In light of the increased worldwide demand for poultry meat, genetic selection efforts have intensified to produce broiler strains that grow at a higher rate, have greater breast meat yield (BMY), and convert feed to meat more efficiently. The increased selection pressure for these traits, BMY in particular, has produced multiple breast meat quality defects collectively known as breast muscle myopathies (BMM). Hypoxia has been proposed as one of the major mechanisms triggering the onset and occurrence of these myopathies. In this review, the relevant literature on the causes and consequences of hypoxia in broiler breast muscles is reviewed and discussed, with a special focus on the hypoxia-inducible factor 1 (HIF-1) pathway. Muscle fiber hypertrophy induced by selective breeding for greater BMY reduces the space available in the perimysium and endomysium for blood vessels and capillaries. The hypoxic state that results from the lack of circulation in muscle tissue activates the HIF-1 pathway. This pathway alters energy metabolism by promoting anaerobic glycolysis, suppressing the tricarboxylic acid cycle and damaging mitochondrial function. These changes lead to oxidative stress that further exacerbate the progression of BMM. In addition, activating the HIF-1 pathway promotes fatty acid synthesis, lipogenesis, and lipid accumulation in myopathic muscle tissue, and interacts with profibrotic growth factors leading to increased deposition of matrix proteins in muscle tissue. By promoting lipidosis and fibrosis, the HIF-1 pathway contributes to the development of the distinctive phenotypes of BMM, including white striations in white striping-affected muscles and the increased hardness of wooden breast-affected muscles.

This review summarizes the most relevant scientific literature related to the use of insects as alternative protein sources in poultry diets. The black soldier fly, the housefly, the beetle, mealworms, silkworms, earthworms, crickets, and grasshoppers are in the spotlight because they have been identified as an important future source of sustainable animal proteins for poultry feeding. Insect meals meet poultry requirements in terms of nutritional value, essential amino acid composition, nutrient digestibility, and feed acceptance. Furthermore, they are enriched with antimicrobial peptides and bioactive molecules that can improve global health. Results from poultry studies suggest equivalent or enhanced growth performances and quality of end-products as compared to fish meal and soybean meal. To outline this body of knowledge, this article states established threads of research about the nutrient profiles and the digestibility of insect meals, their subsequent effects on the growth and laying performances of poultry as well as the quality of meat, carcass, and eggs. To fully exploit insect-derived products, the effects of insect bioactive molecules (antimicrobial peptides, fatty acids, and polysaccharides) were addressed. Furthermore, as edible insects are likely to take a meaningful position in the feed and food chain, the safety of their derived products needs to be ensured. Some insights into the current knowledge on the prevalence of pathogens and contaminants in edible insects were highlighted. Finally, the effect of insect farming and processing treatment on the nutritive value of insect larvae was discussed. Our overview reveals that using insects can potentially solve problems related to reliance on other food sources, without altering the growth performances and the quality of meat and eggs.

Aflatoxin contamination in feed is a common problem in broiler chickens. The present systematic review and meta-analysis examined the impact of aflatoxin-contaminated feed and the efficacy of various feed additives on the production performance of broiler chickens fed aflatoxin-contaminated feed (AF-feed). A total of 35 studies comprising 53 AF-feed experiments were selected following PRISMA guidelines. Feed additives included in the analyses were toxins binder (TB), mannan-oligosaccharides (MOS), organic acid (OA), probiotics (PRO), protein supplementation (PROT), phytobiotics (PHY), and additive mixture (MIX). Random effects model and a frequentist network meta-analysis (NMA) were performed to rank the efficacy of feed additives, reported as standardized means difference (SMD) at 95% confidence intervals (95% CI). Overall, broiler chickens fed AF-feed had significantly lower final body weight (BW) (SMD = 198; 95% CI = 198 to 238) and higher feed conversion ratio (SMD = 0.17; 95% CI = 0.13 to 0.21) than control. Treatments with TB, MOS, and PHY improved the BW of birds fed AF-feed (P < 0.05) to be comparable with non-contaminated feed or control. Predictions on final BW from the broiler-fed aflatoxin-contaminated diet were 15% lower than the control diet. Including feed additives in the aflatoxins diet could ameliorate the depressive effect. Remarkably, our network meta-analysis highlighted that TB was the highest-performing additive (P-score = 0.797) to remedy aflatoxicosis. Altogether, several additives, especially TB, are promising to ameliorate aflatoxicosis in broiler chickens, although the efficacy was low regarding the severity of the aflatoxicosis.

