Rumen degradable protein supply affects microbial efficiency in continuous culture and growth in steers

Abstract

We hypothesized that microbial effi ciency and output from fermentation in the rumen would be optimized when peptide supply was balanced with peptide requirement of ruminal microfl ora. This study was conducted to measure response of varying rumen degradable peptide (RDPep) supply on ruminal fermentation characteristics and steer growth. A continuous culture experiment was conducted with diets formulated to achieve a predicted RDPep balance (RDPep supplied above RDPep required) of -0.30 to 1.45% CP with rumen degradable N (RDN) balance (RDN supplied above RDN required) above dietary ammonia-N requirement of microbes. Two additional treatments had RDPep balances of -0.30 and 0.78% CP with insuffi cient ammonia-N supply to meet microbial requirements. Single-fl ow fermenters (N = 24; n = 6) were inoculated with rumen fl uid and maintained anaerobically at 39°C with a 0.06 h -1 dilution rate. Inadequate RDN decreased OM digestion and microbial N fl ow, and increased rumen undegradable N (P < 0.01). Microbial effi ciency decreased in RDNdefi cient diets and was greatest when RDPep balance did not excessively exceed microbial requirement of RDPep predicted (P < 0.01). A growth study was conducted with 49 yearling, crossbred, Angus steers (initial BW 370 ± 34 kg). Animals were assigned to 1 of 4 treatment groups by BW and further divided into 3 pens with 4 steers per pen to achieve similar initial pen weights. Treatments consisted of 4 isonitrogenous diets balanced for RDN but varying in predicted RDPep balance (0.55%, -0.02%, -0.25%, and -0.65% CP). Animals were maintained on treatment for 70 d with individual BW taken on d 0, 1, 21, 42, 70, and 71. Final BW decreased linearly with decreasing RDPep (P = 0.05). Average daily gain and G:F displayed a quadratic effect with greater ADG and G:F at greater and lesser RDPep levels (P = 0.02). We concluded that balancing RDPep supply to predicted requirement improved fermentation effi ciency and microbial output, which in turn improved animal performance.

The role of condensed tannins in ruminant animal production: advances, limitations and future directions

“…To optimize production efficiency, rumen degradable protein (RDP) must be balanced with energy availability to maximize microbial protein synthesis (Brooks et al, 2012). Post-ruminal amino acid composition can be manipulated through supplying rumen-undegradable protein (RUP) to match the amino acid requirements of the animal (Merchen and Titgemeyer, 1992;Schwab, 1995).…”

Manipulating Protein Degradability in the Rumen to Support Higher Ruminant Production

“…Positive effects of feeding more rumen un-degraded protein (RUP) in lactating dairy cows were indicated by increased feed efficiency and milk fat content (1.8 kg/d greater FCM and 0.08 kg/d greater fat), but milk protein content was lower and milk urea N and urinary urea excretion were elevated (Broderick et al 2009). The ratio between rumen degradable peptide supply and the peptide requirement of microbes for the optimum fermentation has been studied in steers (Brooks et al 2012); the results indicated that average daily gain and G:F displayed a quadratic effect with greater ADG and G:F at higher and lower rumen degradable peptide levels. It was concluded that increasing positive balancing rumen degradable peptide supply to predicted requirement (required minus supply) improved fermentation efficiency and microbial output, which in turn improved animal performance.…”

Amino Acids Metabolism in the Muscle of Sheep fed with Mitchell Grass Hay Supplemented with Gliricidia sepium

“…It was assumed that the spesific radioactivity (SRA) of leucine in the blood would start to plateau at two hours after the infusion started. Blood flow measurement was undertaken between the 3rd and 4th hour of L- [1][2][3][4][5][6][7][8][9][10][11][12][13][14] C]leucine infusion [20] by using 3 HOH (925 kBq/mL) solution that infused for 60 minutes into the right jugular venous catheter.…”

“…2 (2018) 75 -80 Atom Indonesia Journal homepage: http://aij.batan.go.id 0 amino acids needed for protein synthesis. The important of dietary nitrogen for ruminants is not only to supply amino acids, but also as nitrogen sources for microbial protein synthesised in the rumen [8,9]. Rumen microbial protein is also a contributor of amino acids for ruminant animals.…”