Evaluation of camelina seed pods as a novel feed ingredient for ruminants: nutritional value, fermentation characteristics and nutrient digestibility

This study aimed to assess the chemical composition and nutritional value of camelina seed pods (CSP), as well as to investigate how different inclusion levels influence diet digestibility and in vitro rumen fermentation characteristics. Camelina seed pods were analyzed for their chemical composition and nutritional value, and the results were compared to those of wheat straw (WS) and alfalfa hay (AH). The study further investigated the impact of increasing CSP inclusion levels (0, 80, 160, and 240 g/kg DM) as a forage replacement in the diet on in vitro rumen fermentation parameters. Results revealed that CSP had the highest organic matter (OM) content and the lowest acid detergent fiber (ADF) levels (P < 0.05). Its crude protein and neutral detergent fiber (NDF) content were intermediate between WS and AH. Furthermore, CSP outperformed both WS and AH in terms of ether extract and non-fiber carbohydrate content (P < 0.05). Compared to WS, significantly greater gas production (GP) was observed for CSP at 16, 24, 36, 48, and 72 h of incubation, along with increased total GP and greater GP potential (b). After 24 h of incubation, higher fermentation parameters including in vitro DM (IVDMD) and OM (IVOMD) disappearance, estimated metabolizable energy (ME), microbial protein production (MP), ammonia-N (NH₃-N) concentration, pH, and short-chain fatty acid (SCFA) concentration were observed for CSP compared to WS, but lower than those for AH (P < 0.05). Nevertheless, all GP parameters for CSP remained lower than those observed in AH. Increasing CSP supplementation up to 16 % resulted in a linear improvement in IVOMD, estimated ME, and SCFA production compared to other supplementation levels (L, P < 0.05). The activity of fibrolytic enzymes, including CMCase, increased linearly (L, P < 0.05) with higher levels of CSP in the diet. In summary, the results of this study demonstrate that CSP enhanced in vitro gas production, fermentation characteristics, and nutrient digestibility in comparison to WS. Moreover, several of these parameters were found to be comparable to those of AH.