Intake, digestibility and spermatozoa quality of Bali cattle bulls fed diets with various levels of indigofera as a substitute for concentrate

Abstract

This study aimed to evaluate the level of indigofera use as a substitute for concentrate in breeding bulls on the quality of motility and integrity of sperm deoxyribonucleic acid (DNA). The study was conducted using a 3x3 Youden Square design, which used 3 breeding Bali bulls, 4 ration treatments and 4 experimental periods. The evaluated treatments consisted of T1:50% grass + 50% concentrate; T2:50% grass + 37.5% concentrate + 12.5% ​​Indigofera; T3:50% grass + 25% concentrate + 25% Indigofera; T4:50% grass + 12.5% ​​concentrate + 37.5% Indigofera. Each experimental period was carried out for 16 days, namely 10 days of ration adjustment, 5 days of faeces collection, and 1 d of semen collection. Ration and faecal samples were analysed for proximate and fibre fractions and used to calculate nutrient digestibility. Semen was collected from each bull at each period and evaluated macroscopically (volume and colour), microscopically (motility, mortality, normality, concentration, and movement quality), and DNA integrity. Data were analysed for variance, followed by orthogonal polynomial tests. The results showed that increasing the level of Indigofera in the diet quadratically increased dry matter intake, crude protein and hemicellulose digestability, and semen viability, and linearly (P<0.05) decreased semen volume, motility, and abnormalities, but had no significant effect (p>0.05) on the percentage of intact plasma membrane (MPU), mortality, concentration, mass movement, and DNA damage. Considering both digestibility and reproductive parameters, the optimal inclusion level of Indigofera sp. for Bali cattle bulls is recommended to be 25%, as it provides a balance between improved nutrient digestibility and acceptable semen quality without compromising motility.