Breed differences in sheep with respect to the accumulation of copper in the liver

Abstract

Male lambs of the pure breeds Texel, Flemish milk sheep, and Finnish landrace, and of the crossbreds Texel x Friesian milk sheep, Texel x Finnish landrace, Suffolk x Friesian milk sheep, and Finnish landrace x Ile de France were fed hay and concentrates, the latter differing only in the content of copper. At high (+/- 35 ppm) and at moderately low (+/- 10 ppm) copper levels in the concentrate, breed differences in the accumulation of copper in the liver were studied. Hepatic Cu-levels increased significantly in the case of the high Cu-fed animals, but great differences in the metabolism of excessive amounts of dietary Cu exist between the particular breeds and crossbreds. The Texel breed was most susceptible to an excess of dietary Cu and the Finnish landrace was the least susceptible breed, while the Flemish milk sheep and the crossbreds were intermediate. In blood serum, the enzyme activities of sorbitol dehydrogenase, lactate dehydrogenase, gamma-glutamyl transferase, and glutamic oxaloacetic transaminase were increased to a greater or less extent in the high Cu-fed animals, but the correlation with hepatic Cu-content was poor. For the most susceptible breeds, even a level of 10 ppm Cu in a ration with nearly equal amounts of hay and concentrate is insufficiently low for the prevention of Cu-accumulation in the liver.

Long‐Term Observation of Subclinical Chronic Copper Poisoning in Two Sheep Breeds

“…A significant difference between breeds was found at day 30, 75 and 110. Differences in Cu accumulation have often been described in other breeds (Lüke and Marquering, 1972; Van Der Berg et al., 1983; Woolliams et al., 1983; Suttle, 1987; Littledike and Young, 1993). The two breeds used in the present study may both be relatively resistant to Cu poisoning.…”

“…The diagnosis of chronic Cu poisoning in live sheep is difficult because of the very slow progress and the latent character of the disease (Ishmael et al., 1972). Acute haemolytic crisis has occasionally been observed in sheep some weeks after the onset of high Cu supplementation (Ishmael et al., 1972; Gooneratne et al., 1980; Van Der Berg et al., 1983; Zervas et al., 1990). In this study we experimentally exposed sheep to excess dietary Cu for 84 days to observe the development of and recovery from Cu intoxication by clinical and laboratory examination for a period of 978 days (2.7 years).…”

The effects of plastic slatted floor or straw bedding on performance, liver weight and liver copper concentrations in intensively reared lambs

“…One could postulate that, in contrast to the report of Woolliams et al (1983), the copper stored did not interfere with normal hepatic function. Copper is known to be incorporated into the mitochondria, microsomes, nuclei and soluble fraction of the parenchymal cells (Porter et al, 1961) with only small proportions binding to proteins in the liver (Van der Berg et al, 1983). Depending on where copper is stored, it may not restrict liver growth, development or function as sometimes reported, especially when the overall mean liver copper concentration was an acceptable 357 mg/kg DM.…”

Breed differences in sheep with respect to the interaction between zinc and the accumulation of copper in the liver

“…The management, the diets, and the analytical procedures are described in detail elsewhere (9,10). In brief, all animals were held in pens and were groupfed.…”

“…Some authors mentioned a considerable effect from Zn on the hepatic Cu-level, in contrast with other investigators. Where the susceptibility for a chronic Cu-intoxication in sheep was dependent on genetic factors (9,11,12), the mutual interaction between Cu and Zn could therefore also be dependent on genetic factors. The conflicting results regarding this interaction might be due to breed effects.…”