|Sauer, Thomas - Tom|
Submitted to: Professional Animal Scientist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/30/2004
Publication Date: 3/15/2004
Citation: Mcginley, B.C., Coffey, K.P., Sauer, T.J., Humphry, J.B., Goodwin, H.L., Coblentz, W.K., Mcbeth, L.J. 2004. Mineral content of forages grown on poultry litter amended soils. Professional Animal Scientist. 20:136-145. Interpretive Summary: Commercial poultry operations use wood chips and/or grain residues as bedding material for the birds. The combination of bedding material and the manure from the chickens is called litter. Chicken litter is typically spread on fields as a fertilizer for crop growth. This study looked at how the nutrient content in grasses of pastures was affected by many years of chicken litter application. Samples of grass from four pastures in Arkansas and Oklahoma were sampled periodically over two years. It was found that most of the time the grass had enough of the major nutrients needed for proper nutrition of pregnant or lactating beef cows. However, there were some times of the year when some minerals were lacking. This research shows that ranchers should provide mineral supplement that contains magnesium and copper to beef cows to make sure that the cows have enough of these key minerals. This research is important to ranchers who fertilize their pastures with chicken litter as it shows that some mineral supplementation is necessary to keep their herds healthy.
Technical Abstract: Large quantities of poultry litter are applied each year to pastures in the poultry-producing areas of Arkansas and Oklahoma, resulting in an increase of certain soil minerals. The objective of this study was to monitor the mineral concentrations in forages grown on poultry litter-amended soils and compare concentrations of these minerals with those required by beef cows during gestation and early lactation. Forage samples were gathered from four farms in northwest Arkansas and northeast Oklahoma from April 2000 to March 2002. Mean forage Ca, P, K, S, Fe, and Zn concentrations from each farm were greater (P<0.05) than requirements for beef cows in gestation and lactation. Calcium, P, K, and Zn concentrations rarely fell below the lactation requirements on any date. Mean forage Mg concentrations from one farm were (P<0.05) greater than the requirements for lactating beef cows while those from three farms did not differ (P>0.05) from the lactation requirements. Mean tetany ratios from all farms were below (P<0.05) the tetany threshold of 2.2, but forage from two farms surpassed the tetany threshold during the spring of 2000 and one surpassed it during the spring of 2001. Average forage Cu concentrations were above (P<0.05) requirements on one farm, below (P<0.05) requirements on another farm, and did not differ (P>0.05) from the requirements on two farms. Pastures fertilized with broiler litter may meet most but not all mineral requirements of beef cattle and warrant supplementation of specific minerals, particularly Mg and Cu.