Santa Gertrudis Source January 2025

USING SGBI GENETIC EVALUATION

2025 Semen Directory

MILK (MK) – This is a measure of pounds of a calf’s weight at weaning which is attributable to the amount of milk the dam produces. TOTAL MATERNAL (TM) – This is a measure of the com bination of both weaning and milk EPDs which indicate a cow’s ability to bring a heavier calf to the weaning pen. SCROTAL CIRCUMFERENCE (SC) – This is an indicator trait for fertility in bulls as well as for the age of puberty in heif ers. The unit of measure is in centimeters. HEIFER PREGNANCY (HP) – This is a measure of the prob ability that a heifer will get pregnant as a yearling. Heifer Pregnancy EPDs are reported in units of percentage. A higher EPD sire would be expected to have daughters with a greater probability of becoming pregnant as a yearling. This is an important measure of fertility. BREED BACK (BB) – This is a measure of the probability that a 2-year-old will become pregnant given that she was listed as pregnant as a yearling. Breed Back EPDs are re ported in units of percentage; a higher EPD sire would be expected to have daughters with a greater probability of becoming pregnant than a sire with a lower EPD. This is an important measure of fertility. CARCASS WEIGHT (CW) – This is a predictor of the differ ences in hot carcass weight of offspring compared to off spring of other animals. It is expressed in pounds. RIBEYE AREA (REA) – This predicts the differences of car cass ribeye area between the 12th and 13th ribs and is ex pressed in square inches. It is an indicator of muscling. MARBLING (MB) – This is an evaluation of the intramus cular fat deposition in the ribeye and is expressed as a nu merical marbling score. A one-unit change in the numeri cal marbling score is equal to a full USDA Quality grade at carcass maturity. BACKFAT THICKNESS (FT) – This is an indicator of fat thickness on the harvested carcass as measured between the 12th and 13th ribs. BALANCED INDEX (BALANCED) – This index assumes that producers are keeping replacement heifers from the bulls they purchase. It further assumes that producers are ei ther 1) marketing carcasses on the grid or 2) that buyers of their feeder calves base pricing on feedlot and carcass performance. Most large cow-calf operations fall into this category. The SGBI Balanced Index incorporates all EPDs except Carcass Weight and Back Fat into its calculation. COW/CALF INDEX (COW/CALF) – This index assumes that producers are keeping replacement heifers from the bulls they purchase. However, it assumes all calves are marketed at weaning or soon thereafter. It further assumes that feeder calf buyers don’t base decisions on feedlot or carcass per formance, making these traits less relevant to profitability. Many small- to mid-sized herd operations fall into this cat egory. The SGBI Cow/Calf Index incorporates Heifer Preg nancy, Breed Back, Birth Weight, Weaning Weight, Milk and Scrotal Circumference into its calculation. 

THE FOUNDATION OF SELECTION IS EXPECTED PROGENY DIFFERENCES (EPDS). These are predictions of how an animal’s future progeny are expected to perform relative to other animals’ progeny listed in the breed asso ciation’s database. They are expressed in units of measure (plus or minus) consistent with each trait being evaluated, and calculated utilizing pedigree and performance infor mation. Research demonstrates that EPDs are the most reliable indicator of an animal’s true genetic merit. EPDs should be used to select for those traits which will optimize the goals of an operation within the constraints of their environment and marketing plan. SGBI is an industry leader in genomic technology and was the first beef breed association to utilize the single step method for incorporating DNA into EPD calculations. This process utilizes DNA information to measure the ac tual amount of relationship between animals included in the evaluation. In 2013, SGBI released the first genomic enhanced EPDs for Bos indicus -influenced cattle. Incorporation of DNA into the breed’s genetic evalua tion results in information that is more accurate and pre dictable than a pedigree and performance prediction alone. SGBI incorporates the genotypes of 10’s of thousands of animals into the EPD calculations each month. The result is improved confidence that the animals will produce the traits in their offspring that you expect. Following is a list of the types of EPDs you will see in this catalog: BIRTH WEIGHT (BW) – This is an indicator of calf size at birth and calving ease. WEANING WEIGHT (WW) – This is an indicator of growth from birth to weaning, measured from adjusted 205-day weights. YEARLING WEIGHT (YW) – This is an indicator of growth from birth to 1 year of age, measured from adjusted 365 day weights.

26

SANTA GERTRUDIS SOURCE

JANUARY 2025