Gilt development traits associated with genetic line, diet and fertility

Abstract

The objective was to associate gilt development traits with genetic line, diet and fertility group (FG). Gilts (n=1225) were reared from 162 to 265 days of age at a gilt development unit (GDU) and sent to sow farms. Females were Landrace (L), Large White (LW), L and LW F1 or L and LW composite. Estrous traits included age at puberty (AGEPUB), length of estrus (LOE), maximum strength of standing reflex with (MSRBOAR) or without (MSRNOBOAR) a boar present, total strength of standing reflex with (TSRBOAR) or without (TSRNOBOAR) a boar present, vulva redness (VR), strength of vulva reddening and swelling (VISUAL VULVA) and vulva width (VW). Growth and body composition traits were puberty weight, days to 114kg and 10th rib backfat (BF) and loin muscle area (LMA) at 114kg and puberty. Structural conformation traits included muscle mass, rib width, front leg side view, rear leg side view, front legs front view, rear legs rear view and locomotion (LOC). Sow farm entry traits were age, weight, BF and LMA. Sow traits included whether or not a gilt farrowed (STAY), age at first farrowing and total number born (TNB). Fertility groups were; FG0=did not reach puberty at the GDU (NOPUB), did not farrow (DNF); FG1=reached puberty at the GDU (YESPUB), DNF; FG2=NOPUB, farrowed; FG3=YESPUB, farrowed. Genetic lines differed (P<0.05) for estrous traits LOE, TSRBOAR, MSRNOBOAR, TSRNOBOAR, VR, VISUAL VULVA and VW. Females fed restrictively vs. ad libitum had a longer (P<0.05) LOE (2.18 vs. 2.03d), higher (P<0.05) TSRBOAR (15.4 vs. 14.0) and younger (P<0.05) AGEPUB (219 vs. 225d). Fertility groups 0, 1, 2 and 3 contained 45 (4%), 255 (24%), 66 (6%) and 698 (66%) gilts, respectively. Gilts from FG3 in comparison to FG1 had a longer (P<0.05) LOE (2.16 vs. 2.06d), greater (P<0.05) MSRBOAR (7.6 vs. 7.4) and greater (P<0.05) TSRBOAR (15.4 vs. 14.6). Fertility group 0 had less (P<0.05) BF, poorer (P<0.05) LOC and was narrower (P<0.05) ribbed compared with the other FG's. Based on these results it was concluded that gilts with LOE ≤1 day or weak standing reflexes were less likely to farrow a litter.