Dr Gareth Kelly, Boehringer Ingelheim

Heifers are the future of a productive herd. Not only do they represent the next generation of genetic merit, they are also the animals in the herd with the longest productive lifespan.

Heifers which calve with increased liveweight yield more milk, protein and fat in their first lactation and during their lifetime. 

The success of heifer raising programs hinges on the reproductive health of the heifer group, and how well they have been prepared for their first breeding season.

Well-grown heifers are not only more fertile, they produce more milk, compete better with mature cows and survive longer in the herd than poorly grown animals. 

Good nutritional management is an essential part of successful reproductive management, especially in the heifer group.

The link between gastrointestinal worms, nutrition and reproduction

The effect of gastrointestinal roundworms is often described as a nutritional disease.

Worms reduce both the amount of feed a heifer consumes, and how that feed it utilised.

These factors combine to reduce growth rates that will potentially prevent heifers from reaching mating and calving target weights.

This reduced liveweight is responsible for poorer fertility ratesand increased time to conception.

Effect on feed intake

The most significant impact of worms on heifers is the effect of infection on feed intake.

Heifers with a worm infection have been shown to spend on average 105 minutes less per day grazing than treated animals, resulting in a 17 per cent reduction of daily dry matter intake. 

This reduction in feed intake lowers the total amount of energy and protein supplied to heifers, and has a direct impact on growth rates of heifers.

Changes in feed utilisation

While reductions in feed intake may account for the majority of differences in weight gain in parasitised cattle, other changes caused by worms account for significant production loss.

Changes in the gut reduce in response to worm infection reduce the rate of passage of ingesta and changes to gut secretions impair digestion.

These adjustments may reduce the amount of energy that can be digested from the dry matter ingested by the heifer.

Worm infection also alters how digested energy and protein is utilised. In the growing heifer, meeting energy and protein requirements for growth is required to meet weight targets for mating.

However, immune response and gut repair in the infected heifer diverts these resources away from growth, reducing the utilisation of feed for animal growth.

Eprinex Pour-On is an ideal choice to ensure effective control of worms that may reduce growth rates and growth targets from being achieved.

Managing heifers for reproductive success

Ideally heifers should be mated at 65 per cent of their mature weight at 14-16 months of age and calve at 85 per cent of their mature weight at 23-25 months of age.

Poorly grown heifers will reach puberty later, are less likely to be cycling at the start of the mating period, take longer to get in calf, and will calve late.

Reaching these growth targets can be helped with effective worm control and management of nutrition.

Trace minerals play a significant role in growth of heifers to reach the above targets, with deficiency reducing growth rates.

In addition, they also play an important role in enabling a heifer to conceive.

Reproductive failure may occur if deficiencies or imbalances occur of trace minerals.

Copper, selenium, zinc, manganese and vitamin B12 have all been shown to be implicated in the reproductive process.

The use of injectable trace mineral supplementation at critical times has been associated with positive reproductive outcomes, including improved conception and increased odds of pregnancy and greater final in-calf rate.

Sub-optimal trace mineral and vitamin B12 status of the heifer during growth and/or at mating will negatively impact production, reproduction, and health.

Marks-Min provides trace minerals and vitamin B12 in one convenient injection, to support optimal health, production and fertility, removing the guesswork during the critical period of heifer development and mating.