Early-age thermal manipulation and supplemental antioxidants on physiological, biochemical and productive performance of broiler chickens in hot-tropical environments.

Heat stress has been ranked as a critical environmental issue confronting chicken farmers worldwide because of its detrimental effect on the growth, performance and health of the birds. This study evaluated the effects of early-age thermal manipulation (EATC) and supplemental antioxidants on the physiological responses of broilers in a hot tropical environment. A total of 300 day-old Ross broiler chicks were allocated to five thermal and dietary treatments, having 5 replicates of twelve birds each. The treatments were: chicks reared using the conventional method (CC), chicks exposed to early thermal manipulation with a temperature of 38 °C at day 5 with no antioxidant supplementation (TC), TC plus vitamin E at 250 mg/kg of feed (TV), TC plus selenium at 0.5 mg/kg of feed (TS) and the combination of TS and TV(TVS). The experiment was laid out in a Completely Randomized Design and data collected were analyzed using SAS (2008). The results showed that TVS broilers had significantly higher (P < 0.05) body weights at the finisher phase than the other treatment groups. The feed conversion ratio of TVS broilers was comparable to the TV group but lower (P < 0.05) than the other treatments. Reduced levels (P < 0.05) of heterophil, lymphocytes and hetrophil and lymphocyte ratio were recorded in the TVS compared to TV, TS and TC broilers. On day 42, the rectal temperature was significantly higher in CC than those in other treatment groups, which were comparable. TVS birds had higher (P < 0.05) weights of spleen, liver and lower abdominal fat than other treatments. The lowest concentration of plasma malondialdehyde and the highest activity of superoxide dismutase and glutathione peroxidase were recorded in TV and TVS birds. The study concluded that the growth performance and oxidative status in broilers were improved by the combination of EATC with supplemental Se and vitamin E (TVS).

Climate change and broiler production.

Climate change has emerged as a significant occurrence that adversely affects broiler production, especially in tropical climates. Broiler chickens, bred for rapid growth and high meat production, rely heavily on optimal environmental conditions to achieve their genetic potential. However, climate change disrupts these conditions and poses numerous challenges for broiler production. One of the primary impacts of climate change on broiler production is the decreased ability of birds to attain their genetic potential for faster growth. Broilers are bred to possess specific genetic traits that enable them to grow rapidly and efficiently convert feed into meat. However, in tropical climates affected by climate change, the consequent rise in daily temperatures, increased humidity and altered precipitation patterns create an unfavourable environment for broilers. These conditions impede their growth and development, preventing them from reaching their maximum genetic influence, which is crucial for achieving desirable production outcomes. Furthermore, climate change exacerbates the existing challenges faced by broiler production systems. Higher feed costs impact the industry's economic viability and limit the availability of quality nutrition for the birds, further hampering their growth potential. In addition to feed scarcity, climate change also predisposes broiler chickens to thermal stress. This review collates existing information on climate change and its impact on broiler production, including nutrition, immune function, health and disease susceptibility. It also summarizes the challenges of broiler production under hot and humid climate conditions with different approaches to ameliorating the effects of harsh climatic conditions in poultry.

The role of phytogenic feed additives in stress mitigation in broiler chickens.

The increase in global temperature and consumers' welfare has increased the use of phytogenic feed additives (PFA) to mitigate the negative effects of heat stress on chickens in recent years. Various bioactive compounds capable of improving the thermotolerance of broiler chickens during exposure to thermal challenges have been identified in different plant species and parts. This review is an overview of the roles of bioactive compounds of different PFA, such as polyphenols and flavonoids, antioxidants, growth-promoting and immune-modulating agents, in heat stress management in broiler chickens. Common PFA in use, particularly in tropical environments, are also discussed. An understanding of the roles of the PFA in chickens' thermotolerance could further stimulate interest in their use, thereby improving the birds' productivity and addressing consumers' concerns. This review collates the existing data on the roles of herbs in mitigating heat stress on chickens and highlights future research perspectives.

Alleviating heat stress effects in poultry: updates on methods and mechanisms of actions.

