Manipulation of nitrogen digestion by sheep using defaunation and various nitrogen supplementation regimens.

Abstract

Five ruminally, duodenally, and ileally cannulated sheep (average BW 62 kg) were fed 65% roughage: 35% concentrate diets (CP = 15%) in a 5 x 5 Latin square design to study the applicability of using a combination of defaunation with N supplements (soybean meal [SBM], corn gluten meal [CGM], blood meal [BM], urea, and casein) with different extents of ruminal degradation to manipulate microbial protein synthesis and amount of ruminal escape protein. Diets were fed twice daily (1,759 g DM/d). Defaunation was accomplished with 30-ml doses of alkanate 3SL3 (active ingredient: sodium lauryl diethoxy sulfate)/sheep daily for 3 d with 2 d of fasting. Treatment 1 (control) involved feeding faunated sheep a diet in which the supplemental N (45% of total dietary N) was 67% SBM N and 33% urea N. Treatment 2 involved feeding defaunated sheep the same diet as the control. Treatments 3, 4, and 5 involved feeding defaunated sheep diets in which the supplemental N source was either 67% CGM-BM (1:1 N ratio) N:33% urea N, or 33% CGM-BM N:67% urea N or 33% CGM-BM N:33% urea N:33% casein N, respectively. Compared with the faunated control, defaunation decreased (P less than .05) ruminal ammonia concentration (19 vs 26 mg/dl) and increased (P less than .05) CP flow to the duodenum (253 vs 214 g/d) due to a trend for increases in both bacterial (BCP) and nonbacterial (NBCP) CP flows.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of feeding lauric acid on ruminal protozoa numbers, fermentation, and digestion and on milk production in dairy cows1

“…1). Ruminal ammonia concentration is a good indicator of N utilization within the rumen (Hristov et al, 2004), and reduction in ruminal ammonia concentrations is often reported in studies where RP have been eliminated (Hsu et al, 1991;Williams and Coleman, 1992;Jouany, 1996). Reduction in ruminal ammonia is believed to occur due to a decrease of bacterial N turnover within the rumen, which is a consequence of decreased bacterial predation by RP.…”

The Rumen Microbial Ecosystem

“…In particular, the protozoal proteins, although of similar biological value to bacterial protein, are readily digested (McNaught et al, 1954;Bergen et aI., 1968) and the lipid fraction contains proportionally more unsaturated fatty acids . The consensus of studies undertaken in the 20-year period following on from the work of Weller and Pilgrim (1974) is that whereas bacterial flows from the rumen are similar to predicted outflow rates, the actual flows of protozoa were generally only 20-40% of the calculated outflow rate from the rumen Hsu et al, 1991;Ivan et aI., 1991;Punia and Leibholz, 1994;Punia et aI., 1992). Weller and Pilgrim, 1974;Harrison et aI., 1979;Michalowski et al, 1986) have confirmed that the ciliates are selectively retained within the rumen.…”

Manipulation of amino acid supply to the growing ruminant1

“…Selected data from the report by Hsu et al (1991;Table 2) show the effects of defaunation on postruminal AA supply. Sheep were defaunated by administration of alkanate 3SL3 as described by Hsu et al (1989).…”

“…Supplies of both bacterial and nonbacterial AA are increased by defaunation, and this would predictably have little effect on AA profile. The lack of effect of defaunation on quality of postruminal AA supply is illustrated in Figure 2, in which the average AA profiles of digesta from defaunated and faunated sheep from several studies (Veira et al, 1983; Kayouli et al, 1986;Hsu et al, 1991) are compared.…”