Abstract
Background:
Sumba Ongole (SO) cattle, a valuable local breed in Indonesia known for its adaptability and resilience, face challenges in productivity and genetic conservation. Technological innovations, such as artificial insemination (AI), to enhance genetic quality and ensure the sustainability of this local germplasm during the growing dominance of exotic cattle.

Aim:
This study aimed to investigate the use of local diluent materials [Asian palmyra palm (APP)] to maintain the quality of liquid semen in SO cattle.

Methods:
Four Class I male cattle were selected according to the Indonesian National Standard (2014) on the basis of qualitative and quantitative characteristics. A completely randomized design was employed, consisting of 10 replications with four treatments: T0: cauda epididymal plasma-3 (CEP-3) diluent + 20% egg yolk (EY) (control); T1: 85% APP + 15% EY; T2: 80% APP + 20% EY; and T3: 75% APP + 25% EY.

Results:
Various levels and combinations of APP extract and EY significantly differed (p < 0.01) between treatments, particularly on day 1, which tended to positively influence motility. Viability displayed a comparable pattern, with significant differences noted (p < 0.01).

Conclusion:
The combination of 75% APP and 25% EY was recommended as an effective diluent for maintaining the quality of liquid semen in SO cattle.

Key words: Asian palmyra palm; Egg yolk; Diluent; Sperm quality; Sumba Ongole cattle.