The effect of xylazine and xylazine followed 20 minutes later by insulin upon glucose metabolism and plasma insulin concentrations was examined in three cows. After doses of 0.18 mg per kg xylazine given intramuscularly (IM) or 0.15 mg per kg given intravenously (IV) hepatic glucose production increased, plasma insulin concentrations decreased to 25 to 33 per cent of control values, and there was a prolonged hyperglycaemia. When 200 units of soluble insulin were given 20 minutes after similar doses of xylazine there was a rapid fall in blood glucose and a reduction in the rate of glucose production by the liver. Xylazine-induced hyperglycaemia arose from a combination of increased hepatic glucose production and reduced plasma insulin concentrations. Peripheral tissues were still responsive to insulin and when adequate insulin was available blood glucose concentrations rapidly decreased.
During the grazing seasons of 1978 and 1979, 126 Hereford cross Friesian and 25 Charolais cross Friesian steers were used in controlled trials of the effects of injecting them with copper and, or, selenium. In both seasons the unsupplemented steers had low blood concentrations of copper, selenium and glutathione peroxidase, whereas the supplemented steers maintained their serum copper concentrations within the normal range and had significantly higher whole blood concentrations of selenium and glutathione peroxidase than the unsupplemented animals. Supplementing the steers with 400 mg copper during 1978 increased their growth rate by 0.032 kg/day and supplementing them with 200 mg copper during 1979 increased it by 0.080 kg/day. Supplementing the steers in each year with two doses of selenium, each of 0.15 mg selenium/kg bodyweight, increased their growth rate by 0.041 kg/day in 1978 and by 0.060 kg/day in 1979. There was no interaction between the selenium and copper treatments and the total increases in liveweight gains due to both supplements were around 11 kg in 1978 and 16 kg in 1979.
Twenty Angus cross heifers were fed a complete diet which contained 0.07 mg selenium/kg dry matter. Thirteen were injected subcutaneously with barium selenate at a dose rate of approximately 1 mg selenium/kg bodyweight and seven remained untreated. All the heifers were slaughtered during the following 121 days, the last of the treated group 119 days after injection. Glutathione peroxidase activity in blood increased within four weeks of administration and remained high thereafter. The selenium dependent glutathione peroxidase activity did not increase in liver kidney or muscle. The concentrations of selenium in the blood, liver and muscle were increased significantly from 30 days until 119 days. Between 76 and 99 per cent of the selenium injected remained at the site of injection.
Parenteral treatments can provide a rapid successful method of supplementing ruminants with copper and selenium, and avoid the possible interactions between an oral supplement and other dietary constituents. The copper preparations studied contained copper complexed with calcium edetate (EDTA) or copper methionate , copper oxide or copper oxyquinoline sulphonate. The recommended doses of these commercial preparations contain different amounts of copper only part of which is transferred to the liver stores from which it can be released during the following months. The recommended dose of copper oxyquinoline sulphonate contains only 12 mg copper and the duration of its protective effect is short. Only a small proportion of the copper in copper methionate and copper oxide is transferred to the liver whereas nearly all the copper in a single dose of the EDTA complex (50 mg copper for sheep) is transferred to the liver stores. Although no longer recommended for use in sheep the copper EDTA complex can be administered to cattle to provide up to 1 mg copper/kg bodyweight. Selenium deficiency in both cattle and sheep can be corrected by the subcutaneous administration of up to 0.15 mg selenium/kg bodyweight as sodium selenate. However, if a dietary deficiency persists copper and selenium treatments are effective for only a few months. To avoid the need for repeated treatments, slowly dissolving or controlled release systems have been developed. Subcutaneous depots of barium selenate have been used (1 mg selenium/kg bodyweight) but large residues remained at the site of injection for up to three months. Initial trials with controlled release glasses containing copper have shown that they maybe useful for routine parenteral therapy.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.