Heat stress is a threat that can lead to significant financial losses in the production of poultry in the world's tropical and arid regions. The degree of heat stress (mild, moderate, severe) experienced by poultry depends mainly on thermal radiation, humidity, the animal's thermoregulatory ability, metabolic rate, age, intensity, and duration of the heat stress. Contemporary commercial broiler chickens have a rapid metabolism, which makes them produce higher heat and be prone to heat stress. The negative effect of heat stress on poultry birds' physiology, health, production, welfare, and behaviors are reviewed in detail in this work. The appropriate mitigation strategies for heat stress in poultry are equally explored in this review. Interestingly, each of these strategies finds its applicability at different stages of a poultry's lifecycle. For instance, gene mapping prior to breeding and genetic selection during breeding are promising tools for developing heat-resistant breeds. Thermal conditioning during embryonic development or early life enhances the ability of birds to tolerate heat during their adult life. Nutritional management such as dietary manipulations, nighttime feeding, and wet feeding often, applied with timely and effective correction of environmental conditions have been proven to ameliorate the effect of heat stress in chicks and adult birds. As long as the climatic crises persist, heat stress may continue to require considerable attention; thus, it is imperative to explore the current happenings and pay attention to the future trajectory of heat stress effects on poultry production.

Potential Implication of in ovo Feeding of Phytogenics in Poultry Production.

Hatchery's goals include maximizing revenue by achieving high hatchability with day-old birds of excellent quality. The advancement of technology has benefited the poultry sector since breeding and genetics technology have increased the rates of meat maturation in developing birds in a short period of time. Excessive use of in-feed antibiotics has been shown in studies to increase the chance of resistance to human infections. Bacterial resistance and antibiotic residues in animal products raised concerns about using antibiotics as growth promoters, eventually leading to a prohibition on using in-feed antibiotics in most industrialized nations. In ovo technology is a novel method for delivering bioactive chemicals to developing avian embryos. In ovo feeding technologies may provide additional nutrients to the embryos before hatching. The introduction of bioactive compounds has the potential to assist in decreasing and eventually eliminating the problems associated with traditional antibiotic delivery in chicken production. Phytobiotics were advocated as an alternative by researchers and dietitians. So far, several studies have been conducted on the use of phytogenic feed additives in poultry and swine feeding. They have primarily demonstrated that phytobiotics possess antibacterial, antioxidant, anti-inflammatory, and growth-stimulating properties. The antioxidant effect of phytobiotics can improve the stability of animal feed and increase the quality and storage duration of animal products. In general, the existing documentation indicates that phytobiotics improve poultry performance. To effectively and efficiently use the in ovo technique in poultry production and advance research in this area, it is important to have a thorough understanding of its potential as a means of nutrient delivery during the critical stage of incubation, its effects on hatching events and posthatch performance, and the challenges associated with its use. Overall, this review suggests that in ovo feeding of phytobiotics has the potential to improve the antioxidant status and performance of chickens.

In ovo injection of cinnamon or clove alters the physiology and growth of broilers in a hot tropical environment.

A study was conducted to evaluate the influence of in ovo feeding of clove and cinnamon on broilers. The experiment used 700 broiler (Ross 308) hatching eggs that were incubated at the recommended temperature of 37.8 °C. On day 17.5 of incubation, 100 eggs were randomly assigned to each of the following seven treatments: uninjected eggs (OE), eggs injected 0.5 mL distilled water (DH), 2 mg of clove, 4 mg of clove, 2 mg of cinnamon, 4 mg of cinnamon, and 3 mg of ascorbic acid (AC). During the posthatch period, the chicks were raised for 56 days. Data on physiological parameters, growth performance, and intestinal histomorphology were collected. Results revealed that the plasma triiodothyronine (T3) of AC and CV2 chicken was higher than the others. Additionally, the plasma malondialdehyde levels of the chickens of AC, CV2, and CM2 were improved significantly (P < 0.05). The initial weights of CV2 birds were comparable with AC CV4, CM4, and CM2 birds but heavier than those of OE and DW. The bodyweight gain in the CV2 group was similar to AC, CV4, and CM2 groups but heavier than OE, DW, and CM4 birds. Feed intake of OE and DW groups was similar to AC, CV2, CV4, and CM2 but higher than CM4. The feed conversion ratio of OE and DW chickens was comparable but higher than the value obtained in chickens of other treatments. The intestinal morphology of the birds did not follow a particular trend. The study concluded that the in ovo injection of 2 mg of clove improved broiler birds' metabolic and antioxidant status at hatch. The high and low doses of clove and the low dose of cinnamon improved the performance of broiler chickens at the market age in a hot tropical environment.

