Sheep vitamin requirements

M. O. Schultze stated that cobalt is an essential element for the nutrition of sheep and cattle. Although it is not essential for the growth of the herbage plants, they nevertheless take it up from the soil and make it available for animal nutrition (106) To prevent anemia, even when the diet contains adequate amounts of iron, a small amount of cobalt (not more than four micrograms per day per kilogram of body weight of sheep) is required (124). It is an important constituent of vitamin B 2. 

Pantothenic acid is found in extracts from nearly all plants, bacteria, and animals, and the name derives from the Greek pantos, meaning everywhere. It is required in the diet of all vertebrates, but some microorganisms produce it in the rumens of animals such as cattle and sheep. This vitamin is widely distributed in foods common to the human diet, and deficiencies are only observed in cases of severe malnutrition. The eminent German-born biochemist Fritz Lipmann was the first to show that a coenzyme was required to facilitate biological acetylation reactions. (The A in... 

The human body contains only about 1.5 mg of cobalt, almost all of it is in the form of cobalamin, vitamin B12. Ruminant animals, such as cattle and sheep, have a relatively high nutritional need for cobalt and in regions with a low soil cobalt content, such as Australia, cobalt deficiency in these animals is a serious problem. This need for cobalt largely reflects the high requirement of the microorganisms of the rumen (paunch) for vitamin B12. All bacteria require vitamin B12 but not all are able to synthesize it. For example, E. coli lacks one enzyme in the biosynthetic... 

In terms of human dietary requirements, much of the wheat for breadmaking in the United States is produced in selenium-adequate sections of the country. Bread is generally a good source of dietary selenium, Selenomethionine decomposes lipid peroxides and inhibits in vivo lipid peroxidation in tissues of vitamin-E-deficient chicks. Selenocysdne catalyzes the decomposition of organic hydroperoxides. Selenoproteins show a high degree of inhibition of lipid peroxidation in livers of sheep, chickens, and rats, Thus, some forms of selenium exhibit in vivo antioxidant behavior,... 

The role of selenium in human medicine has been reviewed. Animal studies in the 1950s demonstrated the nutritionally beneficial, effects of selenium by showing that there was a selenium-responsive liver necrosis in vitamin E-deficient rats. There are important selenium-dependent diseases in farm animals, such as white muscle disease in sheep and cattle, and myopathy of cardiac and skeletal muscle in lambs and calves. In these animals, some cause of oxidative stress, such as increased physical activity or vitamin E deficiency—together witli dietary selenium deficiency—is required to elicit the disease. 

Palatability Trials. Two to five sheep were placed in a pen containing a feeder with four movable compartments. The compartments were numbered and their positions randomized each day. Two feeds were compared in each pen. Each day a known amount of feed was placed in each compartment and the position was determined at random. Twenty-four hours later the refusals were removed, weighed, and fresh feed added. A normal test period was seven days. The first trial was designed to determine the relative palatability of hemicellulose and molasses. The basal ration consisted of timothy hay, 68% com, 28.16% 44% CP soybean oil meal, 2.31% urea, 0.77% dicalcuim phosphate, 0.26% salt, iodized, 0.50% and vitamin A and D concentrate to meet NRC requirements. Other rations were prepared by removing com and increasing the soybean meal and adding 5% dry matter from cane molasses, LHC, dried molasses, or dried LHC. 

Ruminants require cobalt for the bacterial biosynthesis of vitamin B12 in the first stomach. Cobalt-deficient sheep or cattle show diminished feed intakes and weight loss. In cows, milk production declines and the fre-... 

For these reasons alone, a vitamin E symposium will not be short of problems and material for discussion. Many more unanswered questions come to light, however, when the biochemical and physiological properties of vitamin E are considered. The program of this meeting includes papers on the metabolism of vitamin E interrelations among vitamin E, metals, and ubi( uinones vitamin E and nucleic acid metabolism interrelations between vitamin E and polyunsaturated fatty acids vitamin E requirements of human infants vitamin E in health and disease of poultry, sheep, cattle, and pigs and so on. Everywhere, alongside established facts, there are unanswered questions and unsolved problems. 

