Efficacy of Copper Supplementation in the Prevention of Molybdenosis in Cattle

Abstract

Revegetation and sustainable cattle grazing are major objectives in the reclamation of mine tailings at the Highland Valley Copper mine in British Columbia, Canada. A total of 150 cows with their calves grazed forage extremely high in molybdenum (Mo) for 5-6 weeks in the summer and fall for 3 consecutive years (2002-2004). The average stocking rate was 0.89 ha per animal unit month. The animals' diet consisted primarily of alfalfa (Medicago sativa L.) and orchardgrass (Dactylis glomerata L.) containing 100-400 ppm Mo. Each year, the herd was divided into 2 groups of approximately 25 cow-calf pairs. One group was supplemented with 2.5% copper sulphate (CuSO 4 5H 2 O) in loose salt, and the other group was only given loose salt. Clinical signs of Mo toxicity, including lameness, diarrhea, and a faded hair coat, were significantly reduced in the supplement cows compared to control cows, which demonstrated the efficacy of the copper supplement treatment. Cattle also developed a tolerance to grazing high-Mo forage, as lameness and diarrhea were reduced in cows that had previous exposure to the site. However, lameness, the primary sign, and diarrhea were resolved in all cows by the end of each trial without treatment and hair coats returned to normal by the following spring. Only 4 calves showed signs of lameness or diarrhea in the 3-year study. Cattle grazing is a viable option for the end land use plan for Highland Valley Copper, provided a CuSO 4 5H 2 O supplement is available to counteract the toxic effects of the high-Mo forage. As well, animals with previous exposure to the site should be utilized, as they appear to develop a tolerance to the Mo in the forage. Resumen La revegetació n y el apacentamiento sostenible de ganado son los principales objetivos en la restauració n de las pilas de colas de la mina Highland Valley Copper en British Columbia, Canadá. Un total de 150 vacas con sus becerros apacentaron forraje con contenidos extremadamente altos de molibdeno (Mo) durante cinco o seis semanas en el verano y otoñ o por tres añ os consecutivos (2002-2004). La carga animal promedio fue de 0.89 ha por unidad animal mes. La dieta de los animales consistió principalmente de ''Alfalfa'' (Medicago sativa L.) y ''Orchardgrass'' (Dactylis glomerata L.) conteniendo 100-400 ppm de Mo. Cada añ o, el hato se dividió en dos grupos de aproximadamente 25 pares de vaca-becerro, uno de los grupos fue suplementado con 2.5% de sulfato de cobre (CuSO 4 5H 2 O) mezclado con sal suelta mientras que al otro se le suministro solo sal suelta (control). Los signos clínicos de intoxicació n por Mo, incluyendo la incapacidad para caminar por cojera, diarrea y decoloració n del pelo, fueron reducidos significativamente en las vacas suplementadas en comparació n con las vacas del grupo control, lo cual demostró la eficacia del cobre como tratamiento suplementario. El ganado también desarrolló una tolerancia a apacentar forraje con alto contenido de Mo ya que la cojera y la diarrea se redujeron en vacas que previamente habían sido expuestas ...

Chelation of Molybdenum in Medicago sativa (Alfalfa) Grown on Reclaimed Mine Tailings

“…Studies have shown however that residual Mo in the tailings is imbibed by vegetation and can accumulate to extremely high levels depending on the plant species and site , . Medicago sativa L. (alfalfa), a major forage at the Highmont site at HVC, accumulated 95−460 ppm Mo on a dry matter basis with no evidence of significant decreases in Mo since 1999, the year of establishment of plant cover at Highmont , . Animal health guidelines recommend a maximum level of 5 ppm Mo in feed for beef cattle .…”

Elimination of residual molybdenum in cattle exposed to high molybdenum forage

“…1, Table 2). The higher r 2 in 2004 compared with 2003 was attributed to decreased animal variability as 80% of the animals were new to the site in 2004 (Majak et al 2006). The parameter a of the In summary, the tissue elimination studies from 2003 and 2004 demonstrated that muscle and fat products from animals grazing Highmont could be used for human consumption one month after their departure from the site without significant tissue residues of Mo.…”

“…Cattle grazing trials were conducted during [2002][2003][2004] on the reclaimed Highmont tailings pond at HVC to determine whether forage high in molybdenum (Mo) could sustain cattle grazing without ill effects to livestock. Forage levels of Mo in alfalfa (Medicago sativa L.) and orchardgrass (Dactylis glomerata L.) at the site ranged from 100 to 400 ppm and did not change significantly between years (Majak et al 2006). Dietary levels of Mo in excess of 10 ppm are considered toxic (Puls 1994).…”

“…Hepatic levels of Mo that escalated during autumn grazing trials returned to normal baseline levels of 4.0 ± 0.2 ppm Mo by spring, approximately 6 to 8 mo later (Majak et al 2004(Majak et al , 2006. Cows that were used in the fall grazing trials were normally sold the following spring, which permitted the Mo to be dissipated during winter.…”

“…Each year, 10 different cows were randomly selected from the control group (Majak et al 2006) on the last day of the grazing trial and randomly divided into two groups of five (A and B). In addition to liver biopsies, which were normally obtained at the end of the grazing trials at Highmont, flank muscle and fat samples were also obtained from group A by surgical incision under local anesthesia.…”