Abstract #T185

# T185
Adding medium quality hay to the diet of stocker calves grazing annual ryegrass did not improve beef production.
Guillermo Scaglia*1, Cathy Williams2, Ashley Dolesji2, 1LSU AgCenter, Iberia Research Station, Jeanerette, LA, 2LSU AgCenter, School of Animal Sciences, Baton Rouge, LA.

Strategic use of hay may allow increasing the stocking rate of small areas of high nutritive value pastures, benefiting producers by keeping a greater number of calves for stocker programs. The objective was to compare performance and blood metabolite concentrations of beef steers continuously stocked on annual ryegrass (Lolium multiflorum Lam. ‘Marshall’) or grazing and strategically receiving bermudagrass (Cynodon dactylon ‘Jiggs’) hay (CP = 9.6%; TDN = 50%; NDF = 67%). For 3 consecutive years, 54 steers (BW = 229 ± 2.9 kg) were used. Treatments (3 replicates; n = 6 steers) evaluated were: 1) steers (CON) continuously stocked on ryegrass (1.33 ha; 4.5 steers/ha; 1040 kg BW/ha); 2) steers grazed 50% of the area assigned to CON (0.67 ha; 9 steers/ha; 2081 kg BW/ha) on alternate days (HAY24) and fed hay in a barn; 3) steers grazed 50% of the area assigned to CON (0.67 ha; 9 steers/ha; 2079 kg BW/ha) for 96 h, then were hay-fed in the barn for 72 h (HAY72). Steers were individually fed hay using Calan gates. Blood samples were obtained on 4 consecutive days (d1 after 24 h on ryegrass). Data were analyzed using Proc mixed. Pastures grazed by HAY24 and HAY72 steers had greater (P < 0.05) forage mass than CON from d 28 until the end of the grazing season. Concentrations of ADF (27 and 23%) and NDF (41 and 37%) were greater and IVDMD (74 and 78%) was lower (P < 0.05) in ryegrass grazed by HAY72 vs. CON, respectively. Production (kg/ha) and ADG (kg) were greater (P < 0.05) for CON (498 and 1.2, respectively), intermediate for HAY24 (418 and 0.8, respectively), and lowest for HAY72 (352 and 0.6, respectively). Plasma urea nitrogen (PUN) concentration was greatest (P < 0.001) for CON (28 mg/dL), intermediate for HAY24 (24 mg/dL), and lowest for HAY72 (21 mg/dL). NEFA concentrations were similar for CON and HAY24 (0.32 mEq/L) but lower (P < 0.001) than HAY72 (0.47 mEq/L). Concentration of PUN decreased (26 to 23mg/dL) and NEFA increased (0.31 to 0.45 mEq/L) linearly (P = 0.003; P < 0.001, respectively) from d1 to d4 of sampling. Steers in HAY72 consumed 13% less hay (P < 0.05) than those on HAY24. In the present experiment, hay feeding strategies negatively affected animal performance.

Key Words: hay, ryegrass, stocking rate