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https://hdl.handle.net/2142/19960
Description
Title
Genetic analysis of hoof traits
Author(s)
Huang, Yu-Chia
Issue Date
1994
Doctoral Committee Chair(s)
Shanks, Roger D.
Department of Study
Animal Sciences
Discipline
Animal Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Genetics
Agriculture, Animal Culture and Nutrition
Language
eng
Abstract
Heritabilities of heel erosion and laminitis were more than 10% and improvement by traditional quantitative methods should be possible. Ranges of incidences of hoof traits varied from.6% to 2.1% (interdigital hyperplasia) to higher than 50% (heel erosion) in reference herds. Means of fifteen hoof traits collected from University of Illinois dairy farm for genetic analysis were all inside 80% range of reference herds. Estimated heritabilities based on Snell transformed scores were.05,.12,.06,.14,.02 and.08 for corkscrew claw, heel erosion, interdigital dermatitis, laminitis, sole ulcers and white line separation. Severity of laminitis and sole ulcers peaked at four to five months postpartum approximately two months after peak milk yield. Heel erosion and interdigital dermatitis were worst in Holsteins. Generally, Ayrshires and Jerseys had better claw scores than Holsteins. November was the highest risk season for heel erosion, sole ulcers and laminitis, whereas the frequency of slight separation of white line was higher in July. Seasonal variation of interdigital hyperplasia was not detected, but Holsteins were found at higher risk. Daughters of dams affected by interdigital hyperplasia were 5.3 times more frequently affected than daughters of normal dams and some sire families had more affected daughters than expected. Trials of DFA (Dominance, Inbreeding, and Additive Relationships) plots for hoof traits confirmed the usefulness of graphical diagnosis for genetic inferences. For interdigital hyperplasia, DFA plots showed higher densities of additive relationships among affected animals. Genetic predisposition was implied for interdigital hyperplasia and a rapidly diminishing population incidence was expected by selection. From the predicted response surfaces, highest additive relationships were observed between the most severely affected cows for all hoof traits except sole thickness, sole ulcers and white line separation. Analyses of contingency tables on daughters and dams using ten log-linear models supported genetic predisposition for most hoof traits (heel height, hoof texture, subsole, toe growth, interdigital hyperplasia, corkscrew claw, heel erosion, interdigital dermatitis and laminitis). Results of hoof trait analyses suggested that genetic effects existed but environmental effects were evident, also. Maximizing net income for diary producers or welfare of dairy cows, management should be as important as genetic practice.
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