Manganese for Animals

Manganese was first recognized as a necessary nutrient for animals in the early 1930s. Because manganese is found in many different feeds, a deficiency is less likely than with most of the other trace minerals. However, manganese deficiency does occur in sufficient magnitude to justify consideration in this text.

Bone, kidney, liver, pancreas, and pituitary gland are the sites of highest manganese concentration. Relative concentration is quite low compared to the other trace minerals. For example, in humans, total body manganese is approximately 1% of the zinc and 20% of the copper. Although concentrations are low, it is a critical nutrient for several functions.

Manganese is essential for chondroitin sulfate synthesis, which is critical to the organic matrix of bone. Many enzymes required for the synthesis of polysaccharides and glycoproteins require manganese to be active. Manganese is a key component of the metalloenzyme, pyruvate carboxylase, a critical enzyme in carbohydrate metabolism. Lipid metabolism is also dependent on manganese to allow the liver to convert mevalonic acid to squalene (215).

High dietary intake of calcium, phosphorus, and iron reduce manganese absorption. The body has only a limited storage of mobilizable manganese reserves. The absorption of manganese in all domestic livestock is poor (93). Research with humans showed that manganese absorption from normal dietary ingredients ranged from 1.7 to 5.2%. Even manganese chloride was only absorbed at a rate of 8.9% (252).

Manganese deficiency in the diet of growing chicks and poults results in perosis, or slipped tendon. Manganese-deficient chicks have less proteoglycan in the cartilage of the tibial growth plate than manganese-repleted chicks (253). This contributes to the perosis condition which involves a twisting and bending of the tibia, and slipping of the gastrocnemius tendon from its condyles. With increasing severity chicks are reluctant to move, squat on their hocks and soon die. In laying and breeding birds, a manganese deficiency results in lowered egg production and hatchability and reduced eggshell strength. In many cases, embryos that die as a result of manganese deficiency exhibit chondrodystrophy, a condition characterized by a parrot-like beak, wiry down and shortening of the long bones (95, 141).

Table 28 gives information on the manganese requirement of poultry and other animals. It varies considerably with the different classes of poultry. Ducks normally require 30-50 ppm (300). Manganese source also influences requirement. Manganese sulfate has the highest bioavailability, while manganese oxide and manganese carbonate are only about 30 and 55% as available as the sulfate (254).

Class of Animal	Manganese Requirement in Total Diet (ppm)	Toxic Level in Total Diet (ppm)
Poultry	25-90	4,800
Dairy Cattle	17-24	1,000
Swine	3-20	4,000
Beef Cattle	40 (20-50)	1,000²
Horses	40	--
Sheep	20-40	--
Goats	45-50	--
Other Animals	25-95	--

¹ All levels are those recommended by the latest NRC publications, except as indicated.

Only about 1% of the manganese in ruminant diets is absorbed (337). General symptoms of manganese deficiency include impaired growth, skeletal abnormalities, disturbed or impaired reproduction, and abnormalities of the newborn. Deformed calves at birth have weak legs and pasterns, enlarged joints, stiffness, twisted legs, general weakness, and reduced bone strength. Low-manganese diets cause heifers and cows to be slower in exhibiting estrus and more likely to have "silent heats," and a lower conception rate. Abscessed livers and practically no bile in the gall bladder have also been reported (91, 156).

In cattle the manganese requirement for growth is lower than that required for reproduction and birth of normal calves. Ohio researchers used regression techniques to estimate the intake required to meet the metabolic fecal manganese requirement (313). The corresponding dietary concentrations, assuming dry matter intakes of 21 and 12 kg/day for lactating and dry cows, respectively, were 28 and 49 ppm in the diet on a dry matter basis. These concentrations are approximately 1.6 and 2.7 times higher than those needed to meet the manganese requirements for lactating and dry cows, respectively, as calculated using the 2001 National Research Council dairy requirements model.

Signs of a manganese deficiency include abnormal skeletal growth with an altered ratio of fat-to-lean body tissue; absence of, or irregular, estrual cycles; poor mammary development and lactation; resorption of fetuses; and at birth, small, weak pigs whose sense of balance is poor. Decreased growth rate and feed efficiency also occur with a manganese deficiency (87, 92).

Data on the requirement for manganese have varied a great deal. This is probably due to the high ash, calcium, phosphorus, and other constituents in some diets which can increase manganese needs.

Deficiency symptoms in the cow are characterized by reproductive disorders. These include delayed estrus, reduced fertility, abortions, and deformed young. Calves born to cows deficient in manganese have exhibited poor growth, weak and shortened bones, and deformed legs with enlarged joints, stiffness, twisted legs, and "over-knuckling." In the male, manganese deficiency causes impaired spermatogenesis, testicular and epididymal degeneration, sex hormone inadequacy, and eventual sterility (85, 157).

Information on manganese requirements indicates that 20 ppm is probably adequate for growth, whereas about 40 ppm is needed for satisfactory reproductive performance. High intakes of calcium and phosphorus increase manganese needs (85, 93, 157).

Manganese requirement and the effect of a deficiency of manganese are not known. The National Research Council’s Committee on Nutrient Requirements of the Horse recommends the 40 ppm manganese in the diet (154). Recent studies indicate that 45 ppm manganese are required for mature idle horses (298). This is a good recommendation because manganese is associated with proper bone development and formation, which is very important in all horses. Moreover, manganese can affect reproduction in both the male and female. Severe deficiency can cause resorption of the fetus in utero or death at birth (298). Because the foal crop is often low, it is important that manganese levels be adequate.

Depressed or delayed estrus and poor conception rates occur in ewes with a manganese deficiency. More services per conception have also been reported (93). One report indicates that manganese may have a possible role in the functioning of the corpus luteum (109). Early weaned lambs on a purified diet containing less than 1 ppm manganese exhibited bone changes similar to those seen in other manganese deficient animals (155). This indicates that sheep probably need manganese for skeletal development, as various other species do. The levels of manganese in wool appear to be quite sensitive to changes in the manganese status of the lamb (155).

The exact requirements for manganese are not known, but the National Research Council committee on sheep recommends a level of 20 to 40 ppm in the diet (155). High intakes of calcium and iron may increase manganese needs.

Symptoms of manganese deficiency include reluctance to walk, deformity of the forelegs, and reduced reproductive efficiency (100). The growth of female goats fed 20 ppm manganese for the first year of life and 6 ppm the following year was not affected, but the low manganese level delayed the onset of estrus and required more inseminations per conception (155). In mature goats the manganese content of the hair is a better indicator of manganese status than manganese in any other part of the body (155). Goats also show tarsal joint excrescences, leg deformities, and ataxia due to a manganese deficiency (93). A decrease of 25% in the body fat content of kids born from goats on manganese deficient diets has been reported (93).

Information on manganese requirements of the goat is meager. A level of 45 to 50 ppm is suggested for sheep until more definitive data become available (100).

Unfortunately, there is very little information on manganese requirements of small animals. In some cases, the latest National research Council publications suggest levels of manganese that have been used successfully. They are, in ppm in the total diet: fish, 95; rat, 50; dog, 5; cat, 10; rabbit, 2.5 to 8.5; guinea pig, 40; non-human primate, 40; mouse, 45; gerbil, 3.3 to 45; and hamster, 3.65 ppm. These levels can be used as a guide until more definitive information is obtained. In the few instances where deficiency symptoms were given, there was some similarity to those reported for domestic livestock.