Global trends and research frontiers on heat stress in poultry from 2000 to 2021: A bibliometric analysis.

Background: Heat stress remains a major environmental factor affecting poultry production. With growing concerns surrounding climate change and its antecedent of global warming, research on heat stress in poultry has gradually gained increased attention. Therefore, this study aimed to examine the current status, identify the research frontiers, and highlight the research trends on heat stress in poultry research using bibliometric analysis. Methods: The literature search was performed on the Web of Science Core Collection database for documents published from 2000 to 2021. The documents retrieved were analyzed for their publication counts, countries, institutions, keywords, sources, funding, and citation records using the bibliometric app on R software. Network analysis for co-authorship, co-occurrence, citation, co-citation, and bibliographic coupling was visualized using the VOSviewer software. Results: A total of 468 publications were retrieved, and over the past two decades, there was a gradual increase in the annual number of publications (average growth rate: 4.56%). China had the highest contribution with respect to the number of publications, top contributing authors, collaborations, funding agencies, and institutions. Nanjing Agricultural University, China was the most prolific institution. Kazim Sahin from Firat University, Turkey contributed the highest number of publications and citations to heat stress in poultry research, and Poultry Science was the most productive and the most cited journal. The top 10 globally cited documents mainly focused on the effects of heat stress, alleviation of heat stress, and the association between heat stress and oxidative stress in poultry. All keywords were grouped into six clusters which included studies on "growth performance", "intestinal morphology", "heat stress", "immune response", "meat quality", and "oxidative stress" as current research hotspots. In addition, topics such as; "antioxidants", "microflora", "intestinal barrier", "rna-seq", "animal welfare", "gene expression", "probiotics", "feed restriction", and "inflammatory pathways" were identified for future research attention. Conclusion: This bibliometric study provides a detailed and comprehensive analysis of the global research trends on heat stress in poultry over the last two decades, and it is expected to serve as a useful reference for potential research that will help address the impacts of heat stress on poultry production globally.

Evaluation of Light Color Manipulation on Behavior and Welfare of Broiler Chickens.

This experiment evaluated the effect of light manipulation on the behavior and welfare of broilers using 280-day-old Arbor-Acre chicks, which were weighed and assigned to 7 treatments having 4 replicates and 10 birds per replicate. The light treatments were as follows: white light (WH), blue light (BL), green (GR), blue light switched to green light at 14 days (2BG), green light switched to blue at 14 days (2GB), blue light switched to green light at 28 days (4BG), and green light switched to blue light at 28 days (4GB). Feeding, drinking, resting, standing, walking, foraging and preening behaviors were observed using the scan sampling method. Behavior and welfare parameters such as footpad dermatitis and hock burn were evaluated and analyzed in a Completely Randomized Design. The results showed that feeding behavior of birds of BL, 2BG, and 2GB treatment groups was significantly higher (P < 0.05) than those of WH and GR at the starter phase. At the finisher phase, resting behavior of birds of 4GB was similar to those of 2GB but higher than those of the other treatments. It was concluded that switching of light from green to blue (4GB) at four weeks of age fostered ideal behavior and stimulated growth in broilers but had no effect on welfare parameters.

Hepatoprotective Effects of Vernonia amygdalina (Astereaceae) Extract on CCl4-Induced Liver Injury in Broiler Chickens.

