Long-term effect of Bt cottonseed cake on nutrient utilisation, growth performance and health of rams in tropical conditions.

Abstract

Cottonseed cake (CSC) is a cost-effective and important protein source for ruminants. In India, Bt cotton has replaced 96% of non-Bt, making Bt CSC, the predominant byproduct available for animal feeding. While some studies have assessed the effect of Bt genes and proteins on livestock health, no long-term evaluations have been conducted. This study investigated the prolonged effects of feeding Bt cottonseed cake on growth performance, feed intake, and blood parameters in rams, particularly within tropical systems Eighteen male rams were divided into three treatment groups: G₁ (0% CSC), G₂ (35% non-Bt CSC), and G₃ (35% Bt CSC). The results revealed that body weight (30.50 to 30.90 kg), dry matter intake (3.22 to 2.28 kg/100 kg body weight), and nutrient digestibility had non-significant differences among the treatments. The nitrogen (N) intake ranged from 16.87 to 17.20 g/day, and N retention was between 15.74% and 17.38%. Similarly, blood metabolites (plasma protein, creatinine, and superoxide dismutase) were found within the normal range. Semen volume (0.85 to 0.90 mL), sperm count (3475-3500 × 10⁶/mL), and sperm motility (75.2-76.05%) were also within normal ranges. The results of the experiment indicate that no apparent detrimental effects were observed from long-term (320 days) feeding of Bt cottonseed cake at up to 35% in the concentrate mixture for rams.