Effects of diets differing in protein source and technical treatment on digestibility, performance and visceral and biochemical parameters of fattening pigs

ABSTRACT

The aim of the experiment on 100 cross-bred barrows was to compare commercial diets for fattening pigs based on either soya bean meal (SBM) imported from non-European countries with diets based on a mixture of locally produced rape seed meal, distillers’ dried grains with solubles and soya beans as main protein sources. In addition, these both types of diets were processed by two different technical feed treatments, i.e. coarse grinding without hydrothermal treatment or fine grinding and pelleting. With only few exceptions, nutrients of the diet without SBM were more digestible (p < 0.05) resulting in a higher metabolisable energy (ME) content. Fine grinding and pelleting increased also the ME content and the nutrient digestibility with the exception of crude fibre. Higher feed intake of animals that fed diets without SBM (p < 0.01) resulted in higher average daily gain (p < 0.01). However feeding this diet, the higher digestibility was not reflected in a decreased feed-to-gain ratio (FGR), but fine grinding and pelleting reduced FGR (p < 0.001). A higher pH value and a lower DM content of caecal chymus were detected in animals that received coarsely ground feed (p < 0.05). Animals that fed finely ground and pelleted feed had higher slaughter and relative liver weights and higher blood cholesterol concentrations (p = 0.040). The urea concentrations of blood were lower (p = 0.019) after feeding diets without SBM. In conclusion, SBM imported from non-European countries can be replaced by alternative local protein sources without compromising digestibility or performances of animals. Although fine grinding and thermal treatment particularly seemed to be advantageous for digestibility and performance, the possible risk of development of stomach lesions should be considered.

KEYWORDS:

• Blood physiology
• digestibility
• fattening performance
• particle size
• pelleting
• pigs
• protein sources
• soyabean oilmeal

Acknowledgements

The authors would like to thank the IFF (Research Institute of Feed Technology of the International Research Association of Feed Technology e.V.) for manufacturing and supply of feedstuffs. Further, they gratefully acknowledge the Thüringer Landesanstalt für Landwirtschaft for the planemetric calculation of lean meat percentage, the Technical University Munich for analysis of protein solubility and the Julius-Kühn-Institute for glucosinolate analyses in feeds. In addition the authors would like to thank the H. Wilhelm Schaumann Stiftung.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Arbeitsgemeinschaft industrieller Forschungsvereinigungen “Otto von Guericke” e.V. (AiF) [6439].