Abstract
In ruminant feeding, mechanisms for controlling the rate of ammonia release in the rumen are important for increasing the efficiency of transforming dietary nitrogen into microbial protein. Three microencapsulated formulations, with increased urea concentrations of 10 (MPec1), 20 (MPec2) and 30% (MPec3) from the w/w, based on the mass of citrus pectin solution, employ the external ionic gelation/extrusion technique. The properties of microencapsulated urea were examined as a completely randomized design with 5 treatments each with 10 replicates for evaluation, and the ratios of dietary to free urea were compared using 5 fistulated male Santa Ines sheep in a Latin 5 × 5 square design. The degradation kinetics showed that the rate of controlled release from the microencapsulated systems was significantly reduced compared with that of free urea (p < 0.05). The population density of ruminal protozoa increased when sheep received the microencapsulated urea (p < 0.05). The disappearance of dry matter and crude protein reached a degradation plateau during the first minutes for the MPec1 and MPec2 systems and was slower for MPec3. The MPec1 and MPec2 systems presented higher (p < 0.05) blood serum concentrations of albumin, urea nitrogen (BUN), creatinine and total cholesterol and did not affect (p > 0.05) the other blood metabolites. The MPec2 systems are recommended because they consist of microspheres with more (p < 0.05) controlled core release, delaying the peak of urea released in the rumen and BUN without affecting (p < 0.05) ruminal pH and temperature. Microencapsulation with calcium pectinate provided better utilization of urea, reducing the risk of ruminant intoxication.
Highlights
The use of urea ((NH2)2CO) as a source of nonprotein nitrogen (NPN) has been applied on a large scale in ruminant diets, mainly to reduce production costs. (NH2)2CO is hydrolyzed by ureolytic bacteria in the rumen into ammonia nitrogen (NH3-N) and incorporated by ruminal microorganisms for microbial protein production, which is very important to ruminants [1]
The low palatability of urea and its intoxication capacity when converted to ammonia in the rumen by ruminal microorganisms limits its inclusion in concentrate mixtures to 2% or 40 g/100 kg body weight, and the supply to the animals must be conducted in covered troughs to avoid volatilization [4,5]
The micrographs (Figure 1) demonstrated that compared to calcium pectinate microparticles, all systems were whitish in color due to the presence of urea
Summary
The use of urea ((NH2)2CO) as a source of nonprotein nitrogen (NPN) has been applied on a large scale in ruminant diets, mainly to reduce production costs. (NH2)2CO is hydrolyzed by ureolytic bacteria in the rumen into ammonia nitrogen (NH3-N) and incorporated by ruminal microorganisms for microbial protein production, which is very important to ruminants [1]. The use of urea ((NH2)2CO) as a source of nonprotein nitrogen (NPN) has been applied on a large scale in ruminant diets, mainly to reduce production costs. The low palatability of urea and its intoxication capacity when converted to ammonia in the rumen by ruminal microorganisms limits its inclusion in concentrate mixtures to 2% or 40 g/100 kg body weight, and the supply to the animals must be conducted in covered troughs to avoid volatilization [4,5]. The speed of ammonia release in the rumen is the determining factor in the transformation of dietary nitrogen into microbial protein [6,7], and the adaptation of the ruminal environment of animals to urea is essential. Several materials are being tested as encapsulating systems with very promising results [6,9,10]
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