It concentrates the nitrogen fraction of the diet, creating dry matter space for more fiber and energy. After being launched only a few years ago, Optigen has become a solution to feed and environmental problems. Alltech Headquarters. Czech Republic. New Zealand. Artboard 1.
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As a result of the cost of grains, the replacement of grains by co-products i. DDGS in feedlot diets is a common practice. This change produces diets that contain a lower amount of starch and greater amount of fibre. Hypothetically, combining feed grade urea U with slow release urea Optigen in this type of diet should elicit a better synchrony between starch high-rate of digestion and fibre low-rate of digestion promoting a better microbial protein synthesis and ruminal digestion with increasing the digestible energy of the diet.
Three S:F ratios 3. Additionally, a treatment of 4. The S:F ratio of the diet was manipulated by replacing the corn grain by dried distillers grain with solubles and roughage. Urea combination did not affect ruminal pH. The urea combination did not affect ADF ruminal digestion. Irrespective of the S:F ratio, the urea combination improved 2. The combination of urea at 4.
Combining urea and Optigen resulted in positive effects on the MN flow and DE of the diet, but apparently these advantages are observed only when there is a certain proportion of starch:ADF in the diet. The N retention in the rumen is mainly mediated by the rate of degradation of N compounds and carbohydrates and by the energy available for the process of protein synthesis. It has been observed that in high-grain diets ratio of starch vs. The latter can be partially explained by the possible synchrony of ruminal degradation rates between urea and starch.
Currently, as a result of the cost of corn grain, the replacement of corn grain by dried distillers grain with solubles DDGS in feedlot diets is a common practice Klopfenstein et al.
Hypothetically, combining feed grade urea with slow-release urea in finishing diets should promote the synchrony between starch high-rate of digestion and fibre low-rate of digestion , promoting better microbial protein synthesis and increases in ruminal digestion and the digestible energy of the diet. The beneficial effects of the supplementation of slow-release urea has been extensively studied in cattle that were fed a high-forage diets, i.
Therefore, the purpose of this study was to evaluate the effects of combining feed grade urea and a slow-release urea product OPT on the characteristics of digestion, microbial protein synthesis and digestible energy in steers fed diets with different starch:ADF ratios. All animal management procedures were conducted within the guidelines of locally-approved techniques for animal use and care NOMZOO humanitarian care of animals during mobilization of animals; NOMZOO technical specifications for the care and use of laboratory animals.
Livestock farms, farms, centres of production, reproduction and breeding, zoos and exhibition hall, must meet the basic principles of animal welfare; NOMZOO animal health stipulations and characteristics during transportation of animals. Additionally, a treatment of 4 S:F ratio with urea 0. For the above, four dietary treatments were compared:. Diet formulated to supply 2. The S:F ratio in the diet was manipulated by replacing the steam-flaked corn grain by dried distillers grain with solubles DDGS and forage sudangrass hay and wheat straw to reach S:F ratios of 3.
Chromic oxide used as a source of chromium to estimate nutrient flow and coefficient of digestion was added to the diets 3. All steers received ad libitum access to the control diet U To avoid refusals once the experiment started, dry matter intake was restricted to 4. The slow-release urea product was hand-weighed using a precision balance Ohaus, mod AS, Pine Brook, NJ , and was added top-dressed in equal proportions to the diet at time of feeding.
Diets were fed in two equal portions at and h daily. Animals were housed in individual pens 3. Experimental periods consisted of a d diet adjustment period followed by a 4-d collection period. During the collection period, duodenal and faecal samples were taken from all steers, twice daily as follows: d 1, and h; d 2, and h; d 3, and h; and d 4, and h. Individual samples consisted of approximately mL of duodenal chyme and g wet basis of faecal material. Samples from each steer and within each collection period were prepared for analysis.
Upon completion of the trial, ruminal fluid was obtained from all steers and composited for isolation of ruminal bacteria via differential centrifugation Bergen et al. The microbial isolate served as the purine:N reference for the estimation of microbial N contribution to chyme entering the small intestine Zinn and Owens, USA was determined for feed and faecal samples.
Ammonia N method Ether extract method Microbial organic matter MOM and microbial nitrogen MN leaving the abomasum were calculated using purines as a microbial marker Zinn and Owens, Organic matter fermented in the rumen OMF was considered equal to the OM intake minus the difference between the amount of total OM reaching the duodenum and the MOM reaching the duodenum. Feed N escaping to the small intestine was considered equal to the total N leaving the abomasum minus ammonia-N and MN and, thus, includes any endogenous contributions.
