Effects of rumen-degradable-to-undegradable protein ratio in ruminant diet on in vitro digestibility, rumen fermentation, and microbial protein synthesis

Abstract

Background and Aim: Feeding ruminants must notice the degradability of feed, especially protein. Microbial rumen requires ammonia from rumen degradable protein (RDP) beside that ruminant require bypass protein or rumen undegradable protein (RUP) and microbial crude protein. The aim of the study was to discover the best RDP:RUP ratio in beef cattle diets commonly used by Indonesian farmers using an in vitro methodology. Materials and Methods: Samples of Pennisetum purpureum, Leucaena leucocephala, Indigofera zollingeriana, cassava, maize, palm kernel cake, rice bran, and tofu waste were formulated into dietary treatments (dry matter [DM] basis). All experiments were carried out using a 3×3×2 factorial, randomized block design with three replications. Treatments consisted of three protein levels (12%, 14%, and 16%), two energy levels (65% and 70%), and three RDP:RUP ratio levels (55:45, 60:40, and 65:35). The experimental diets were incubated in vitro using buffered rumen fluid for 48 h at 39°C. After incubation, the supernatants were analyzed to determine pH, ammonia concentration, total volatile fatty acid (VFA), and microbial protein synthesis. The residues were analyzed to determine DM, organic matter, protein, and RUP digestibility. Results: Increased protein, energy, and RDP levels increased digestibility, ammonia concentrations, total VFAs, and microbial protein synthesis (p<0.05), while rations with 16% protein lowered these parameters (p<0.05). Conclusion: Increased dietary protein (from 12% to 14% DM), energy (from 65% to 70% DM), and RDP (from 55% to 65% crude protein [CP]) levels increased nutrient digestibility, ammonia concentration, total VFA levels, and microbial protein synthesis. The diet containing 14% DM dietary protein and 70% DM energy, which contained 55%, 60%, or 65% CP RDP optimally increased nutrient digestibility, ammonia concentration, total VFA levels, and microbial protein synthesis. Thus, feed based on these RDP:RUP ratios can optimize ruminant productivity.

Effect of rumen degradable protein and sulfur supplementation on in vitro digestibility and ruminal fermentation

“…Rumen pH was not significantly affected by RDP levels and sulfur supplementation (p>0.05). This is in line with other studies that reported rumen pH did not affect by different RDP levels [27,28] and sulfur supplementation [16,17]. The rumen pH value in all treatments was in the normal range (6.86-7.00) to support the fermentation process.…”

“…The combination between treatments R1 (60% RDP) and S2 (0.1% sulfur supplementation) had the highest total VFA concentration. According to Putri et al [28], increasing total VFA concentration was followed by increasing RDP in the rumen. Total VFA concentration was increased by sulfur supplementation with Na 2 SO 4 due to attributed increasing cellulolytic bacteria population [14].…”

Synchronization of rumen degradable protein with non-fiber carbohydrate on microbial protein synthesis and dairy ration digestibility

“…In this study, MPS was 6.94-7.56 mg/10 mL; this was lower than the range reported by Putri et al [70], who reported a MPS of 10 mg/10 mL produced from a legume-based ration with 16% protein content and different RDPR levels (55:45, 60:40, and 65:35). This difference in MPS is due to the difference in feed ingredients (leguminous vs. concentrate) and types of NFC used in the rations.…”

“…The different degradability in the rumen was compensated by different post-ruminal digestibility, which resulted in similar total DMD and OMD. One previous study reported that an increasing RDPR level improves DMD and OMD [70]; this is true for rations high in fiber that rely mainly on rumen fiber degradation, but this was not the case in the current study.…”

Optimization of Rumen Bioprocess through The Addition of Phosphorus and Sulfur Minerals on Ammoniated Palm Leaves and Fronds (Elaeis Guineensis Jacq.)

“…The pH value is measured using a pH meter. The concentration of NH3 and total VFA analysis as described in Putri et al (2021). Chemical composition of PLF before and after ammonization can be seen in Table 1.…”