Effect of supplemental lysocellin and tetronasin on growth, ruminal and blood metabolites, and ruminal proteolytic activity in steers grazing ryegrass.
Forty-eight Angus and Brangus steers (249 kg initial BW) were used in a randomized complete block design. Steers grazed annual ryegrass (Lolium multiflorum [L.] Lam.) for 107 d and were sampled at 35 and 70 d. Treatments consisted of a corn supplement (C) or corn supplement plus either 80 mg.steer-1.d-1 of lysocellin (L) or 60 mg.steer-1.d-1 of tetronasin (T). When compared with C, ADG of L- and T-fed steers was higher (P less than .05) for the complete 107-d study (1.15 vs 1.25 kg/d). At 35 d, ruminal acetate:propionate ratio tended (P = .07) to be higher for C than for L- and T-fed steers (4.6 vs 3.8). When compared with T, steers fed L tended (P = .11) to have higher acetate:propionate ratios. Ruminal concentrations of ammonia and free amino acids were not affected (P greater than .05) by treatment, but ruminal proteolytic activity tended (P = .13) to be lower for L- and T-fed than for C steers at 70 d. Ionophores did not alter (P greater than .05) ruminal mineral concentrations, but ruminal Mg concentration tended (P = .14) to be higher for T- than for L-fed steers at 70 d. When compared with L- and T-fed steers, C steers had lower (P less than .05) plasma concentrations of Mg (23.7 vs 21.9 mg/liter) and Ca (113.0 vs 104.2 mg/liter) at 35 d. Plasma mineral concentrations were similar (P greater than .05) for L- and T-fed steers. Data are interpreted to indicate that L and T may improve ADG, decrease ruminal acetate:propionate ratio, and alter mineral metabolism.
Sticker
L S
LS
Dept. of Anim. Sci., Louisiana State Univ., Baton Rouge 70803.
Bunting
L D
LD
Wyatt
W E
WE
Wolfrom
G W
GW
D000596:Amino Acids / Q000032:analysis; D000641:Ammonia / Q000032:analysis; D000821:Animal Feed; D000818:Animals; D002118:Calcium / Q000032:analysis / Q000097:blood; D002417:Cattle / Q000097:blood / Q000254:growth & development* / Q000378:metabolism; D004987:Ethers / Q000494:pharmacology; D005232:Fatty Acids, Volatile / Q000032:analysis; D005663:Furans / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology*; D008129:Lolium; D008274:Magnesium / Q000032:analysis / Q000097:blood; D008297:Male; D011897:Random Allocation; D012417:Rumen / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D015430:Weight Gain / Q000187:drug effects
D000596:Amino Acids; D004987:Ethers; D005232:Fatty Acids, Volatile; D005663:Furans; D007476:Ionophores; C009818:lysocellin; D000641:Ammonia; C055416:tetronasin; D008274:Magnesium; D002118:Calcium