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The use of entire males for pork production has been discussed despite of their improved growth performance in detrimental of effects of boar taint due to elevated concentrations of androstenone, indole and skatole in pork meat. In this study there were evaluated the consequences for the concentration of substances contributing to off odour of pork (skatole, indole). Feed intake behaviour was studied between 9 weeks of age and slaughter in a total of 36 gilts, 32 immunocastrates, 33 surgically castrated barrows and 33 boars from 36 litters. Animals were kept in groups of 12 pigs of the same sex and treatment and fed ad libitum. Individual feed intake behaviour was recorded by an electronic feeder. Immunocastration was carried out with two injections of a commercial vaccine to stimulate antibody production against GnRF.
Feed intake/day increased from an average of 0.91 ± 0.02kg/day up to 3.15 ± 0.04 kg/day before slaughter. This increase was associated with a 50% reduction in the number of meals/day (from 15.8 ± 0.44 to 7.2 ± 0.29 meals/day). The larger meal sizes resulted from an increase in both, the duration of feed intake/meal and the feed intake rate (g/min). Differences were observed in sex and treatment: feed intake in boars was lower than in all other groups due to a reduction in the number of meals/day and in the time spent feeding/day. In females, time spent feeding/day was quite similar to boars, but resulted from a higher number of meals of shorter duration. Barrows had higher feed intake due to a large number of meals/day resulting in more time spent feeding/day. Occupation time per day increased in barrows to a maximum of 1.2 h /day from weeks 13 to 17 and dropped thereafter to about 1h/day. Higher time was spent for boars and gilts from week 16 until week 24 (P<0.01).The feed intake rate was similar in boars, gilts and barrows. Immunocastration affected feed intake behaviour severely, especially dramatically increasing the meal size because of higher feed intake rate, which exceeded that of all other groups by 25% at the end of the study. Highest skatole concentrations were measured in fat of boars, whereas indole concentrations were higher in immunocastrates than in all other groups. In gilts and barrows, skatole concentrations were related to growth rate. Additionally, the feeding rate was an important factor explaining the variability in skatole/indole concentrations in adipose tissue.
It is concluded that the differences observed in feed intake behaviour contribute to the variability of skatole and indole concentrations within a gender group.
U Weiler, M Götz, A Schmidt, M Otto and S Müller, 2013. Influence of sex and immunocastration on feed intake behavior, skatole and indole concentrations in adipose tissue of pigs. Animal, 7-2: 300–308 doi:10.1017/S175173111200167X
