Length of the interval between immunocastration and slaughter in relation to boar taint and carcass traits

The objective of the present study was to study the effect of the interval between effective immunisation against GnRH (immunocastration) on boar taint elimination and carcass quality and to compare meat quality of immunocastrates and entire males. Among 40 commercial fatteners, 10 animals were left entire (EM27), while the remaining (IC) were vaccinated with ImprovacR at the age of 12 (V1) and 19 (V2) weeks. IC pigs were slaughtered in three batches of 10 at the age of 21 (IC21), 24 (IC24) and 27 (IC27) weeks, while EM27 were slaughtered along with the last group. After the slaughter, weight of the reproductive organs, boar taint compounds, carcass traits and meat quality (IC27 and EM27) was measured. Results show that 2-week interval from V2 to slaughter seems enough for elimination of boar taint, although firm conclusions cannot be made (uncertainty regarding sexual maturity), while boar taint does not occur with prolongation V2-slaughter interval to 8 weeks. Comparison of IC24 and IC27 showed that three weeks delay of slaughter resulted in gaining on carcass weight but loosing on meat percentage, mainly due to the increasingly high increment of fat depots in the last fattening period. Meanwhile, slaughter at earlier age (IC21) showed no important advantage in carcass meat % (beside lighter carcasses) over IC24. EM27 resembled IC27 regarding weight and muscularity traits while being significantly less fat (resembling IC24). There was no major difference in meat quality between EM27 and IC27, except the tendency (P < 0.10) for the tougher meat in EM27.