Modern pig breeds, which have been genetically improved to achieve fast growth and a lean meat deposition, differ from local pig breeds with respect to fat deposition, fat specific metabolic characteristics and various other properties. The present review aimed to elucidate the mechanisms underlying the differences between fatty local and modern lean pig breeds in adipose tissue deposition and lipid metabolism, taking into consideration morphological, cellular, biochemical, transcriptomic and proteomic perspectives. Compared to modern breeds, local pig breeds accumulate larger amounts of fat, which generally contains more monounsaturated and saturated fatty acids; they exhibit a higher adipocyte size and higher activity of lipogenic enzymes. Studies using transcriptomic and proteomic approaches highlighted several processes like immune response, fatty-acid turn-over, oxidoreductase activity, mitochondrial function, etc. which differ between local and modern pig breeds.

Meta-analytical approach was used to quantitatively synthesize the effect of immunocastration on growth, carcass, meat quality, reproductive organs and boar taint compounds. Altogether, 41 papers were collected for effect size (θ) calculation and the comparisons were made with entire males (EM) and surgical castrates (SC). The data for reproductive organs and growth performance are numerous enough to draw firm conclusions. In contrast, data for carcass and meat quality are more limited. Results of meta-analysis show efficient immunocastration with the magnitude of the response being by far the largest for reproductive organs (θ = -2.8 to -5.0) and boar taint substances (θ = -2.8 and -0.8 for androstenone and skatole, respectively). However, compared with SC, the immunocastrates exhibit larger bulbourethral glands (θ = 1.3) and slightly higher concentrations of androstenone and skatole (θ = 0.1 and θ = 0.2, respectively). The impact of immunocastration is also remarkable on performance, where the main advantage of the immunocastrates is their boar-like performance until revaccination. In the period following the second vaccination, they eat much more than EM (θ = 2.1), resulting in large effect size for growth rate compared with both EM and SC (θ = 1.1 and θ = 1.4, respectively). Considering the whole fattening period, their feed conversion ratio is higher compared with EM (θ = 0.6) and much lower than that of SC (θ = -1.3), although exhibiting moderately faster growth compared with both (θ = 0.6 and θ = 0.2, respectively). With regard to carcass quality, the immunocastrates take intermediate position between EM and SC. Besides, our analysis suggests no difference in meat quality with SC and some meat quality advantages of immunocastrates over EM because of higher intramuscular fat content (θ = 0.4) and lower shear force (θ = -0.6).

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. Copyright © 2012. American Society of Animal Science .

Immunocastration is a sustainable alternative to piglet castration but faces limited market acceptance. The phenomenon of non-responders has not to date been examined in detail, but adverse and stressful housing conditions (e.g., mixing of groups) might impair the success of vaccinations. Therefore, we evaluated the influence of housing conditions on the immune response after two Improvac^® vaccinations at an age of 12 and 22 weeks, respectively. Boars, immunocastrates and barrows (n = 48 each) were assigned to three different housing conditions (n = 36 enriched, n = 36 standard n = 72 repeated social mixing). Immune response was quantified by measuring GnRH-binding and its consequences for testosterone concentrations, development of the genital tract and boar taint. Growth performance was evaluated via average daily gain (ADG). GnRH-binding and testosterone levels revealed that immunocastration reliably suppressed testicular functions after the 2nd vaccination. Housing conditions did not modify testicular function but influenced ADG as animals under mixing grew slower than those under enriched conditions. Gonadal status had only a slight impact on ADG except in immunocastrates, which showed a temporarily higher ADG after the 2nd vaccination. The results show that immunocastration is a reliable procedure under different housing conditions and competitive in terms of growth performance.

Dry-fermented sausages were produced in a traditional way, without addition of nitrites and starter cultures, from meat of an autochthonous breed (Krškopolje pig) raised either in a conventional indoor or organic husbandry system. Physicochemical and sensory analyses were performed at the end of processing to characterize their quality. Dry-fermented sausages from organic pork retained more moisture, which resulted in higher water activity and softer texture (instrumental and sensory). They were more oxidized (higher thiobarbituric acid reactive substances (TBARS)), in agreement with more unsaturated fatty acid profile, a higher score for rancid taste, and a higher relative abundance of volatiles from lipid β-oxidation. Overall, dry-fermented sausages from organic pork had lower levels of volatile compounds, particularly, those originating from spices (despite the same quantity added) and lower levels of amino-acid degradation. Sensory analysis showed that dry-fermented sausages from organic pork had less intensive and vivid color, tasted more bitter and sour, and had more off-tastes. The observed differences could be related to initial differences in raw material (differences in meat pH and level of polyunsaturated fatty acids) affecting the process of fermentation.