Lincoln Cluster Analysis

Data file statistics & edits

NLSBA provided NAGP with access to their database for this analysis.  There were 13,458 records from animals born from 1976-2007.  Of these, 8,972 (66.7%) were ewes and 4,486 (33.3%) were rams.  Birth years were unknown for 12.9% of the data.  The only data edits needed were for 2 rams that appeared as their own sire.  Their sire was converted to unknown.  Sires were known for 89.0% of the animals and dams were known for 88.9%.  There have been 1,136 sires and 4,501 dams during the lifetime of the database.

Registrations by birth year

The oldest registered animal was born in 1976; registrations did not greatly increase until 1993.  The number of registrations by birth year have remained relatively stable since 1994, as shown in Figure 1.  Registrations for 2007 are incomplete.

Figure 1.  Registrations by Birth Year

Color

For all of the animals in the file, 14% registered were colored and 86% were white.  However, this has not remained consistent over time, as shown in Figure 2.  Starting in 2002, there has been an explosion of colored Lincoln registrations.  If the rest of 2007 follows the current trend, more colored Lincolns will be registered than white.

Figure 2.  Percent Colored and White Registrations by Birth Year

Birth type

The majority of lambs are born as twins, followed by singles and triplets.  Only 0.3% of registered lambs were born as quads or quints.  Figure 3 shows the trend over time for single, twin, and triplet registrations.  The trend has remained fairly stable over time, but the proportion of singles has increased in recent years.

Figure 3.  Birth Type by Birth Year

Breeders

There are 340 breeders in the database.  The number of birth years a breeder has registered sheep ranges from 1 to 17, with an average of 3.7 years.  The vast majority have only registered sheep for 1 or 2 years, as shown in Figure 4.  Conservation of a rare breed requires a careful breeding strategy due to the limited gene pool available from which to select breeding animals.  Managing these limited resources is made more difficult if breeders are transient.  It is encouraging to see that a fairly large number of breeders have been registering animals for 5+ years.

Figure 4.  Number of Birth Years a Breeder has Registered Sheep

Even though there are a lot of breeders entering and leaving the industry each year, the total number of breeders has remained stable since 1994 (Figure 5).  Although the breed isn't expanding, it also isn't shrinking.

Figure 5.  Number of Breeders by Birth Year

Exchange of genetics

While mapping out the current location of active rams, defined as those who sired lambs in 2006 and/or 2007, it became clear that the majority of rams were not being retained by their breeders.  Of the 149 active rams, 116 (77.9%) were owned by someone other than the person that bred them.  This is a surprisingly large exchange of genetics.  Not only are the rams being exchanged, they are moving throughout the country.  Eighty-six of the 149 rams are owned in a different state than the one in which they were born.

The 2006-2007 lamb crop is primarily concentrated in the Northeast and the eastern section of the Midwest with another group in the Pacific Northwest.  The most lambs in this period were born in Illinois (163), Michigan (121), and Oregon (92).

Current breeding population

There were 149 rams and 722 ewes that produced the lambs born in 2006 and 2007 (to date).  The birth year of the rams ranged from 1998 to 2006.  There were 5 2006 born rams that have already had offspring in 2007, indicating a relatively young age at puberty for such a large-framed breed.  Table 1 shows the number of lambs these rams sired in 2006-2007.  The industry is using a large number of rams, with the most dominant ram siring only 60 lambs in this period of time; the next highest had 37 lambs.

Table 1.  Number of Rams that Sired 2006-2007 Born Lambs

The ewes that produced the 2006-2007 lamb crop ranged in birth year from 1994 to 2006.  There were 5 2006 born ewe lambs that have already had lambs in 2007, indicating age at puberty is early on the female side as well.

 Inbreeding (F)

The pedigree was traced back until ancestors were unknown.  The final pedigree file contained 13,558 animals.  Since the breed registry is relatively new, the pedigrees are shallow and inbreeding levels are likely higher than shown here.  The average inbreeding across the breed was 2.7%, with a range from 0 to 53.1%.  The frequency distribution of inbreeding percentage is shown in Table 2.  The vast majority have an inbreeding coefficient of 0, but some of these are animals with unknown pedigrees, such as foundation animals.

Table 2.  Frequency Distribution of Inbreeding Across Lincoln Pedigree