The objective of this systematic review was to compare the efficacy of antibiotic and non-antibiotic alternatives in the prevention and treatment of necrotic enteritis (NE) in broiler chickens. In vivo experimental and observational studies that compared the administration of non-antibiotic compounds with antibiotics to prevent or treat NE in broiler chickens and that evaluated mortality and/or clinical or subclinical NE outcome measures were eligible. Four electronic databases were searched in December 2019 and updated in October 2021. Retrieved studies were evaluated in two phases: abstract and design screening. Data were then extracted from included studies. Risk of bias was assessed by outcome following the Cochrane Risk of Bias 2.0 tool. A meta-analysis was not conducted due to heterogeneity across interventions and outcomes. The non-antibiotic and antibiotic groups were compared at the outcome level for individual studies using the mean difference and 95% confidence interval (CI) calculated post hoc from raw data. In total, 1282 studies were originally identified, and 40 were included in the final review. The overall risk of bias for the 89 outcomes was either \"high\" (n = 34) or \"some concerns\" (n = 55). Individual study comparisons showed a beneficial trend toward the antibiotic group for reduced mortality, NE lesion scores (overall, jejunum, and ileum), Clostridium perfringens counts, and for most histologic measurements (duodenum, jejunum, and ileum villi height, and jejunum and ileum crypt depth). The non-antibiotic groups showed a beneficial trend for NE duodenum lesion scores and duodenum crypt depth measurements. Based on this review, there is a trend that mostly favors antibiotic compounds in preventing and/or treating NE, but the evidence also suggests no difference when comparing them with non-antibiotic alternatives. Studies assessing this research question were heterogeneous in their intervention conditions and outcomes measured, and there were key aspects of the experimental design not reported in some of the studies.
Eficacia de las intervenciones con antibióticos y compuestos no antibióticos para prevenir y tratar la enteritis necrótica en pollos de engorde: Una revisión sistemática El objetivo de esta revisión sistemática fue comparar la eficacia de antibióticos y alternativas a los antibióticos en la prevención y tratamiento de la enteritis necrótica (NE) en pollos de engorde. Se incluyeron estudios experimentales in vivo y estudios observacionales que compararon la administración de compuestos no considerados antibióticos con compuestos antibióticos usados para prevenir o tratar la enteritis necrótica en pollos de engorde, y que evaluaran mortalidad, signos clínicos, u otros resultados subclínicos. Se buscaron referencias en cuatro bases de datos bibliográficos en Diciembre de 2019 y por segunda vez en Octubre de 2021. Los estudios que se encontraron se evaluaron en dos fases: resumen y diseño del estudio de escrutinio. Posteriormente se extrajeron los datos de aquellos estudios que se incluyeron después del escrutinio. Se evaluó el riesgo de sesgos siguiendo la herramienta de Cochrane Risk of Bias 2.0. No se pudo realizar un meta-análisis debido a la heterogeneidad de las intervenciones y de los resultados de los estudios incluidos. Los grupos de compuestos no antibióticos y de antibióticos se compararon con base a los resultados individuales de cada estudio usando la diferencia entre medias e intervalos de confianza al 95%, calculados post-hoc usando los datos originales. Se identificaron un total de 1282 estudios, y 40 fueron finalmente incluidos en la revisión. El riesgo de sesgos para el total de los 89 resultados individuales fue alto (n = 34) o con “ciertos problemas” (n = 55). Las comparaciones individuales entre estudios mostraron una tendencia beneficiosa hacia el grupo de antibióticos en términos de mortalidad reducida, puntaje de lesiones de enteritis necrótica (total, yeyuno e íleo), conteos de Clostridium perfringens, así como para la mayoría de las medidas histológicas (altura de las vellosidades del duodeno, yeyuno e íleo, y profundidad de la cripta del yeyuno e íleo). El grupo de no antibióticos mostró una tendencia beneficiosa para el puntaje de lesiones de enteritis necrótica del duodeno y para las medidas de profundidad de la cripta del duodeno. Según esta revisión, hay una tendencia que favorece al grupo de antibióticos en la prevención y/o tratamiento de enteritis necrótica, pero la evidencia también sugiere que no hay diferencia entre los grupos. Los estudios incluidos en la comparación eran muy heterogéneos en cuanto a las condiciones de las intervenciones y a los resultados que se midieron, además de que algunos aspectos importantes del diseño experimental en algunos de los estudios no se reportaron.