The aim of this study was to evaluate the effect of Vernonia amygdalina leaf extract (VALE) on the carbon tetrachloride-induced hepatotoxicity (CCl4) in broiler chickens. A total of 360-day-old broilers were divided into 4 treatments of 90 birds each consisting of 6 replicates of 15 birds each. The treatments were birds offered 1 mL/kg BW saline (control group), 100 mg/kg BW VALE, 1 mL/kg BW CCl4 (CCl4-treated group), and 100 mg/kg BW VALE + 1 mL/kg BW CCl4 (VALE + CCl4 group). Blood samples were collected at 42 days of age and analyzed for the liver enzymes: alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and selected biochemical parameters. The experiment was laid out in a completely randomized design. The results obtained showed that VALE had the potential to mitigate the adverse effects of CCl4 on protein and lipid metabolism as reflected in the low serum malondialdehyde (MDA) levels, which is a marker of lipid peroxidation. The aqueous extract of Vernonia amygdalina (VA) at a dose of 100 mg/kg body weight showed a moderate hepatoprotective effect by reducing serum AST levels (p < 0.05). The levels of serum AST, ALP, ALT, and GGT were significantly increased in CCl4-treated birds compared to the control group, reflecting carbon tetrachloride-induced liver damage. The VALE + CCl4 group showed a significantly higher amount of ALP compared to birds treated with carbon tetrachloride, suggesting a hepatoprotective effect. To conclude, Vernonia amygdalina aqueous extract can be used to confer protection against hepatotoxicity, which can induce severe hepatocellular damage in birds.

Evaluation of access to different legume pastures on performance and welfare of broiler chickens during dry season under tropical environment.

There have been a plethora of studies on the effects of access to runs on chickens' welfare and behavioural repertoire with a paucity of information on the comparative advantage of various legume pasture and deep litter system. A total of 200-day-old unsexed Marshall Broiler chicks were weighed and assigned randomly into five experimental groups, viz. deep litter without access to run (DL), deep litter with access to Stylosanthes hamata (SH), Stylosanthes guanensis (SG), Mucuna pruriens (MP) and free run (FR) during dry season. Each treatment had 4 replicates of 10 birds. Data were collected on growth performance, behaviour, tonic immobility (TI), gait score and blood parameters. The data obtained were subjected to One-Way Analysis of Variance in a Completely Randomized Design. Results showed that the final body weight of birds in SH was significantly higher (p Ë‚ .05) than those of SH, MP, FR and DL which were comparable. The feed intake of the birds of DL, SH and FR was higher than those of the other treatment groups. The feed conversion ratio (FCR) of the birds on legume pastures was lower than those without access to pasture. The birds of SH, SG and MP spent higher (p Ë‚ .05) time drinking, preening, dust-bathing, spot pecking and walking standing behaviours while those in DL and FR spent more (p Ë‚ .05) time feeding. Generally, the gait score of the birds on the different legume pastures was similar but better than those without access to pasture. Tonic immobility of the DL birds was longer than that of FR whose duration was longer than those of the birds on the pastures. The study concluded that access to different legume pastures, particularly Stylosanthes hamata, improved the welfare of broiler chickens without adverse effect on the performance of the birds.

Broiler production challenges in the tropics: A review.

Under tropical climate, broiler production is encumbered by several constraints which make it difficult for them to attain their genetic potential. The scarcity and high price of poultry feed and veterinary services and the harsh environmental conditions with respect to thermal stress are some of the challenges that hinder optimal growth of the birds. Limited availability of feedstuffs, including crucial feed ingredients like maize and oil seedcakes, is an important challenge to the sector, since feed still represents a major cost of producing broiler chickens. Additionally, the problem of climate change, which has become a global concern, is the main problem in broiler production under hot and humid climate. Under high ambient temperature, feed intake decreases, carbohydrates metabolism and protein synthesis efficiency are disturbed. Lipid utilization is lower and glucose or insulin homeostasis is altered while fat deposition and oxidative stress increases. Several strategies are used to ameliorate the effect of heat stress in poultry. The objective of this review was to summarize the challenge in broiler production under hot and humid climate and different approaches to fight heat stress in poultry.