Development of new systems of lamb finishing for the late winter/spring market involving an extended housed store period on a predominantly straw diet are constrained by unacceptable reduction in muscle mass arising from inadequate protein supply during dietary adaptation from grass to straw. Problems with subsequent finishing on forage brassicas fedin situ arise from carcass contamination due to soiled wool of crossbred lambs which grow long fleeces over the extended store I finishing period. In order to study the effect of fish-meal supplementation on dietary change over from grass to straw 116 Mule wether lambs were allocated to four treatments, three of which received a supplement of 100 glday fish meal for 28 days from housing and introduction of a diet of straw ad libitum and 225 glday grain distillers' dark grains, the fourth group received no fish meal and was unshorn (No F/US). Shearing treatments of shorn (F/S), unshorn (F/US) and crutched (F/C) were applied to fish-meal supplemented group's. After 112 days, the housed lambs were grazed outside on swedes (Brassica napus) and effects of treatments on performance and bacterial contamination of carcasses (shearing treatments only) were studied. Fish-meal supplementation significantly reduced weight loss on dietary change by 2·2 kg after 45 days (P< 0·001). Of fishmeal supplemented lambs 83% eventually ‘finished’ (defined as Meat and Livestock Commission fat class 3LI3H) v. 34% of unsupplemented lambs. Shearing or crutching had little effect on store or finishing performance indicating adequate fleece regrowth for insulation purposes after turn-out. Shorn and crutched lambs had lower levels of bacterial carcass contamination with reductions of 0·06, 0·42 and 0·40 in counts for colony forming units per cm2, coliforms and Escherichia coli on leg sites (P < 0·05). Economic evaluation indicated financial advantage from fish-meal supplementation with an increase in margin over food costs of €3·50 as a result of heavier carcass weight and a reduced need for remedial concentrate feeding in the store period.

In three experiments with 60, 72 and 72 housed Greyface (Border Leicester × Scottish Blackface) and Suffolk × Greyface lambs on silage-based diets, a range of barley and fish-meal supplementation levels was compared. In experiment 1, six barley levels ranging from 0 to 625 glday were offered to lambs on flail-harvested and precision-chopped silages. In each of experiments 2 and 3, three levels of barley, 200, 400 and 600 g/day, were factorially arranged with four levels of fish meal, 0, 40, 80 and 120 g/day. The daily intake of flail-harvested silage was proportionately 0·76 of that of precision-chopped silage but because of a slower rate of gain the total requirement of silage dry matter (DM) per kg carcass gain was greater with flail-harvested than with precision-chopped silage. On average, over all barley supplemented diets in experiment 1, the requirement per kg carcass gain was 9·2 kg silage DM and 4·9 kg barley DM, with flail-harvested silage, compared with 8·2 kg silage DM and 3·4 kg barley DM with precision-chopped silage. Increasing barley supplementation in experiment 1 from 125 to 625 gl day reduced the silage DM requirement for carcass gain by 4·7 kg/kg increase in barley DM given. The corresponding figure over the range 200 to 600 g barley in experiments 2 and 3 was 2·6 kg silage DM per kg increase in barley DM given. The reduction in silage requirement with increasing barley was generally greater at low than at high levels of barley supplementation within the ranges examined. On silage-based diets optimum barley supplementation level was estimated to be in the region of 500 g/day.

Increasing fish-meal supplementation from 0 to 40 g/day, in experiments 2 and 3, reduced the requirement per kg carcass gain by 2·78 kg silage DM and 1·25 kg barley DM for an increase of 0·40 kg in input of fish meal DM. A further increase from 40 to 80 g/day fish meal reduced the silage DM requirement per kg carcass gain by 1·44 kg and the barley DM requirement by 0·50 kg, for an increase in input of 0·26 kg fish meal DM. A further increase to 120 g/day fish meal resulted in increases in both the silage and barley requirement per kg carcass gain. The optimum level of fish-meal supplementation was between 40 and 80 g/day and was not affected by the level of barley given.

There was evidence of an increase in carcass fat at the higher levels of gain achieved through increasing barley supplementation, but no evidence of increase in carcass fat at the higher levels of gain achieved through fish-meal supplementation.

Two feeding experiments with housed lambs of the Spanish Manchega breed were carried out over 2 years with the aim of assessing the suitability of field beans in lamb finishing diets. In the 1st year field beans were compared with soya-bean meal as a protein source in a factorial experimental design with the proportion of maize in the diet being 0·15, 0·25 or 0·35. In the second experiment the effect of replacing soya-bean meal and sunflower meal by inclusion of field beans at proportions, 0, 0·1, 0·2, 0·3 and 04 of the diet was studied. All diets were isoenergetic and isoproteic. The composition of the diets had no significant effects on the average daily gain or the food conversion ratio in either experiment. Results from experiment 2 showed that the increasing amount of field beans in the basal diet did not affect protein, fat and water content of a loin sample of meat, or fatty acid composition of kidney fat.