The aim of this study is to evaluate if dietary Cu supplementation that leads to a hepatic Cu accumulation over the normal range has an influence on trace element status that could contribute to the pathogenesis of other mineral related disorders. Samples (liver, kidney, spleen, diaphragm and brain) of beef calves receiving typical commercial diets Cu supplemented and non-supplemented were tested for differences in non-essential and essential trace elements determined by ICP-MS. As (kidney and diaphragm), Hg (liver and kidney), and Pb (liver, kidney and spleen) were significantly lower, while Cd residues (liver and kidney) were significantly higher in the Cu supplemented group. Mn and Ni significantly decreased and Mo increased in the brain, and Se (diaphragm) decreased in the Cu supplemented group. These interactions are unknown, and possibly with more than two metals involved as suggested in the case of the ratio Se:Cu in the animals of this study. The possible role of Cu supplementation on the status of certain metals associated to neurological diseases (Mn-Ni) in the brain deserves further investigation. Finally new research on Cu-Se supplementation is necessary to better understand the risk of the animals to suffer from Se deficiency.
To evaluate the influence of breed on the accumulation of dietary copper (Cu) in tissue, and on blood parameters indicative of Cu status, ten Galician Blond, nine Holstein-Friesian and ten Galician Blond x Holstein-Friesian cross (GB x HF) steers were fed diets supplemented with 35 mg/kg DM of CuSO4 during their growing and finishing periods. Blood samples were taken monthly, and samples of liver, kidney, brain, heart, spleen and muscle were taken at slaughter. Cu concentrations were determined by ICP-AES. Holstein-Friesian calves had significantly higher total liver Cu contents than Galician Blonds and GB x HF crosses (mean 1070, 663 and 868 mg, respectively), combined with higher hepatic Cu concentrations (174, 140 and 166 mg/kg wet weight, respectively). Holstein-Friesian calves had also the highest prevalence (89%) of hepatic Cu concentrations exceeding the toxic limit of 150 mg/kg wet weight. Breed did not have a statistically significant influence on blood parameters. With the exception of the semitendinosus muscle, where Holstein-Friesians (0.790 mg/kg) had significantly higher Cu levels than Galician Blonds (0.541 mg/kg) or GB x HF crosses (0.631 mg/kg), no other statistically significant differences by breed in the extrahepatic tissue Cu distribution were observed. A negative statistical association between carcass performance and the ratio of semitendinosus and liver Cu concentration could indicate that the animals with a better carcass performance (Galician Blonds) could need a higher Cu mobilisation into the muscle, resulting in a lower hepatic storage.
Abstract. The aims of the present study were 1) to evaluate the interlobular distribution of copper (Cu) in the liver of beef calves on a high-Cu diet, 2) to determine whether this distribution differs between Galician Blonds and Holstein Friesians, and 3) to determine whether in vivo needle biopsy provides an appropriate measure of overall hepatic Cu status. Liver biopsies were performed before slaughter on twenty-nine 10-month-old beef calves fed growing and finishing diets supplemented with 35 mg/kg of Cu sulfate (10 Galician Blonds, 9 Holstein Friesians, and 10 Galician Blond 3 Holstein Friesian crosses). At slaughter, samples taken from 6 regions of the liver (the internal and external faces of the right lobe; the left, caudate, and quadrate lobes; and the processus papillaris) were acid digested, and their Cu contents were determined by inductively coupled plasma atomic emission spectrometry. The highest Cu concentrations were found in the left lobe, followed by the processus papillaris, and the lowest Cu concentrations were found in the caudate and quadrate lobes. Different breeds differ in absolute hepatic Cu levels, but interlobular Cu distribution does not appear to depend on breed, at least when Galician Blonds are compared with Holstein Friesians. In vivo needle biopsy afforded accurate estimates of overall hepatic Cu status.
A feedlot growth-performance trial was conducted to evaluate the relative response to tempering when flake density (FD) of corn is increased from 0.31 kg/L (24 lb/bushel) to 0.39 kg/L (30 lb/bushel). Treatments were (1) non-tempered, FD = 0.31 kg/L; (2) non-tempered, FD = 0.39 kg/L; (3) tempered, FD = 0.31 kg/L and (4) tempered, FD = 0.39 kg/L. Tempering prior to flaking increased (21%, P < .01) the moisture content of corn as it exited the rolls and decreased (14%, P = .02) the starch enzymatic reactivity. Increasing roll tension to reduce FD decreased flake thickness (24%, P < .01) and increased starch reactivity (43%, P < .01). Increasing FD decreased (P = .03) estimated dietary NEm and NEg, and the estimated NEm and NEg values of steam-flaked corn by 2.3% and 2.9%, respectively. We conclude that whereas tempering corn grain before steam flaking increases the moisture content of corn as it exits the roles, it has minimal influence on the feeding value for corn for feedlot cattle. Increasing FD from 0.31 to 0.39 kg/L decreases starch reactivity and the net energy value of corn, but does not affect daily weight gain or carcass characteristics.
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