Impacts of increasing amounts of supplemental soybean meal on intake and digestion by beef steers and performance by beef cows consuming low-quality tallgrass-prairie forage.

Abstract

Two experiments were conducted to evaluate the impacts of increasing levels of supplemental soybean meal (SBM) on intake, digestion, and performance of beef cattle consuming low-quality prairie forage. In Exp. 1, ruminally fistulated beef steers (n = 20; 369 kg) were assigned to one of five treatments: control (forage only) and .08, .16, .33, and .50% BW/d of supplemental SBM (DM basis). Prairie hay (5.3% CP; 49% DIP) was offered for ad libitum consumption. Forage OM intake (FOMI) and total OM intake (TOMI) were increased (cubic, P = .01) by level of supplemental SBM, but FOMI reached a plateau when the daily level of SBM supplementation reached .16% BW. The concomitant rises in TOMI and OM digestibility (quadratic, P = .02) resulted in an increase (cubic, P = .03) in total digestible OM intake (TDOMI). In Exp. 2, spring-calving Hereford x Angus cows (n = 120; BW = 518 kg; body condition [BC] = 5.3) grazing low-quality, tall-grass-prairie forage were assigned to one of three pastures and one of eight treatments. The supplemental SBM (DM basis) was fed at .08, .12, .16, .20, .24, .32, .40, and .48% BW/d from December 2, 1996, until February 10, 1997 (beginning of the calving season). Performance seemed to reach a plateau when cows received SBM at approximately .30% BW/d. Below this level, cows lost approximately .5 unit of BC for every .1% BW decrease in the amount of supplemental SBM fed. Providing supplemental SBM is an effective means of improving forage intake, digestion, and performance of beef cattle consuming low-quality forages.

Methodology for concurrent determination of urea kinetics and the capture of recycled urea nitrogen by ruminal microbes in cattle

“…Given the low N content of our diet, the low ruminal ammonia concentrations previously reported with a similar diet (Koster et al, 1996), and the availability of fermentable OM, we expected urea recycling to play a significant role in meeting ruminal N demands, especially for the control treatment, due to the relationships of these factors to urea transfer to the rumen (Kennedy and Milligan, 1980). Although supplementation of SBM corrected the degradable intake protein deficiency, in accordance with previous observations (Mathis et al, 1999), urea recycling still played a significant role in meeting microbial N demands and accounted for more microbial N mass than it did in the unsupplemented controls; however, a similar fraction of total microbial N was provided by recycled urea-N for both treatments.…”

Protein supplementation of ruminants consuming low-quality cool- or warm-season forage: Differences in intake and digestibility

“…For example, greater forage intake is routinely observed (forage DMI >1.7% of BW) in almost all studies with low-quality C3 forages, resulting in no increase in forage intake attributable to CPSupp (Mathis et al, 2000;Bohnert et al, 2002a,b;Currier et al, 2004). In contrast, intake of low-quality C4 forages is almost never maximized without CPSupp (routinely less than 1% of BW) and has been shown to increase with CPSupp from 30 to 100% compared with unsupplemented controls (DelCurto et al, 1990;Köster et al, 1996;Mathis et al, 1999).…”

Performance of Beef Cows Supplemented with De-oiled Rice Bran

“…However, the numerical decrease in hay DM intake noted with increasing DORB supplementation resulted in total DM intake not being significantly affected (P20.49). Positive responses in hay DM intake and animal performance have been observed when supplementing low-quality hays with protein (Mathis et al, 1999). The average CP concentration of the hay (6.9% CP, DM basis) in the present study was at the threshold (7% CP, DM basis) as to whether or not a response to CP supplementation would be expected (Mathis et al, 2000).…”