The effect of increasing extruded linseed level on nutrient digestibility, growth, carcass characteristics, and non-carcass components of lambs from two genotypes

This research aimed to study the effect of extruded linseed level on digestibility, growth, carcass, and non-carcass components of two genotypes' lambs. For this, 36 lambs, with an average body weight (BW) of 21.3 +/- 3.4 for Queue Fine de l'Ouest (QF) and 17.8 +/- 2.9 kg for the cross QF x D'man (QF x D), were randomly divided into three groups of 12 lambs each (six per genotype) in a 12-week experiment. Sheep in each group received individually oat hay ad libitum and one of three concentrates containing 0% (control), 15% (L15), and 30% (L30) of extruded linseed on a dry matter basis. All concentrates were isocaloric and iso-nitrogenic. In the last 2 weeks, digestibility was measured, and then all lambs were slaughtered. The increasing level of extruded linseed did not affect hay and total dry matter (DM) intake as well as nutrient digestibility, except the neutral detergent fiber (NDF) digestibility which was significantly (P < 0.05) reduced by the diet treatment (66.4, 57.8, and 53.0% for C, L15, and L30, respectively). In addition, the different linseed levels resulted in similar average daily gain, final BW, carcass traits, and non-carcass components except the rumen and liver weights which were significantly (P < 0.05) reduced by the increasing linseed level. However, the addition of extruded linseed improved (P < 0.05) the weight of the heart. The carcass tissular composition was not affected by the dietary treatment guarding a similar proportion of muscle, bone, and fat. However, the growth performance and carcass traits were higher for cross QF x D than QF lambs. In addition, the carcasses were leaner (less fat and more muscle) for the cross genotype (P < 0.05) than the pure QF breed. It was concluded that extruded linseed can be used in lamb diet without adverse effects on growth performance and carcass components. Furthermore, the cross could be planned given it resulted in higher growth and better carcass composition.