Nutritional Interventions to Improve Fertility in Male Broiler Breeders
Infertility is becoming a common problem in broiler breeder production. Data published in March 2025 in the Journal of Poultry Science by a research team led by Dr. Giridhar Athrey from Texas A&M University indicated that hatchability of broiler breeders has been rapidly decreasing in the United States over the past decade.
This group used data from the USDA National Agricultural Statistics Service from 2013 to 2022, estimating that hatchability rates could decrease to approximately 60% by 2050 if no corrective actions are taken.
This alarming value underscores a crucial factor that can significantly impact the productivity of the broiler industry.
These authors concluded that infertility is the leading cause of reduced hatchability, but their data do not support this conclusion, as they did not include embryo diagnosis data.
Egg management, and other incubation factors, together with egg contamination, are also significant contributors to hatchery losses.
However, we can make a similar prediction about hatchability using data from AgriStats, which we published in AviNews International in March 2024 (Figure 1).
AgriStats is the largest benchmarking company in the United States and may have more updated and complete data. Presently, Agristats data does not include reports of fertility. However, multiple scattered reports from poultry veterinarians and broiler breeder managers indicate that infertility is also on the rise.
Figure 1. Average hatchability of the broiler US industry between 2012 and 2022 according to hatchery egg set capacity from 650,000 to 1.5 million eggs per week. Source: AgriStats (Fort Wayne, IN).
Fertility can be affected by both males and females; however, generally, each male is responsible for fertilizing around 1,000 to 1,800 eggs or more in commercial flocks. Stressors, mycotoxicosis, toxicosis, and aging can impair male reproductive capacity, including fertilizing ability.
Roosters aged over 40 to 45 weeks tend to exhibit:
- Testicular regression
- Reductions in testosterone levels
- Sexual behavior
- Semen volume
- Sperm concentration
- Viability
- Forward mobility,
- and levels of polyunsaturated fatty acids, particularly omega-3, as well as type of proteins in the seminal fluid, antioxidant levels, and increase lipid peroxidation.
Management practices like spiking and intra-spiking are generally effective strategies for maintaining fertility in aged broiler breeder flocks. However, spiking raises concerns about biosecurity and variation in progeny size when younger males are used.
The detrimental effects of aging in roosters can be mitigated by closely monitoring nutrient levels, feeding practices, and the use of feed additives.
Male diets vs. female diets
The decision to establish specific diets for males, particularly during the egg production phase, is a topic of frequent debate in the rearing of broiler breeder males. This is because the amino acid and calcium requirements of roosters are lower than those of hens.
There are nutrient recommendations from genetic companies for male diets that contribute to managing body weight and body composition.
However, in practice, many breeder flocks receive only female diets due to a lack of additional feed bins, automatic feeder settings, and a lack of personnel to manage two diets.
Despite this issue, fertility in those flocks ingesting only female diets is not always worse than that of those flocks that use male diets.
In many farms, insufficient control in feeding each diet separately can make it challenging to determine which option is better, as males also may consume some female feed.
In all breeder flocks, there is variability in the response of roosters to each diet type. For example, considering only the calcium level, it is known that in chickens, calcium plays a primary role in determining sperm motility.
Excessive calcium uptake by spermatozoa can lead to mitochondrial degeneration, a condition observed in roosters with low sperm motility.
Recent proteomic studies observed that some roosters express proteins in the seminal fluid that may regulate calcium uptake by spermatozoa, thereby minimizing this issue.
Then, this genetic variability may explain why not all males ingesting female diets with calcium levels three to four times higher than those in male diets can still exhibit good reproductive performance. In contrast, other roosters may be negatively affected by high dietary calcium levels.
Adaptations of seminal fluid can modulate the dietary excess of nutrients. Nevertheless, aging affects the regulatory capacity of seminal fluid, which may impact fertility. Consequently, male-specific diets may always have a value.
PUFAs and Dietary Antioxidants in Fertility
A common agreement is that aging causes a reduction in the antioxidant capacity of the reproductive organs of roosters. The sperm plasma membrane of roosters has high concentrations of polyunsaturated fatty acids (PUFAs), especially docosatetraenoic acid (22:4n-6), which is highly susceptible to peroxidation.
The concentrations of this PUFA in sperm plasma membranes is four to five times higher in roosters than in sperm of mammalian males.
Consequently, increasing omega-3 PUFAs and antioxidant capacity with higher dietary intake of feed additives that have this property has been a strategy to maintain fertility in aging roosters.
The supplementation of omega-3 PUFAs with fish oils like:
- 4% salmon
- 3% tuna
- 2% menhaden,
- 2 to 6% linseed (flaxseed) oil
have improved fertility in roosters of different genetic lines. These effects could be due to higher levels of eicosapentaenoic (EPA; C20:5 n3) and docosahexaenoic (DHA, C22:6 n-3), improved energy production by the activation of beta-oxidation in the spermatozoa that increases their forward-motility, and enhanced testosterone synthesis by the testicular Leydig cells, semen volume, sperm viability, and total sperm count.
However, there are differences in the responses to the inclusion levels of these oils in rooster fertility because avian species and poultry genetic lines differ in their fatty acid desaturation and elongation processes, and consequently, in the generation of EPA and DHA.
To improve broiler breeder male fertility, several antioxidants have been employed. Vitamin E deficiency has been shown to impact the fertility of avian males negatively.
However, various studies have yielded conflicting results regarding the additive effects of vitamin E and ascorbic acid on male fertility.
For example, dietary supplementation with low doses of vitamins C and E did not show any impact on spermatozoal quality; however, high amounts (300 mg/kg vitamin C and 150-200 mg/kg vitamin E) of these vitamins decreased the number of spermatozoa per milligram of epididymis. They increased the percentage of spermatozoa with misshapen heads.
