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Opis: The influence of the immunocastration (immunisation against GnRH) on pig performance (growth, carcass and meat quality traits) was investigated in two parallel experiments (on two farms) with two crossbreeds – G1 (50% Duroc) and G2 (50% Pietrain). Within the crossbreed, the pigs were assigned to three experimental groups; entire males (EM, n=49), immunocastrates (IC, n=45) and surgical castrates (SC, n=45). Those assigned to IC group were vaccinated at the age of 12 and 19 weeks. Pigs were individually housed, their feed intake (ad libitum) and weight (at 12, 19 and 24 weeks) were recorded. At the age of 24 weeks, the pigs were slaughtered and their carcass and meat quality traits were assessed. We hypothesized that treatment response could have been different in two crossbreeds. However the interaction was insignificant, thus the treatment effect is presented on pooled results for both crossbreeds. Until the revaccination, IC were similar to EM pigs, thereafter they exhibited an increase in feed intake and growth rate. Overall, they presented an advantage in growth rate and feed efficiency as compared to SC. They also exhibited better carcass properties as SC without any major effect on meat quality. The present study provides the initial information on the immunocastration effect in Slovenian herds that should further be supported by testing it in usual rearing conditions and group housing.
Ključne besede: pig, immunocastration, growth performance, carcass properties, meat quality
Objavljeno v DKUM: 24.08.2017; Ogledov: 1983; Prenosov: 103
Celotno besedilo (122,14 KB)
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Opis: In recent years, immunocastration, a vaccination against gonadotropin releasing hormone, has been proposed as an alternative to surgical castration of intact male pigs without anaesthesia. However, the effects of immunocastration on metabolic changes, nutritional requirements and growth potential have not been quantified. Thus in the present thesis, the meta-analytical approach was used to quantitatively synthesize the effects of immunocastration and four studies were conducted to evaluate the effects of quantitative and qualitative feed restriction on growth performance, heat production and energy metabolism, carcass and meat quality. Results show that boar taint compounds are dramatically reduced in immunocastrates, still they remain slightly higher than in surgical castrates. Immunocastrates are less feed efficient, fatter but grow more rapidly and may have better meat quality than entire males. Compared to surgical castrates, immunocastrates have superior performance with no difference in meat quality. It is more economical to fatten immunocastrates than surgical castrates, but production costs and carcass quality are less favourable than in entire males because of the huge increase in voluntary feed intake during the weeks preceding slaughter. Applying quantitative feed restriction after active immunization did not significantly affect growth performance or carcass composition; however, restrictively fed immunocastrates were closer to entire males, whereas ad libitum fed immunocastrates were closer to surgical castrates. Meat quality is also unchanged by the restriction. However, higher incidence of carcass lesions in restricted immunocastrates together with higher plasma cortisol level indicates more aggression prior to slaughter and can be considered as a negative aspect of the quantitative restriction. Total heat production, assumed to be the major factor contributing to the differences in feed efficiency of pigs, is changed after the immunocastration. Additional energy retained due to higher feed intake is directed towards lipid deposition. Increased fatness of immunocastrates is a result of increased daily lipid deposition caused by higher energy intake, lower fasting heat production and improved energy retention. Hence, dietary energy intake should be limited after immunocastration. Moreover, according to the results of the nitrogen balance study, dietary crude protein content could also be decreased. By reducing net energy concentration of the diet up to 10 % using higher fibre content, similar energy efficiency (gain to net energy intake ratio) may be achieved, with an advantage in terms of reduced lipid deposition, and no effect on growth rate after effective immunization. This is particularly important when immunocastrated pigs are fattened to higher body weights, i.e. when longer delays between full immunization and slaughter are practiced.
Ključne besede: pig, immunocastration, growth performance, carcass characteristics, meat quality, heat production, lipid metabolism, fat deposition, feed restriction
Objavljeno v DKUM: 27.07.2015; Ogledov: 2916; Prenosov: 312
Celotno besedilo (19,44 MB)