Feeding For Fertility

In the dairy industry of late we have noticed a distinct trend towards pushing cows to achieve higher production levels.

This has led to the industry becoming more aware of the impact of management on herd fertility.

There are several factors that can affect herd fertility;

• Cow - Age, anatomy, genetics,
• Environmental - weather conditions, stress factors
• Management - Calving patterns, heat detection, insemination technique, record keeping, herd health
• Nutrition

In this instance let us look at the last point and elaborate what can be done to maximize the reproductive performance through correct nutritional management.

As higher production levels are reached, keeping up with the nutrient requirement becomes harder, and cows who's energy needs are not being met will mobilize body fat reserves to make up the difference, which can result in the delayed onset of ovulation.

Cows normally lose body condition during early lactation because their daily appetite take several weeks longer to peak than their daily milk yields. Until a cow's daily intake of energy from the feed eaten exceeds the amount of energy she needs each day for milk production, walking and regular body functions, she will utilize body reserves (“burn the fat from her back”).

Some body condition loss in early lactation is normal but excessive loss (more than one condition score between calving and joining) reduces reproductive performance and increases the risk of metabolic disease.

A feeding program that maximizes dry matter intake (DMI) and allows for a smooth transition from the dry period to peak milk yield with minimal body condition loss has the greatest beneficial effect on the reproductive process.

Positive energy balance at the time of joining is critical and it impacts reproductive performance because it influences the time taken between calving and first ovulation. As a cow's energy balance becomes positive, ovarian follicle activity increases, leading to ovulation. Therefore the quicker the cow is able to move to a positive energy status after calving, the earlier she cycles.

The earlier she cycles after calving the greater her chance of early conception. Cows will have about a 70% chance of conceiving if they are gaining weight and only about 17% if they are still losing weight during joining.

The financial implications of delayed conception on an average producing herd is around $5.50 per day. This figure takes into account loss of annual yield, extended dry period costs, slipping of the calving pattern in the next lactation and extra inseminations.

It is also important to ensure the diet contains the correct level of protein during the joining period. If there is too much protein in the diet the rumen bacteria are unable to convert it into microbial protein.

This results in a high level of ammonia in the rumen, which is absorbed across the rumen wall into the blood stream, where it's carried to the liver and converted into urea. Excess urea in the blood or blood urea nitrogen (BUN) can be toxic to sperm, eggs and embryos.

The way that we can influence positive energy balance at and before mating is to make sure that the diet is balanced with adequate levels of high quality pasture, high energy concentrate such as Barastoc Pasture Optimiser and adequate high quality, effective fibre.

Once the cow is joined the job isn't finished as correct nutrition after joining enables restoration of body weight lost in early lactation and plays an important role in maintaining the growing foetus. If there is too much weight loss after conception the rate of abortion can increase significantly.

Vitamins and minerals play a significant role in fertility by maintaining membrane integrity, being involved in hormone production and maintaining a strong immune system. Of particular importance are vitamins A, D and E, macro minerals such as calcium, magnesium and phosphorus and micro minerals such as;

• Copper - used in enzymes systems
• Selenium - Essential for development and growth of foetus
• Zinc - for formation of healthy oocytes.

These vitamins and minerals are present in the mineral premix supplied in all Barastoc feeds.

Excessive body condition loss (not high milk production) reduces reproductive performance. Herds and cows that achieve high milk yields without excessive body condition loss in early lactation have good reproductive performance.

The key to avoiding excessive body condition loss is to keep cows eating as much high-quality feed as their appetites allow. So to increase your reproductive performances contact your local Ridley AgriProducts territory manager to assist in balancing your ration.

David Conheady
Territory Manager,
Ridley AgriProducts