Effect of Chihua Pumpkin Residue (Cucurbita argyrosperma) in Ruminal Gas Production and Digestibility in vitro

The care and handling of animals from which ruminal fluid was obtained was performed in accordance with the guidelines of Mexican Council of Animal Care (SAGARPA, 1999).

In accordance to nutrient requirements of small ruminant: Sheep, goats, cervids and new world camelids (NRC, 2007).

ChP residue samples were collected from the experimental field of Colegio de Postgraduados Campus Campeche, Mexico, after seed collection. ChP residue (pulp and peel) was dried in an oven at 60°C for 96 h, ground and stored at room temperature (25°C) until analysis. The in vitro study was conducted at the Laboratorio de Nutrición Animal del Postgrado en Recursos Genéticos y Productividad-Ganadería del Colegio de Postgraduados, Campus Montecillo, Estado de México, México.

Four treatments were evaluated: a control using a standard diet elaborated with ingredients commonly used in rations for sheep, and three experimental with 10, 20 and 30% dry residue of ChP instead of corn stover. Ingredients and nutritional composition are presented in Table I. Dry matter (DM), crude protein and ether extract were performed according to AOAC (2000). Neutral detergent fiber (NDF) and acid detergent fiber (FDA) were performed according to Van-Soest et al. (1991). Gross energy was determined in a bomb calorimeter (Parr, Mod 1241; oxygen pump model 1108). Dry matter digestibility (DMD) (Tilley and Terry, 1963) and gas production (GP) were assesed by water displacement (Fedorak and Hrudey, 1983) at 24 h of incubation in ruminal fluid from two, three years old ruminally cannulated Holstein cows, fed with alfalfa hay and commercial concentrate.

A randomized block experimental design was used. The results were analyzed with the GLM procedure of SAS 9.0 (2002) and the comparison of means was by the Tukey test (Steel and Torrie, 1988).

The results are shown in Table II. After 24 h of in vitro incubation of diets, DMD increased significantly (P ≤ 0.05), NDF digestibility decreased and ADF digestibility remained unchanged. GP tended to decrease (P≤0.1) with the addition of residue ChP. The decrease in NDF digestibility with increasing the DMD may be due to degradation of other non-fibrous carbohydrates. According to Zhang et al. (2013), pulp powder of Cucurbita moschata has high sugar content (44% of dry product), and is a source of a heteropolysaccharide composed of four different monosaccharides with important antioxidant and pharmacological properties. Such carbohydrates could be quickly fermented in this study. In addition, the antioxidants contained in the residue of ChP could increase the DMD. Hino et al. (1993) found that ruminal digestion of cellulose and other fibrous components increased when tocopherol and α-β-carotene were added in in vitro ruminal cultures, stimulating cellulolytic activity of rumen bacteria. Also, because of high content of NDF, ChP could improve ruminal characteristics and microbial fermentation, avoiding rumen discoloration. According with Alhidary et al. (2017) rumen color of lambs fed with diets containing less of 30% of NFD is lighter than those fed with more NDF.

Table II.- Effect of chihua pumpkin (Cucurbita argyrosperma) residue on gas production and digestibility of dry matter, neutral detergent fiber and acid detergent fiber after 24 h of in vitro incubation.

1Standar error of mean; 2Means with different letter in the row are statistically different (P≤0.05); 3Means with different letter in the row tend to be statistically different (P≤0.1).

Theoretically, there is a close relationship between DMD and GP, which indicates that microbial biomass is improved and methane production is reduced with substrates with higher DMD per gas unit and, therefore, could be considered of a better nutritional quality (Posada-Ochoa et al., 2014). In this study methane production was not assessed; however, there was a significant increase in DMD and a tendency to decrease GP by effect ChP in the diet, so ChP residue could decrease methane emissions.

It should be noted that there are few studies on the effect of pumpkin on productive performance. Razzaghzadeh et al. (2007) indicate that up to 60% forage silage ration can be replaced by pumpkin (Cucurbita pepo) without negative effects on gain weight of buffaloes; however, further studies evaluating the use of pumpkin in the diet of animals are necessary.

Under the conditions of this study, ChP residue could be an environmentally ecologic alternative for feeding ruminants, and can be incorporated into the diet as much as 30% of the ration. Because this study is limited to an in vitro assay and there are no previous studies, in vivo and in vitro studies are necessary to evaluate the potential of ChP residue in ruminal fermentation, productive performance of ruminants, and possibility methane reduction. It would be appropriate to evaluate the feed intake behavior, productive performance and nutritional status of animals fed with different forms of processing of ChP.

Authors have declared no conflict of interest.