enhancing nutrient intake, egg production, and egg quality by fermented Leucaena leucocephala leaf meal in a diet of laying quail

Background and Aim

The inclusion of Leucaena leucocephala leaf meal (LLM) in poultry feed is often limited due to its high crude fiber and mimosine content. This study investigates the potential of fermented LLM (FLM) to enhance nutrient intake, egg production, and egg quality in laying quails by reducing anti-nutritional factors through fermentation.

Materials and Methods

Two hundred 42-day-old laying quails were assigned to five dietary treatments: T0 (control) = 100% basal diet (BD), T1 = 98% BD + 2% FLM, T2 = 96% BD + 4% FLM, T3 = 94% BD + 6% FLM, and T4 = 92% BD + 8% FLM. Parameters including nutrient intake (energy, protein, fat, calcium, phosphorus), feed conversion ratio (FCR), egg production, egg weight, eggshell thickness, Haugh unit, and yolk color were measured over a 28-day trial. Data were analyzed using a one-way analysis of variance, followed by Duncan's test for significant differences (p ≤ 0.05).

Results

FLM supplementation significantly improved energy, protein, fat, calcium, and phosphorus intake while reducing FCR. At 4% FLM inclusion, significant enhancements in egg production, eggshell thickness, Haugh unit, and yolk color were observed. Conversely, fiber intake and overall feed intake remained unaffected across treatments. The highest egg production (56.43%) and best yolk color (8,95) were observed in the 8% FLM group.

Conclusion

Incorporating FLM into the diets of laying quails effectively enhances nutrient utilization and improves egg production and quality without increasing feed intake. The optimal inclusion level for maximizing benefits appears to be 4-8% FLM.

Poultry Nutrition: Achievement, Challenge, and Strategy

Poultry, a vital economic animal, provide a high-quality protein source for human nutrition. Over the past decade, the poultry industry has witnessed substantial achievements in breeding, precision feeding, and welfare farming. However, there are still many challenges restricting the sustainable development of the poultry industry. First, overly focused breeding strategies on production performance have been shown to induce metabolic diseases in poultry. Second, a lack of robust methods for assessing the nutritional requirements poses a challenge to the practical implementation of precision feeding. Third, antibiotic alternatives and feed safety management remain pressing concerns within the poultry industry. Lastly, environmental pollution and inadequate welfare management in farming have a negative effect on poultry health. Despite numerous proposed strategies and innovative approaches, each faces its own set of strengths and limitations. In this review, we aim to provide a comprehensive understanding of the poultry industry over the past decade, by examining its achievements, challenges, and strategies, to guide its future direction.

Influence of extruded soybean meal with varying fat and oleic acid content on nitrogen-corrected apparent metabolizable energy in broilers

High oleic (HO) soybeans may serve as a value-added feed ingredient; providing amino acids and estimating their dietary energy value for broilers is essential. In this study, we determined the apparent metabolizable energy (AME), AME corrected for zero nitrogen retention (AMEn), digestibility, and nitrogen (N) retention of HO full-fat (HO-FF) soybean as compared to solvent-extracted soybean meal (SE-SBM), normal oleic full-fat (NO-FF) and extruded expeller (NO-EE) soybean. A total of 240 Ross-708 male broilers were selected, with 8 replicates per treatment and 6 chicks per cage. The AME and AMEn were estimated using the difference method with a 30% inclusion of test ingredients using a corn-soy reference diet with partial and total excreta collection. The index method with partial excreta collection used titanium dioxide as an inert marker. The same starter diet was provided for all birds for 14 d, followed by the reference and assay diets for the next 6 adaptation days. Total excreta were collected twice a day for 3 d. The AME and AMEn values determined for the HO-FF and NO-FF were higher (P < 0.001) than the NO-EE and SE-SBM. The AME of SE-SBM and NO-EE were similar with both methods, but the AMEn of SE-SBM was lower than the NO-EE only with the partial collection method. The agreement between AME and AMEn values determined by partial and total excreta collection analysis was 98%. Data from the total excreta collection method yielded higher AME and AMEn values (P < 0.001) than those from the partial collection method. In summary, HO-FF and NO-FF soybean meals had similar AME and AMEn values. The HO-FF soybean had 39 and 24% higher AME and AMEn than SE-SBM. Hence, high oleic full-fat soybean meal could serve as a valuable alternative feed ingredient to conventional SE-SBM meals in broiler diets, providing additional energy while providing amino acids and more oleic acid to enrich poultry meat products.

