Dr Susheel Kumar1*, Dr Bhuvnesh Thakur1, Dr Harshita Sood2, Dr Prachurya Biswal2
Introduction:
Reproductive performance of dairy animals decides their efficiency of production. It is affected by various factors, such as nutritional, biological, environmental and managemental etc. As reproduction is a luxurious process, so nutrition play an important role in reproduction. Due to high production and deficient feeding dairy animals most commonly suffer with the mineral deficiencies which lead to poor reproductive performance. Minerals are very essential part of dairy animal’s feeding. In dairy animals the problems such as retained foetal membranes, abortion, milk fever and weak calf syndrome may be linked to minerals deficiency. It has been seen that mineral deficiency reduces dairy cow fertility involve transition cow health and immunity, the mineral status of dry cows is very important for fertility in the succeeding lactation. Minerals are involved in several biological processes and play crucial roles in the proper functioning of enzymes, hormones and cells. As minerals are involved in carbohydrate, protein and nucleic acid metabolism so any change in its level may alter the production of reproductive and other hormones that ultimately leads to the reproductive problems.
Macro Minerals
Calcium (Ca):
Lactating dairy animals should be provided with adequate amounts of calcium to maximize production and minimize health problems. Calcium deficiency related disorders are commonly occurred during parturition or after parturition. Calcium helps in maintaining the muscle tone of the uterus, uterine involution and assist parturition. Low calcium level in blood is associated with anoestrus whereas excess of calcium can affect the absorption of other minerals like phosphorus, zinc, manganese, copper from gastro intestinal tract thus impaired reproductive status of dairy animals. The ratio (Ca:P) between 1.5:1 and 2.5:1 is optimum for lactating cattle, any alteration in this ratio may affect ovarian function through its blocking action on pituitary gland that results in prolongation of estrus and ovulation, increased incidence of dystocia, retention of placenta, delayed uterine involution, and prolapse of uterus.
Phosphorus (P):
Phosphorus is involved in many metabolic reactions and energy transfer processes. In dairy animals, phosphorus has been most commonly associated with decreased reproductive performance. For normal sexual behaviour phosphorus is considered to be one of most important element. It has been seen that animals from phosphorus deficient areas exhibited delayed onset of puberty and silent or irregular estrus in heifers, failure of estrus and long inter calving period in cows and still born or weakly expelled calves or even embryonic death due to lack of uterine muscle tone. Phosphorus deficiency in dairy animals lead to decline in fertility rate, ovarian activity, irregular estrous cycles, increased occurrence of cystic ovaries, delayed sexual maturity and low conception rates.
Potassium (K):
Potassium is the third most abundant mineral element in the animal body after Ca and P. Ruminants have a higher potassium requirement than non-ruminants as potassium is essential for rumen microorganisms. Feeding high levels of potassium may delay the onset of puberty, delay ovulation, effect corpus luteum development and increase the incidence of anoestrous in heifers.
Salt (NaCl):
Salt contains sodium (Na) and chloride (Cl) and is often supplemented in concentrate feed or as free lick to dairy animals. Na involve in maintaining the osmotic balance, cellular uptake of glucose and amino acid transport. Salt indirectly affects the reproductive health of the animal due to digestive systems problems. It has been seen that lactating dairy animals in the tropical areas may require more Na due to the hot and humid climatic conditions. The daily requirements of salt for dairy animals can be easily met by adding 1 percent salt to concentrate mixture and offering additional salt lick.
Magnesium (Mg):
Magnesium involve in maintaining normal bone growth, various enzyme systems and nervous system. Magnesium have an indirect effect on reproductive health as it antagonizes with calcium, so any change in Ca-P-Mg homeostasis will lead to reproductive problems. Decreased reproductive efficiency can occur due to magnesium deficiency following general loss of appetite.
Micro Minerals:
Copper (Cu):
Copper is an essential component of various enzymes including superoxide dismutase, lysyl oxidase and thioloxidase. Copper deficiency in dairy animals is mainly due to dietary antagonists, such as sulphur, molybdenum and iron that reduces the bioavailability of copper. Its deficiency is associated with anestrus, decreased conception rates, embryonic death, resorption of the embryo, increased chances of retained placenta and necrosis of placenta. For production of quality semen proper copper supplementation of the sire is required. It has been seen that copper treatment improves the conception rate compared to untreated cow.
Cobalt (Co):
Cobalt acts as a vital component in many enzyme systems as cofactors. If dairy animals are fed with high level of molybdenum it can cause cobalt deficiency. It is an important component of vitamin B12, dairy animals required cobalt to fulfil the requirement of vitamin B12 of both the ruminal bacteria and the host animal. Cobalt deficiency in dairy animals associated with a delayed onset of puberty, delayed uterine involution, increased incidence of silent heats, non-functional ovaries, and abortions. It has been seen that cobalt supplementation improves the conception rate.
