Chromosome--Chromosomes are long DNA molecules on which genes (the basic genetic codes) are located. Domestic cattle have 30 pairs of chromosomes.

Closed herd--A herd in which no outside breeding stock (cattle) are introduced.

Collateral relatives--Relatives of an individual that are not its ancestors or descendants. Brothers and sisters are an example of collateral relatives.

Conception--The fertilization of the ovum (egg). The act of conceiving or becoming pregnant.

Congenital--Acquired during prenatal life. Condition exists at or dates from birth. Often used in the context of congenital (birth) defects.

Contemporary group--A group of cattle that are of the same breed and sex and have been raised in the same management group (same location on the same feed and pasture). Contemporary groups should include as many cattle as can be accurately compared.

Correlation--A measure of how two traits vary together. A correlation of + 1.00 means that as one trait increases the other also increases a perfect positive relationship. A correlation of -1.00 means that as one trait increases the other decreases--a perfect negative, or inverse, relationship. A correlation of 0.00 means that as one trait increases, the other may increase or decrease--no consistent relationship. Correlation coefficients may vary between +1.00 and -1.00.

Crossbreeding--The mating of animals of different breeds (or species). Crossbreeding usually results in heterosis (hybrid vigor).

Culling--The process of eliminating less productive or less desirable cattle from a herd.

Cutability--An estimate of the percentage of salable meat (muscle) from a carcass versus percentage of waste fat. Percentage of retail yield of carcass weight can be estimated by a USDA prediction evaluation that includes hot carcass weight, ribeye area, fat thickness, and estimated percent of kidney, pelvic, and heart fat.

Dam--The female parent.

Deviation-- difference between an individual record and the average for that trait for that contemporary group. These differences sum to zero when the correct average is used. A ratio deviation is the ratio less the average ratio or 100.

Dominance--Dominant genes affect the phenotype when present in either homozygous or heterozygous condition. A dominant gene need only be obtained from one parent to achieve expression.

Dystocia (calving difficulty)--Abnormal or difficult labor causing difficulty in delivering the fetus and/or placenta.

Economic value--The net return within a herd for making a pound or percentage change in the trait in question.