Effect of ammonium sulfate fertilization on bahiagrass quality and copper metabolism in grazing beef cattle

Abstract

To assess the impact of S fertilization on bahiagrass (Paspalum notatum) quality and Cu metabolism in cattle, two studies were conducted during the summer grazing season (1999 and 2000). Pasture replicates (16.2 ha; n = 2/treatment) received the same fertilizer treatment in each growing season, consisting of 1) 67 kg N/ha from ammonium sulfate (AS), 2) 67 kg N/ha from ammonium nitrate (AN), and 3) control (no fertilizer; C). Forage sampling was conducted at 28-d intervals following fertilization by the collection of whole plants (four samples/pasture) in randomly distributed 1-m2 grazing exclusion cages and analyzed for CP, in vitro organic matter digestibility, S, P, Ca, K, Mg, Na, Fe, Al, Mn, Cu, and Zn. To determine the effect of fertilizer treatment on liver trace mineral concentrations in grazing cattle, random liver tissue samples were collected (n = 12; four/treatment) at the start and end of the study period in 2000. Ammonium sulfate fertilization increased (P < 0.001) forage S concentration in both years. Plant tissue N concentrations were increased by N fertilization, regardless of source, in 2000, but not in 1999. Cows grazing AS pastures had lower (P < 0.05) liver Cu concentrations at the end of the study period in 2000 compared to AN and C. In Exp. 2, 37 Cu-deficient heifers grazing AS fertilized pastures were obtained from the same location and allocated to one of two treatments, consisting of supplements providing 123 mg/d of either inorganic (Cu sulfate; n = 12) or organic (Availa-Cu; n = 15) Cu. Treatments were delivered for 83 d. Liver Cu increased over time in all heifers regardless of treatment; however, heifers supplemented with Availa-Cu tended (P = 0.09) to have higher mean liver Cu concentrations than those receiving Cu sulfate. The results of these studies indicate that AS fertilization of bahiagrass increases forage S concentrations. When provided free-choice access to a complete salt-based trace mineral supplement, cows grazing AS-fertilized pastures had lower liver Cu concentrations than cows grazing pastures fertilized with AN; upon removal from high-S pastures, cattle were able to respond to Cu supplementation.

Polioencefalomalacia experimental em bovinos induzida por toxicose por enxofre

“…A explicação para incremento do enxofre no feno pode ser justificada pela intensa adubação com sulfato de amônio realizada pela empresa que comercializou o volumoso objetivando aumentar o seu valor nutritivo. O sulfato de amônio quando utilizado como fertilizante proporciona aumento na concentração de enxofre na forragem (Arthington et al 2002) e melhora a digestibilidade da fibra em detergente ácido e da fibra em detergente neutro das forragens cultivadas nestes solos, quando fornecida aos ruminantes (Ahmad et al 1995).…”

Land Application of Aluminum Water Treatment Residual: Aluminum Phytoavailability and Forage Yield

“…Plant Al concentrations (21-80 mg kg 21 ) were within the range of common (nontoxic) plant Al concentrations (10-1000 mg kg 21 ) reported by Pais and Jones (1997). Arthington et al (2002) also found an average Al concentration of (Hylton et al 1965;Kincheloe et al 1987;USDA 1996;Arthington 2002). In addition, and most importantly, no visual symptoms of Al toxicity were observed in any treatment throughout the study.…”

Molybdenum and Copper Uptake by Forage Grasses and Legumes Grown on a Metal‐Contaminated Sludge Site

“…Elevated forage sulfur can increase the severity of copper deficiency in grazing cattle for any particular Cu:Mo ratio in the forage (Arthington et al 2002;Suttle 1991). Because sewage sludge application to pastures increases the S concentration in forage legumes and grasses (McBride and Cherney 2004;Tiffany et al 2000b), there is potential for this practice to increase risk of Cu deficiency in grazing ruminants.…”