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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.

Objective: This experiment aimed to evaluate the effects of replacing concentrates with cassava root-top silage (CARTOS) on feed intake, digestibility, rumen fermentation, blood parameters, and growth performance of beef cattle., Methods: Twenty crossbred bulls with a body weight (BW) of 226±56 kg were randomly assigned to one of five treatments for 90 d in a randomized complete block design having four blocks based on BW. The concentrates were replaced by CARTOS at levels of 0%, 25%, 50%, 75%, and 100% dry matter (DM). Animals were fed dietary treatments at 1.8% BW, with rice straw offered ad libitum., Results: The DM and crude protein (CP) intake were decreased (p<0.01, p = 0.04) when the diet's CARTOS level was increased. The digestibility of DM, OM, and CP were not different among treatments, while fiber digestibility was increased with the inclusion of CARTOS (p = 0.03). The addition of CARTOS to replace concentrates did not change ruminal pH or volatile fatty acid proportions except for acetic acid, which increased with the addition of CARTOS (p = 0.03). The ruminal ammonia-nitrogen (NH3-N) was decreased (p<0.01) with increasing levels of CARTOS. The blood glucose and blood urea nitrogen decreased (p = 0.01) with the addition of CARTOS at 100%, whereas total protein and hematological parameters did not change with increasing levels of CARTOS. The use of CARTOS to substitute concentrates at 75% and 100% decreased average daily gain (ADG) and gain to feed ratio (G:F) (p<0.01); therefore, the addition of CARTOS up to 50% maintained ADG and G:F in beef cattle., Conclusion: CARTOS can replace concentrates up to 50% in beef cattle diets without adversely affecting feed intake, nutrient digestibility, rumen fermentation characteristics, blood parameters, or growth performance of beef cattle.