Determining Chemical Composition and Nutritional Value of Tomato Shoot Silage Supplemented with Different levels of Beet Pulp by Using Nylon Bag and in vitro Gas Production Method

The processed crop by-products can be used as a suitable feedstuff to meet livestock dietary requirements. Tomato shoots that left on the field surface after harvest, is a major valuable by-product. In Iran, the estimated annual tomato shoots production is about 100 million ton. We evaluated the nutritional value of ensiled tomato shoots processed by beet pulp as a fermentation enhancer. Tomato shoots were collected from tomato farms in Semnan, Iran. The shoots were ensiled with 0, 4 or 8% (W/W) air-dried beet pulp. After 60 days, the silos were opened and ensiled materials were evaluated for sensitive characteristics as well as pH. The ensiled samples were also analyzed for chemical composition after 48 h oven drying at 60° C. Rumen degradability and fermentation characteristics were measured by using a nylon bag method and an in vitro gas production technique, respectively. For in vitro gas production technique, 200 mg of dry matter was incubated for 96 h at 39° C. Cumulative gas volumes were recorded 2, 4, 6, 8, 12, 24, 36, 48, 72 and 96 h after incubation. To estimate the gas production parameters, an exponential model was fitted for data. Rumen degradability parameters of dry matter (DM), crud protein (CP) and neutral detergent fiber (NDF) were determined by incubation of 5 g sample for 0, 2, 4, 8, 16, 24, 48, 72 or 96 h in the rumen of a fistulated steer. Similar analysis and measurements were also performed for oven dried tomato shoot samples. All data were subjected to ANOVA using the GLM procedure of SAS and means were compared by using Duncan's multiple range test at 5% probability level. At the end of fruit harvest, the measured DM and CP content of tomato shoot samples were 26 and 14% respectively that are in agreement with previous reports. Ensiled tomato shoots had a significant higher content of CP than oven-dried shoots; more likely due to losses of soluble components during the ensiling process. However, the content of CP was decreased with increase in beet pulp level in the tomato shoot silage. Similarly, the tomato shoot silages with 4 or 8% beet pulp showed lower values of NDF and ADF in comparison with tomato shoot silage without beet pulp. Due to lower protein and fiber percentage of beet pulp, the decreases in CP, ADF and ADF contents of omato shoot silages by adding beet pulp were expected.
Although the potential of gas production was enhanced by increased levels of beet pulp in the silages, no
significant difference was observed among tomato shoot silages. The silages were also similar for gas production parameters. However, cumulative volumes of gas produced at 96 h incubation for silages with 4 and 8% beet pulp were significantly higher than other treatment. The highest values of rapidly degradable DM, degradation rate constant and degradation potential were observed in tomato shoot silage supplemented with 8% beet pulp. However, there was no significant difference between tomato shoot silages with 4% beet pulp and without beet
pulp supplementation. Tomato shoots are a suitable source of nutrient for ruminant. Our results indicated that ensiling increases nutritional value of tomato shoots. The in vitro rumen fermentation characteristics as well as rumen degradability of tomato shoot silages were improved by adding 8% beet pulp. However, future studies are needed to confirm these results and elucidate the potential use of tomato shoot silage in ruminant's diet.