Multiple stressors can affect the functioning of body cells, therefore performance and economic profitability of breeder chickens during their production cycle. As opposed to the early laying phase where the intrinsic antioxidant capacity is usually sufficient, birds during Phase 2 of lay do suffer from excessive stress. Their oxidative challenge leads to a reduced production-, fertile fraction- and hatchability of hatching eggs. Consequently, for an optimal performance these breeders can truly benefit from tools such as bioactive antioxidants added sufficiently to their diet.
Global Product Manager Antioxidants
Impextraco – Belgium
OXIDATIVE STRESS, AN IMPORTANT METABOLIC CHALLENGE
Oxidative stress is a major and still underestimated issue in breeder production leading to significant egg performance- and reproductive losses. It can be caused by multiple factors such as
• aging
• climatic stress, e.g. heat stress
• animal stocking density
• vaccinations
• pathogenic pressure (low hygiene)
• antibiotic treatments
• animal handling
• feed quality and -transitioning
• ventilation and lighting
• induced molting
High metabolic activity, linked to intensive production systems, also represents a key predisposing factor. When too many of these stressors impact the bird, they create an imbalance between the formation of unstable oxidants (i.e. free radicals) and the biological capacity of body cells to detoxify them. Thus, during such challenging conditions, the bird fails to produce sufficient endogenous antioxidants itself. Such an oxidative pressure causes damage to biological constituents of all body cells (incl. lipids, DNA, proteins) and leads to tissue injury. Especially in heavyweight Phase-2 broiler breeders, such oxidative stress occurs and results in a suboptimal functioning of vital organs (e.g. intestines, liver, bones and the sensitive reproductive tract) as well as in an increased disease susceptibility. Economically, this affects laying performance, egg fertility, hatchability (incl. egg quality/embryonic development) and day-old chick quality. To avoid this common state of oxidative stress, aging breeders are in need of bioactive antioxidants provided sufficiently to their diet. Bioavailable and potent polyphenols, for instance, are such highly protective compounds and of plant origin.
KEY CRITERIA FOR BIOACTIVE DIETARY ANTIOXIDANTS
Truly preventing a body state of oxidative stress requires extra dietary supplementation of in vivo antioxidants. Certain vitamins (E, C or A), carotenoids and selenium are commonly used antioxidants in feed. However, for various reasons (incl. cost-effectiveness and toxicity) they are not the most ideal type to fully prevent an increased negative impact of cellular oxidation on the aging animal. Distinct classes of polyphenols, originating from specific botanical sources, however, have proven to be powerful and versatile antioxidant solutions. Of course, not all polyphenolic types are as suitable or efficient in mitigating the stress level in the bird. For polyphenols to be truly impactful antioxidants within the body, they require particular characteristics. Firstly, they should have a moderate chain length or molecular weight to guarantee a sufficient gut absorption (i.e. for exerting a systemic effect). Secondly, an adequate water solubility is of utmost importance to also provide intra-cellular protection of key biological structures. Moreover, a low redox potential is a crucial chemical property also for polyphenols to easily neutralize free radicals. It refers to the tendency to donate an electron to different oxidizing agents. Multiple polyphenols show a lower reduction potential and thus higher antioxidant activity than Vit. E, and some specific types even outperform Vit. C. This property also enables polyphenols to regenerate antioxidative vitamins when these are in their used form.
Overall, selected polyphenols should dispose of multiple antioxidant mechanisms such as a:
1. broad-spectrum neutralization of different radical types (i.e. scavenging power),
2. significant recycling of oxidized in vivo antioxidants (i.e. regenerating power),
3. active stimulation of the endogenous antioxidant system (i.e. upregulating power)
Dietary polyphenols of such specific nature will prevent oxidative damage to a significant level in breeders. This includes reducing inflammation of the intestinal epithelium to safeguard nutrient absorption and a sufficient barrier against invading pathogens. After gut absorption, they will also help minimize inflammatory processes within the radical-challenged reproductive tract. As such, these polyphenols secure rooster semen quality as well as ovarian follicle quality in the breeder hen for a successful egg fertilisation. But also during the subsequent egg incubation, accumulated polyphenols in ovo help improve the antioxidant status of hatching eggs, thereby supporting optimal embryo growth. Because they effectively recycle and spare Vit. E as potent in vivo antioxidants, such polyphenols also help preserve a high level of transferred Vit. E from the maternal diet to the yolk sac (which is retracted into the embryo’s abdominal cavity by the time of hatching). This built up reserve is of high nutritional importance as newborn chicks during their first week(s) of life show great difficulties to assimilate Vit. E from their diet.
Next to reducing disease susceptibility and fertility issues, such phytogenic bioactives will also allow a higher integrity (i.e. less oxidative damage) of systemic body cells in general and thus save metabolic resources. By doing so, much more nutrients will become available for egg production and will not be redirected or lost to the repair of injured cells for body maintenance (i.e. homeostasis). Therefore, under stressful field conditions, these polyphenolic types will contribute to keeping the bird’s metabolism in a balanced state by efficiently closing the ‘antioxidant gap’. Given the reduced endogenous antioxidant capacity of breeders as they age, this particularly will be the case during the critical Phase 2 of lay (highest sensitivity to oxidative stress).
