Dried tomato vines in substitution to alfalfa hay to feed Barbarine lambs: Effects on diet intake, growth performances and carcass quality

Tomato vines are a by-product of tomato plants pruning at different stage of growth and production. Large quantities of tomato vine biomass are produced and accumulated near greenhouses and cause environmental problems. Tomato vines could be used (DTV) as dry roughage to feed livestock. The objective of this study was to evaluate the effects of substituting dried tomato vines (DTV) to alfalfa hay at two levels (50% and 75%) on feed intake, growth performances, non-carcass components, and carcass characteristics of Barbarine lambs. Twenty four 8 months-old Barbarine lambs, with an average weight of 31 kg, were divided into three groups of 8 each and fed diets with different compositions of the roughage portion: the Al100 group received only alfalfa hay as forage, the Al50-T50 group received equal portions of alfalfa hay and DTV, and for the T75-Al25group, the roughage portion was composed of 75% of DTV and 25% of alfalfa hay. All lambs received the same amounts of forage (increasing from 1000 to 1400 g) and the same quantities of concentrated feed (increased from 500 to 700 g). The trial lasted 88 days, after which all of the animals were slaughtered. It was found that substituting DTV to alfalfa hay at the levelof 50% had no effect on roughage and total diet intake. In addition, DTV intake did not affect the slaughter weight (P > 0.05), although the average daily gain and total weight gain were 136 g and 11.5 kg for the Al100 and Al50-T50 groups vs. 125 g and 9.6 kg,; for the T75-Al25 group. Overall, carcass yields and non-carcass components were similar for the three groups of lambs. However, DTV incorporation at the levels of 50% and 75% resulted in leaner carcasses for both tomato groups compared with the Al100 group (54.3 vs.49.9% of muscle and 24.4 vs. 28.8% of fat, respectively). Nevertheless, the highest level of tomato incorporation (75%) promoted the development of the leaner second meat grade (SMCC)(18.2%; P = 0.02) compared to the medium (50%) and null level (0%) of DTV incorporation, which resulted in the same proportion of SMCC(17.5%).