ASHLEY ENGLAND and ISABELLE RUHNKE
Worldwide, commercial laying hens are frequently being used for only one production cycle mainly due to a decline in egg quality and/or egg quantity at 70-80 weeks of age. Extending the production cycle of these hens by improving or maintaining their egg quality and laying persistency could lead to both economic and environmental benefits as well as a more sustainable egg industry. Laying performance of the modern-day laying hen is highly dependent upon the light source used during housing and artificial lighting programs have been used for years to control egg production. Birds are able to perceive coloured light (400-700 nm) as well as the ultraviolet part of the spectrum (100-400 nm) due to the presence of an extra retinal cone in the eye. Studies have shown that red light, due to its longer wavelength of 660 nm, is able to stimulate the hypothalamus and elicit a photosexual response in all animals including birds. This can result in increased egg production in comparison to green, blue or white light exposure, although responses may be variable depending on bird strain and the intensity of the light used. Ultraviolet light has a shorter wavelength (100-400 nm) than visible light (400-700 nm) and so its effects on egg production are likely to be weak to non-existent. The benefits of UV light are mediated through its ability to activate cholecalciferol from 7-dehydroxycholesterol in the skin resulting in improvements in egg shell quality. These improvements in shell quality are most likely to occur in birds that are exposed to (natural) day light, as UV light can compensate to some extent the lack of Vitamin D in poultry diets. This review highlights the variable effects of light of different wavelengths and intensity on laying hen production, egg quality and its potential to extend the end of lay in commercial hens.
F. NABI, M.A. ARAIN, F. HASSAN, M. UMAR, N. RAJPUT, M. ALAGAWANY, S.F. SYED, J. SOOMRO, F. SOOMRO and J. LIU
Selenium (Se) is an essential trace element with diverse physiological functions related to cellular homeostasis, body metabolism and antioxidant defence. Selenium is an integral constituent of at least 25 selenoproteins in the body that regulate cellular redox and antioxidant defence enzymes systems control free radicles of reactive oxygen species (ROS). Dietary Se plays key role in immunity, growth and fertility in chickens, which require optimum levels in their diets to maintain high reproductive and productive performance of birds. In the last decade, dietary supplementation with selenium nanoparticles (SeNPs) has enhanced the growth performance, feed conversion ratio (FCR), reproductive performance, egg production, immune response and antioxidant status, as well as improved the quality of meat and eggs and promoted microflora. Selenium has been shown to increase relative weights of immune related organs (burse and thymus) to enhance immunity. Feeding Se-NPs can improve antioxidant status and glutathione peroxidase (GSH-Px) activities in both broilers and layers. Use of Se-NPs at 0.9 mg/kg diet in broilers improved the intestinal health via increasing the population of beneficial bacteria and producing short chain fatty acids. This review focuses on the significance of selenium nanoparticles in poultry industry and provides insights about its comparative advantages over conventional sources of Se in poultry diets.
EVELIEN LAMBRECHT, LEONIE JACOBS, EVELYNE DELEZIE, HANS DE STEUR, XAVIER GELLYNCK and FRANK TUYTTENS
Day of hatch and pre-slaughter processing are stressful events (involving selection, handling and transport) for broiler chickens, putting pressure on welfare, which has economic consequences. This case-study documented common industry practices and evaluated poultry industry stakeholder perceptions related to broiler welfare during day-of-hatch processing and the pre-slaughter phase. Twenty-three individual in-depth interviews were conducted with representatives of key stakeholders in the Flemish poultry sector: hatchery personnel (5), farmers (6), poultry catchers (2), transporters (3), and slaughterhouse personnel (7). The findings showed various factors influencing broiler welfare during day of hatch processing and the pre-slaughter phase, with some discrepancies between stakeholder views and the scientific evidence. While stakeholders perceived the day of hatch processing procedures of chicks to be relatively under control, with no major issues, literature points out several issues, including first-week mortality and time without feed and water as major welfare problems. For broilers at slaughter age, the industry stakeholders’ views aligned well with scientific evidence on major welfare issues, such as injuries, thermal stress, mortality during fasting, catching, loading, transportation and lairage. This study provides novel insights in stakeholder perceptions, and potential avenues for future research and actions to reduce animal welfare problems in the poultry sector.