Dynamic Changes in Egg Quality, Heritability and Correlation of These Traits and Yolk Nutrient throughout the Entire Laying Cycle

Egg quality and nutritional value are becoming increasingly important to consumers, offering a new direction for the development of high-quality eggs. In this study, we conducted a comprehensive analysis of egg quality and nutrient profiles in native breeds at different ages, integrating pedigree data. Our results reveal dynamic changes in egg qualities, stronger associations among eggshell-related traits, and the effect of onset production and body weight on egg qualities. The heritability of different traits was estimated, ranging from 0.05 to 0.62. Subsequently, we elucidated that the moisture and nutritional content in the egg yolk were not influenced by the percentage of yolk but were indeed subject to age regulation. There was a notable decrease in moisture, an elevation in crude fat, and an increase in the diversity of fatty acids of yolk with advancing age. In summary, investigating the trends and interrelationships in egg quality, nutrient content, and heritability across the whole laying cycle offers valuable insights for breeders to optimize feeding management strategies and aids consumers in meeting their expectations of egg quality.

Effects of metabolizable energy and emulsifier supplementation on growth performance, nutrient digestibility, body composition, and carcass yield in broilers

This study aimed to investigate the effect of metabolizable energy (ME) levels and exogenous emulsifier supplementation on growth performance, apparent ileal digestibility (AID), body composition, and carcass yield in broilers. The experiment was designed as a 2  ×  2 factorial arrangement with ME levels (control ME vs. reduced 100 kcal/kg ME) and exogenous emulsifier supplementation (0 vs. 0.05 %). A total of 1,000 one-day-old male Cobb 500 broilers were randomly allocated into 4 treatments with 10 replicates and 25 birds per floor pen for 42 d (starter, d 0-14; grower, d 14-28; and finisher, d 28-42). Growth performance was measured biweekly, and AID was evaluated using the indigestible indicator method during d 21 to 28. Body composition was measured at d 35 using Dual-Energy X-Ray Absorptiometry (DXA), and carcass yield was evaluated at d 42. Data were analyzed using the GLM procedure for 2-way ANOVA. Results indicated reduced ME decreased body weight gain and feed intake (P < 0.05). Exogenous emulsifier supplementation improved FCR during the finisher and overall periods (P < 0.05). Reduced ME decreased AID of dry matter (DM), fat, and gross energy (P < 0.05) but increased AID of Val (P = 0.013). Exogenous emulsifier supplementation increased AID of DM, crude protein, His, Ile, Lys, Thr, Val, Pro, Ala, and Tyr (P < 0.05). Reduced ME decreased dressing rate and the relative weight of abdominal fat (P < 0.05). DXA results indicated that reduced ME decreased bone mineral density and fat (P < 0.001) but increased bone mineral contents and muscle (P < 0.05). Therefore, a reduction of 100 kcal/kg ME in the diet had adverse effects on the growth performance and carcass characteristics, but the use of exogenous emulsifier supplementation improved growth performance and nutrient digestibility.

Modelling nitrogen-corrected apparent metabolisable energy requirement for egg production of 3 BW types of Yellow Broiler breeder hens during the egg-laying period

