ANIMAL-MODEL ESTIMATES OF CYTOPLASMIC LINE CONSTANTS FOR YIELD IN HOLSTEINS

An animal model was used to investigate cytoplasmic effects on 3.7% fat corrected ME milk (kg) in registered Holsteins. Data were from 3413 cows with 8414 lactations in six North Carolina Department of Agriculture and State University Holstein herds. Data sets included first lactations only, lactations greater-than-or-equal-to 2 or all lactations. Subsets were constructed by including only lines with greater-than-or-equal-to 5 cows or greater-than-or-equal-to 20 cows. Correlations between number of cows in a maternal lineage and cytoplasmic constants were small. Highest FCM lines were not necessarily lines with the largest number of cows. Ranges for lines (58) containing greater-than-or-equal-to 5 cows were approximately 1447 to 1846 kg FCM, while corresponding values when data were limited to lines (24) containing greater-than-or-equal-to 20 females were 669 to 769 kg FCM. Standard deviations of line solutions were equal to .1 to .3 genetic SD for FCM. Correlations between different estimates of cytoplasmic constants were generally positive and high. Estimates of cytoplasmic line solutions from animal models including all relationships and external sire breeding value information were not different from those estimated without additive genetic relationships and sire breeding values for FCM. Results suggest that additive genetic covariances among animals did not contribute to estimates of cytoplasmic effects.