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Title:Effect of sire line and selection index category on pig growth performance from weaning to harvest and carcass characteristics
Author(s):Stas, Nathaniel Mark
Advisor(s):Ellis, Michael
Department / Program:Animal Sciences
Discipline:Animal Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:M.S.
Genre:Thesis
Subject(s):Sire line
Selection index category
Growth
Pigs
Abstract:The objective of this study was to compare 3 sire lines and the effect of selection index category within sire line on growth performance (from 6.1 ± 0.29 to 129.8 ± 2.16 kg BW) and carcass characteristics of pigs under commercial conditions. A randomized complete block design (blocking factor being day of start on test) was used with a 3 × 2 factorial arrangement of treatments: 1) Sire Line (Green line vs. Blue line vs. Yellow line) and 2) Selection Index Category (High vs. Low). The lines were representative of those widely used in the industry. The High Index Category sires were from the top 25% index values within each line; the Low Index Category sires were at the mean index value for each line. Ten sires from each Selection Index Category from each line were mated to approximately 15 crossbred dams each; dam lines were equally represented across sires. Progeny (n = 2880) were housed in mixed-sex groups (barrows and gilts) of 32 pigs (15 replicates) at a floor space of 0.66 m²/pig. Pigs had ad libitum access to feed and water throughout the study period. Pen was used as the experimental unit and data were analyzed using PROC MIXED of SAS; the model accounted for the effects of Sire Line, Selection Index Category, 2-way interaction, block, and replicate. There were Sire Line by Selection Index Category interactions (P < 0.05) for most measurements. For ADG, there was no difference (P > 0.05) between High Index Category and Low Index Category for the Green line (0.76 vs. 0.77 kg, respectively) or the Yellow line (0.76 vs. 0.76 kg, respectively), however, ADG was greater (P < 0.05) for High Index Category than Low Index Category for the Blue line (0.83 vs. 0.80 kg, respectively). For G:F, there was no difference (P > 0.05) between High Index Category and Low Index Category for the Green line (0.402 vs. 0.410 kg:kg, respectively) or for the Blue line (0.425 vs. 0.429 kg:kg, respectively), however, G:F was greater (P < 0.05) for High Index Category than Low Index Category for the Yellow line (0.432 vs. 0.419 kg:kg, respectively). For carcass lean, there was no difference (P > 0.05) for High Index Category and Low Index Category for the Green line (53.34 vs. 53.51 %, respectively) or for the Blue line (53.44 vs. 53.30 %, respectively), however, carcass lean was greater (P < 0.05) for High Index Category than Low Index Category for the Yellow line (54.71 vs. 54.18 %, respectively). In addition, there were main effect differences (P < 0.05) between sire lines for growth and carcass characteristics. The Blue sire line had higher carcass weight ADG than the Green and Yellow lines, which were similar (0.62, 0.59, and 0.59 kg, respectively). For carcass weight G:F, the Blue and Yellow lines were similar (P > 0.05) and had greater carcass G:F than the Green line (0.327, 0.327, and 0.313 kg:kg, respectively). The Blue line had lower (P < 0.05) carcass yield than the Green and Yellow lines (74.31, 75.17, and 75.00 %, respectively), and the Yellow line had lower (P < 0.05) ultrasonic backfat depth than the Green and Blue lines (12.95, 15.49, 14.22 mm, respectively). The difference between sire lines for Longissimus muscle depth was similar for measurements taken on the live animal (ultrasonic) or the carcass (Fat-O-Meater), with the Blue line having lower (P < 0.05) muscle depth than the Green and Yellow lines which were similar (55.88, 58.17, and 57.40 mm, and 58.42, 62.23, and 62.74 mm, respectively). These results show commercially important differences in growth performance and carcass characteristics between sire lines. They also suggest that the relative differences between progeny of sires with high and low selection index differs between sire lines which probably reflects differences in the weighting given to traits in each line-specific index, a finding that warrants further investigation.
Issue Date:2017-03-27
Type:Thesis
URI:http://hdl.handle.net/2142/97282
Rights Information:Copyright 2017 Nathaniel Stas
Date Available in IDEALS:2017-08-10
Date Deposited:2017-05


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