Effect of diets differing in rumen soluble nitrogen on utilization of poor-quality roughage by sheep

Abstract

This study investigated the effects of replacing rapid-release nitrogen (N) from urea with a graded level of slow-release N (Optigen® II) source on intake, digestibility, rumen fermentation and microbial protein synthesis, when sheep were fed a poor-quality roughage diet. Five rumen cannulated wethers were used in a 5 x 5 Latin square experimental design. The treatments had various proportions of urea to Optigen® II (0 : 100, 25 : 75, 50 : 50, 75 : 25 and 100 : 0), with the same inclusion level of starch and a mineral premix on an iso-nitrogen basis. The 25% urea : 75% Optigen® II treatment showed significantly higher intakes of dry matter, organic matter, neutral detergent fibre and digestible organic matter than in the other treatments. No differences were recorded for apparent dry matter digestibility, organic matter digestibility and neutral detergent fibre digestibility among the treatments. However, sheep on the 100% Optigen® II treatment had a significantly lower apparent nitrogen digestibility. No differences were observed for ruminal pH and volatile fatty acid concentrations among the treatments, except for butyrate and isobutyrate concentrations. The butyrate concentration of the 100% Optigen® II treatment was significantly lower than the other treatments, whereas the isobutyrate concentration was significantly lower than in Treatments 2 (75% urea : 25% Optigen® II) and 5 (100% Optigen® II). The rumen NH 3 -N concentration of the 100% Optigen® II treatment was significantly lower than the 100% urea treatment at two and four hours after infusion. Based on biological responses, results suggest that up to 75% of urea could be replaced with Optigen® II in supplements.

Conventional Feed-Grade or Slow-Release Coated Urea as Sources of Dietary Nitrogen for Fattening Lambs

“…In the present study, urea concentrations in plasma were much higher than those indicated in the cited works, suggesting an excess of nitrogen in both treatments for the synthesis of microbial protein. Regarding the molar proportion of butyric acid, no effects [9,11,14,16,42,54,55], increases [17,56,57], or reductions [44] have been reported, but these changes have been related with an opposite change in the proportion of acetic acid. However, in the present study, the proportion of acetic acid decreased in the in vivo trial and was not affected in the in vitro assay.…”

Effect of cooking time and urea level on dry matter loss, nitrogen fixation and digestibility of dry matter, organic matter in vitro in the combined products of urea-pith Gewang (Corypha Utan Lamk.) starch

“…Supplementation of feed sources containing nitrogen becomes the priority in solving this problem [1]. Sources of non-protein nitrogen (NPN) such as urea, are commonly used in protein supplementation because ruminants are able to utilize it, have low nitrogen density and low cost per unit nitrogen [2]. In the diet of ruminants, it can be used as an alternative source to true protein, since it is capable of replacing it with the advantage of being less expensive [3].…”

Effect of the Use of Cooking Product of the Stem Content of Gebang (Corypha Utan Lamk.) Plant With Urea on the Growth of Bali Cattle

“…The use of NPN, such as urea as feed supplement can increase the consumption and digestibility of feed as well as the performance of livestock that consume low-quality forage and most importantly it costs less than using natural protein. Urea can also be used as an effective alternative to replace soybean meal based supplements and produces more N than pure protein sources per unit of N (Mentz et al, 2015;Gardinal et al, 2016). Cattle that consume high amounts of forage will generally meet their nitrogen needs with urea supplementation (Gardinal et al, 2016).…”