Inclusion of Cactus Pear Cladodes in Diets for Finishing Lambs in Mexico
Keywords:fodder, Opuntia, live-weight gain, feed intake, feed conversion, profitability.
The objective of this study was to evaluate the effect of forage cactus pear (nopal) cladodes in diets for growing-finishing lambs on dry-matter intake (DMI), total and daily live-weight gain (LWG and DLG), feed conversion (FC), and profitability (P). Fifty-four male lambs (Corriedale x Criollo) with an average live weight of 20.2 ±3.2 kg were used. Triads of lambs were formed with similar live weights and housed in a pen (experimental unit), which were randomly allotted to the following treatments: T0% no nopal (Control), lambs were fed with a regular growing-finishing diet; T15% Nopal, cactus pear cladodes at 15% (DM basis) of the ration; T30% nopal, cactus pear cladodes at 30% (DM basis) of the ration arranged as a completely randomized design with three treatments and six replicates. The diets were formulated in order to fulfill the nutritional requirements for growing-finishing lambs according to NRC (1985). The cladodes were chopped (approximately 2.5 cm2 and mixed by hand with the diet in the feedbunker at each feeding. Lambs were fed twice a day, at 08:00 h and 16:00 h. The experiment lasted 71 days (adaptation: 14 days; experimental period: 56 days). Inclusion of cactus pear represented 55% and 75% of as-fed basis for T15% and T30%, respectively. Results showed that initial live weights were similar (P>0.01) among treatments, as well as the LWG between T0% (34.54 kg) and T15% (33.95 kg), but T30% (30.71 kg) was lower (P<0.01). DMI was consistently similar (P>0.01) between T0% (0.928 kg) and T15% (0.993 kg) and higher (P<0.01) than T30% (0.615 kg). Average feed conversion was similar (P>0.01) between T0% (5.14) and T15% (5.09), but higher (P<0.01) than T30% (3.44). Lambs fed with a high ratio of cactus pear (T30%) were more efficient in converting feed to LWG. The inclusion of cactus pear reduced feed cost approximately 48% and 65% for T15% and T30%, respectively, relative to T0%. Thus, LWG cost was reduced about 29.1% and 64.3% in T15% and T30%, respectively, relative to T0%. The inclusion of cactus pear between 15% and 30% may represent an important alternative to feeding growing-finishing lambs without affecting animal performance while reducing production costs.