Effect of feed restriction on hormones, performance, carcass traits, and meat quality in immunocastrated pigs1

Abstract

The aim of this study was to assess the effect of feed restriction applied to immunocastrated pigs in the period after the second vaccination (V2) against GnRH on hormonal status, performance, carcass traits, and meat quality. Immunocastrated pigs (IC) were compared with entire males (EM) and surgical castrates fed ad libitum. Pigs (Large White × Landrace) × Pietrain were either left entire or surgically castrated within 1 wk after birth (SC, n = 22). At 83 d of age, the entire males were further allotted to treatment groups (individual housing) of ad libitum fed EM (n = 24), ad libitum fed IC (IC-L, n = 21), or restrictively fed IC (IC-R, n = 21). At that time, the first vaccination (V1) was applied to IC-L and IC-R pigs. One week after V2 (age 130 d), feed restriction (≈ 80% of the ad libitum feed intake of SC pigs) was applied to IC-R pigs. The experiment ended 5 wk after V2, when pigs were 165 d old. Immunocastration successfully reduced boar taint compounds and size of reproductive organs. At 130 d, serum leptin concentrations were similar in all groups, whereas IGF-I concentration was less in SC (P ≤ 0.002) than in the other groups. Three weeks after V2, leptin concentrations of both IC groups were in between EM (least) and SC (greatest). The reverse was observed for IGF-I. Feed restriction had no effect on leptin or IGF-I concentrations in IC pigs. In the period V1 to V2, performance differed mainly between EM and SC, whereas both IC groups had feed intake and feed conversion ratio similar to EM and intermediate daily BW gain, not differing from either EM or SC. After V2, IC-L pigs increased their feed intake to the concentrations of SC, with faster growth compared with the other 3 groups (P < 0.05) and fatter carcasses compared with EM pigs (P = 0.007). Similar performance and carcass leanness were observed for IC-R and EM pigs. During preslaughter handling more carcass lesions were noted in EM and IC-R than in IC-L or SC pigs (P < 0.002). Neither immunocastration nor feed restriction had any effect on meat quality, but EM had greater drip loss, less intramuscular fat, and decreased tenderness than SC pigs. In conclusion, restricting feed intake can increase production efficiency but also aggressiveness of IC pigs.

Field experience with surgical castration with anaesthesia, analgesia, immunocastration and production of entire male pigs: performance, carcass traits and boar taint prevalence

“…Both trials confirm the better G : F ratio in ad libitum fed EM and IM in comparison with SCM (Dunshea et al, 2001;Morales et al, 2010;Batorek et al, 2012b). This is a result of lower feed intake without clear differences in ADG.…”

“…This is a result of lower feed intake without clear differences in ADG. After the second vaccination, however, ADFI and DG of IM strongly increases (Schmidt et al, 2011;Batorek et al, 2012b;Weiler et al, 2013). We showed that this increase is very abrupt and noticeable within 1 week after the second injection.…”

“…For IM, results for DG for the overall fattening period differed between studies (Millet et al, 2011). Some studies did not show significant differences in ADG (D'Souza and Mullan, 2003;Morales et al, 2010), whereas others found a higher ADG for IM when fed ad libitum compared with EM, due to the increased ADG after the second vaccination Batorek et al, 2012b;Furnols et al, 2012). Whether or not a difference over the entire fattening period is observed probably depends on the magnitude of the feed intake response after the second vaccination and the time between the second vaccination and slaughter.…”

Ractopamine supplementation improves leanness and carcass yield, minimally affecting pork quality in immunocastrated pigs

“…However, in this study, the cortisol levels in the blood were not altered by either immunocastration or the addition of RAC, suggesting that these treatments did not induce stress in the animals. These findings agree with Batorek et al (2012).…”

Influence of housing and season on pubertal development, boar taint compounds and skin lesions of male pigs

“…The samples of subcutaneous fat were taken at the level of the last rib for determination of androstenone and skatole concentrations. They were measured using an HPLC according to the procedures described by Batorek et al (2012). Concentrations were expressed per gram of the lipid fraction from the adipose tissue.…”