Accurate prediction of energy requirement is important in formulating diets, but an energy model for Yellow Broiler breeder hens is publicly unavailable. The objective of this study was to establish energy prediction models for the nitrogen-corrected apparent metabolisable energy (AMEn) requirement of different categories of Yellow Broiler breeder hens during the egg-laying period. Data for modelling were collected from research papers, public databases and production data from companies. Breeder hens were generally categorised into three BW types: heavy, medium and light (HBWT, MBWT and LBWT). Published articles were cited for providing coefficients of AMEn maintenance requirement (AMEnm, 101 kcal/kg BW^0.75, 423 KJ/kg BW^0.75) and growth requirement (AMEng, 5.33 kcal/g, 22.3 KJ/g), respectively. Models of AMEn for egg production (AMEnp) were established from the known daily intake of AMEn (AMEni) and those of maintenance and growth by the factorial approach: AMEnp = AMEni - AMEnm - AMEng. For the three types of hens, AMEnp HBWT (kcal, KJ) = 2.55 kcal (10.7 KJ) × egg mass (EM, g); AMEnp MBWT (kcal, KJ) = 2.70 kcal (11.3 KJ) × EM (g), and AMEnp LBWT (kcal, KJ) = 2.94 kcal (12.3 KJ) × EM (g) were determined. The total AMEni requirements, depending on Gompertz models, were HBWT: BW (g) = 3 144 × e^{-EXP(-0.162×(week of age (wk)-15.6))}; MBWT: BW (g) = 2 526 × e^{-EXP(-0.333×(wk-19.1))}; LBWT: BW (g) = 1 612 × e^{-EXP(-0.242×(wk-16.5))}. Models of egg production, HBWT: egg production (%) = 124 × e^-0.017×wk/(1 + e^{-0.870×(wk-26.2)}); MBWT: egg production (%) = 144 × e^-0.020×wk/(1 + e^{-0.751×(wk-24.9)}); LBWT: egg production (%) = 163 × e^-0.024×wk/(1 + e^{-0.476×(wk-26.5)})) and egg weight for each wk of the three types of hens during the egg-laying period were all established. These models showed good applicability in simulating and predicting the literature or production data.

Comparative study of apparent metabolizable energy and net energy values of dephenolized cottonseed proteins for laying hens

Optimizing the energy utilization of nutrients and ensuring maximum benefits are continuous goals for livestock producers. The net energy (NE) value of feed reflects its nutritional value in the precision feeding system. An experiment was conducted to determine the apparent metabolizable energy (AME) and NE values of 3 types of dephenolized cottonseed protein (DCP) for Hy Line Brown hens aged 42 to 45 weeks using the reference diet substitution method. A reference diet based on corn soybean meal was used to meet the nutritional needs of Hy Line Brown laying hens. To render the crude protein and energy values of the 3 test diets similar, 10.5%, 12%, and 16% of the gross energy yielding ingredients from the reference diet were replaced with DCP 1, DCP 2, and DCP 3, respectively. The birds were fed 4 diets during a 7-d adaptation period. After the dietary adaptation period, 2 birds per replicate from each treatment group were placed in an individual open circuit respiratory calorimetry chamber for a 3-d experimental period. Daily O₂ consumption and CO₂ production were recorded, and excreta samples were collected. The AME values of DCP 1, DCP 2, and DCP 3 were 3,049.05, 2,820.13, and 2,982.31 kcal/kg of dry matter (DM), respectively. The NE values of DCP 1, DCP 2, DCP 3 were 1,475.77, 1,910.31, and 1,905.37 kcal/kg of DM, respectively, and the NE:AME ratios were 48.40%, 67.74%, and 63.89%, respectively. Our data show that the AME value of DCP does not reflect the nutritional value of the feed. The NE value of DCP with a high ME value was not necessarily high.

Drying of Food Waste for Potential Use as Animal Feed

A considerable part of food is wasted, causing investment capital loss as well as environmental pollution and health problems in humans. Indirect solar drying was applied to test the potential of drying and reusing this waste as a component of animal feed. The effect of weather changes on drying kinetics and the effective diffusion coefficient, dried feed nutritional composition, and microbiological analysis of the dried product were investigated. A convective laboratory dryer was used as a reference method. Weather conditions have a crucial effect on the use of solar drying; one sunny day with appropriate conditions can reduce the water activity of food waste to below 0.3 and moisture content to below 6%. Much better fitting of experimental and model drying curves was achieved considering sample shrinkage, applying a more complex solution of Fick’s second law combined with an optimization procedure. The studied food waste had a good combination of nutrients, such as protein, fat, and carbohydrates; however, the amount of protein in the dried food waste was found to be lower than that in regular feed, and therefore, adding a protein source is recommended. Autoclaving of fresh samples reduced the total microbial counts of dried samples by more than 50%.

