Summary

The project aimed at generating reliable information on the digestible and net energy content (DE and NE) in growing pigs fed with field peas ground at three different screen-opening sizes (fine, medium and coarse) to obtain different average particle sizes: 156, 650 and 1035µm, respectively. The digestibility values and DE and NE content increased as the pea particle size decreased from 1035 to 156µm. Differences were also observed among pea cultivars. It is concluded that the energy content of peas is influenced by its particle size.

* "Digestible and net energy content increased as the pea particle size decreased from 1035 to 156µm"

Introduction

Previous research at Prairie Swine Centre has shown that field peas vary in energy content by at least 22 per cent, compared to about 15 per cent for wheat and barley. This problem of variability is compounded by our inability to predict the DE content of field peas from chemical or physical composition.

One possibility to improve the nutritional value and, at the same time, reduce variability is the processing of field peas. Grinding improves digestibility by offering a greater surface of contact between the digestive enzymes and the substrate. However, a too-fine grinding is expensive and negatively affects the pig since it causes gastric ulcers. The optimal grinding for the use of field peas in swine nutrition is unknown.

The present project aimed at studying the effects of grinding on the digestible and net energy (DE and NE) content of fi eld peas in growing pigs.

Material and Methods

A total of 204 growing pigs (28 kg on average) were used. Thirty-four experimental diets were prepared: a control diet (composed of wheat, barley, soybean meal and a mineral/vitamin premix) and 33 diets composed of 70 per cent control diet and 30 per cent field peas. The diets were supplemented with Celite®, used as a source of acid-insoluble ash, an indigestible marker. Each diet was tested on six growing pigs (limit-fed). After an adaptation period of 10 days, faecal samples were collected by the grab sampling method for three days. The samples were then pooled per animal, freeze-dried and analysed at the University of Saskatchewan. The digestibility and DE/NE content of the diets were calculated. The digestibility and DE/NE content of the peas alone were then also calculated.

Results

The results of digestibility and energy content are detailed in Table 1. Differences in digestibility, DE or NE content were observed among the field peas (P<0.05). The Pekoe pea cultivar presented the lowest values and Mozart the highest. The digestibility and energy content increased linearly as the screen opening size decreased from 1035 to 156µm (P<0.001). The average DE content was 3.84, 3.52 and 3.34Mcal/kg and the NE content 2.69, 2.47 and 2.34Mcal/kg for fine, medium and coarse grinding peas, respectively (P<0.001).

Conclusions

The digestibility values and energy content of peas improved as the particle size decreased from 1035 to 156µm in growing pigs. However, in order to determine the optimal particle size of peas for growing pigs, it will be necessary to establish a compromise between energy costs and nutritional value. In the present case, energy cost was not evaluated.

June 2010