In contrast, positive results have been obtained by supplementing with another antioxidant, such as trimethylglycine, also known as betaine, at a dose of 1,000 mg/kg.
In older roosters, 300 mg CoQ10/kg of feed increased sperm production, motility, membrane integrity, and fertility percentage due to enhanced seminiferous tubule diameter, germinal cell layer thickness, and seminal antioxidant status.
In testes, from Selenium-deficient roosters and toms, fewer Sertoli cells and hierarchies of spermatogonia were committed to spermatid formation than those fed Selenium (0.3 mg of Se/kg).
Furthermore, Leydig cell formations appeared to be less developed in the basal-fed birds, which negatively affected testosterone production and secretion, as well as ejaculate volume and spermatozoal concentrations.
The Selenium-methionine and other sources of selenium (sodium selenite Na2SeO3 or nanoSe) are beneficial in semen quality and testis development for older (>55 weeks old) roosters or under injection of dexamethasone, heat stress, and cadmium intoxication, but not always mitigates infertility and on occasions, high doses (>0.4 mg/kg) be detrimental in some experiments.
Related to other trace minerals, Zinc (Zn) supplementation has been one of the most investigated for male broiler breeders. Organic Zn supplementation (100-110 mg Zn/kg diet) increased gonadal maturation, enhanced IGF and testosterone, testicular histology, improved semen quality, morphology, and motility, and consequently fertility
Phytochemical Antioxidants
Research studies have demonstrated the positive antioxidant effects of several phytochemicals in improving semen traits, testosterone, and fertility in roosters, toms, and quails. The supplements evaluated with positive results include:
– curcumin from turmeric (Curcuma longa) at 0.8 mg/kg diet or 30 mg curcumin/rooster/d
-gingerol and gingerdione from ginger (Zingiber officinale) at 15 g of ginger root powder/kg diet or 100 μL of ginger essential oil/kg BW.
– lycopene from tomatoes and fruits at 5 g/L or 0.05 mg/mL of drinking water,
– 6 mg of canthaxanthin/kg diet,
– 100 mg/kg of astaxanthin
– 50 mg of chrysin (5,7-dihydroxyflavone a flavonoid and polyphenol) per day,
– 5 mg of soybean isoflavones per kg of diet,
– rosemary leaves at 5 g/kg diet,
– 0.25 mg of cinnamon bark oil/kg diet, and
– 20% inclusion of dried apple pomace.
– 120 mg/bird of alpha-lipoic acid
– Rooibos (Aspalathus linearis) at 3%.
– Black seed (Nigella sativa) or black cumin at 1.0%.
Functional amino acids
The supplementation of L-arginine, endogenous amino acids, or metabolites such as D-aspartic acid, L-carnitine, and guanidinoacetic acid (GAA) has been demonstrated to improve the fertility of aged roosters over 55 weeks old.
L-arginine has been supplemented at 0.14% of the diet, D-aspartic acid at 200 mg/kg body weight, L-carnitine at 150 mg/kg diet, and GAA at 1,200 mg/kg feed with positive effects on libido, testicular development, and semen quality.
Mechanisms include enhanced testosterone plasma levels, development of the testes, and the formation of Sertoli, Leydig, and spermatogonia cells, as well as semen quality characteristics such as sperm concentration, membrane integrity, forward motility, and sperm penetration.
D-aspartic acid and L-carnitine are involved in mechanisms to suppress lipid peroxidation. L-carnitine also participates in lipid metabolism by transporting long-chain fatty acids into the mitochondria to initiate fatty acid ß-oxidation.
L-arginine produces nitric oxide and GAA, which are involved in fatty acid oxidation. GAA is required to make creatine, and in its phosphorylated form, phosphocreatine generates energy for the spermatozoid.
Avoid toxins potentially present in feed
Several mycotoxins can negatively impact the reproductive organs of roosters, leading to reduced weights and potentially affecting semen quality. Specifically, diacetoxyscirpenol (DAS), a type of trichothecene, has been shown to induce degenerative processes in the testes, resulting in reduced size and impaired testicular function.
Other mycotoxins, such as aflatoxins, fumonisins, zearalenone, ochratoxins, and trichothecenes (including deoxynivalenol and T-2 toxins), are also associated with reproductive issues in poultry.
Then, mycotoxin binders and plans to minimize mycotoxin contamination and impact are essential.
Currently, herbicide-tolerant corn and soy varieties comprise 90 and 94%, respectively, of the acres of these crops planted in the United States, and glyphosate-tolerant varieties account for roughly 50% of corn and soy grown in the United States.
These glyphosate-tolerant cultivars are typically exposed to glyphosate-based herbicides (GBHs) throughout their production period, and due to their tolerance to glyphosate, crop production is unaffected.
Exposure to GBH ingredients through animal feeds, at even legal levels, can significantly influence the reproductive health of broiler breeder roosters. Both the gross histopathology of the rooster testis and sperm mobility, the most critical component of rooster sperm quality, are seriously impacted by exposure to GBH ingredients.
Research conducted by Zachery Jarrell at the University of Georgia demonstrated that the addition of humic acids reduces the effect of GBH.
In conclusion, infertility is a crucial issue to address in broiler breeder production, as it can contribute to reduced hatchability.
Male fertility has a significant impact that can be modulated with nutrition. Specific male diets tailored to their nutritional needs can help breeder managers better manage rooster body weight and body composition.
Increasing antioxidant capacity through proper vitamin and mineral levels, supplementation with phytochemicals, and functional amino acids can be beneficial, especially for aging males.
Finally, avoiding mycotoxins and addressing their potential contamination with these toxins and others like glyphosate-based herbicides can help to minimize the infertility issues observed.