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Impact of sex on composition and quality of fresh loins, bellies, and fresh and processed hams
The objective was to characterize the effect of sex across production focus on primal quality of pigs slaughtered in marketing groups designed to reduce variability. Pigs (N=7,672) from a lean growth [n=1,468 barrows (LB); n=2,151 gilts (LG)] or superior meat quality [n=1,895 barrows (QB); n=2,158 gilts (QG)] production focus were slaughtered over two seasons. Data were analyzed as a 2x2 factorial design. Unequal magnitudes of differences of sexes within production focus drove interactions. Random effects included: barn (N=8), marketing group (N=3), and season (N=2). Variability between sexes was measured using a Levene’s test. Carcass composition, subjective loin quality, and gluteus medius color were collected on all carcasses. In-plant loin quality and belly quality analyses were conducted on 52.0% and 47.5% of carcasses, respectively. Loins and hams from select carcasses (N=862) were collected for slice shear force (SSF) analysis and processed ham characteristics. Barrows (95.01 ± 2.41 kg) had a heavier HCW than gilts (94.17 ± 2.40 kg; P<0.0001), but did not differ (P=0.09) in variability. Fat depth was greater (P<0.0001) and more variable (P<0.01) in barrows (16.83 ± 0.76 mm) than gilts (14.65 ± 0.76 mm). However, LB had a 13.86% greater fat depth than LG (P<0.01), and QB had a 15.65% greater fat depth than QG (P<0.01). Gilts (68.46 ± 2.49 mm) had a greater loin depth than barrows (P<0.01; 67.22 ± 2.49 mm) with no differences (P=0.60) in variability between sexes. Gilts (58.16 ± 0.58%) had a greater percent lean (P<0.01) with less variability (P<0.01) than barrows (56.66 ± 0.58%). Lean percentage was increased 1.28 units in LG compared with LB, but was increased 1.71 units in QG compared with QB (P<0.01). Barrows had heavier (7.60 ± 0.26 v. 7.32 ± 0.26 kg) and firmer (2.26 ± 0.12 vs. 1.88 ± 0.12) bellies than gilts (P<0.01). Loin marbling was not different between sexes (P=0.89). Gilts (15.11 ± 2.02 kg) had a greater SSF than barrows (14.07 ± 2.02 kg; P<0.01). Pre-trim ham weights were not different between sexes (P≥0.39); post trim ham weights were heavier in gilts (9.86 ± 0.19 kg) than barrows (9.70 ± 0.19 kg; P=0.01). Gilts (5.14 ± 0.10 kg) had a greater cooked ham weight than barrows (4.97 ± 0.10 kg). Although marketing groups aim to eliminate variability, sex contributes variation to a population. Sex significantly altered primal weight and quality differences across and within production focuses. Supported by National Pork Board Grant #14-221.
Keywords: pork, sex, variability