Effects of supplementing rumen-protected rubber seed oil to dairy cattle on feed digestibility and milk production.

Objective: The aim of this study was to determine the effect of rumen-protected rubber seed oil supplementation on feed digestibility, milk yield, and milk composition in tropical dairy cows.

Methods: Twelve crossbred Holstien-Friesian dairy cows (75% Holstein-Friesian, 25% Thai native breed) with a mean body weight (BW) of 460 ± 30 kg and 20 ± 5 days in milk were randomly assigned to 1 of 3 treatments according to a completely randomized design. The treatments were as follows: a basal diet without rumen-protected fat (RPF) (control) or supplementation of rumen-protected palm oil (RPPO) at 300 g/h/d and rumen-protected rubber seed oil (RPRSO) at 300 g/h/d. Each cow was fed a total mixed ration ad libitum.

Results: The nutrient intake was similar among treatments (p>0.05). Adding RPF did not affect nutrient digestibility, while organic matter digestibility increased in dairy cows receiving RPRSO (p<0.01). Blood urea nitrogen, total protein, or glucose did not alter among treatments (p>0.05), while triglycerides and cholesterol were increased when cows were fed RPPO (p<0.01). Adding RPF increases milk yield in cows (p<0.01). The supplementation of RPRSO increased milk fat (p=0.04). Milk fat yield was higher in RPPO and highest in RPRSO (p<0.01). The addition of RPF increased the oleic acid (OA, C18:1 cis-9) in milk (p=0.01). In addition, cows fed RPRSO increased linoleic acid (LA; C18:26 cis-9,12 + trans-9,12) and -linolenic acid (ALA; C18-33 cis-9,12,15) in milk (p<0.01). The addition of RPF increased milk unsaturated fatty acids (UFA) and monounsaturated fatty acids (MUFA) (P≤0.04). The PUFA in milk increased with RPRSO supplementation (p<0.01).

Conclusion: Supplementation of RPRSO during early lactation can increase feed digestibility and the concentration of milk fat with PUFA (LA and ALA) in tropical dairy cows.