Growth performance of beef cattle fed corn silage-based rations without Cu, Zn, Mn, Co and Se supplementation

SUMMARY: The objective of the present study was to investigate whether corn silage-based rations require a supplementation with copper, zinc, manganese, cobalt and selenium. For this purpose, young bulls of German Simmental breed were divided into 7 groups and fed diets based on corn silage and 2.4 kg concentrate supplemented with adequate Cu, Zn, Mn, Co and Se (control group), without any trace element supplementation, or without one of these elements over a total of 301 and 308 days, respectively. The experimental period was subdivided into 3 fattening periods differing in weight categories (207-350 kg, 350-475 kg, >475 kg). Feed analyses showed that the native amounts of Cu and Zn in corn silage-based rations were on average 6.5 mg/kg DM and 27 mg/kg DM, respectively, which were moderately below the supplemented levels. Native Mn (19 mg/kg DM), Co (87 μg/kg DM), and Se (50 μg/kg DM) levels were distinctly below the control levels. Bulls finished on a trace element-non-supplemented ration markedly reduced their mean daily feed intake relative to the controls (5.86 kg DM vs. 7.65 kg DM), and developed impaired growth. These alterations were most pronounced in the 3rd fattening period. This was obvious by an extremely reduced final live weight compared to the controls (536 kg vs. 636 kg), and by weight gain reduction in each fattening period which was 13%, 41% and 66% below the control level. On closer examination, sub-optimal Co was mainly responsible for the reduced feed consumption and growth. Bulls non-supplemented with Co diminished feed consumption already 70 days after the beginning of the experiment. From half of the experimental period, feed intake was diminished by about 1.5 kg DM compared to the controls. Also daily weight gain was markedly lowered during the experiment (991 g vs. 1426 g). The alterations in growth performance were accompanied by a significant deposition of body fat of 30% in the group without trace element supplementation and 23% in the group without added Co. Also non-supplementation of Mn moderately affected growth, which was shown in a daily weight gain reduction of about 70 g, whereas the tissue composition remained unchanged. In contrast, the lacking addition of Cu, Zn and Se did not contribute to the impaired growth performance and altered carcass characteristics under these experimental conditions.