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.
Valkeners
D
D
Faculté universitaire des Sciences agronomiques, Passage des Déportés, 2 B-5030 Gembloux, Belgium.
Théwis
A
A
Amant
S
S
Beckers
Y
Y
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