Nutritional Causes of Infertility

Nutritional causes of infertility are deficiencies of various trace minerals, inadequate vitamin intakes, energy protein imbalances, excessive protein intakes, etc.

The major contributors to infertility and poor reproductive performance are:

• Deficiencies of various trace minerals
• Inadequate vitamin intakes
• Energy protein imbalances
• Excessive protein intakes

Excessive energy intake during late lactation and the dry period can cause “fat cow” problems which lower reproductive efficiency in the next lactation.

The most severe consequence of inadequate nutrition is:

• Cessation of cyclical activity (anestrus)
• Silent estrus
• Ovulatory defects
• Fertilization failure
• Embryonic or fetal death

The two main ways in which energy deficiency is believed to affect pregnancy rates is via:

• GnRH system
• Metabolic regulators of ovarian function

Negative energy balance does not affect FSH secretion but LH secretion is impaired.

Energy

Although protein, vitamins and mineral deficiencies are capable of producing poor fertility, the main effect is that of the deficient energy intake.

Gross under nutrition leads to:

• Delayed puberty-the puberty depends on body weight than age.
• Cessation of the cylical activity or anestrus.

A marginal deficiency causes:

• Silent estrus.
• Ovulatory defects.
• Conception failure.
• Fetal and embryonic death.

Body weight changes:

• The conception rate was found to be higher in cows which gained weight than in those which lost weight.
• 10% fall in live weight postpartum was associated with low fertility.
• Highest rates of infertility was found in cows of poorest condition.

Metabolities:

• Blood glucose levels < 30 mg/dl were associated with reduced fertility.
• The milk protein concentration is primarily affected by energy intake and not by protein intake. Significant inverse relationship exists between the calving conception interval and milk protein concentration.

Fatty Liver Syndrome

Excessive energy intakes during the late lactation and dry periods can lead to “fat cow” problems.

Over conditioned cows have a higher incidence of retained placenta, more uterine infections, and more cystic ovaries.

Cows have poor appetite and body fat reserves are mobilized to meet the energy deficit for lactation. Inadequate supplies of endogenous and exogenous protein exacerbate the syndrome.

Protein

Protein deficiency can occur concurrently along with energy deficiency.

Insufficient dietary non-protein nitrogen and rumen degradable protein reduce the digestibility of the feed.

This causes a dietary energy deficiency and flow of microbial protein

It slows the growth rate, delays and inhibits puberty and commencement of the estrous cycle after calving. So, reduces conception rate.

Crude protein levels of 13-20% in the concentrate diet sustain normal reproduction.

High levels of protein also affect reproduction, increase the incidence of anestrus and decrease the conception rate.

Deficiency of protein is seldom encountered except in severe inanition or underfeeding where Vitamin A and phosphorous are often complicating factors.

High levels of protein in the diet also affect reproduction due to the following facts:

• Degradation of excess Rumen Degradable Protein leads to increased circulating concentrations of ammonia and urea which when present in high levels in the uterus may be toxic to spermatozoa, oocytes or embryos or may adversely affect uterine function.
• In addition, abnormally high circulating concentrations of urea may also have an effect upon the hypothalamic-pituitary axis by.
• Increasing basal blood LH concentrations, and an exaggerated LH response to GnRH stimulation.
• reducing blood progesterone concentrations and luteal progesterone synthesis.

Vitamins

Vitamins involved in nutritional causes of infertility in animals are:

• Vitamin A
• Vitamin B (Complex)
• Vitamin D
• Vitamin E

Vitamin A

Deficiency in cattle causes delayed sexual maturity, abortion, birth of dead or weak calves, retained placenta and metritis. The recommended daily supplementation for dairy cows is 30,000-50,000 units.

Deficiency of β-carotene in diet causes:

• Delayed uterine involution.
• Delayed first estrus after calving.
• Delayed ovulation.
• Increased incidence of cystic ovaries.
• Early embryonic death and abortion.

Vitamin B (Complex)

Reduced food intake or starvation.

Vitamin D

Vitamin D is required for normal calcium and phosphorus metabolism.

Vitamin E

Selenium deficiency in dry cows has been reported to cause retained placenta, abortions, a high incidence of embryonic-fetal loss, poor fertility, and increased incidence of metritis, a higher level of general infection and the birth of dead or weak calves in some problem herds.

Minerals

Minerals involved in nutritional causes of infertility in animals are:

• Cobalt
• Copper
• Iodine
• Manganese
• Phosphorus
• Zinc

Cobalt

Cobalt deficiency causes:

• anaemia.
• inappetance.
• poor bodily condition.
• thriftiness.
• loss of condition.

Fertility is affected by:

• increased number of ‘silent‘ estruses.
• poor pregnancy rates
• irregular inter estrus intervals.

Deficiency occurs when diets contain < 0.07 mg/kg DM cobalt and is due to failure of vitamin B12 synthesis, which is an essential co-factor for carbohydrate metabolism.

Copper

Copper deficiency results in:

• Anestrus
• Sub estrus
• Poor pregnancy rates

When this occurs in association with other signs of hypocuprosis, such as anaemia, poor growth, bleached coat colour and diarrhoea, a diagnosis is likely. Hypocuprosis can be either direct or indirect.

Indirect deficiency occurs due to excessive molybdenum, iron or sulphur intake and, possibly, calcium or zinc.

Copper deficiency occurs when cattle are fed diets containing <3mg/kg copper, if the molybdenum content is <3mg/kg; 3 to 10 mg/kg; or >10mg/kg if the molybdenum content is >10 mg/kg.

Iodine

Reproductive failure resulting from iodine deficiency is invariably related to impaired thyroid function in the dam, embryo or fetus, which in the last two can cause embryonic death, abortion, stillbirth or weak goitrous calves.

High levels of goitrogenic substance can produce anestrus in heifers. Since iodine is needed for thyroxine synthesis, iodine deficiency is largely manifested through the effects of a lack of thyroxine.

Manganese

Manganese deficiency include anestrus, poor follicular development, delayed ovulation, silent estrus and reduced conception rates it also causes joint and limb deformities in calves.

Phosphorus

The evidence for the importance of hypophosphatemia as a cause of infertility is conflicting.

A number of authors have described infertility, anoestrus, sub estrus, irregular cycles and low conception rates in the absence of other clinical signs of phosphorus deficiency. A number of authors have described infertility, anoestrus, sub estrus, irregular cycles and low conception rates in the absence of other clinical signs of phosphorus deficiency.

If hypo phosphatemia is suspected, a rapid response can follow the feeding of dicalcium phosphate or bone meal. It is important to ensure that the ratio of calcium to phosphorus is 1:1.

Zinc

Uptake of zinc is impaired by copper, calcium, iron, molybdenum and cadmium. Excessive levels of zinc supplementation can lead to perturbation of essential fatty acid metabolism, which affects prostaglandin synthesis. Its potential role as an antioxidant is considered below.

General Recommendations

With no record of the body weight changes, only body condition is the indicator of the nutritional status.

If the animal is not in good body condition it is advisable to add or increase the concentrate or grain feeding by atleast 1 or 2 kgs depending upon the body condition in order to improve it.

It is advisable to include atleast a small amount of green fodder. It is very difficult to accurately say which specific nutrient is deficient. It is better to add a standard mineral mixture to the ration to improve the nutritional status (20-30 g/day).

Non Infectious Causes of Infertility

Non specific infections of the genital tract causing infertility in female farm animals include endometritis, cervicities and vaginitis.