Masters Theses

Date of Award

12-1983

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

E.R. Lidvall

Committee Members

J.B. McLaren, F.B. Masincupp

Abstract

Data from 789 crossbred Duroc, Hampshire, Yorkshire, and Landrace litters, as well as 174 purebred litters from Duroc, Hampshire, and Yorkshire sows were used to evaluate factors influencing problems in rebreeding. The management and care of the herd was considered typical of the production system, and a consistent level of management was maintained throughout the study. Sows were separated into parity groups as well as farrowing interval groups and analyzed separately. The farrowing interval groups separated sows and gilts into rebreeding groups which were considered to be on or off schedule.

Results showed that first litter sows which were older and gained weight at a slower rate during gestation tended to be on schedule and, thus, have normal farrowing intervals. Second through fifth litter sows that showed more body weight fluctuation between weight gain during gestation and weight loss due to the products of reproduction and lactation tended to have longer farrowing inter vals. Sows with parities of six and greater showed no differences in response among the variables used to classify them into interval groups. Sows that had lactation lengths of approximately 35 days and greater tended to rebreed on schedule, compared to those with shorter lactation lengths.

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