Internal causality in agri-food Life Cycle Assessments: Solving allocation problems based on feed energy utilization in egg production

Physical allocation in Life Cycle Assessment (LCA) should, ideally, be based on underlying causal relationships. While both cause-oriented and effect-oriented causality referred to in LCA literature are forms of external causality, internal causality addresses the actual flow of materials and inputs in a system - in other words, the real behaviour of the system under study. While a number or examples of allocation based on physical causality have been used in poultry LCAs, none of these represent the internal causality (the actual biological processes) in egg production. The current study remedies that gap by proposing such a method. Agri-food LCAs, in particular LCAs of livestock production, were used to identify existing physical allocation approaches consistent with internal causality. The most commonly used approach was found to be based on the allocation of feed energy to support the various physiological functions of the livestock species. A feed energy - Metabolizable Energy (ME) - utilization model for allocation in egg production LCAs is hence similarly proposed. Using the inventory of a previous LCA study of egg production in Canada, allocation ratios for eggs and spent hens were developed. Feed utilization models specific to each unit process were identified. The overall differences between ME utilization (∼95% eggs, 5% spent hens) and gross chemical energy content (92% eggs, 8% spent hens) for allocation were relatively small. Scenario analysis, however, showed that the allocation ratios can be considerably different if the causal relationship is interpreted differently. Differences over ∼20% was seen in a scenario which did not allocate between the co-products of each unit process in the system, but rather to the products at the end of a biological causal chain straddling multiple unit processes. The proposed approach is consistent with the interpretation of LCA as a natural sciences framework, and with the ISO 14044 multi-functionality hierarchy, because it reflects actual biological causality in egg production systems. The study results also underscore that practitioners should not only clearly justify their choice of allocation strategy, but also describe its application in detail, since small differences in methods can result in divergent outcomes.

Feed form and nutritional level for rearing growing broilers in thermoneutral or heat stress environments

The present study aimed to investigate the effects of different physical forms of feed and feeding programs on nutrient digestibility and performance of grower-finisher broilers under thermoneutrality or thermal stress. Three experiments were conducted using male broiler chickens (n = 720) aged 19-42 d. The design of two of the experiments was fully randomized in a 2 × 2 factorial arrangement with two forms of feed (mash and pellet) and two nutritional levels (13.19 MJ/kg and 194.8 g/kg CP - normal level and 13.61 MJ/kg and 210.3 g/kg CP - high level). The experiments took place in a climate-controlled room: Experiment 1 at thermoneutrality (21-23 °C and 58-60% relative humidity) for 24 h/day; Experiment 2 under thermal stress cycle (31-32 °C and 63-65% relative humidity), for 6h/day and thermoneutrality (21-23 °C, 58-60% relative humidity) for 18h/day. The nutrient digestibility and performance was analyzed. The design of the third experiment was fully randomized with two ambient condition treatments (thermoneutral and thermal stress) on heat production, caloric increment and net energy. Pellet feed obtained higher digestibility of dry matter, digestibility of crude protein, AME and AMEn (P < 0.05) than mash feed for broilers reared in the thermoneutral environment. At the high nutritional level there was no effect of treatments on the coefficient of dry matter and crude protein (DCCP) (P > 0.05), while the highest digestibility of AME and AMEn were obtained by the high nutritional level diet (P < 0.05). Pellet feed had higher DCCP (P < 0.05) than mash feed for broilers reared under cyclic heat stress. Broiler chickens under cyclic stress experienced increased caloric increment, rectal temperature and respiratory rate. The appropriate strategy to minimize these effects in both ambient conditions is to pellet feed.

Effects of phytase supplementation and increased nutrient density on growth performance, carcass characteristics, and hypothalamic appetitive hormone expression and catecholamine concentrations in broilers from 1 to 43 days of age

Two experiments were conducted to evaluate extra-phosphoric effects of phytase and nutrient density on growth performance, meat yield, and hypothalamic appetitive hormone expression and catecholamine concentrations of broilers. Experiment 1 determined differences of digestible amino acid concentrations and AME_n using 256 Yield Plus × Ross 708 broilers (32 cages, 8 birds/cage) fed diets without or with 4,500 phytase units (FTU)/kg inclusion (16 reps/treatment). In Experiment 2, 832 Yield Plus × Ross 708 broilers (32 pens; 26 birds/pen) were provided diets in a 2 × 2 factorial arrangement consisting of 2 nutrient contents (without or with increased density) and 2 phytase inclusions (0 or 4,500 FTU/kg). Increased nutrient density was formulated to contain 0.007, 0.015, 0.013, 0.021, 0.024%, and 61 kcal/kg higher digestible SAA, Lys, Thr, Val, Ile, and AME_n (from Experiment 1) respectively, compared with the control diet. Growth performance was determined at 14, 28, and 40 d of age and carcass characteristics at 41 d of age. At 43 d of age, plasma inositol, hypothalamic appetitive hormone expression, and catecholamine concentrations were determined from 4 birds/pen. Additive effects of phytase inclusion and increased nutrient density resulted in the lowest (P < 0.05) feed conversion from 1 to 40 d of age and the heaviest (P < 0.01) breast meat weights among dietary treatments. Phytase addition numerically increased feed intake (P = 0.06) and BW gain (P = 0.051) compared with birds fed diets without phytase from 1 to 40 d of age. Plasma inositol and dopamine concentrations were 2.3- and 1.2-fold higher (P < 0.01), respectively, in broilers fed phytase-added diets than birds fed diets without phytase inclusion. However, mRNA expression of neuropeptide Y, agouti-related peptide, proopiomelanocortin, cholecystokinin A receptor, ghrelin, and serotonin concentration were not different (P > 0.05) among treatments. These data indicated additive effects of phytase supplementation and increased nutrient density on growth performance and meat accretion of broilers. However, the influence of phytase on feed intake warrants future research.