M. BOZKURT, I. GIANNENAS, M.ÇABUK and A.E.TÜZÜN
A large amount of existing evidence shows that the micro- and macrostructure of feed has a strong influence on the function, development and health of the gastrointestinal tract (GIT), which, in turn, affects the performance of poultry birds. Notably, the majority of data corresponding to feed structure-induced changes in the productivity of birds has been generated from studies using broiler chickens. However, feed particle size and feed form remain an obscure and undervalued area of study in the feeding of layer chickens, with sparse evidence reported between the 1940s and 2000s. Moreover, feed in the form of crumbles and pellets, which has made a major contribution to broiler production efficiency, has not been the feed of choice for layers, where mash diets have been common practice worldwide for many years. Nonetheless, the role of feed structure in the feeding of layer chickens has recently begun to attract more interest. However, results are divergent and often not as satisfactory as expected, except in the case of gizzard weight, which typically decreases by 8% and 16% on average with finely ground and pelleted feed, respectively. The results for most performance parameters, however, are typically insignificant. In some cases where the effect of the feed form was significant, pelleting increased feed consumption by 6%, whereas a clear 9% reduction was observed in another example. The incongruities in the results are likely due to confounding factors, such as management conditions and ingredient composition of the diets. Nevertheless, the effect of feed form on the investigated parameters was more evident than the effect of feed particle size. The following review provides an overview of data from seven decades regarding the implications of feed structure on the physiology, histology, metabolism and development of the gut and the performance of egg-laying chickens.
ANDREW WALES and ROBERT DAVIES
Commercial poultry hatcheries potentially provide a sanitary barrier between breeder flocks and their progeny. This is important, particularly within the pyramid breeding structures in integrated poultry production systems. However, the operation of hatcheries and their focal position connected with multiple flocks, both on the input and output sides, means that they are vulnerable to being reservoirs of infectious agents. Of particular concern for hatcheries is the pseudo-vertical transmission of bacteria that are initially deposited at the surface of forming or freshly-laid eggs. These bacteria (of which Salmonella enterica is a prime example) can subsequently be present in the chick, as well as spreading within the hatchery environment to colonise other hatching birds. Furthermore, if such infectious organisms become persistent in parts of the hatchery environment, this allows their repeated transfer to hatching individuals or even (via personnel and fomites) to transfer back into breeding flocks supplying the hatchery. The use of antimicrobial drugs in hatcheries adds the further hazard of seeding progeny with antimicrobial-resistant (AMR) organisms. The mechanisms of hatchery, egg and subsequent chick contamination have been understood, and strategies to counteract the spread and persistence of infectious agents are well-established. However, many studies examining bacterial pathogens and AMR organisms in poultry production implicate hatcheries, either as a link in a chain or as a source of such agents. This review outlines the challenges posed by hatchery operation to control of bacterial transmission, it examines the contemporary and historical evidence for such phenomena, and it briefly discusses strategies to counteract the issue.
S. GREENHALGH, P.V. CHRYSTAL, P.H. SELLE and S. Y. LIU
The justification for the chicken-meat industry to develop reduced-crude protein (CP) diets is compelling. Environment pollution by nitrogen and ammonia emissions can be improved, as a dietary reduction of 25 g/kg CP has been shown to generate a 25.8% reduction in N excretion. Bird welfare can be enhanced, as lower CP excretion improves litter quality and lessens incidence of foot-pad dermatitis and related conditions. Flock health can be improved by reductions in the flow of undigested protein into the hindgut which, in unchecked, fuels the proliferation of potential pathogens at a time when in-feed inclusions of antibiotics are in decline. Moreover, reduced-CP diets have the potential to lessen feed ingredient costs as prices of ‘synthetic’ amino acids are likely to decrease due to economies of scale in production. The successful development and adoption of reduced-crude protein (CP) diets may reduce the chicken-meat industry’s demand for sources of ‘intact’ protein, e.g. where soybean meal is dominant and in demand from many quarters. Using synthetic methionine, lysine and threonine in maize-soy diets been shown to lead to a substantial reduction in dietary CP from 356 to 200 g/kg, along with reductions in soybean meal from 709 to 293 g/kg feed. Reductions of 40% of soyabean use in feed have been postulated.
