Effects of polymer coated slow-release urea on ruminal fermentation and nutrient total tract digestion of beef steers

Abstract

-The objective of this study was to evaluate the effects of polymer coated slow-release urea (SRU) in high-forage diets of beef steers on nutrient intake and digestibility, ruminal fermentation, microbial protein synthesis, and energy balance. Eight 24-mo-old rumen-fistulated castrated Nellore steers (average body weight = 418.0±40.0 kg) were used in a replicated 4 × 4 Latin square design. Animals were randomly distributed to receive one of the following diets: no urea inclusion; 1.0% inclusion of feed grade urea in the diet (dry matter [DM] basis); 1.0% inclusion of slow-release urea 1 in the diet (DM basis); and 1.0% inclusion of slow-release urea 2 in the diet (DM basis). Slow-release urea 2 had a similar composition to that of slow-release urea 1 and differed in that it contained 2.95% sulfur. A high-forage diet was provided (75% of total DM) and corn silage was used as the forage source. Diets with urea had increased crude protein (CP) intake, and CP and total digestible nutrients total tract digestion. Urea sources increased ruminal concentrations of ammonia nitrogen and acetate, and decreased butyrate concentrations. The polymer coated urea did not alter ruminal fermentation when compared with feed grade urea. Diets did not affect the energy balance of steers. Feed grade urea presented greater microbial protein synthesis than polymer coated slow-release urea. The partial replacement of soybean meal by 1% slow-release urea in a diet with 75% forage does not improve ruminal fermentation and microbial protein synthesis, and shows similar results as feeding feed grade urea to beef steers.

Influence of polymer-coated slow-release urea on total tract apparent digestibility, ruminal fermentation and performance of Nellore steers

“…Sulphur supplements can enhance the nutrient digestibility because the synthesis of amino acids that contain sulphur is critical for microbial growth [26–27]. Nevertheless, we did not detect differences on microbial protein synthesis agreeing with [28] who reported no differences in purine derivatives production of Nellore steers fed the urea sources of the current study. In addition, Calomeni et al [9] found no differences in DM intake, apparent digestibility and microbial protein synthesis of dairy cows fed the same polymer-coated SRA as used in this study or feed grade urea, but the authors added 0.9 g/kg DM of the commercial products.…”

Technical cashew nut shell liquid associated with non-protein nitrogen sources in high-grain diets for ruminants: intake and digestibility of nutrients, ruminal fermentation, and microbial protein synthesis

“…However, as discussed earlier, tCNSL may not have influenced the responses of the variables in Table 4 due to the characteristic of its composition since it did not present significant amounts of anacardic acid, which is the antimicrobial agent responsible for altering the ruminal microflora and, consequently, the verified answers. Taylor-Edwards et al (2009) and Gardinal et al (2016) evaluated the effect of urea and SRU on the digesta of steers fed a diet with approximately 40% NDF and verified that NPN sources did not influence rumen pH values, being close to 6.5 and 6.42, respectively. However, the animals that fed SRU had lower N-NH 3 concentrations in the rumen fluid in both cases when compared to the use of urea.…”

“…The optimal N-NH 3 level varies according to the feed and availability of fermentable carbohydrates in the rumen. However, it is expected that the availability of N-NH 3 from NPN sources may be more limiting for animals with high ruminal N requirements, such as those with a high intake or production demands or those that consume highly degradable feeds when compared to animals that require less N ruminal Hours after 1 st meal Taylor-Edwards et al (2009) and Gardinal et al (2016) evaluated the effect of urea and SRU on the digesta of steers fed a diet with approximately 40% NDF and verified that NPN sources did not influence rumen pH values, being close to 6.5 and 6.42, respectively. However, the animals that fed SRU had lower N-NH 3 concentrations in the rumen fluid in both cases when compared to the use of urea.…”

Effect of soybean meal replacement by slow-release urea on ruminal parameter, blood metabolites, and microbial protein synthesis in Zel ram

“…Additionally, no change in the total VFA or VFA proportions were reported using urea compared to the SRU. Researchers observed comparable urea effects and recommended that greater acetate and lower butyrate concentrations in diets containing urea produced a lower acetate transformation in conformity with ruminal butyrate (Gardinal et al, 2016;Xin et al, 2010). Khattab, Salem, Abdel-Wahed, &and Kewan (2013) observed greater acetate concentration after feeding urea, and an expansion in microbial protein synthesis.…”