Growth performance and carcass quality of immunocastrated and surgically castrated pigs from crossbreds from Duroc and Pietrain sires1

Abstract

In total, 240 pigs were used to compare growth performance and carcass quality traits of immunocastrated males (ICM), surgically castrated males (SCM), and intact females (IF) of crossbreds from Large White × Landrace females and Duroc (DU) or Pietrain (PI) sires destined to the dry-cured industry. Between the 2 Improvac injections (87 and 137 d of age), ICM and IF had less ADG than SCM (P < 0.01). Also, ICM ate less feed than IF and both less than SCM (2.33, 2.55, and 2.77 kg/d; respectively; P < 0.001) and consequently, ICM had better G:F than SCM and IF (P < 0.001). From second Improvac injection to slaughter (137 to 164 d of age), ICM were more efficient than IF and both more efficient than SCM (0.346, 0.323, and 0.300 g/g; respectively; P < 0.001). The differences in growth performance among genders observed in this period were more pronounced for the PI than for the DU crossbreds (P < 0.05 for the interaction). For the entire experimental period (87 to 164 d of age), gender did not affect ADG for DU crossbreds but for PI crossbreds ICM and SCM had greater ADG than IF (P < 0.05 for the interaction). The ICM pigs had better feed efficiency (0.406, 0.364, and 0.380; g/g; P < 0.001) and lower carcass yield (76.6, 78.1, and 78.8%; P < 0.001) than SCM or IF. Carcasses from IF were leaner than carcasses from SCM with carcasses from ICM being intermediate (P < 0.01). Ham and loin (P < 0.001) yields were greater for IF than for ICM or SCM. Intramuscular fat content was lower for IF than for SCM with that of ICM being intermediate (3.5 vs. 3.9 and 3.7%; P < 0.05). Cumulatively, crossbreds from DU sires had greater ADG (1.167 vs. 0.986 kg/d; P < 0.001) and ADFI (3.07 vs. 2.56 kg/d; P < 0.001) and more intramuscular fat (P < 0.001) but less ham and loin yields (P < 0.01) than crossbreds from PI sires. It is concluded that growth performance was better but carcass yield less for ICM than for SCM and IF. Intramuscular fat content in LM was less for IF than for SCM with ICM intermediate. Crossbreds from Duroc sires grew faster and had more intramuscular fat but less ham yield than crossbreds from Pietrain sires. Therefore, ICM should be preferred to SCM and Duroc crossbreds should be preferred to Pietrain crossbreds to produce carcasses destined to the production of primal cuts for the dry-cured industry.