Suchergebnisse

Ruminal fermentation is accompanied by losses of the energy and protein consumed by dairy cows (Tamminga, 1992; Busquet et al., 2006) which may limit productive performance and contribute to release of pollutants to the environment (Calsamiglia et al., 2007). Ionophores have been used to reduce these losses (McGuffey et al., 2001), but the use of antibiotics in animal feeds has been banned in the European Union since January 2006 (Jiménez-Peralta et al., 2012) due to potential appearance of residues in milk (Russell and Houlihan, 2003). For this reason, there is substantial interest in evaluating the potential of using natural antimicrobials, such as plant extracts generally recognized as safe for human consumption (Busquet et al., 2006; Fandiño et al., 2008), to modify rumen microbial fermentation. Extract of Salix babylonica (SB) have been evaluated for their anti-microbial effects and for their potential to modulate ruminal fermentation and improve nutrient utilization in ruminants (Mejía-Hernández et al., 2013; Salem, 2012; Salem et al., 2010, 2011).The antimicrobial activity of SB extracts has been attributed to a number of plant secondary metabolites (PSM) such as alkaloids, saponins and phenolics (Jiménez-Peralta et al., 2011). Rumen microorganisms have the ability to degrade low concentrations of PSM without negative effects on rumen fermentation. Rumen microorganisms can also degrade alkaloids (Lanigan, 1970; Wachenheim et al., 1992), saponins (Lu and Jorgensen, 1987; Hu et al., 2005; Hart et al., 2008) and phenolics (Varel and Jung, 1986; Varel et al., 1991) and utilize them as an energy source. Some PSM can enhance protein metabolism and decrease methane production (Benchaar et al., 2007), and have the ability to suppress or stimulate microbial growth, increase binding of ammonia during urea ammoniation of straw and reduce odours from cattle manure in dairy barns (Makkar et al., 1998; Salem et al., 2012). In addition, some PSM reduce nutritional stress such as bloat and/or improve animal health and productivity (Patra et al., 2006; Benchaar et al., 2007, Xhomfulana et al., 2009; Salem et al., 2010). Positive effects on daily gain, voluntary feed intake and milk production (Salem et al., 2011) have been demonstrated, as well as a protective effect on dietary protein in the rumen in order to promote duodenal absorption, minimize excretion of nitrogen, modify the acetate to propionate ratio in rumen fluid and decrease the parasitic load (Salem et al., 2010; Jiménez- Peralta et al., 2011). Use of plant extracts could be limited by their secondary compound concentrations as consumption of large amounts of tannins or saponins may have a direct haemolytic effect and may even cause death (Athanasiadou and Kyriazakis, 2004). Moreover, long term feeding of plants rich in secondary compounds may have detrimental effects on animal health (Mahgoub et al., 2008). This experiment was conducted to determine effects of SB extract mixed in the diet on milk production and composition in Brown Swiss cows in addition to in vitro gas production of the diet fed to the cows with different doses of SB. ; A 3×3 Latin Square design was used to evaluate effects of 0, 150 and 300 mL of Salix babylonica (SB) extract mixed into the diet on daily milk production and composition in cows. Three Brown Swiss dairy cows (420±30.3 kg body weight), at late lactation (220±25.1 d in milk), were fed a diet with a restricted amount of concentrate and oat hay ad libitum twice daily in equal amounts. The SB extract was mixed daily with a small amount of concentrate and fed to the cows. In vitro gas production of the diet fed to the cows was recorded at 2, 4, 6, 8, 10, 12, 24, 48, and 72 h of incubation with 0, 0.6, 1.2 and 1.8 mL SB/g DM.