ANA MARQUIZA M. QUILICOT, ŽELJKO GOTTSTEIN, ESTELLA PRUKNER-RADOVČIĆ and DANIJELA HORVATEK TOMIĆ
The impact of Dermanyssus gallinae infestation on poultry health and production has driven the poultry industry to look for efficient control measures to be incorporated in integrated pest management (IPM). Attempts have been employed to control, if not, eliminate the infestation which includes application of chemicals, implementation of biological and/or physical measures, vaccination, or use of plant-derived products; or a combination of two or more of these measures. Chemical control, though efficient, has limitations such as the development of resistance in mite populations and safety issues concerning environmental residues and non-target organism toxicity. These limitations resulted in banning most of the previously applied synthetic acaricides; thus, attention has been directed to the potential of plant-derived products (PDPs). Among the PDPs reviewed, essential oils of bay, lime dis 5F, pimento berry, spearmint, cade, clove bud, penny royal, coriander, thyme, mustard, horseradish, sweet basil, peppermint and summer savoury results in up to 100% mortality by direct contact or fumigation. Whereas, garlic extract and essential oils of thyme, manuka, Eucalyptus citriodora and lavender produce mortality rates from 66-95.35% when applied directly or through spray. Three essential oils (penny royal, cinnamon bark and garlic) has ovicidal effect by direct contact. Other PDPs have the potential to reduce mite population and reproduction rates. This paper reviews PDPs on their efficacy, mode of action and effect on target organisms, advantages, and limitations. Recognizing the potentials and limitations of the different PDPs is important in formulating an effective product (combination of two or more PDPs) for the control of D. gallinae.
There is considerable interest in the development of reduced protein diets with supplemental amino acids (AA) for broiler chickens due to economic, environmental, health and bird welfare advantages. Lowering levels of protein, or using local sources, which may be more poorly digested or have an unbalanced AA profile, has implications for both animal performance and health. However, reduced protein diets may result in amino acid redistribution away from growth and production processes, toward intestinal cells involved in immune and inflammatory responses. Certain gut diseases are related to higher protein diets, and low protein formulations can reduce the risk of such problems. However, in low protein diets, a reduced or unbalanced supply of AA in the diet can be deleterious to the immune system. Therefore, an ideal dietary AA profile is crucial for broiler chicken gut health, especially in AGP free situations. All AA are in ratio to dietary Lys, and when Lys concentration is increased, both essential and non-essential AA concentrations need to be increased accordingly. Currently when dietary standardised ileal digestibility (SID) for Lys is 1.3%, the SID of total sulphur-containing AA (TSSA) may need to increase to 0.975%, Arg to 1.43%, Thr to 0.884%, Val to 1.04%, Ile to 0.884% and Phe to 0.845%. In wheat-soy based diets, reduced protein diets may lead to deficiencies in His and Ala, potentially affecting chicken gut health. Possibly the SID of His needs to increase to 0.53%. Some non-essential AA profiles need to increase, such as SID of Gly to 0.884%, Glu to 3.54% and Ala to 0.845%. Compared with DL-Methionine and DL-HMTBA, L-Met is the natural form of Met and its relative biological value (RBV) has remained controversial due to unsuitable statistical models and other limiting AA influence. Increasing AA levels in reduced protein diets has been shown to maintain growth and ensure less incidence of gut disorders.
