Nutritive value of cactus pear silages for finishing lambs

Abstract

The objective of the present research was to evaluate the nutritive value and the fermentation
characteristics of cactus pear silages and diets including them for growing lambs. There were
two cactus pear silage types: one made from cladodes and the other combining cladodes and
cactus pear fruit. Similarly, it was calculated the gas potential emission index (GPEI; dL lamb-1
day-1). The four diets: control (with not silage, NSD), including corn silage (CSD), or cladode
cactus pear silage (CCSD), or cladode-fruit cactus pear silage (CFSD) were iso-nitrogenous
(15% CP) and iso-energetic (2.7 Mcal of ME kg-1 of dry matter) fulfilling the requirements for
finishing lambs. Eight commercial cross lambs (23±3.0 kg liveweight) were used, under a 4 x 4
replicated Latin Square design. The results indicated that the CCSD and CFSD had 3% more
(P<0.05) dry matter (DM) content than the CSD, but the later had more (P<0.05) protein (80 g
kg-1) and greater digestibility (60%) than the CCSD and CFSD (50 g kg-1 and 50%). The diets
with CCSD and CFSD had more (P<0.05) crude protein (160 g kg-1) than the control and CSD
(150 g kg-1 DM). The in vitro digestibility of the control diet was greater (P<0.05) than the other
diets, although the DM voluntary intake, apparent digestibility, and the acid detergent fiber
(ADF) were not different (P>0.05). The neutral detergent fiber (NDF) was greater (P<0.05) in
diets including silages in comparison to the control diet. Lambs fed with control or CCSD diets
had a gas potential production of 350 and 370 L lamb-1 d-1, in comparison to 200 and 210 L
lamb-1 d-1 from CSD and CFSD diets. It is concluded that the nutritive and in vitro fermentative
qualities of the CCS and CFS were similar to CS, thus, their inclusion in diets for finishing lambs
can be considered as a feeding alternative, and more importantly, CFS could mitigate the
emission of greenhouse gases.