Productive and reproductive status, hematological traits, biochemical blood parameters, and immune response of Sinai chicken breeders as influenced by the dietary addition of bee venom during the second production cycle and summer season

Bee venom (BV) is a product of bees and is produced by female worker bees. It contains several bioactive molecules, including peptides such as apamin, melittin, and adolapin, as well as enzymes such as phospholipase A2. These molecules have potential advantages for the treatment of central nervous system diseases and inflammation. Adding BV-derived material to animal diets has been shown to enhance productivity, provide health benefits, and act as a therapeutic agent. The present study tested the hypothesis that BV supplementation can ameliorate the stress induced by ambient temperature and advanced age in Sinai chicken breeders during the second production cycle (108-116 weeks of age). A total of 200 aged Sinai layer hens and 20 cocks were randomly allocated to four trial groups. Each trial group comprised 50 females and 5 males, further divided into 5 replicates, each with 10 females and 1 male. The first group received a control diet, while the other three groups (2, 3, and 4) received the control diet supplemented with 0.3, 0.4, and 0.5 g BV kg-1, respectively (BV 0.3, BV 0.4, and BV 0.5). The present findings indicated that BV addition significantly (P < 0.05) improved the layers’ final body weight (FBW), body weight gain (BWG), egg production (EP), egg weight (EW), egg mass (EM), and feed conversion ratio (FCR) at the 0.3, 0.4, and 0.5 g BV kg-1 levels compared to the control treatment. Moreover, serum total protein, total lipids, and total cholesterol, as well as immunoglobulin IgY and IgM, thyroid hormones (triiodothyronine and thyroxine), and redox status (total antioxidant capacity and malondialdehyde) were significantly (P < 0.05) improved in response to adding BV to layers’ diets during the summer season compared to the control treatment. Despite these improvements, BV supplementation did not significantly (P > 0.05) affect red blood cell count, mean corpuscular volume, or lymphocyte, eosinophils, or monocyte counts at the 0.3, 0.4, and 0.5 g BV kg-1 levels compared to the control treatment. Moreover, significant improvements (P < 0.05) were detected in hatchability traits for the aged Sinai layer hens with only (BV 0.4 and BV 0.5) supplementation during the summer season. The number of unfertilized eggs decreased by 29.41% and 17.65% in the groups administered 0.4 and 0.5 g BV kg-1 of diet, respectively, compared to the control group. Simultaneously, the number of fertilized eggs increased by 7.54% and 4.52% in these respective groups, and the total number of chicks hatched rose by 27.14% and 17.14% in the 0.4 and 0.5 g BV kg-1 treatments, respectively, compared with the control. These outcomes validate the hypothesis that dietary BV could enhance productive, reproductive, and certain physiological parameters in aged Sinai layer hens.