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Title: Intake, digestibility, and passage rate of three warm-season grass hays consumed by beef steers

Author
item Turner, Kenneth
item Coleman, Samuel
item Chase, Chadwick - Chad

Submitted to: Joint Meeting of the ADSA, AMSA, ASAS and PSA
Publication Type: Abstract Only
Publication Acceptance Date: 3/7/2013
Publication Date: 7/8/2013
Citation: Turner, K.E., Coleman, S.W., Chase, C.C. 2013. Intake, digestibility, and passage rate of three warm-season grass hays consumed by beef steers. Joint Meeting of the ADSA, AMSA, ASAS and PSA. 91:702-703.

Interpretive Summary: Abstract only

Technical Abstract: Florida-44 bermudagrass [Cynodon dactylon (L.) Pers.] is a fine-stemmed forage selected from a Tifton-44 field near Brooksville, FL that had drifted from the original and is highly desired for horses. The objective here was to assess quality of warm-season grass hays at different maturities in stall-fed beef steers. Florida-44 bermudagrass (FL44); Tifton-85 bermudagrass (TF85); and Tifton-9 bahiagrass (Paspalum notatum Flueggé; TF9) were staged and harvested as hay at 5-wk and 7-wk intervals beginning 25 June from the ARS Station in Brooksville. Thirty-six steers were allotted to one of six hays fed in individual pens. After a 13-d adaptation, individual steers received a continuous release bolus containing C32 and C36 alkane wax as external markers to estimate fecal output, and a pulse-dose of Yb-labeled forage to estimate passage rate. Fecal samples were collected daily while forage and refusal samples were collected weekly. Fecal and forage samples were lyophilized and analyzed for n-alkane concentrations by GC and Yb by ICP. Forage digestibility (D) was estimated as the mean of D by the ratio of C31, C33, and C35 n-alkanes in forage and feces. Rate of passage was calculated by non-linear regression of Yb appearance on time from dosing. There was a hay x maturity stage interaction for DMI (g/kg BW; P < 0.05), D (P < 0.03) and passage rate (P = 0.09). Intake of hays at 5-wk regrowth was not different, but at 7-wk, rank was FL44 > TF85 > TF9. The DMI of 5- and 7-wk regrowth were similar for FL44 (mean 21 g/kg) and TF85 (mean 19 mg/kg), while DMI of 5-wk TF9 (18 g/kg BW) hay was greater (P < 0.05) than 7-wk TF9 hay (15 g/kg BW). The D of TF85 and TF9 (mean 59.4%) at 5-wk regrowth was greater (P < 0.01) than FL44 (52.8%) at 5-wk regrowth, whereas D of TF85 (57.3%) was greater (P < 0.02) than TF9 (52%) at 7-wk regrowth. Passage rate of the three hays at 5-wk regrowth were all similar (mean 4 %/hr), while at 7-wk regrowth TF85 and FL44 were similar (mean 5 %/hr); both were greater (P < 0.01) than TF9 (3%/hr). Quality of TF9 bahiagrass declined more rapidly than bermudagrass.