Protein Levels In Single Cells Research Articles

Evaluation of a Yeast Single Cell Protein with Young Pigs

The digestibility and utilization of nitrogen (N) were compared between a yeast single-cell protein (SCP) and dehulled soybean meal (SBM) during two, 5-day total collection periods. Semipurified diets supplying 18% crude protein from either SCP or SBM as the only protein sources were fed in a metabolism trial to 12 pigs that weighed 5.6 kg at the beginning of the experiment. Both diets were supplemented with methionine. These same pigs were used in an intermediate period to obtain estimates of metabolic fecal nitrogen (MFN) and endogenous urinary nitrogen (EUN) of .101 and .313 g/lOOg of feed intake, respectively. These estimates were made by extrapolating nitrogen intake to zero from low protein (3, 6, 9 and 12%), dried skim milk diets. Apparent dry matter and N digestibility coefficients were higher (P<.01) for the SCP than for the SBM diet. The differences between diets were greater in period 1 than in period 2 (interactions, P<.01 for DM and P<.05 for N). Apparent biological values (BV) of 72.5 and 73.7 for SBM and SCP, respectively, were not significantly different (P>.10). Apparent net protein utilization (NPU) values of 64.8 and 69.3 for SBM and SCP diets, respectively, differed (P<.10) and the source difference was greater in period 1 than in period 2 (interaction, P<.10). True BVs of 84.4% and 84.1% were similar, as were true NPU values of 78.1 and 81.6% for SBM and SCP diets, respectively. Plasma urea N levels, but not plasma α-amino N, were higher (P<.05) 4 hr after feeding in pigs fed SBM than in those fed SCP. In a second experiment the yeast SCP product replaced none, one-third, two-thirds or all of the SBM in the diet of weanling pigs. Diets were not supplemented with methionine. The SCP levels did not affect (P>.05) average daily gain (ADG), average daily feed intake (ADF) and gain to feed ratio (G:F). As SCP level increased, the plasma urea N (PUN) level decreased (linear and quadratic effects, P<.01). Diets did not affect plasma α-amino N concentration. In a third experiment, the SCP product, at a level that replaced 50% of the SBM in the diet, was compared with a second SCP product at the same feeding level and with a control diet containing no SCP. Diets were not supplemented with methionine. Source of protein did not (P>.05) differentially affect ADG, ADF, G:F, PUN and plasma a-amino N of weanling pigs. Results of these experiments indicate that the SCP product described and tested is an excellent protein feedstuff for use in diets fed to weanling pigs.

Evaluation of a Yeast Single Cell Protein in Pig Diets

SUMMARY The value of a yeast single cell protein (SCP) as a partial replacement of dehulled soybean meal (SBM) in the diet for baby pigs and growing pigs was investigated in two experiments. In the first experiment, SCP replaced 0, 26.6, 53.2 and 79.8% of the SBM in the diet. The average daily gain response to increasing levels of SCP was quadratic and was maximized in baby pigs fed the diet in which SCP replaced 53.2% of the SBM. Response of average daily feed intake to treatments was similar to rate of gain. There was a linear improvement in feed efficiency as yeast SCP replaced soybean meal. The linear improvement suggested that palatability, not toxicity or nutrient imbalance, caused the reduced feed intake and rate of gain by pigs fed the highest level of SCP. Increasing levels of yeast SCP resulted in a linear decrease in plasma urea nitrogen, a linear increase in plasma a-amino nitrogen and no change in plasma uric acid. In experiment 2, yeast SCP replaced 0, 25 and 50% of the dehulled SBM in the diet of growing pigs (28 kg average initial weight). No significant treatment differences were observed for average daily feed and average daily gain, but gain:feed ratio increased linearly as the level of yeast SCP increased in the diets. In a third experiment, nitrogen digestibility and retention of the yeast SCP was evaluated with baby pigs. Comparisons were made between a diet with corn, SBM and dried whey as protein sources, a diet with these sources finishing half the protein and SCP furnishing the other half, and a third diet with all protein from SCP. Both nitrogen digestibility and nitrogen retention as a percentage of nitrogen

Single Cell Protein in the Diets of Pigs and Chickens

Pigs and chickens were fed diets containing increased concentrations of the single cell protein (SCP), Pruteen, in order to investigate the effects of a diet containing high levels of nucleic acids on the activity of DNase in intestinal contents. Increased levels of SCP in the diet generally resulted in increased DNase activity in intestinal contents. Significant differences at P≦0.05, were found between the control groups and most of the experimental groups in both species. With the exception of the 2 groups given the highest levels of SCP in the chicken experiment, the DNases in the large intestines were not inhibited by antisera produced against DNase in pancreatic juice.