Masters Theses

Date of Award

8-1990

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

John P. Hitchcock

Committee Members

Henry G. Kattesh, Frank B. Masincupp

Abstract

Fifty littermate gilt pairs were classified according to their rate of gain during the finishing period. Body weight and backfat thickness at day 110 of gestation and weaning were recorded in addition to the sow productivity traits of total number bom, number born alive, pig birth and weaning weights and number of pigs weaned. Females were evaluated for three parities. Gilts exhibiting slower rates of developmental growth (65 kg gain in body weight) produced more pigs bom (8.6 vs. 6.4, p=.05), more born alive (8.2 vs. 6.0, p<.05) and more pigs weaned (7.4 vs. 5.1, p<.05) in parity one in addition to more pigs weaned in parity three (8.6 vs. 7.3, p<.10) than faster gaining gilts (73 kg gain in body weight). Over three parities, slow gaining gilts produced 26.4, 25.8 and 23.4 pigs bom, bom alive and weaned, respectively, compared to 25.6, 24.0 and 20.3 pigs, respectively, for fast gaining gilts. Gilt rate of gain did not affect progeny birth or weaning weights (p>.27) nor sow 110 day gestation weights or backfat thicknesses (p>.25 and p>.17, respectively). Fast gaining gilts were heavier at selection (106 kg vs. 96 kg, p=.0001) and at first breeding (145 kg vs. 139 kg, p<.05) although the only difference observed in sow weaning weight was in parity two where slow growing gilts were heavier (159 kg vs 146 kg, p<.10). Slow growing gilts gained 82 kg of body weight (BW) from selection through parity three weaning compared to a 73 kg BW gain for faster growing gilts. Slow growth rate females lost more backfat during their first and third lactations and had negative backfat gains during gestation in parities two and three. Slow growing females had lower culling rates (35%) than faster growing females (39%). Fraternal litter size tended to affect litter sizes produced by the gilts in this experiment though the effect was observed mostly in the third parity. Parity of the dam in which the gilts were born influenced pig birth weights and number weaned but not until the third parity. Correlations of gain to sow body weights were positive and moderate to high but were low for backfat thickness and productivity traits. These results indicated that fast growing females used for sow herd replacements were not reproductively nor productively superior than their slower growing littermates.

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