Protease supplementation in maize-based diet influenced net energy and nutrient digestibility in broilers

This experiment evaluated the effects of supplemental protease in maize-based diets formulated with reduced density of digestible amino acids (dAA) on net energy (NE) utilisation and nutrient digestibility in broilers. A total of 312, one-day-old, male broilers (Ross 308) were randomly distributed into 24 floor pens and fed one of three treatments, with eight pen replicates per treatment throughout the starter (1 to 14 d of age) and grower (15 to 28 d of age) phases. Dietary treatments consisted of a positive control (PC) reference diet, a negative control diet (NC; dAA density 60 g/kg less than PC diet), and a NC diet with supplemental protease (200 mg/kg). All diets contained supplemental phytase (200 mg/kg) and xylanase (200 mg/kg). The reduction in dAA density between the PC and NC did not affect (P>0.05) NE, but protease supplementation in the NC diet increased (P<0.05) NE by 0.27 MJ/kg, compared with those receiving the NC diet without protease. The reduction in dAA for broilers fed the NC and PC diets did not (P>0.05) affect nitrogen, starch, or DE in the jejunum or ileum. Likewise, no differences (P>0.05) in jejunal (nitrogen, starch, and DE) and ileal (starch and DE) digestibility values were observed between those offered the NC diets without or with protease, but a small difference (P<0.05) in ileal nitrogen digestibility was observed.

Characterizing Woody Breast Myopathy in a Meat Broiler Line by Heat Production, Microbiota, and Plasma Metabolites

Selection for quantitative traits in meat broilers such as breast yield and growth rate exert physiological pressure leading to ante mortem histological and biochemical alterations in muscle tissues. The poultry industry has recently witnessed a myopathy condition affecting Pectoralis major (breast muscle) of broilers, called woody breast (WB), an etiology still unclear to scientific community. A study was conducted to characterize the WB myopathy in a meat broiler line at its finishing phase (d 41) in terms of heat production (HP), microbiota and plasma metabolites. Two treatment groups were studied-WB affected (myopathy) and normal (non-myopathy) broiler; n = 20 in each group. Indirect calorimetry was utilized for HP measurement. Furthermore, body composition (BC) analysis was also performed using dual-energy x-ray absorptiometry (DEXA). Microbiota in ileal digesta was studied with PCR amplified 16s rRNA gene. LC-MS targeted metabolomics was performed to understand differential expression of plasma metabolites. Results showed that there was difference in fasting HP (P < 0.05) between these two treatment groups, with non-myopathy broiler producing more heat which was indicative of higher body protein content validated by higher protein: fat ratio by BC results. Less protein content in myopathy bird could be due to probable higher mixed muscle degradation occurring in lean tissue as marked by elevated 3-methylhistidine expression in plasma. Microbiota results showed unclassified Lactobacillus as predominant genus with higher abundance occurring in myopathy group; whereas at species level, L. acidipiscis was predominant bacteria for non-myopathy broiler. Differentially significant metabolites (P < 0.05) identified from plasma metabolome between these two treatment groups were homocysteine, cyclic GMP, trimethylamine N-oxide (TMAO), tyramine, carnitine, and acetylcarnitine, which were all associated to cardiovascular system. The findings suggest that more research in meat broilers could be opted toward delivering reduced vascularity issues to alleviate this myopathy condition.