Evaluating supplementation programs for growing calves grazing bermudagrass pastures

Abstract

Objective

Our objective was to determine gain in response to hand-fed (HF) or self-fed (SF) summer supplementation programs at the University of Arkansas Livestock and Forestry Research Station, on twenty 0.81-ha common bermudagrass (Cynodon dactylon [L.] Pers.) pastures at a stocking rate of 6.17 calves/ha (BW ± SD = 247 ± 24.6) over 3 yr.

Materials and Methods

This experiment was designed in a 2 × 2 + 1 factorial arrangement of treatments including control (CON), with only free-choice mineral; HF, 1.13 kg/d byproduct-based supplement offered only late summer (LS) or all summer (AS); or SF tub supplement (PVM Cattle Tub, Positive Feed Ltd., Sealy, TX) either LS or AS. The HF supplement in yr 1 was a 50:50 blend of soybean hulls and corn gluten feed, in yr 2 an extruded dried distillers grains cube (MasterHand Milling, Lexington, NE) was used, and in yr 3 corn gluten feed was the HF supplement. Data were analyzed as a generalized randomized complete block design using the mixed procedure of SAS (SAS Institute Inc., Cary, NC). Fixed effects in the model included supplementation treatment, year, and year × treatment interaction.

Results and Discussion

Even though different HF supplements were used each year, there were no year × treatment interactions. Early summer ADG was greater for HFAS than CON and SFAS, whereas supplemental efficiency (kg added gain/kg supplement) in early summer was less for SFAS than HFAS. Late summer ADG was greater for HF treatments than SF treatments and CON, whereas SF did not differ among supplement treatments. Cost of added gain was $28.33 and $16.14/kg for SFAS and SFLS, respectively, compared with $3.32 and $1.68/ kg for HFAS and HFLS, respectively.

Implications and Applications

Calves on this experiment did not respond as expected to the SF supplement, likely because the bermudagrass pastures in this experiment averaged over 13% CP and were in excess of 10% even in the LS sampling periods. Depending on supplement delivery costs, the most cost-effective way to add gain with supplement to growing calves grazing bermudagrass pasture is by HF.