Comparison of Venom Yield of Naja naja (Indian Black Cobra) and Bungarus caeruleus (Common Krait) through Housing and Diet Manipulation

Venomous snakes pose substantial public health risks, but also offer potential biomedical resources (Koh et al., 2006; Gutiérrez, 2012). Snake bite is a neglected tropical disease declared by the World Health Organization (WHO, 2007). Millions of people worldwide experience snakebites each year, and a significant proportion develop clinical envenoming, resulting in thousands of deaths and long-term disabilities (Gutiérrez et al., 2017; WHO, 2019; Roberts et al., 2022). The impact is even more severe in the remote regions of Africa and Asia, where the availability of care following a snake bite, or even antivenoms, is poor (Alirol et al., 2010; WHO, 2016; Afroz et al., 2024). Snake venom is a natural reservoir of bioactive molecules evolved to interact with human physiological targets (Lewis and Garcia, 2003; Abd El-Aziz et al., 2019; Oliveira et al., 2022). Venom components have contributed to the development of clinically useful medicines and continue to advance drug discovery, particularly for cardiovascular diseases, pain, inflammation, thrombosis, and cancer biology (Bedraoui et al., 2024; da Silva et al., 2025; Zona-Rubio et al., 2005). The successful use of venom in the development of antivenom and drugs in adequate amounts, proper reflection of regional venom diversity, and appropriate scientific management for the animal source(s) from which the venom is derived are important goals that need to be addressed when working with venom (Chippaux, 2010; Roque, 2025).

Venom production units also experience challenges in terms of the capture as well as the identification of the snake, apart from the high mortality rates and low survival rates in the serpentariums (Halm, 2024). The World Health Organization’s technical information suggests that the management of serpentariums is an important factor for the quality of venom production, with attributes of quarantine, disease, and proper housing and feeding systems being of considerable interest to the same (WHO, 2023). Consequently, improvements in daily husbandry practices represent a central mechanism for enhancing both animal welfare and public health outcomes (Santos et al., 2021).

This study was conducted to quantitatively compare venom yields of two medically important snake species, the black cobra (Naja naja) and the common krait (Bungarus caeruleus), under varying housing densities and feeding frequencies, relative to the standard husbandry and venom extraction protocols of the National Institutes of Health (NIH) Islamabad, Pakistan.

We conducted this study at the National Institute of Health. We utilized institutional facilities dedicated to sera and anti-sera testing and production. The biological production division (BPD) of the NIH has been the only manufacturing unit of anti-snake venom serum (ASVS), as well as other varieties of sera, within the country since the year 1960 (https://bpd.nih.org.pk/).

We divided 20 captive snakes of the common krait and cobra each into two groups: 10 snakes in the control group (kept and fed as per NIH routine) and 10 snakes in the experimental group (kept and fed with manipulation as mentioned in the following section).

We housed the experimental group of common krait and cobra individuals in glass enclosures (each with 49″ × 23″ × 24″) and assigned each enclosure a unique ID (E1-E4). We housed one individual (each species separately) in Group 1 (E1), two individuals in Group 2 (E2), three individuals in Group 3 (E3), and four in Group 4 (E4) (Supplementary Figs. 1-3). We kept individuals as the control group together in one enclosure (each species separately). We provided sunlight during the daytime and maintained the ambient temperature between 26 and 30 °C for both groups. We ran five trials, based on venom extraction and feeding frequency, for each group of each species (Supplementary Table I). We fed snakes in the experimental groups at a feeding frequency lower than that of the control group, for which we followed the NIH routine (Supplementary Table I). The feed quantity in all experimental trials was 50 mL for the common krait and 60-70 mL for the black cobra, relative to their body mass. We maintained the feeding type almost the same in each case, i.e., a mixture of eggs (chicken) and fresh milk, except in the fourth trial. In the fourth trial, chicken soup, along with a mixture of eggs and milk, was fed to each snake in the experimental group (Supplementary Table I). We performed snake milking using the standard protocol mentioned in Santos et al. (2021). We then measured the quantity of venom in milliliters using a 5 mL plastic syringe. We pooled venom from multiple snakes (10 experimental pooled and 10 control pooled), resulting in a single mean value per group for each trial.