Palm oil is a natural energy source ingredient in poultry diets that offers a broad range of beneficial effects on the performance of broiler chickens. This review was conducted to highlight the impact of palm oil as a feed ingredient on growth performance and carcass quality, as well as the biochemical, antioxidant activity and tissue fatty acids (FA) composition of broiler chickens. Palm oil inclusion in broiler chickens\' rations contributes significantly to the high metabolisable energy (ME) of feed formulation, increases feed palatability and decreases digesta passage rate in the intestine. The reviewed literature indicated that dietary palm oil has a beneficial effect on broiler chickens\' overall growth performance traits. The addition of palm oil can also improve the heat tolerance of chickens reared in high ambient temperature conditions. Regardless of breed and breeding conditions, palm oil exhibits good oxidative stability in broiler chickens due to the presence of prevalent phytonutrient elements in this oil. The inclusion of palm oil increased palmitic (C16:0) and oleic (C18:1) acids in tissue deposits, which improves meat stability and quality. Moreover, molecular studies have revealed that higher mRNA expression of several lipid-related hepatic genes in broiler chickens fed palm oil. Nonetheless, dietary palm oil can influence FA deposition in tissues, modulate lipoprotein and triglycerides (TG) levels, and cytokine contents in the blood serum of broiler chickens.

In line with the substantial increase in the broiler industry worldwide, Clostridium perfringens-induced necrotic enteritis (NE) became a continuous challenge leading to high economic losses, especially after banning antimicrobial growth promoters in feeds by many countries. The disease is distributed worldwide in either clinical or subclinical form, causing a reduction in body weight or body weight gain and the feed conversion ratio, impairing the European Broiler Index or European Production Efficiency Factor. There are several predisposing factors in the development of NE. Clinical signs varied from inapparent signs in case of subclinical infection (clostridiosis) to obvious enteric signs (morbidity), followed by an increase in mortality level (clostridiosis or clinical infection). Clinical and laboratory diagnoses are based on case history, clinical signs, gross and histopathological lesions, pathogenic agent identification, serological testing, and molecular identification. Drinking water treatment is the most common route for the administration of several antibiotics, such as penicillin, bacitracin, and lincomycin. Strict hygienic management practices in the farm, careful selection of feed ingredients for ration formulation, and use of alternative antibiotic feed additives are all important in maintaining broiler efficiency and help increase the profitability of broiler production. The current review highlights NE caused by C. perfringens and explains the advances in the understanding of C. perfringens virulence factors involved in the pathogenesis of NE with special emphasis on the use of available antibiotic alternatives such as herbal extracts and essential oils as well as vaccines for the control and prevention of NE in broiler chickens.

