Pre-conditioning beef calves with high moisture forages and co-product feeds

Abstract

A 45-d backgrounding study was conducted at the E.V. Smith Research Center in Shorter, AL to determine animal performance differences of pre-conditioned beef calves fed annual ryegrass (Lolium multiflorum) baleage, bermudagrass (Cynodon dactylon) hay, or corn (Zea mays) silage-based diets. Annual ryegrass (cv. Marshall) was harvested for baleage on 22 Apr 2015 at the late boot stage of maturity. The forage was allowed to wilt for 48 h until it achieved 60% moisture, baled and wrapped. Tifton 85 bermudagrass used for the study was harvested at a 4 to 5 wk interval in early summer 2015. Based on forage quality, calves were supplemented with an energy-protein based ration (50:50 soybean hulls and corn gluten feed for baleage and hay treatments, and 85% corn, 15% cottonseed meal mix for corn silage treatments) to target 0.7 kg/day ADG according to NRC (2000) recommendations. The 45-d background trial began on 9 September 2015 after animals were sorted and acclimated to the diets. 108 weaned calves [heifers (n = 54; mean initial BW 283 kg) and steers (n = 54; mean initial BW 284 kg)] were placed into nine pens (n = 12/pen, 3 pens/treatment). Sex was distributed evenly across treatments. Animals were weighed on d 0, 22, and 44, and the study concluded on 23 October 2015. Animal performance measures were analyzed using PROC Mixed in SAS 9.4 as a completely randomized design, and pen was the experimental unit. Mean initial and final BW of the animals did not differ (P = 0.50 and P = 0.99, respectively) across treatments. Average daily gain for annual ryegrass baleage, bermudagrass hay, and corn silagebased diets were 0.61 kg/day, 0.72 kg/day, and 0.72 kg/day, respectively, and did not differ across treatments (P = 0.57). Based on these results, these forage options achieved a similar level of gain when supplemented for pre-conditioning beef calves. In vitro dry matter digestibility (DMD) of diets used for pre-conditioning calves did not differ across a six-time point evaluation, and had an IVDMD of 70.1% at the 48 h digestion point. Results of the digestion trial indicate that supplementation of stored forages did not improve diet digestibility compared to forage alone. Economic analysis revealed that the cost of feeding a baleage diet in this system was higher than that of corn silage or bermudagrass diets with a cost of $1.37/hd/d compared to $1.02 and $0.95/hd/d, respectively.