Response of the Calf Pancreas to Differently Processed Soya Bean and Pea Diets

The purpose of this study was to determine the effect of replacing skimmilk powder by differently treated soya bean or pea products on growth, pancreas size and pancreatic enzyme activities in calves. Three separate experiments have been performed. In experiments 1 and 2, 28 and 21 male Holstein calves were divided into 4 or 3 groups, respectively, and fed either dairy products or milk substitutes in which protein was mainly provided by soya bean products differing in their protein concentration due to the technological processing applied. In experiment 3, 45 male Holstein calves were divided into 3 groups and were fed either dairy products, or raw or flaked pea flour as a protein source. After an experimental period of 99 ± 4 days in experiments 1 and 2, and of 88 days in experiment 3, animal growth rate was significantly lower with raw pea flour (16%) and with the soya bean diet, which was highly concentrated in carbohydrates and allergenic proteins (13-27%). Pancreas weight decreased significantly (16-18%) with pea diets and tended to be lower (NS) with the water extracted, concentrated and heated flour (soya bean). Amylase-specific activity increased significantly (43%) with pea diets but showed opposite tendencies with the most refined soya bean products. Proteolytic enzyme activities were slightly influenced by dietary protein source, but this was not as obvious as in the literature reviewed. Specific messenger RNAs corresponding to amylase, trypsin and chymotrypsin seemed to increase (NS) with the soya bean diets, particularly with the less elaborated one. However, further investigations are required before any conclusions may be drawn concerning regulation levels of pancreatic adaptation to dietary protein. According to this study and the literature, results concerning pancreatic response to diets were different suggesting that the origin of soya bean, pea seeds and technological treatments applied to them were of great importance. Also, the level of incorporation into milk substitute and the presence of more or less antinutritional factors could influence pancreatic enzyme variations by complex mechanisms.