The interrelations between vitamin E and selenium in cattle and sheep are undoubtedly as complex as they are in other species. It seems reasonable to state that vitamin E, in combatting the toxicity of unsaturated fat, acts as an antioxidant, for its effect can be duplicated by many other antioxidants and redox dyestuffs. Similarly it is indisputable that selenium is a dietar essential for ruminants and that its absence from their diet results in muscular disease. Both unsaturated fat excess and selenium deficiency must produce primary disturbances in the muscle cells. These disturbances need not be common to both, for muscle reacts similarly to a variety of biochemical insult. In the presence of selenium and the absence of unsaturated fat, vitamin E requirements of ruminants appear to be extremely small. The failure to produce reproductive disorders in ruminants by experimental vitamin E deficiency, and the failure to produce muscular disease on fat-free diets deficient in vitamin E but likely to have been adequate in selenium content is evidence of this contention. How vitamin E acts in preventing muscular disease due to selenium deficiency, however, is not known, and this aspect needs elucidation. 

The propionyl CoA carboxylation is another reaction in which the energy required to synthesize a car-bon-to-carbon bond is provided by ATP. Thus, the free energy of the pyrophosphate bond is transferred to CO2, which forms an N-carboxy bond with the biotin enzyme complex. Some of the molecular details of the propionyl carboxylation reaction are presented in Fig. 1-27. The isomerization of methylmalonyl CoA to succinyl CoA also involves vitamin B12. At first it was demonstrated that the activity of the isomerase was considerably decreased in the liver of vitamin B 12-deficient rats. Later the stimulating effect of 5,6-dimethylbenzimidazole carbamide coenzyme was demonstrated with partially purified preparations of the liver enzyme. The methylmalonate CoA-isomerase complex purified from sheep liver has been divided into two different protein fractions, one with isomerase and the other racemase activity. The isomerase acts on only one of the enantiomorphs of methylmalonyl CoA, but the absolute formula of the enantiomorph that serves as substrate for the isomerase is unknown. A racemase catalyzes the conversion of the alternate enantiomorph to the substrate of the isomerase. 

Like vitamin A, it was thought that the transfer of vitamin E across the placenta was limited, with the neonate relying on colostrum to meet its requirements. More recent evidence in sheep indicates that placental transfer does occur, with increased muscle and brain concentrations in lambs born from ewes fed higher levels. Nonetheless, colostrum is a very important source of vitamin E for the new born. 

Although an excess of cobalt can be toxic to animals, there is a wide margin of safety between the nutritional requirement and the toxic level. Cobalt toxicosis is extremely unlikely to occur under practical farming conditions. Unlike copper, cobalt is poorly retained by the body tissues and an excess of the element is soon excreted. The toxic level of cobalt for cattle is 1 mg cobalt/kg body weight daily. Sheep are less susceptible to cobalt toxicosis than cattle and have been shown to tolerate levels up to 3.5 mg/kg. Excessive cobalt supplementation of ruminant diets can lead to the production of analogues of vitamin B12 and a reduction in the quantity of the true vitamin. Cobalt compounds pose a risk to human health as they cause cancer if inhaled and they irritate the skin for this reason, their use has been restricted in the... 

Beneficial aspects of selenium started with its establishment as an essential trace element for animals. Schwartz and Foltz [42] found selenium prevented liver degradation in rats, and a number of subsequent studies showed that it was responsible for the prevention of myopathic diseases in poultry and sheep [31, 34]. Selenium is the third factor, in addition to vitamin E and cystine, that prevents myopathy [32], and it may be a key factor in the absorption of vitamin E. Most selenium is adequately supplied through diets, although some areas such as Oregon and New Zealand have selenium deficient forage and provide supplementary selenium in the feed. Levels below 1 ppm are considered safe, and the required level is estimated to be 0.2 ppm [32]. 

The synthesis of riboflavin, like thiamin, was observed in various animals. In the rat the site of synthesis seems to be the colon (25, 26, 40). When synthesis of riboflavin is increased the requirement of the rat for the vitamin diminishes. In the rumen of sheep (49) there is even greater synthesis. The rumen contents showed a riboflavin value about one hundred times that of the feed used (68, 69). In the cow marked synthesis also takes place (51, 52, 53, 68). The daily output of riboflavin in the milk alone was found to be ten times the intake (68). This impressive amount of synthesis affords adequate explanation for the observation that the riboflavin content of the ration of the cow (70) and goat (71) does not appreciably alter the amount of riboflavin secreted in the milk. Riboflavin synthesis also occurs in the feces of fowl, particularly after passage (72) from the body. 

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