Effects of slow-release urea on in vitro rumen fermentation parameters, growth performance, nutrient digestibility and serum metabolites of beef cattle

Abstract

Two experiments were conducted to investigate the effects of slow-release urea (SRU) on in vitro rumen fermentation parameters, growth performances, nutrient digestibility, and serum metabolites of beef cattle. The single factor design was applied in both experiments. Three diets with different nitrogen sources including soybean meal (Control group), slow-release urea (SRU group), and common urea (Urea group) was designed (concentrate to forage ratio was 4:6). The diets were formulated to be isoenergetic and isonitrogenous, 75% of the soybean meal in the control diet was replaced by 1.41% SRU and 1.15% urea in SRU group and Urea group, respectively. In experiment 1, five healthy Jinjiang cattle (average body weight (BW) was 380 ± 17.1 kg) with permanent rumen fistulas were used in in vitro ruminal fermentation experiment. The results showed that supplementing SRU increased the dry matter degradation rate (DMD), digestible organic matter (DOM) and propionic acid concentration in cultivated fluid, and SRU supplementation decreased pH, NH3-N, total volatile fatty acid (TVFA), acetic acid, butyric acid concentration and microbial growth efficiency (MOEFF) in cultivated fluid. In experiment 2, eighteen Simmental crossbred cattle BW= 315 ± 5.2 kg) were stratified by BW and then assigned to the three groups to have equal BW among groups. The results showed that supplementing SRU reduced the average dry matter intake (ADMI), apparent digestibility of ether extract (EE), the activity of glutathione peroxidase (GSH-Px), the levels of IgG and IgA, and the production of thiiodothronine (T3) in serum, SRU supplementation increased the apparent digestibility of dry matter and organic matter (OM) and alanine aminotransferase (ALT) concentration in serum. These results indicated that some soybean meal could be replaced by SRU and urea in the production of beef cattle. In addition, compared with urea, SRU had a good sustained-release effect. The replacement of some soybean meal by SRU in the diet had no adverse impact on rumen fermentation, growth performance, and serum metabolites of beef cattle.

Effect of Different Slow‐Release Urea on the Production Performance, Rumen Fermentation and Blood Parameter of Angus Heifer

“…The NH3-N concentration in rumen can reflect the urea decomposition by rumen microorganisms and the utilization of protein in diet, with high values indicating that the nitrogen source in diet is sufficient, and rumen microorganisms may not be fully utilized, resulting in nitrogen waste; while low values indicate insufficient nitrogen availability for the cellulolytic bacteria which reduces the activity of cellulolytic bacteria and the efficiency of fiber decomposition [32]. In line with previous studies, the results of this study showed that there was no significant difference in NH3-N concentration in each treatment group [33]. NH3-N in the rumen of ruminants is the main source of nitrogen for the synthesis of microbial proteins, which are the primary source of nitrogen for the synthesis of MCP [34].…”

“…Urea is rapidly hydrolyzed into ammonia by urease secreted by bacteria after entering the rumen, and then synthesized into microbial protein to make use of the organism. However, the rate of hydrolysis of urea in the rumen is much faster than the rate of ammonia utilization by rumen microorganisms, thus causing the accumulation of ammonia in the rumen or polluting the environment by excreting with urine, resulting in the waste of nitrogen source [3]. Therefore, synchronizing N supply with microbial requirements in the rumen is an essential nutritional strategy to improve rumen energy and N utilization.…”

The impact of using slow-release urea instead of fast-release urea in feed on the milk production of Awassi sheep and some blood traits

“…As for the AST enzyme, the statistical analysis results indicate that there are no significant differences in the concentration of the AST enzyme, as it ranged between (17.83-18.88 units/liter), which is an indication of the ewes' response to the addition of slow-release urea that improved the performance of blood enzymes as mentioned by some researchers in their studies [22,25]. However, it did not agree with the results of some studies [29,30], who indicated a significant decrease in the ALT enzyme while there were no significant differences for the AST enzyme.…”

Growth and economic value of goat rations supplemented with ground corn gelatinization product with urea

“…Goats treated with the use of ground corn gelatinization product with urea at 2.5% (T2) had significantly (P<0.05) higher consumption of total dry matter in the ration than those treated with 1.25% and 3.75%. When associated with the replacement of pure protein sources, the use of slow-release urea products can replace soybean meal in the ration without affecting the growth performance of beef cattle or milk production of dairy cows [22]; [23]. In this study, the product of gelatinized ground corn with urea can replace soybean meal up to 50% in concentrate feed.…”