This study aimed to evaluate the influence of different physical forms of complete diets on performance, feeding behaviour, digestibility, ruminal health, blood and carcass indices in fattening lambs. A randomised complete block design was used to assign thirty male Lohi lambs (300 ± 15 d old) with an initial body weight of 33 ± 1.4 kg in ten replications to one of three physical forms of the diet. For different treatments, the dietary ingredients were ground and mixed as (I) ground conventional mash (CM), (II) whole corn grains were mixed with the remaining pelleted ingredients as a texturised diet (TX), and (III) whole corn grains and the remaining ingredients were mixed as an unprocessed diet (UP). During the 60-d growth trial and 7-d digestibility experiment, individually housed lambs were fed ad libitum. Feeding diet UP improved (p < 0.05) dry matter intake, average daily gain and feed-to-gain ratio of fattening lambs. The ruminal pH tended to be lower in group TX compared with the other groups. The incidence of loose faeces consistency was 3.5 times higher (p < 0.05) in group TX compared to group UP. The daily intakes of dry matter (DM) and neutral detergent fibre (NDF), the rumination time and chewing activities were highest (p < 0.05) for lambs fed on the UP diet. The digestibility of DM, NDF and ether extract were greater (p < 0.05) for diet UP as compared to diet TX. The chilled and hot carcass weights were highest (p < 0.05) for group UP. The papillae density tended to be greater for group UP. However, blood metabolites, intestinal morphology, carcass marbling, tenderness, meat pH, cooking loss, and meat composition were similar across the treatments. It can be concluded that the unprocessed diet based on whole corn grain and soybean hulls improved growth performance, feeding behaviour and carcass yield through better nutrient utilisation and a stable ruminal environment.
Keywords: Concentrates; fattening performance; feeding behaviour; lambs; meat characteristics; physical properties; rumen epithelium.