Yield and Composition of Midland Bermudagrass Selected by Beef Cows and Calves2

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Abstract
The effect of nitrogen fertilization on yield and composition and animal selectivity of Midland bermudagrass (Cynodon dactylon) was studied; three forage sampling techniques were used. Fifty-three hectares of bermudagrasss were divided into 12 pastures, and each pasture was fertilized in three split applications (May, July and September) with one of three levels of N (67, 202 and 336 kg N/ha) and one application (May) of P2O5 and K2O on the basis of soil analysis. Forage production was determined monthly by cage clipping (CC) under wire exclosures. Esophageal fistulated cows (12) and calves (12) were used to sample the composition of bermudagrass being selected (ES). Hand-clipped (HC) samples were used to estimate yield and quality of available forage. The high level of N fertilizer increased total and monthly average DM yield (P<.05) over that of the low level. Average total yields were 6,716 and 8,494 kg/ha in the low N and high N pastures, respectively. Chemical analysis of CC samples indicated that crude protein (CP) generally increased with increasing levels of N fertilizer in months when adequate moisture was available. However, overall average CP values were 15.6, 15.1 and 15.1% for low N, medium N and high N, respectively. In vitro dry matter disappearance (IVDMD), CP, gross energy (GE), and residual ash decreased from trial 1 (May) to trial 2 (July), whereas acid-detergent fiber (ADF), lignin and cellulose increased from trial 1 to trial 2. Animals selected forage that contained more CP and residual ash, and less GE and cellulose in trial 2 than trial 1. IVDMD and CP values from CC samples were more similar to ES samples than were values from HC samples. Copyright © 1975. American Society of Animal Science . Copyright 1975 by American Society of Animal Science.