Ruminants calcium

In food-producing animals, tetracyclines can be administered orally through feed or drinking water, parenterally, or by intramammary infusion. However, oral administration suppresses initially die ruminal fermentation of plant fiber. The absorption of tetracyclines can be further adversely affected by the presence of metallic ions in the gastrointestinal tract. All tetracyclines have an affinity for metallic ions and should not be administered with milk or high calcium levels in feed unless an upward adjustment in the dosage is made (226-228). 

Several other procedures have been developed to protect unsaturated fatty acids from ruminal biohydrogenation. Of these, only the amide derivative has extensive research documentation (Jenkins, 1998, 1999), but has not been applied commercially. Often, calcium soaps of palm oil or canola fatty acids are referred to as protected. These are not protected from ruminal biohydrogenation (Table 2.2), but rather are ruminally inert with regard to their effects on the rumen microbial population. 

Vitamin B12 is synthesized in large quantities by the intestinal flora, particularly in ruminants. The exact amount of vitamin B12 required by the normal human is not known. The absorption of vitamin B12 from the gastrointestinal tract is dependent on the presence of a gastric mucoprotein called intrinsic factor. Calcium ions seem to be necessary for the interaction of vitamin B12 with this intrinsic factor. Vitamin B12, which is absorbed only in the ileum, is stored in the liver. There are two transport proteins for vitamin Bj2 transcobalamin I and II, the latter being physiologically more important. Vitamin B12 plays an important role in the metabolism of functional groups with one carbon atom such as the methyl group... 

Klusmeyer, T. H., Lynch, G.L., ClaiL, J.H. and Nelson, D.R.. (1991). Effects of calcium salts of fatty acids and protein source on ruminal fermentation and nutrient flow to duodenum of cows. Journal of Dairy Science, 74,2206-2219. 

Grummer, R. R. (1988). Influence of prilled fat and calcium salt of palm oil fatty acids on ruminal fermentation and nutrient digestibility. Journal of Dairy Science, 71,117-123. 

The availability of nutrient P is >95% from the calcium phosphates, bone meal and urea phosphate, although it is somewhat lower in the other sources quoted. It is believed that the P in condensed phosphates is unavailable to non-ruminant animals. 

Lundy III, FR, E. Block, W.C. Bridges, Jr., J.A. Bertrand, and T.C. Jenkins. Ruminal Biohydrogenation in Holstein Cows Fed Soybean Fatty Acids as Amides or Calcium Salts, T. Dairy Sci. 87 1038-1046 (2004). 

Most treatments in ruminants require the addition of calcium to the magnesium salts to correct the hypocalcemia that is commonly observed in these animals. Magnesium enemas have also been used [86]. Injectable or rectally administered magnesium is then followed by the use of oral magnesium preparations until the Mg levels have stabilized and the underlying cause has been corrected. 

Because calcium salts of fatty acids are insoluble in the rumen, they are partly protected against biohydrogenation (76). Therefore, it is logical, although untested, to assume that feeding calcium salts of CLA to ruminants would result in less conversion of CLA to stearic acid in the rumen than would feeding the free fatty add form of CLA this result would make CLA from the dietary caldum salt of CLA more available for absorption from the intestine. A study was conducted at Iowa State University to determine the effect of feeding CLA as a free add and as a calcium salt on CLA content of milk (77). The six different diets, with suppl ental fat concentrations expressed on a dry matter basis, for Holstein cows were as follows (i) control, (ii) control + 5% soy oil, (iii) control +1% CLA as CLA-60, (iv) control +1% CLA + 4% soy oil, (v) control +1% Ca(CLA)2, and (vi) control + 1% Ca(CLA)2 + 4% soy oil. 

Phosphorus has more known fimctions than any other mineral element in the animal body. The close association of phosphorus with calcium in bone has already been mentioned. In addition, phosphorus occms in phosphoproteins, nucleic acids and phosphohpids.The element plays a vital role in energy metabolism in the formation of sugar-phosphates and adenosine di- and triphosphates (see Chapter 9). The importance of vitamin D in calcimn and phosphorus metabolism has already been discussed in Chapter 5. The phosphorus content of the animal body is considerably less than that of calcimn content. Whereas 99 per cent of the calcium found in the body occurs in the bones and teeth, the proportion of the phosphorus in these structures is about 80-85 per cent of the total the remainder is in the soft tissues and fluids, where it serves the essential fimctions mentioned above. The control of phosphorus metabolism is different from that of calcium. If it is in an available form, phosphorus is absorbed well even when there is an excess over requirement. The excess is excreted via the kidney or the gut (via sahva). In monogastric animals, the kidney is the primary route of excretion. Plasma phosphorus diffuses into saliva and in ruminants the large amount of chewing during rumination results in saliva being the major input of phosphorus into the rumen rather than the food. 

The capacity of rumen microorganisms to digest lipids is strictly limited. The lipid content of ruminant diets is normally low (i.e. <50 g/kg), and if it is increased above 100 g/kg the activities of the rumen microbes are reduced. The fermentation of fibre is retarded and food intake falls. Saturated fatty acids affect rumen fermentation less than do unsaturated fatty acids. Calcium salts of fatty acids have little effect on rumen fermentation and are used as fat supplements for ruminants. 

The availability of mineral elements is commonly high in young animals fed on milk and milk products but declines as the diet changes to solid foods. An additional complication is that the absorption, and hence apparent availability, of some mineral elements is under homeostatic control (determined by the animal s need for them). Iron absorption, discussed in Chapter 8, is the clearest example of this effect, but in ruminants the efficiency of calcium absorption also appears to be dependent on the animal s requirements. 

The mineral requirements presented in Appendix 2 are based partly on factorial calculations and partly on feeding trials. For all species, the elements that are most likely to be deficient are calcium and phosphorus. Consequently, these have been subject to most investigation. In the case of ruminants, estimates of calcium and phosphorus requirements have changed markedly over the past 50 years as new information on endogenous losses and availability has become available. For example, the UK Agricultural Research Council in 1965 stated the phosphorus requirement of a 400 kg steer gaining 0.75 kg/day to be 26 g/day however, in 1980 this was revised to 18 g/day, and in 1991 it was revised again to 20 g/day. 

The calcium content is low. The phosphorus content is moderate but has a reduced availability to non-ruminants, much of it being in the form of phytate phosphorus. 

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