Due to greater reproductive efficiency, gendered semen and improvements in heifer rearing, heifers make up a larger proportion of our milking herds today. As a result, the milking herd could see better performance if its heifers are well grown and “ready to get to work” when they freshen.
For example, a heifer gaining 1.8 pounds per day will reach about 1,400 pounds by 24 months old, but a heifer gaining 2 pounds per day will reach that same target weight at 21 months. Heifers achieving 80 percent of mature bodyweight by calving have the capacity to eat more feed – and therefore make more milk – than heifers that do not achieve this growth rate.
An important phase of heifer growth occurs between 2 and 8 months old when they grow from 190 to 600 pounds of bodyweight (Holsteins). During this time, heifers have many new experiences, including changes in feed intake and digestion, adaptation of feeding behavior, social behavior development and housing adaptations such as pen moves and interaction with pen resources.
These factors can have a short-term impact on heifer growth and health, and a longer-term impact on performance as they enter the milking herd. Focusing on several heifer nutrition and management factors can have significant impacts on your farm’s bottom line and overall success.
Prepare pre-weaned calves for transition success
One of my favorite things to remind producers is: We grow calves from the inside out, and this does not happen overnight.
What I mean by this is: Growing calves is more than just weight gain. Growth is about developing a calf’s gastrointestinal tract, including a functioning rumen with a diverse microbial ecology capable of holding and digesting adequate amounts of nutrients to meet the heifer’s requirements for both maintenance and growth.
Rumen development is instrumental to providing metabolizable protein and energy to heifers for both rapid and efficient growth.
Rumen health and function impacts consistency of dry matter intake. Heifer dry matter intake should slowly increase over time, and manure should be firm and dark in color. Inadequate rumen development in heifers can be characterized by erratic intake and inconsistent manure.
Providing calves with adequate amounts of dietary fiber has clear and important roles in rumen development and function. I target dietary neutral detergent fiber (NDF) concentration at a minimum of 15 percent and prefer 20 percent in starter grain during the nursery phase to speed rumen development.
This allows calves to consume more dry matter, increase rate of growth through the weaning phase and carry momentum into the transition phase.
Consistency and comfort key to transition
Calf transition occurs during the first month after the nursery phase. These heifers typically range in size from 190 pounds at the beginning to 250 pounds at the end of the transition phase. Transition heifers thrive on feed consistency targeted to not greatly exceed or limit nutrient requirements for maintenance and growth.
The first week of the transition diet should be the same as the weaned calf diet. Slowly blend in grower feed to transition calves completely onto the grower feed by the second or third week of transition.
I typically target a dry matter intake of 3 percent of calves’ bodyweight and an NDF intake of 0.8 percent of bodyweight to achieve an average daily gain of 2 pounds per day. Coccidiosis and fly control measures should be in place during this time.
Feeding behavior and positive interaction with the feeding system are also important for transition calves. This is often the first time heifers have to reach through a fence to eat with their heads down, and it takes some time to develop this behavior.
Many producers successfully use slant bars or trainer (Y-bars) instead of headlocks at this age. Feed deck height should be a minimum of 4 inches higher than the scrape alley.
Transition calves thrive in small groups with a bedded pack of straw or wood shavings and minimum ventilation rates of six to eight air exchanges per hour. The smaller the heifer is, the more heat it can lose or gain from the environment, so bedding management is an important determinant of transition calf success.
A manure scrape alley between the bedded pack and the feedbunk contributes greatly to bedding pack hygiene. Freestalls are typically reserved for heifers weighing at least 300 pounds.
Feed grower appropriate for age and size of animal
At around 100 days old, heifers that have successfully navigated through the transition phase should tip the scales at 250 to 300 pounds. This is typically the age and size of a heifer ready for an introduction to TMR to increase fiber intake, make use of homegrown feeds and decrease off-farm feed purchase.
Heifers can eat a maximum of about 3 percent of their bodyweight in dry matter per day, about 1 percent of their bodyweight as NDF per day and about 5 percent of their bodyweight in as-fed feed per day.
Let’s take a 300-pound heifer as an example. That heifer can eat:
- A maximum of 9 pounds of dry matter per day (3 percent of bodyweight)
- A maximum of 3 pounds of NDF per day (1 percent of bodyweight)
- A maximum of 15 pounds of as-feed feed per day (5 percent of bodyweight)
This means if the maximum NDF in the diet is 3 pounds per 9 pounds of dry matter, the maximum NDF concentration of the diet is 33 percent.
This also means the heifer TMR needs to be about 60 percent dry matter. To make use of wet feeds such as corn and alfalfa silage, the first TMR needs to be about 60 percent from concentrate and 40 percent forage to meet these conditions.
Diets formulated to exceed these guidelines tend to limit dry matter intake, which will constrain growth in heifers and increase risk of energy and intestinal barrier function-related health challenges, including respiratory disease.
Decreased nutrient intake and increased concentration of some blood metabolites, because of tissue mobilization, have been associated with reduced neutrophil functionality, increasing susceptibility to respiratory disease.
When heifer diets exceed NDF and moisture limits, we tend to see heifers with loose manure and dirty tails, decreased body condition or failure to gain body condition, increased respiratory challenges and decreased average daily gain, especially during the first 30 days of diet adaptation and rumen expansion.
As we look for opportunities to improve efficiency and production on our farms, increasing first-lactation performance could provide a significant boost to the bottom line. Focusing on heifer growth is key to achieving a higher level of performance.
However, we can’t make this change overnight. Rather, a heifer’s performance is the result of rumen development and solid growth throughout the nursery, transition and grower phases. Evaluate heifer development in your herd to find opportunities to influence heifer size and milk potential at calving by increasing success in all stages of their development. 
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Noah Litherland
- Nutritionist
- Vita Plus
- Email Noah Litherland
