Data Collection for NSIP

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Data collection is the cornerstone of obtaining Estimated Breeding Values (EBVs) through the National Sheep Improvement Program (NSIP). But the need for good records and accurate data is not limited to producers submitting data to NSIP. All flocks can benefit from good data collection since selection and culling decisions should be based on measured production criteria. Those considering joining NSIP at some point, will find collecting accurate data from the start will be helpful. There are many excellent resources (see Resources below) that describe the individual traits and/or give detailed instructions for entering the data into Pedigree Master. This document will describe what data is required by NSIP, what is optional, and when collection of the data is necessary. Collecting just the required data will give you EBVs as related traits can be extrapolated from those data points. The more optional data points you collect, the more accurate your EBVs will become, and the faster progress you can make in your selection.

Contemporary Groups

Before we get started, a review of contemporary groups is important. EBVs are designed to identify what part of the differences among lambs is due to genetics vs environment. To do that, comparisons are made between animals. The fewer variables (e.g., age, management, nutrition, etc.) the more accurate the EBVs. When entering your data into Pedigree Master, you will be asked to assign each animal to a contemporary group. A contemporary group is a group of animals about the same age that are managed together under the same conditions during the time when their performance is recorded. Differences in forage or feed, exposure to parasites and pathogens, access to shelter, and even stocking rates can affect an animal’s performance. For instance, if ewes are separated by litter size and fed differently, their lambs should be considered as different contemporary groups. Even animals remaining together should be assigned to a separate contemporary group if differences in management affect their performance (e.g., treatments that are given to some but not all animals such as supplementing some lambs with a bottle or treating for pneumonia or deworming individual lambs). The EAPK NSIP Concept sheet “Contemporary Groups” has detailed information and examples of different contemporary groups. The more animals being compared in a contemporary group the more accurate the resulting EBVs. Producers should thoughtfully make contemporary group assignments and strike a balance between management needs and ideal contemporary group structure.

What Is Needed

  1. A scale – To start, you will need a way to capture birth weights, weaning weights, post-weaning weights, etc. A lamb sling and handheld fish scale or even a bathroom scale work great for birth weights and small lambs. There are many types of livestock scales that can be used for older animals.
  2. Animal Identification – All animals will need to be identified with an ear tag showing the individual lamb’s identification number. Most people use the lamb’s flock ID in their barn records and convert that to the NSIP number when entering data into Excel or Pedigree Master.
  3. Records – Recording the data can be as simple as handwriting the data in a lambing notebook in the barn and keying it into an Excel spreadsheet later, or as sophisticated as using an electronic ID (EID) system with associated software via Bluetooth technology. Once data is in a spreadsheet format, it can easily be transferred directly to Pedigree Master, so data does not have to be keyed twice. A sample record is shown below and links to instructions for entering the data into Pedigree Master are included under Resources.

Getting Started

Each lamb will need to be recorded by its own individual unique number. The dam and sire IDs will also need to be recorded for each lamb. The flock ID is sufficient for barn records, with the 16-digit NSIP number added when entering data into your spreadsheet or Pedigree Master.

With the exception of birth records, it is important that all data is collected on all the lambs in the same contemporary group on the same day. The accuracy of EBVs is improved when there is a wider range of differences between lambs. By including all of your lambs, both poor-doers and over-achievers, extremes in each trait can be distinguished from the average.

The NSIP chart below shows age ranges for each age category. There is actually some overlap between each age category except birth, but this chart gives a good approximation.

At Birth

Much of the required data will be collected at birth, including the lamb’s unique ID, date of
birth, dam ID, sire ID, sex, birth type (single, twin, triplet, etc.) and rear type.
Birth weight is optional but improves accuracy and is strongly recommended. Birth weights need to be collected within the first 24 hours after birth.

It is important to accurately record the number of lambs born (single, twin, triplet, etc.) and reared. This seems obvious, but it is important to include every lamb born. This includes lambs born dead, lambs dying shortly after birth, and those that are bottle raised or fostered on another ewe. When entering the data into Pedigree Master you will be asked to record the number of lambs born (birth type) and the number of lambs raised (rear type). Lambs that are born dead or die before weaning will be recorded as born but not reared. When entering data, there are specific instructions for how to code lambs based on birth type and rear type, including those that are stillborn or that die any time between birth and weaning, including accidental deaths and orphaned lambs that are grafted or artificially reared (see References).

Many shepherds also find it helpful to record lambing ease and/or a mothering score. Although not used for calculating EBVs, many shepherds find it useful to collect this data and enter it into Pedigree Master for future reference.

