New spreadsheet helps track heifer growth

New spreadsheet helps track heifer growth

*Krissa Welshans holds a bachelor's degree in animal science from Michigan State University and a master's degree in public policy from New England College. Welshans has long been involved in agriculture and has worked with numerous agricultural groups, including the Animal Agriculture Alliance.

PENNSYLVANIA State University Extension has released a new spreadsheet that generates a customized growth curve for an individual herd based on that herd's goal for age at first calving and the mature size of animals in the herd.

Producers who use the tool will be able to tell whether heifers are on track to calve at the right size and age, eliminating the delay that comes with not measuring heifer performance until first calving.

Monitoring the height and weight of calves and heifers is essential to tracking the progress of each animal throughout the heifer-rearing period. Pennsylvania State University Extension noted that although spotting fat and thin heifers is fairly easy, it is difficult to look at a heifer and determine if her height and weight are appropriate for her age.

Using the spreadsheet, called the "Customized Dairy Heifer Growth Chart," with just a few objective measurements, tracking heifer performance becomes much easier, according to Penn State Extension.

Traditionally, heifer growth has been compared to breed standards to determine normal progress. Penn State Extension pointed out that this type of comparison is not useful if the group of heifers producers want to monitor happen to be genetically programmed to be larger or smaller than the breed average or if there is considerable variation in the genetics within a group of heifers.

For example, crossbred heifers can be challenging to benchmark because they fall between the standards for the breeds of their sires and dams. Additionally, there are certain physiological changes (such as the start of puberty) that happen because she has matured to a certain proportion of her final mature size and body composition.

For these reasons, recommendations for heifer growth benchmarks, based on the mature size of the animal, were adopted in the 2001 "Nutrient Requirements of Dairy Cattle."

According to Penn State Extension, if both the mature size of a heifer and her current size are known, it is relatively simple to figure out what growth rate is needed to move from the current size to the mature size or to benchmark times in between, such as breeding. Penn State's new growth tracking spreadsheet automates growth rate calculations to generate a customized growth curve for each individual herd.

The spreadsheet asks producers to enter the average bodyweight and height of third-lactation cows in their herd, the average birth weight of calves, the average services per conception for heifers and the goal for age at first calving. From this information, a customized growth chart is generated (Figure), allowing producers to track heifer performance against the growth required to meet herd goals.

The customized growth goals are presented in table form as well as in graphs for height and weight (using inches and pounds) and a graph of the percent of mature size. Users can plot growth data from heifers on these graphs to compare individual heifer performance to the goals. A version of the spreadsheet using metric units is also available.

The spreadsheet assumes a target bodyweight of 55% of mature weight at first conception and 85% of mature weight after first calving, as cited in the 2001 dairy requirements.

Height targets are assumed to be 55% of mature height at birth, 85% of mature height at conception and 96% of mature height at first calving.

These targets were derived from a comparison of heifer growth data from all breeds to mature heights and were calculated by assuming mature bodyweight and using the relationship between withers height and bodyweight.

Withers and hip height are assumed to change at the same rate throughout the growing period, meaning either one can be used to monitor growth as long as the same measurement is used for heifers and mature cows. The size of mature cows can be entered as a herd average or individually for each heifer's dam.

 

Strong kids project

The Family Resiliency Center and department of nutritional sciences at the University of Illinois at Urbana-Champaign and the Dairy Research Institute recently announced a new partnership that will help fill critical research gaps in how healthy eating habits are formed from the earliest ages.

The Dairy Research Institute is providing $1 million of support over five years for "STRONG Kids 2: A cells-to-society approach to nutrition." The project will provide unique insights into how individual biology and the family environment interact to promote healthy eating habits, including milk and dairy consumption, in young children.

It is one of the first longitudinal studies to take a look at the interaction between biological and environmental factors in predicting eating habits, starting at birth.

"This research project is timely and important as we know that birth to three years of age is a critical time for establishing food preferences, immune tolerance and the gut microbiome," said Dr. Sharon Donovan, professor of food science and human nutrition at the University of Illinois. "We are very excited to be working with the Dairy Research Institute to define how dairy products contribute to the growth and development of young children."

"For generations, dairy farmers have been committed to children's health, wellness and learning," said Dr. Greg Miller, president of the Dairy Research Institute. "We're proud to be part of this important research initiative that will provide critical new insights for health and wellness professionals to use in helping kids establish good nutrition habits they need for a lifetime, such as drinking milk."

The project is part of the larger STRONG Kids Program based at the Family Resiliency Center and is being co-directed by Donovan and Dr. Barbara Fiese.

"The Family Resiliency Center is excited about this partnership as this research project will make important contributions toward informing policy and practice that help families create healthy habits for their children from the beginning," Fiese said.

STRONG Kids 2 is built upon previous research with preschool-aged children, documenting the relationship among genetic, child and family factors in predicting body mass index and dietary habits.

 

School snack foods

New U.S. Department of Agriculture rules affecting foods sold in schools will ensure that nutrient-rich dairy products will continue to be offered to students in a variety of forms and settings, according to the National Milk Producers Federation (NMPF).

On June 27, USDA released its "Smart Snacks in Schools" nutrition standards, affecting the calorie, fat, sodium and sugar content of foods that are offered apart from the school lunch line (Feedstuffs, July 1). These "competitive" foods may be offered in vending machines or other a la carte settings.

The snack regulations are similar to overall nutritional rules applied last year to school lunches and breakfasts via the adoption of the Healthy, Hunger-Free Kids Act of 2010.

"The nutrients in dairy foods are an important answer to the question of how we can improve the diets and health of young people. The rules released today will ensure that milk, cheese and yogurt are offered beyond the school lunch line in places where they can contribute to healthy eating," said Jim Mulhern, chief operating officer of NMPF.

Under the new regulations, competitive foods must meet all of the rule's nutrient standards and either have as the first ingredient one of the major food groups or, until June 30, 2016, contain 10% of the daily value of a nutrient of public health concern (e.g., calcium, potassium, vitamin D or dietary fiber). NMPF noted that dairy foods are a key source of calcium, potassium and vitamin D.

The regulation's nutrient standards affect the following products, including dairy products:

* Low-fat and fat-free unflavored milk and fat-free flavored milk can be offered at all grade levels, with 8 oz. portions for elementary schools and 12 oz. portions in middle and high schools;

* Reduced-fat cheeses (including part-skim mozzarella) are exempt from fat standards but must meet sodium limits of 230 mg through June 30, 2016, and then 200 mg after July 1, 2016.

* Yogurt is subject to a sugar limit (35% by weight) that should facilitate dairy consumption.

* Entrées, such as pizza, that are offered in the National School Lunch Program are exempt from the standards when offered in the same or smaller portion size and available on the day the entrée is served and the following day.

* Caloric soft drinks are not allowed, and sports drinks cannot exceed 40 calories per serving (and are only available in high school).

"The goal of the regulations — the first comprehensive rule to cover school foods beyond federally reimbursed lunches and breakfasts — is to improve the health of the nation's children and increase their consumption of healthy foods," Mulhern said. "As an important source of nine essential nutrients kids need, milk and dairy foods figure prominently in the new standards. We look forward to working with USDA to implement the standards and to continuing to improve the health of our children."

Volume:85 Issue:27

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