Lanthanides
379
As feed additives, LAs improve body weight gain and feed conversion, in nearly
all categories of farming animals (chickens, pigs, ducks, cattle). Additionally,
improvements in milk production of dairy cows, egg production in laying hens, and
output and survival rate of fish and egg hatching of shrimps were noticed.
At present, no definitive statement on optimum LA levels can be made. However,
a dose dependency was observed in several trials, and better effects have been
achieved when the mixture of LAs was applied, instead of a single element. Feed
additives used contain predominantly LAs (La, Ce, Pr, Nd). Both organic and inorganic LA feed additives are commercially available, but organic ones are claimed to
provide better results. This is probably ascribable to different chemical characteristics, which lead to variations in both absorption and bioavailability (Redling 2006).
The highest LA concentrations in organs of fattening bulls was measured in the
liver followed by the kidneys and rib bones. In the liver, the concentration amounted
to (in μg/kg) 22–482 for La, 37–719 for Ce, and 4–73 for Pr. The muscle tissue,
playing an important role to evaluate food safety, showed the lowest La, Ce, and Pr
concentrations with [in μg/kg dry matter (DM)] 3–5, 5–7, and 0.5–0.7, respectively.
The health risk to humans consuming edible tissues of LA-supplemented animals is
very low (Schwabe et al. 2012).
It has been suggested that LAs may promote growth, by influencing the development of undesirable bacterial species within the gastrointestinal tract. For example,
La may bind to the surface of bacteria. Another explanation for the growth-promoting
effects of LAs is due to improvements in nutrient digestibility and availability.
LAs have several properties that make them attractive alternatives to antibiotics.
Generally, absorption of orally applied LAs is low, with more than 95% being recovered in the feces of animals. As a result, the chances of LA residues present in meat
are low and similar to their levels in muscle tissues of animals fed with commercial diets. There have been no reports on the development of bacterial resistance in
treated animals (Thacker 2013).
379
As feed additives, LAs improve body weight gain and feed conversion, in nearly
all categories of farming animals (chickens, pigs, ducks, cattle). Additionally,
improvements in milk production of dairy cows, egg production in laying hens, and
output and survival rate of fish and egg hatching of shrimps were noticed.
At present, no definitive statement on optimum LA levels can be made. However,
a dose dependency was observed in several trials, and better effects have been
achieved when the mixture of LAs was applied, instead of a single element. Feed
additives used contain predominantly LAs (La, Ce, Pr, Nd). Both organic and inorganic LA feed additives are commercially available, but organic ones are claimed to
provide better results. This is probably ascribable to different chemical characteristics, which lead to variations in both absorption and bioavailability (Redling 2006).
The highest LA concentrations in organs of fattening bulls was measured in the
liver followed by the kidneys and rib bones. In the liver, the concentration amounted
to (in μg/kg) 22–482 for La, 37–719 for Ce, and 4–73 for Pr. The muscle tissue,
playing an important role to evaluate food safety, showed the lowest La, Ce, and Pr
concentrations with [in μg/kg dry matter (DM)] 3–5, 5–7, and 0.5–0.7, respectively.
The health risk to humans consuming edible tissues of LA-supplemented animals is
very low (Schwabe et al. 2012).
It has been suggested that LAs may promote growth, by influencing the development of undesirable bacterial species within the gastrointestinal tract. For example,
La may bind to the surface of bacteria. Another explanation for the growth-promoting
effects of LAs is due to improvements in nutrient digestibility and availability.
LAs have several properties that make them attractive alternatives to antibiotics.
Generally, absorption of orally applied LAs is low, with more than 95% being recovered in the feces of animals. As a result, the chances of LA residues present in meat
are low and similar to their levels in muscle tissues of animals fed with commercial diets. There have been no reports on the development of bacterial resistance in
treated animals (Thacker 2013).