A. AL-NASSER, H. AL-KHALAIFAH, F. KHALIL and H. AL-MANSOUR
In Kuwait, per capita consumption of poultry meat was 64.4 kg/cap/yr from 2004-2016. This indicates the high demand for poultry meat in Kuwait, which cannot be met by local production alone. The Kuwait Institute for Scientific Research (KISR) has conducted poultry research projects into high quality and added-value poultry products, which could be utilised to enhance competitiveness in Kuwait production systems. Their scientific achievements include developing broiler and layer feed rations, improving FCR of broilers from 2.0 to 1.4, production of high-quality broilers, strict biosecurity measures on farm and enhanced diversity of poultry products, such as meat and eggs from Arabi chickens, quails, and ducks. However, more work is needed in areas of poultry feed and added value product technology. In addition, technology transfer of KISR Intellectual property (IP) and knowledge to the poultry industry is necessary. The goal of this paper was to show the major achievements of KISR poultry research; identify gaps and propose solutions to improve production and enhance local industry competitiveness, in addition to conservation of the endangered avian species; Falcons and Houbara.
A.J.W. MENS, M.M. VAN KRIMPEN and R.P. KWAKKEL
Feather pecking (FP) by laying hens is a significant welfare issue in the poultry industry. Pecking at and pulling out feathers of conspecifics can seriously reduce the well-being of birds and cause economic losses for the farmer. Records of the prevalence of FP in laying hen flocks from the last 20 years show a prevalence of between 24-94%. Several research groups world-wide have hypothesised about the causes of feather pecking. From a nutritional point of view, re-directed behaviour and feather eating seem to be the most plausible causes. The gut microbiome seems to be involved in FP due to its influence on hormonal pathways and as it is influenced by the diet, which might include feathers ingested by the hens. Bird experiences during the rearing period are related to FP in later life by possible effects on the physiological development of the pullets. Most likely, pullets experience a sensitive period within the first few weeks post-hatch during which FP can develop due to various factors such as hormonal influences, nutrition and (the lack of) environmental enrichment. Nutrition could influence FP in two ways. Deficiencies or imbalances in certain nutrients, such as amino acids may have a direct effect on physiological mechanisms that trigger FP. Furthermore, ingredients such as roughages, fibres and non-nutritive ingredients may have an effect on exploratory and foraging or feeding behaviour. Literature (mainly in adult layers) shows that nutritional interventions increased eating time by 23-45% and/or the mean retention time of feed in the gut by 2.9-6.0 min/g fibre, and reduced or delayed FP behaviour. Using such nutritional strategies (i.e. provision of specific AA profiles and/or high fibrous ingredients) during the sensitive period during rearing could prevent ultimately the development of FP, by altering the pullets’ (gut) physiology and/or her time budget allocation. Research with a focus on critical periods during rearing should be initiated.
H. ÇAPAR AKYÜZ and E.E. ONBAŞILAR
The incidence of non-infectious skeletal disorders has been reported to increase over the past decade. Both genetic selection and rearing conditions cause skeletal disorders in the broilers. The rapid increase in broiler body weight, along with weakened, immature tissues, causes deformations by putting extra load on the skeletal system. Non-infectious skeletal disorders found in commercial broilers include articular gout, degenerative joint disease, dyschondroplasia, rickets, rotational-angular deformities, spondylopathies and ruptured gastrocnemius tendon. In broilers, bilateral abnormalities affect around 17% of the population, but the most common disorders are unilateral abnormalities in terms of leg disorders. Articular gout occurs, causing up to 40% mortality, and femoral degeneration incidence ranged between 81.67 and 85.00% in commercial broilers. The heritabilities were found for tibial dyschondroplasia ranged from 0.13 to 0.18 in different broiler breeds. Non-infectious skeletal disorders have led to significant welfare problems, including pain and high mortality rate in broilers and losses to the producer, influencing the production and quality. The most crucial point here is to optimise the welfare conditions of the poultry administration.