We found that in the control group, mean venom yield declined from 1.9 mL in the first trial to 0.9 mL in the fifth trial (Fig. 1), resulting in the mortality of two snakes. The decrease in venom yield in the control group appeared to correspond with longer extraction intervals in some trials (Fig. 2). In contrast, experimental snakes, which were

Table I. Effect of housing density and feeding frequency on venom intervals, sample size, and mean venom yield in the black cobra (Naja naja) and the common krait (Bungarus caeruleus).

Cobra: Control mean = 1.30; experimental mean = 1.96; Krait: Control mean = 0.42; experimental mean = 0.47. *Number after mortality

subjected to control housing and feeding manipulations, showed higher and more variable venom yields, ranging from 1.5 mL to a maximum of 2.8 mL. The highest venom production in the experimental group occurred in trials with intermediate extraction intervals (15–22 days) under the modified feeding regime (Table I).

We found that the mean venom yield declined from 0.9 mL in the first trial to 0.2 mL in the fifth trial in the control group with no mortality (Fig. 1). The experimental group showed higher and more variable venom yields, ranging from 0.3 mL to a maximum of 0.7 mL. The highest venom production occurred in trials with moderate extraction intervals (16–28 days) (Fig. 2), whereas longer intervals were associated with a slight decline in yield.

This study examined whether practical husbandry modifications, such as snake housing density, feeding schedule, and a standardized supplement diet, could enhance venom yield and survival in two medically important elapids: the black cobra and the common krait. This work addresses a gap in venom production management.

The availability of antivenoms is influenced not only by species-specific biology but also by husbandry practices, including handling, feeding, enclosure design, and stress experienced in captivity (Chippaux et al., 1991; Hayes et al., 2002; Grego et al., 2021). In Black Cobras, mean venom yield was higher under experimental husbandry conditions compared to the NIH control, indicating that enhanced feeding frequency, diet quality, and optimized housing conditions can directly support venom replenishment. Venom production is physiologically costly and depends on energy and nutrient availability (Pintor et al., 2010), and standardized prey diets in serpentariums are known to maintain snake condition and venom output (Harris et al., 2020; Weiss and Kalki, 2023). Although our experimental diet (egg-milk paste) did not replicate natural prey, its high protein and energy content, combined with increased feeding frequency, likely facilitated improved physiological condition and venom regeneration after extractions (Pintor et al., 2011).

The common krait did not show a clear increase in venom yield under experimental conditions. Several factors may explain this outcome. First, venom production in krait is influenced by seasonal physiology and feeding status, and our experimental and control data were collected at different times, potentially confounding the effects of husbandry (Mirtschin et al., 2002; Cooper et al., 2014). Second, krait is ecologically and behaviorally distinct from cobra, exhibiting nocturnal habits and specific prey preferences, which complicates captive maintenance and feeding (Theakston et al., 1990; Pandey et al., 2020).

These factors, combined with irregular acceptance of experimental diets, may have limited body condition recovery and, consequently, venom production. Third, krait possesses venom systems that differ markedly from cobra, with highly neurotoxic components such as phospholipase A₂ and β-three-finger toxins (Siang et al., 2010; Oh et al., 2017; Liang et al., 2021), which may respond differently to feeding state, stress physiology, and replenishment dynamics. Our findings suggest that krait may require species-specific feeding strategies, such as whole-prey items aligned with natural diet, nocturnal feeding schedules, and minimized handling stress, to achieve measurable improvements in venom yield.

Limitations of this study include the pooling of venom, which prevented measurement of per-individual venom yield and precluded standard statistical tests at the snake level. The seasonal variation may have influenced outcomes, particularly for the common krait. Future research should aim to refine species-specific feeding and housing strategies, use of equipment with a precision to measure small quantities, explore alternative diets that better mimic natural prey, and investigate the physiological mechanisms linking nutrition, stress, and venom synthesis.

We thank the National Institutes of Health for supporting this study by providing the snakes, all necessary personnel, equipment, and resources. No external funding was received for this work.

The study did not receive any external funding.

We followed institutional animal-care, ethics, and biosafety guidelines and performed the experiment after obtaining the required ethical approval (dated 18th December, 2023).

There is supplementary material associated with this article. Access the material online at: https://dx.doi.org/10.17582/journal.pjz/20260308154408

The authors declare that no generative AI and AI assisted technology was used in the creation of this manuscript.

The authors have declared no conflict of interest.