Intake, digestibility, and rumen fermentation by lactating beef cows offered bermudagrass hay with different sources of dried distillers grains

Abstract

Supplements of protein co-products, such as dried distillers grains with solubles (DDGS), are often offered to lactating beef cattle consuming bermudagrass [ Cynodon dactylon (L.) Pers.]. The quality of DDGS can vary greatly by source, including levels of ADIN, which could influence hay intake and digestibility. The aim of the experiment was to evaluate bermudagrass hay intake, digestibility, and in situ forage disappearance for lactating beef cows consuming DDGS from different sources and ADIN levels. Four 8-yr-old multiparous, ruminally cannulated lactating beef cows (535 ± 6.3 kg) were offered each of 4 diets during 1 of the 4 periods in a 4 × 4 Latin square design. Diets consisted of bermudagrass hay (17.7% CP) without supplement (CON) or with supplementation with 0.45% of BW (DM basis) from either DDGS source 1 (DG1; 29.7% ADIN), DDGS source 2 (DG2; 31.2% ADIN), or DG2 that was heated (HDG2; 41.3% ADIN). Hay and NDF intake (g/kg of BW) were greater ( P = 0.04) from CON compared with DG1 and DG2; HDG2 did not differ from any treatment. Ruminal ammonia concentrations were greater ( P = 0.05) from DG1 and DG2 compared with the CON, and DG1 was greater than HDG2. However, HDG2 did not differ from DG2 or CON. Ruminal acetate ( P = 0.03) and butyrate ( P = 0.01) had diet-by-time interactions, and propionate was less ( P < 0.05) in CON compared with the other diets. The water-soluble fraction for bermudagrass hay was greater ( P = 0.05) from cows offered DG1 compared with DG2 and HDG2 but not different from that of CON cows. Different DDGS sources and ADIN of 41.3% of N did not affect total intake or digestibility of bermudagrass for lactating beef cows.