Selenium (Se):
Selenium deficiency is quite rare in dairy animals than its toxicity. Selenium is naturally originating from plants, in the form of seleno-amino acids, including selenomethionine and selenocysteine. Inorganic selenium in the form of selenate and selenite are two major sources of selenium for dairy animals. Its deficiency associated with weak silent or irregular estrus, early embryonic death, retained fetal membranes and abortions where as in males it is associated with reduced sperm motility. In sub clinical selenium deficiency, reproductive performance of dairy animals may be impaired with increased number of services per conception, retained fetal membrane and high incidence of mastitis.
Manganese (Mn):
Manganese is an essential mineral for dairy animals. Feed concentrate ingredients may be deficient in manganese compared to fodders and it is more available in hay than silage. Manganese is required for cholesterol synthesis which is required for synthesis of the steroids, estrogen, progesterone and testosterone hormones. Its deficiency cause anoestrus or irregular estrus, silent estrus, decrease conception rate, and abortions in females, whereas in males its deficiency causes decrease or absence of libido and improper or failure of spermatogenesis. In number of studies it has been seen that the post-partum anestrus can be decreased in dairy animals by supplementation of manganese.
Zinc (Zn):
Zinc plays an important role in certain reproductive hormones and its deficiency associated with abortion, fetal mummification, lower birth weight and prolonged labour as it plays critical role in the repair and maintenance of the uterine lining following parturition. Zn deficiency in bulls cause poor semen quality, reduced testicular size and libido. It also helps in increase the plasma β-carotene level which is correlated in improvement of conception rates and embryonic development.
Iron (Fe):
Iron is necessary for the synthesis of haemoglobin and myoglobin as well as many enzymes and cytochrome enzymes of electron transport chain. Functions of iron are transport of oxygen to tissues, maintenance of oxidative enzyme system and are concerned with ferretin formation. Due to its ubiquitous nature in the feed stuffs its deficiency in adult animals is rare. The reproductive performance of iron deficient animals may be badly affected due to anaemia, reduced appetite and lower body condition. A deficient animal becomes repeat breeders and require increased number of inseminations per conception and occasionally may abort.
Iodine (I):
Iodine requirement is also essential for dairy animals as it involves in the development of fetus and maintenance of general basal metabolic rate. Iodine deficiency cause delay in puberty, suppressed or irregular estrus, failure of fertilization, early embryonic death, abortion, increased chances of retained placenta in females and decreases in libido and affects the semen quality in males. Anovulatory estrus has been seen in cows maintained on iodine deficient diet which might be due to disorder of the thyroid and pituitary functions. Subclinical deficiency of iodine in breeding females results in suppressed estrus, abortions, increased frequency of retained placentas and increased gestation periods. A number of studies have shown that lugol’s iodine has beneficial effect in treatment of silent estrus, repeat breeding and in conception rate.
Chromium (Cr):
Chromium improves the sensitivity of insulin, which results in increased the uptake of glucose and amino acids by cells of the body, therefore improves the energy balance in the body, which in early lactation leads to improved reproductive health. For the secretion of pregnancy specific proteins from the uterine endometrium chromium plays an important role, which is helpful in preventing early embryonic death. Chromium also affects the follicular maturation and LH release.
Molybdenum (Mo):
Molybdenum and copper are antagonistic to each other so proper balance of molybdenum and copper in soil and plant is essential for their normal absorption in dairy animals. Molybdenum deficiency is responsible for delayed puberty, reduced conception rate and anestrus in females where as in males it decreases libido, reduced spermatogenesis and cause sterility.
Mineral requirement of dairy cattle (NRC, 2001)
Macro mineral (% of diet) Growing cattle -Lactating cattle
Ca 0.50 0.70
P 0.31 0.48
Mg 0.16 0.20
K 0.65 1.0
Na 0.10 0.18
S 0.16 0.25
Micro mineral (mg/kg DM intake
Cu 10.0 10.0
I 0.25 0.60
Fe 50.0 50.0
Mn 40.0 40.0
Mo – 4.0
Se 0.30 0.30
Zn 40.0 40.0
Co 0.10 0.10
Conclusion:
For normal growth, production and reproduction of dairy animal minerals in the feed to be provided in appropriate amounts and forms that are biologically more useful. Mineral requirements of animal depend upon age, species, breed, physiological conditions of animals. Dairy animals are most commonly suffered with the mineral deficiencies due high production and deficient feeding ultimately leads to poor reproductive performance. Hence minerals are very essential part of dairy animal’s feeding.