INCREASED EGG LAYING PERSISTENCY
In this article, an interesting broiler breeder trial is described. ELIFE®, a synergistic and concentrated blend of carefully selected natural extracts – fully complying with above polyphenolic criteria -, was evaluated as a possible dietary antioxidant solution. Two identical laying houses each containing ± 20,000 hens (and ± 2,000 roosters) of Ross 308 genetics were selected in a commercial farm setting (Belgium, 2023). Each house represented 1 treatment group (i.e. Control or ELIFE® on-top supplementation at 1 kg/t), therefore no statistical replicates were available. Both houses had an equal average hen body weight, egg laying- and mortality rate at the start of the supplementation trial (i.e. week 26 of life). During the supplementation trial, all birds had restricted access to both water and commercial mash feed (i.e. wheat-maize-soy based diet) and received 13 hours of lighting per day.
During Phase 1 of lay (up to 44 weeks), hen-week egg production (%) was similar for both groups, however, during Phase 2 of lay (week 45 till 62 of life) it was consistently higher for the antioxidant treated flock compared to the control (Figure 1). On average, the ELIFE® supplementation during this later period elevated laying rate substantially by 1.5 percentage points (Table 1). Therefore, the phytogenic blend increased laying persistency of the breeder hens while aging (i.e. extending their productivity).
Both treatment groups showed an equally low hen mortality at housing of the birds (into the laying unit) up to the onset of the antioxidant supplementation (i.e. week 20 till 26 of life). However, throughout the subsequent trial period (37 weeks long), the ELIFE® group demonstrated a consistently higher hen survival (Figure 2). At the end of production, this treated flock had a cumulative 20–62-week mortality rate of only 5.5% vs. 6.1% for control (Table 1).
BENEFITS UP TO THE HATCHERY LEVEL
Next to egg production, also fertility rate (i.e. via automatic candling at incubation day 18 in the hatchery) of the hatching eggs collected during Phase 2 of lay was higher for the antioxidant treated group (Figure 3). On average, ELIFE® dietary supplementation during this later period increased the fraction of fertile and viable eggs by 1.7 percentage points (Table 1). In line with fertility, also hatchability of the eggs derived from this production phase was higher for the antioxidant supplemented breeders (Figure 4). During this critical end period, ELIFE® on-top addition to the parent stock’s diet raised the hatching rate by more than 2 percentage points on average (Table 1). Nevertheless, all fertility and hatching results were originally similar for both groups at the onset of the supplementation.
Additionally, the fraction of fertile hatching eggs (from this 2nd laying phase) from which embryos successfully hatched was 0.6 percentage points higher for the antioxidant treated group (despite being already very high for the control). In other words, this indicated a better ‘fertile hatchability’ for the ELIFE® supplemented group (Table 1). Therefore, next to the degree of fertile and viable hatching eggs (detected on incubation day 18), also embryonic strength/quality seemed favored as from week 45 of life when adding the phytogenic blend to the parental diet.
3 EXTRA DAY-OLD CHICKS (DOC)
As a summary of the commercial broiler breeder trial, the above overview in Table 1 shows the average value of all relevant parameters during Phase 2 of lay (week 45 till 62 of life) for each treatment group. As depicted, during this 2nd half of production the dietary supplementation of 1 kg/t ELIFE® bioactive antioxidant created relevant improvements from an economic point of view. Combining all its effects on both laying persistency (hen-week), egg fertility and hatchability rate, it was calculated (cumulatively per week) that about 3.4 extra DOC’s were produced per hen over these last 18 weeks of the laying cycle. Overall, this final outcome equated to an interesting return-on-investment of more than 5:1 for the integrated hatchery in question.
CONCLUSIONS
The body tissues of adult breeders, especially the digestive and reproductive organs, are considerably affected under conditions of oxidative stress. This state is induced by many factors including aging, heat stress or a high metabolic rate and -stocking density. It creates oxidative cell damage and several metabolic losses throughout the bird’s body, of which the above-mentioned sensitive tracts. Therefore, oxidative stress leads to a suboptimal egg performance for farms, but also an impaired egg fertility and hatching rate for hatcheries. However, in a recent commercial field trial, it was demonstrated that treating the diet of productive broiler breeders with 1 kg/t ELIFE® natural antioxidant increases laying persistency drastically during Phase 2 of lay (i.e. week 45 till 62 of life). Also during this later phase, dietary supplementation with this multi-botanical blend of selected polyphenols resulted in a higher hen survival, egg fertility and total hatchability rate compared to the control. Fertile hatchability was increased here as well, suggesting the bioactive antioxidant also supported hatching egg antioxidant status and embryonic strength/vitality. Combining all these effects, the ELIFE® treatment yielded more than 3 extra DOC’s per breeder hen over the last 18 weeks of production. By doing so, it has shown the potential to create interesting economic benefits for both commercial parent stock farms and (integrated) hatcheries.
References are available upon request via [email protected]
About Steven Beckers
Steven Beckers is a monogastric nutritionist with a Master’s degree in Applied Bio-Sciences Engineering from the University of Leuven (Belgium). Since 2019, Beckers is a Global Product Manager of multiple specialty feed additives at Impextraco. Here he provides technical support to customers and end users, to help establish innovative concepts in different agricultural markets. He is devoted to maximizing animal health and performance, by correctly advising and optimizing the application of value-added products.