Weaning (60 Days)

Weaning weights, or 60-day weights, and the date they are collected are required data. This age category can be confusing since this is probably not the date you will actually wean the lambs. It is collected on one day when the majority of lambs in the contemporary group average 60 days of age and all are between 40-90 days of age. It provides a standardized age when ewes are still producing a fair amount of milk. This enables representative estimates of the ewe’s milk production and mothering ability as well as the preweaning growth potential of the lamb. Rear type is also required and will need to be updated to account for any lamb losses between birth and 60 days.

Optional data that can be collected at this age category include weaning
fecal egg counts (WFEC). Fecal samples are collected on all lambs in a contemporary group on the same day at approximately 60-90 days of age. More important than age is ensuring that lambs have been challenged by an equal and significant exposure to Barberpole worms. This can be determined by a group average FEC of 500 epg (eggs/gram). Lambs should be grazing during warm/humid conditions for four to six weeks before collection. Due to age, weather and/or grazing conditions, not all flocks will have enough exposure to parasites at this age to submit data for WFEC and should submit early post-weaning data instead. Although not required, a body weight recorded at the same time or within 7 days is preferred.

Early Post-Weaning

All of the data collected at this age category is considered optional. Early post-weaning data is collected on one day when the majority of lambs in the contemporary group average 120 days and all are between 90-150 days of age. Data typically collected at early post-weaning include date, weight (PWWT), and fecal egg count (PFEC).

While it is possible to collect carcass traits (fat depth (PFAT), loin eye muscle depth (PEMD)) as well as scrotal circumference (PSC) at this age, waiting to collect until the animal is older at the post-weaning age category will give more accurate data. For these traits, only the first reported record is used to calculate the EBV, so be sure the most informative measurement is used.

Post-Weaning (Late Post-Weaning)

While all of the data in this age category is considered optional, collecting either Early Post-Weaning or Post- Weaning data, or both, improves accuracy and is recommended. Post-weaning data is collected on one day when the majority of lambs in the contemporary group are between 150-305 days of age. Data typically collected at post-weaning include date, weight (PWWT), and fecal egg count (if not collected at early post- weaning, or if improved accuracy is desired). Carcass traits (fat depth (PFAT), loin eye muscle depth (PEMD)), as well as scrotal circumference (PSC) only need to be collected once. The late post-weaning age category is the preferred time to collect these measurements.

Carcass measurements are made using ultrasound technology at 90-210 days of age and may fall under the Early Post-weaning or Late Post-weaning age categories depending on when animals are scanned. Carcass scanning is usually done when the contemporary group is at or near targeted market weight. Lambs must be both weighed and scanned on the same day. Ultrasound carcass measurements are taken by an NSIP certified technician using approved equipment. Once a suitable image has been obtained, measurements are made on the image of backfat thickness and eye muscle depth.

In Katahdins, the most useful scrotal circumference measurement is taken at post-weaning (approximately 6 to 9 months of age) and is recorded in centimeters. Although not required, a body weight recorded at the same time or within 7 days of the post-weaning scrotal measurement is preferred. Scrotal circumference should be measured at the greatest circumference of the scrotum. A scrotal tape is most often used for measuring due to its repeatability and ease of use. Currently, NSIP generates PSC EBVs for early-maturing maternal breeds based on the first PSC recorded which is normally at the late post-weaning measurement. Early post-weaning measurements taken before puberty are less accurate.

Adult Weights

EBVs are calculated for yearling weights, but not adult weights. Yearling (10-14 months old), hogget (13-18 months old), and 2, 3, 4, and 5 year old
weights are optional. If you breed your ewe lambs to lamb at one year of age, you might not be able to take yearling weights as the ewe lambs will be pregnant or lactating during this time frame. It is generally best to take weights just before breeding, at the hogget age category, so pregnancy and lactation do not confound the measurement. Remember to put your ewe hogget weights in two separate contemporary groups if some lambed as yearlings and others did not. Collecting hogget weights before breeding works well for young rams as well, as they usually lose weight from breeding.




Contemporary Group

Birth Weight

Birth Date

Early Post-Weaning Weight

Animal ID (flock and NSIP 16-Digit ID)

Post-Weaning Weight

Dam ID

Weaning Fecal Egg Count

Foster Dam ID (if needed)

Post-Weaning Fecal Egg Count

Sire ID

Post-Weaning Backfat

Birth Type

Post-Weaning Eye Muscle Depth

Rear Type

Post-Weaning Scrotal Circumference

Weaning Weight Date

Adult Weights

Weaning Weight



NSIP resources

    How, when, and what data to collect (Cody Hiemke)

    Forming NSIP ID Numbers

    Importing a Spreadsheet of Data

    Basic Data Input

    List of Certified NSIP Scanners

EAPK educational materials

Fact sheets on individual traits

Contemporary Groups

By EAPK Communications Committee

Kathy Bielek, Roxanne Newton, Isabel Richards


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