The statistical model for the trial was as follows:. The ruminal pH values, which were recorded at 0, 2, 4, and 6 h post-feeding, were analysed with a linear mixed model for repeated measures in a Latin square design according to SAS SAS Inst. The effects of treatment on ruminal pH are shown in Table 2.
The ruminal pH observed for each treatment in the present study was slightly greater 3. This may be because of the incorporation of 1. Ruminal pH was not affected by urea combination. As consequence of the rapid ruminal fermentation of starch, diets that contain increasing amounts of starch grains tend to promote a lower ruminal pH than those that contain lower quantities of starch Huntington, In this sense, the S:F ratio of 6.
This indicates that, although U Treatment effects on the characteristics of ruminal and total tract digestion are summarized in Table 3. It has been observed that the depression in fibre digestion is largely a function of ruminal anion concentration Peters et al. Russell and Wilson observed that fibre digestion decreases because cellulolytic bacteria cannot adequately control their intracellular anion gradient as pH declines. Grant and Weidner further verified this concept in vitro by fermenting various forages in cultures of ruminal fluid wherein pH was controlled experimentally by means of citrate buffers.
They observed that both the lag phase and the rate of fibre digestion were sensitive to sustained culture pH below 6. The ruminal pH with the OPT-6 treatment was consistently maintained below 6. Influence of treatments on characteristics of ruminal and total tract digestion in Holstein steers.
In the same manner, compared to the control diet, at an equal S:F ratio 4. Burroughs et al. The MN flows of the U In contrast, the urea combination for an S:F ratio of 4. It has been observed that MN production, among others, is a result of synchronization between the rate of hydrolysis of carbohydrates, and the rate at which N-NH 3 is produced during the hydrolysis of N compounds in the rumen NRC, ; Orskov, The difference in microbial production observed between U Irrespective of the proportion of starch and fibre in the diets, the combination of two urea sources improved post-ruminal N digestion by an average of 2.
Compared to the control diet, the inclusion of OPT in the diets increased the total tract apparent N digestion 2. However, this effect may be more a function of the increased N content of the diet brought about by the replacements Holter and Reid, Thus, at a ratio of 4.
This improvement represents an increase of 0. If we consider that: i the contribution of digestible energy content in diets is mainly due to changes in the participation of corn and DDGS; ii that the DDGS contains a similar energy concentration as corn Depenbusch et al.
It is concluded that combining feed grade urea and Optigen resulted in positive effects on the MN flow and digestible energy of the diet, but apparently these advantages are observed only when there is a certain proportion 4. Either a higher or lower S:F ratio than 4. It is necessary to continue research on the conditions of the finishing diet so that it is possible to get the most out of it with the use of slow release urea. National Center for Biotechnology Information , U.
Asian-Australas J Anim Sci. Barreras , J. Estrada-Angulo , 1 and Y. Author information Article notes Copyright and License information Disclaimer. This article has been cited by other articles in PMC. Abstract As a result of the cost of grains, the replacement of grains by co-products i. For the above, four dietary treatments were compared: Diet formulated to supply 2.
Table 1 Ingredients and composition of experimental diets. Item Treatments U Open in a separate window. Table 2 Effects of treatments on ruminal pH taken at 0, 2, 4, and 6 h post-feeding. Table 3 Influence of treatments on characteristics of ruminal and total tract digestion in Holstein steers.
Official methods of analysis. Effect of ration on the nutritive quality of rumen microbial protein. J Anim Sci. Protein physiology and its application in the lactating cow: The metabolizable protein feeding standard. Corn distillers grains with solubles derived from a traditional or partial fractionation process: Growth performance and carcass characteristics of finishing feedlot heifers.
Comparative feeding value of distillers dried grains plus solubles as a partial replacement for steam-flaked corn in diets for calf-fed Holstein steers: characteristics of digestion, growth-performance, and dietary energetic.
Guide for the care and use of agricultural animals in agricultural research and teaching. Digestion kinetics of fiber: Influence of in vitro buffer pH varied within observed physiological range.
J Dairy Sci. Effect of crude protein level and limestone buffer in diets fed at two levels of intake on rumen pH, ammonia-nitrogen, buffering capacity and volatile fatty acid concentration of cattle. Comparison of metabolizable energy and productive determinations with growing chicks. J Nutr.
Optigen II Feed additive for dairy cows