Submitted to: American Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 4/25/1997
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Mature ewes (24; 21 mo of age), of four breed groups (St. Croix, S; St. Croix x Romanov, SR; St. Croix x Texel, ST; Gulf Coast Native, N) and in early to mid-gestation, were used (4 x 2 x 3 factorial; eight simultaneous 3 x 3 Latin squares) to determine interactions in feed intake and digestion of breed group, tropical grass source (Eastern gamagrass, GG; switchgrass, SG), and hay cutting treatment (1=primary growth harvested on June 12, 1995; 2=primary growth harvested on August 14, 1995; 3=regrowth from June 12 to August 14, 1995). Soybean meal was supplemented, and BW was 39, 49, 46, and 59 kg (SE 2.5) for S, SR, ST, and N, respectively. Interactions between breed groups and forage treatments did not occur (P>.10). Hay DMI ranked (P<.05) hay cutting treatment 3>2>1 for GG and 2<1 and 3 for SG (59, 50, 67, 49, 38, and 46 g/kg BW.75 for GG-1, GG-2, GG-3, SG-1, SG-2, and SG-3, respectively; SE 1.5), and was 60, 57, 48, and 40 g/kg BW.75 for S, SR, ST, and N, respectively (SE 2.6). Hay OM digestion was greater (P<.05) for GG vs SG and for cuttings 1 and 3 vs 2 (52, 41, 53, 36,. 22 and 34% for GG-1, GG-2, GG-3, SG-1, SG-2, and SG-3, respectively; SE 2.1). Digestible hay OM intake differed among treatments as noted for hay intake (28.1, 20.1, 32.8, 16.8, 8.0, and 14.8 g/kg BW 75 for GG-1, GG-2, GG-3, SG-1, SG-2, and SG-3, respectively; SE 1.22), and was 23.1, 23.5, 19.0, and 14.9 g/kg BW 75 (SE 1.63) for S, SR, ST, and N, respectively. In conclusion, effects on intake and digestion of grass source and hay cutting treatment were similar among breed groups. St. Croix and SR may be better suited for early to mid-gestation consumption of such tropical grass hay sources compared with ST, and N may require supplementation for BW maintenance.