Benny E. Mote
Date of this Version
Trenhaile Grannemann, M.D. 2021. Quantification and repeated measurements of conformation traits in replacement females to optimize sow longevity, Ph.D. Dissertation. University of Nebraska - Lincoln. Lincoln, Nebraska, United States.
The objectives were to 1) assess the reliability of objective conformation trait measurements between evaluators, 2) evaluate effects of dietary energy and lysine during development and housing system during first gestation on longevity, reproductive performance, and conformation, 3) characterize conformation changes throughout life, 4) identify phenotypic associations between conformation and longevity, 5) estimate heritability of conformation traits, and 6) assess genetic relationships between conformation traits measured throughout life in sows. Sows (n = 622) were fed a standard, energy restricted, or standard energy with increased lysine diet during gilt development and housed in either a group pen or stall during first gestation. Conformation traits, including five body size traits, knee, hock, and pastern angles, rump slope, and foot directional position, were objectively measured at 16 time points between 112 days of age and parity 4 weaning. Three types of foot lesions were evaluated at the latter 14 time points. Intra-class correlations demonstrated objectively measured conformation traits are reliable between evaluators; they also improve consistency, encompass the full range of trait phenotypic values, and allow identification of small conformational differences. Energy restriction during development had favorable effects on performance, including increased feed intake and decreased body condition loss during lactation. Pen housing had detrimental effects on conformation, including steeper rumps and pasterns, more “toed out” rear feet, and increased foot lesion severity. Changes over time were observed for all conformation traits. Body size increased while knee and pastern angles decreased. A pattern of change following the gestation cycle was observed for several traits. Associations were identified between sow longevity and conformation traits, including body depth, height, knee angle, rear foot directional position, heel-sole cracks, and total rear foot lesions. Objectively measured conformation traits and foot lesions were heritable (median h2 = 0.11 to 0.37). Genetic correlations between body size traits, knee, hock, and pastern angles, and rump slope evaluated throughout life suggest these traits have the same genetic determinism from first to fourth gestation.
Advisor: Benny E. Mote