Raw and extruded field beans (Vicia faba var. minor) as alternative protein source in heavy lamb diets

The possible nsk connected to G~(O use in animai breeding leads to reconsider animai production processes with special reference to the use of alternative protein sources able to re piace soy bean, whose production accounts for about 6~ G~lO. The aìm of the tria1 was to evaluate the poss1bility to replace soy bean w1th field bean for the heavy lamb d1et an d to study the effect of the processing treatment l enrusion) o n the productive performances, the energy and protein metabolism parameters and on the quantl-quabtauve charactenstocs of the carcass and the meat. Twenty-four male Gentile di Puglia lambs were di\;ded, when 42 days old. into three homogeneous groups according to li ve weight ( 12,0 ~ 0,5 kgJ and assigned to the following feeding treatments: a l soy be11n (contro l); bJ raw field bean: c) extruded field bean. Food consumptions and live weights were recorded weekly 10 order to calculate the daily weight rain and the feed conversion mdex. blood samples were collected every 21 days and plasma concentration of glucose, triglycerides, cholesterol lenergy metabolismi, and BL'N, tota1 proteins. protein electrophoresis (protein metabolismi were measured A t 90 days of age. after 12 hours of fasting, lambs were slaughtered and the dressing percentage was calculated Alter refngeratoon a t 4 oc for 2-1 hours. the carc:uses were sectioned into cuts, 11nd the pelvìc h mb and lumbar reg~on were dissected into tissue components flean. fat and bonei iASPA, 1991). The pH values were measured at slaughtenng and 24 h later on the Longoss1mus dnrSI ILdo and St~mlmembranosus CSm l muscles. Me a t colour features f L. a. b l w ere assessed by using a spectrophotometer 1 Hunter Lab, 065/10o llluminantl. Data were analyzed by A.'liOVA using the GL:\1( procedure of SAS and means were compared using the Student's t test.The use of raw fie l d bean showed better da1ly weight iaon 1250 gl when compared to cl group (220 gl and, especially. al group C200 g, P<0.05) The blood indexes character.nng the ener&"et1c and protein metabolism were affected by lambs' age but not by their (eeding treatment. The pH ofboth the muscles. Ld and Sm. were not influenced by the feedin&" treatment a t the slaughtenng t ime. wh1le 2-l hours later the p H value of the Ld was stg· nificantly h.igher in the contro! group 16,10 ~ 0,181 when compared to cl group (5.71 ~ 0.02; P<O.Olo and bi group (5.78:::0,05: P<0.05l. No statistica! differences with regards to the mc1dence of the d.lfferent cuts of the half carcass were detected among treatments. As for the tissue components of the pelvic limb eu t. the percentage of lean in the contro! group C62.44~1.39J was lightly lower compared to the field bean groups, either extruded o63,28:::2,151 or raw (64.44:::0.67 %). The percentage of fat was lower for the extruded field bean treatment !9.03:0.781 with respect to that recorded with the use of soy bean l 11.23: O 60; P<0.05o or of raw field bean 112.83:0 B. P<O 01). With concero to the colorimetnc characteristic; of the Ld mu.sc!e, the index of redness was greater in the group fed with raw field bean when compared to contro! (10 39:0A2 vs 9 33:0 29. P<0.05o On the other band, the brightness (37.90:1.44 \ and the yeUowness !7.81:0 47) of the Sm musc!e were sign.ificantJy lower IP<O 05o m bl group when compared to al and cl groups. I t is concluded that fie id bean may represent a vahd alternative to soy bean as a protein feed for growing lamb:s m so-called "organic" ammal production systems where tran;gemc soy is banned.