Developing Heifers on Novel Endophyte Tall Fescue

Heifer development is critical for a strong cow/calf production system.  Replacement heifers are typically produced on-farm to replace from 15 to 20% of the cow herd annually.  Heifers are selected from the calf crop based on their own performance, and the performance/genetic merit of their dam and sire. 

Heifer development programs have changed over the years.  When I started working in 1990, there were still many farmers that calved heifers at 3 years of age, and many were insistent that growing heifers to nearly their mature weight before they calved for the first time was important to reducing dystocia and improving rebreeding.

Developing heifers on novel endophyte tall fescue, photo by Matt Poore

Since that time, most progressive cattlemen have moved to calving heifers at 2 years old, which, when done properly, improves their lifetime productivity relative to calving 3 year olds, primarily due to the cost of maintaining an unproductive heifer for an additional year.

To ensure success with heifers calved at 2 years of age, farmers have been encouraged to develop heifers to 65% of their mature weight prior to breeding.  Typically heifers will need substantial supplemental nutrition to reach that target weight which is 850 lbs in a cow destined to weigh 1300 lbs at maturity. 

Recently, the concept of “slow heifer development” has been introduced to cattlemen.  This concept was first developed in the high plains were forages are of relatively low nutritional value, making the high target weights very expensive to achieve.  The logic of this approach is that when you push heifers to a heavy weight (65% of mature weight), the feeding program is expensive and some heifers that need the supplement to grow enough to breed will “crash” at some point, due to their higher nutrient requirements. 

Heifers that are developed more slowly (to about 58% of their mature weight at breeding, or 750 lbs) will typically not lose as much weight and condition as the heavier heifers after they calve and enter their second breeding season.  Some heifers with very high nutritional requirements may not breed the first time in a slow development program, but those big, inefficient heifers are likely to drop out of the cow herd early anyway.

A slow development program means that it is possible to create forage systems where little if any supplementation is needed during development.  A heifer that has a 205 day weight of 550 lbs needs to gain 200 lbs over the next 6 months to be adequately developed; an average daily gain of only about 1.21 lb per day.  It is very possible to achieve that gain without supplement (unless the base forage happens to be toxic KY-31 tall fescue or bermudagrass). 

Over the last two decades we have done extensive research at NCSU on developing heifers using tall fescue, with a focus on supplementation and the use of novel endophyte varieties.  This work has shown that heifers on toxic tall fescue actually have gains comparable to novel endophyte tall fescue in stockpile systems after the toxin levels start to decline in early winter.  However, when warm weather hits in late spring, the gains of heifers on toxic tall fescue are very low, while heifers grazing novel endophyte tall fescue outperform them by about 1 lb/day.  In our work, heifers grazing novel endophyte tall fescue during both the winter and spring season ended up weighing over 100 lbs more than the heifers grazing the toxic tall fescue.  Many of the problems with heifer development on toxic tall fescue can be overcome by feeding additional concentrates, but that is expensive and labor intensive compared to using novel endophyte tall fescue.

We continue to conduct research with heifer development in tall fescue systems and this winter we are evaluating heifer performance and reproduction on toxic KY31 pastures as compared to pastures recently renovated with Texoma MaxQII . 

At my home farm, we use a combination of summer and winter annuals, and novel endophyte tall fescue to create well developed heifers that are not accustomed to a feed bunk and which go on to be efficient cows that excel on an all forage nutrition system.  Kentucky-31 tall fescue continues to dominate our forage systems across the fescue belt, but strategically adding some non-toxic forages to your system, including novel endophyte tall fescue, can yield great benefits.

~ Dr. Matt Poore, NCSU professor and president of the Alliance for Grassland Renewal


The Alliance for Grassland Renewal is a national organization focused on enhancing the appropriate adoption of novel endophyte tall fescue technology through education, incentives, self-regulation and promotion.  For more resources or to learn more about the Alliance for Grassland Renewal, go to www.grasslandrenewal.org

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