Eimeria infections impair digestive tract capacity and barrier function leading to poor growth and feed efficiency. A meta-analysis approach was used to evaluate and quantify impact of Eimeria infection on the apparent ileal digestibility (AID) of amino acids (AA) in broiler chickens. A database composed of 6 articles with a total of 21 experiments was built for the effect of challenge type (a mix of Eimeria spp. vs. E. acervulina) and subdatabase of 3 articles with a total of 15 experiments for the effect of E. acervulina dose response. Regression models were fitted with the mixed model procedure in Minitab 19 with fixed effects of challenge, species, and their interactions. For the sub database, the mixed model procedure was used to fit regression models and identify a linear or quadratic response to dose. Challenge decreased AID (P < 0.05) of both dispensable and indispensable AA except for Trp. Specifically, the largest depression was observed for Cys, Thr, Tyr, Ala, and Val with the magnitude of difference of 8.7, 5.4, 5.2, 5.1, and 4.9%, respectively for challenged vs. unchallenged birds. The type of challenge affected (P < 0.05) AID of AA with exception of Cys, Tyr, Ala, Ser, Leu, Asp, Gly, and Pro. E. acervulina challenge had larger negative effects on AID of Ile, Leu, and Val. Moreover, E. acervulina linearly decreased (P < 0.05) AID of all indispensable and dispensable AA except for Trp and quadratically (P < 0.05) decreased AID of all AA except Cys, Met, Arg, and Trp. The largest linear decrease due to E. acervulina dose was seen for AID of Cys, followed by Ala, Val, Thr, and Ile. Although, AID of Trp was not affected by E. acervulina challenge, mixed Eimeria species challenge decreased (P < 0.05) AID of Trp. Overall, the results confirmed that an Eimeria infection negatively impacted AA digestibility/utilization. The ranking of the most affected AA suggested ground for nutritional intervention during subclinical field Eimeria infections or vaccination programs.

The objective of this systematic review was to evaluate the efficacy of antibiotics to prevent or control colibacillosis in broilers. Studies found eligible were conducted controlled trials in broilers that evaluated an antibiotic intervention, with at least one of the following outcomes: mortality, feed conversion ratio (FCR), condemnations at slaughter, or total antibiotic use. Four electronic databases plus the gray literature were searched. Abstracts were screened for eligibility and data were extracted from eligible trials. Risk of bias was evaluated.Seven trials reported eligible outcomes in a format that allowed data extraction; all reported results for FCR and one also reported mortality. Due to the heterogeneity in the interventions and outcomes evaluated, it was not feasible to conduct meta-analysis.Qualitatively, for FCR, comparisons between an antibiotic and an alternative product did not show a significant benefit for either. Some of the comparisons between an antibiotic and a no-treatment placebo showed a numerical benefit to antibiotics, but with wide confidence intervals. The risk-of-bias assessment revealed concerns with reporting of key trial features.The results of this review do not provide compelling evidence for or against the efficacy of antibiotics for the control of colibacillosis.

Foot pad dermatitis (FPD), a condition of inflammation and necrotic lesions on the plantar surface of the footpads, is commonly observed in fast-growing broiler chickens and turkeys. FPD negatively affects the welfare of birds, performance indices and the economic profit of poultry meat production. Nutrition is an important factor affecting water intake, excreta moisture and litter quality and, in this way, the occurrence and intensity of FPD in birds. This article reviews and discusses the recent results published in the literature on the effects of nutritional factors on litter quality and FPD severity in broiler chickens and turkeys. Literature data on the efficacy of nutritional methods on the litter quality and FPD occurrence are not consistent. However, the results of several experiments indicate that the optimal level of crude protein, biotin and electrolytes (Na, K) in the diet, as well as feed additives such as feed enzymes hydrolysating non-starch polysaccharides and organic sources of microelements (zinc), may reduce the litter moisture as well as FPD incidence and severity in broiler chickens and turkey.

Distiller\'s dried grains with solubles (DDGS), a coproduct of the ethanol industry, are often used as feed material in livestock and poultry nutrition. Results of many experiments have indicated, however, that a high dietary level of DDGS can negatively affect the digestibility of nutrients and the performance of monogastric animals due to their high content of non-starch polysaccharides (NSP). Nevertheless, using high levels of DDGS as a protein source in livestock diets can be still economically justifiable in view of the rising prices of soya bean meal and other protein sources. The aim of some recent experiments with poultry and pigs was to improve the nutritional efficacy of high-NSP diets through the addition of feed enzymes. As presented and discussed in this review article, the efficacy of feed enzymes added to poultry and pig diets containing DDGS is not consistent and depends on many factors. However, NSP-hydrolysing enzymes generally seemed to be more efficient than phytases in terms of the digestibility of nutrients and the growth performance of poultry and pigs fed high-DDGS diets. For this reason, supplementation with NSP-hydrolysing enzymes could be an efficient way to enable the use of increased levels of DDGS in poultry and pig diets.