Effect of various levels of imbalance between energy and nitrogen release in the rumen on microbial protein synthesis and nitrogen metabolism in growing double-muscled Belgian Blue bulls fed a corn silage-based diet.
Seven double-muscled Belgian Blue bulls (initial BW: 341 +/- 21 kg) with cannulas in the rumen and proximal duodenum were used in an incomplete replicated Latin square. The study examined the effect of imbalance between energy and N in the rumen on microbial protein synthesis and N metabolism by giving the same diet according to 3 different feeding patterns. The feed ingredients of the diet were separated into 2 groups supplying the same amount of fermentable OM (FOM) but characterized by different levels of ruminally degradable N (RDN). The first group primarily provided energy for the ruminal microbes (12.5 g of RDN/kg of FOM), whereas the second provided greater N (33.3 g of RDN/kg of FOM). These 2 groups were fed to the bulls in different combinations with the aim of creating 3 levels of imbalance (0, 20, and 40 g/ kg of DM) between energy and N supplies in the rumen. Imbalance was measured by the variation of the degradable protein balance (OEB value in the Dutch system) of the diet between the 2 meals each a day. Diurnal variations in ruminal NH3-N concentrations and plasma urea concentrations were greatly influenced by the feeding patterns of the diet. Introduction of imbalance affected neither microbial N flow at the duodenum (P = 0.97) nor efficiency of growth (P = 0.54). The feeding patterns of the diet had no negative impact on NDF degradation in the rumen (P = 0.33). Nitrogen retention was not affected by imbalance (P = 0.74) and reached 49.7, 52.0, and 51.3 g/d, respectively for 0, 20, and 40 g of OEB/kg of DM imbalance. It seems that introduction of an imbalance between energy and N supplies for the ruminal microbes by altering the feeding pattern of the same diet does not negatively influence the microbial activity in the rumen nor N retention of the animal. Nitrogen recycling in the rumen plays a major role in regulating the amount of ruminally available N and allows a continuous synchronization of N and energy-yielding substrates for the microorganisms in the rumen. Therefore, imbalance between dietary energy and N created over a 24-h interval was not detrimental to rumen microbial growth for the animal as long as the level of imbalance did not exceed 40 g of OEB/kg of DM. Thus, these feeding patterns of the diet can be used under practical feeding conditions with minimal impact on the performance of ruminant animals for meat production.
Faculté universitaire des Sciences agronomiques, Passage des Déportés, 2 B-5030 Gembloux, Belgium.
D
D
Valkeners
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Théwis
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Amant
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Y
Beckers
D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle / Q000145:classification / Q000378:metabolism*; D003433:Crosses, Genetic; D004032:Diet / Q000662:veterinary; D004063:Digestion; D004386:Duodenum / Q000378:metabolism; D004734:Energy Metabolism; D005285:Fermentation; D008297:Male; D009584:Nitrogen / Q000378:metabolism*; D014176:Protein Biosynthesis; D012417:Rumen / Q000382:microbiology*; D012820:Silage; D013997:Time Factors; D014508:Urea / Q000097:blood; D003313:Zea mays
D014508:Urea; D009584:Nitrogen