DEVVRAT KOSTI, D.S. DAHIYA, RAJESH DALAL, B.S. TEWATIA and KENNADY VIJAYALAKSHMY
In order to meet the high demand for eggs, poultry producers are using certain feed strategies which can increase production, but may indirectly cause metabolic and other stress in the birds. To overcome these issues, natural plant extracts and ingredients, such as turmeric, can be added to the diet. The inclusion of turmeric, which has various beneficial properties, at levels of 0.75% and 1% in the diets can improve feed intake and significantly reduce cholesterol in broilers. Cholesterol in eggs has been shown to decrease by 16, 24 and 25% (P<0.05) when layers were fed 1, 2 and 4% turmeric in feed, respectively. Birds fed a high carbohydrate ration and supplemented with turmeric powder for 30 days prior to sexual maturity had 20% more egg production as compared to a control group. Lactobacillus spp. counts were significantly higher (P<0.01) in chickens fed 1% turmeric supplemented feed compared to unsupplemented birds. Hence, this review includes the effect of feeding turmeric on feed intake, feed conversion ratio, nutrient digestibility, biochemical parameters, egg production, egg qualities, intestinal morphology, gut bacteria and the genetic expression of toll-like receptors.
MUHAMMAD ARFAN ZAMAN, RAO ZAHID ABBAS, WARDA QAMAR, MUHAMMAD FIAZ QAMAR, UZMA MEHREEN, ZOHAIB SHAHID and MUHAMMAD KAMRAN
In recent years, the roundworm Ascaridia galli has been found to be the most common poultry parasite, with 64.8% prevalence in flocks globally. It causes a 60% to 84% decrease in egg and meat production. Profitability is reduced without proper control of A. galli, and wide range of chemically synthetic anthelmintics are commonly used. Emergence of drug resistance in nematodes has made scientists search for effective replacements. Among the alternatives to anthelmintics, natural products can be used which are more environment, consumer and host friendly, due to lower or no toxic effects. Certain plants exhibit anthelmintic effects through secondary metabolites (SMB’s), such as terpenes (glycosides and saponins), phenolic compounds (flavonoids and tannins) and nitrogen containing compounds (alkaloids, cyanogenic glycosides and non-protein amino acids). Generally, SMB’s exhibit control of nematodes by causing starvation, damaging the external membrane, impairing fertility and growth rate and damaging musculature. In this review paper, the studies related to the screening of plants and their SMB’s activities (both in vivo and in vitro) are discussed. Some plants have efficacy more than 75% and comprehensive information about their taxonomy and dosage has been documented. Plants that have been found with intense efficacy against A. galli include Acanthus ilicifolius (100%), Cleome viscosa (100%), Osmium sanctum (100%), Murraya koenigii (100%), Sesbania grandiflora (90%), Citrus limon (87.5%), Polygonum hydropiper (83.3%), Swietenia macrophylla (76.6%) and Momordica charantia (75%). Important secondary metabolites include terpenoids (51.72%) followed by phenolic compounds (27.58%) and nitrogen-containing compounds (20.68%). Such plant-derived alternatives are almost 50% more cost effective than synthetic drugs.
A. PRAKASH, V.K. SAXENA, RAVI KUMAR GANDHAM, SIMMI TOMAR and M.K. SINGH
Understanding the expression of genes influencing low and high residual feed intake (RFI) is required to elucidate the basic molecular mechanism influencing feed efficiency. Molecular mechanisms affecting RFI are controlled by many factors, such as neural signals, hormones, mitochondrial efficiency, metabolic pathways, and nitrogen recycling. This review covers different aspects of molecular mechanisms affecting feed intake, growth and, oxidative stress affecting feed efficiency in broilers. Low RFI chickens maintain feed efficiency by reducing feed intake independent of body weight gain, by upregulating CD36, PPARa, HMGCS2 and GCG, and downregulating PCSK2, CALB1, SAT1 and SGK1. Hormones, like cholecystokinin and glucagon, act as an anorexigenic factor, whereas leptin induces feed intake. Various molecular pathways and metabolic signals, such as the central melanocortin system, AMPK pathway, mammalian target of rapamycin (mTOR) pathway and PI3K/Akt pathway control feed intake by determining the energy status of the body. A major cause of low feed efficiency in broilers is due to the reactive oxygen species-mediated oxidation of protein. Genes related to the ubiquitin-proteasome system such as DERL1, UFD1L, and UFM1 are down-regulated in highly feed efficient broilers. In addition, the expression patterns of the genes involved in mitochondrial energy production, such as avANT, COX III, avUCP, iNOS, PPAR2 and avPGC-1a, have been changed, and these can be a marker for selection against lower RFI in chickens.