Effects of different doses of Salix babylonica extract on growth performance and diet in vitro gas production in Pelibuey growing lambs

Pelibuey sheep is the main breed in the tropical and subtropical regions of Mexico, and high demand of sheep meat has favored the finishing of lambs in feedlots with diets containing high levels of grains. The objective of this study was to evaluate the effects of exogenous enzymes (EE) and application method on nutrient intake and digestibility and performance of growing Pelibuey lambs. Treatments were based on comparison of two different methods of adding an enzyme product (sprayed on the total mixed ration or applied orally to the lambs) versus control treatment (no added enzyme). Twenty-one Pelibuey lambs, weighing 15.7 kg (SD = 1.8 kg) initial body weight, were individually housed in shaded pens and assigned randomly to one of the three enzyme treatments. At the end of study (lasting for 45 days), three lambs from each treatment were randomly selected and adapted to a pants and harness designed for fecal collection to measure nutrient digestibilities. Total body gain and average daily gain were affected (P < 0.05) by supplemental EE. The application method of EE had significant (P < 0.05) effect on FCE and FCR, but no effects were observed on nutrient intake. Supplemental EE did improve (P < 0.05) the digestibilities of dry matter, organic matter, neutral and acid detergent fiber, but no differences were observed in crude protein digestibility. The application method of EE had significant (P < 0.05) effect on the digestibility of acid detergent fiber. Supplemental EE can improve body weight gain and nutrient digestibilities without affecting nutrient intake in Pelibuey lambs, but the results of feed conversion efficiency and acid detergent fiber digestibility depend on the application method used of the EE.

A factorial experimental design (3 × 2 × 3) was used to evaluate the effect of season of harvest and type of ruminal inoculums on in vitro ruminal fermentation kinetics and energy utilization of three browse tree foliages ( Lysiloma acapulcencis , Quercus laeta and Pithecellobium dulce ). Browse species were harvested during the dry season (DS) and rainy season (RS) and incubated with three different ruminal inoculums: cow, goats previously adapted (AG) or not adapted (UG) to browse species fed in their daily diet. Chemical composition, total condensed tannin (TCT), free-condensed tannin (free-CT), protein-bound condensed tannin (PCT), fiber-bound condensed tannin (FCT) as well as in vitro assaying of ruminal gas production kinetics was determined, while the short chain fatty acids (SCFA) and metabolizable energy (ME) were estimated. Crude protein (CP) was considerably higher (season × browse; P<0.001) during RS. P. dulce had the lowest neutral detergent fiber (NDFom) and acid detergent fiber (ADFom) in both seasons, while L. acapulcencis had the highest values and Q. laeta values were intermediate, with an overall increase in fiber fractions in DS browse foliages (season × browse; P<0.001). TCT content in tree species revealed differences (P<0.01). FCT and PCT were lower in Q. laeta and P. dulce during the RS than in DS, lower (P<0.01) Free-CT fractions were observed in L. acapulcencis and Q. Laeta than in P. dulce , during both seasons. in vitro gas production parameters was increased (P<0.05) in DS than in RS in browses with low and medium tannins contents ( i.e ., P. dulce and Q. laeta ); consequently, browses energy utilization ( i.e ., SCFA and ME) and organic matter degradability (OMD) as well as fermentation efficiency ( i.e ., partition factor; PF) were improved (P<0.05). Generally, P. dulce had the highest (P<0.001) ruminal fermentation parameters and energy utilization values (more in DS than RS), while lowest values were founded in L. acapulcencis . Ruminal fluid of AD and UG had higher (P<0.001) browse ruminal fermentation kinetics, efficiency and energy utilization than cow's rumen fluid. The browse fermentation and energy utilization was improved in DS versus in RS and the browse fermentation and utilization were highest (P<0.05) in AG ruminal fluid than the others. Our results suggested a better nutritive value of P. dulce and Q. laeta with low and medium tannins contents and high CP concentration in cows and goats during the DS. Goats previously fed browse species in diets had a better ability to degrade and ferment the browse species than other animals. Abbreviations AG adapted goats AOAC Association of Official Analytical Chemists DM dry matter OMD organic matter degradability DS dry season GP in vitro gas production RS rainy season UG unadapted goats ADFom acid detergent fiber NDFom neutral detergent fiber CP crude protein TCT total condensed tannins Free-CT free-condensed tannins PCT protein-bound condensed tannins FCT fiber-bound condensed tannins Keywords Browse Cow Dry season Gas production Goats Rainy season 1 Introduction Browse tree fodders could play an important role as a source of nutrients to feed grazing small ruminants under the extensive livestock production systems ( Norton, 2000; Salem et al., 2006 ). Shrub legumes have been considered a promising option due to their rapid growth, provided high-protein content and good drought tolerance ( Paterson et al., 1998 ) that could be also used to supplement low protein feeds ( Leng, 1997; Salem et al., 2006 ). Unfortunately, many tropical tree fodders and shrub legumes contain high concentrations of secondary compounds, particularly tannins ( Salem et al., 2006; Mbugua et al., 2008 ) that can be reacting negatively with others nutrients ( Mangan, 1988 ) and could be have detrimental or beneficial effects on animal nutrition ( Waghorn and McNabb, 2003; Mbugua et al., 2008 ). Although the digestive tract of goats is anatomically similar to that of sheep and cows, goats have a large physiological capacity to adapt to high tannin levels in the diet. In vivo and in vitro studies conducted revealed that goats are more efficient than sheep digesting feedstuffs with low nitrogen, high fiber or high tannin contents of tree fodders and shrubs ( Salem et al., 2006; Tefera et al., 2008 ). There are some comparative studies in the in vitro digestibility and fermentability of forages using sheep, goats and cow's rumen fluid as inoculums sources, but few comparisons between cows and goat have been reported up to date ( Calabró et al., 2004; Mould et al., 2005; Salem, 2005 ). In vitro ruminal evaluations of such browse fodders should not only be based on in vitro gas production kinetics because partitions of energy released from degraded substrate contribute both to short chain fatty acids (SCFA) production and for microbial protein synthesis ( Blümmel et al., 1994 ). The concept of partitioning of fermentation products (partitioning factor; PF) was introduced recently to express the conversion of energy from truly degraded substrate required to yield 1 ml of gas ( Blümmel et al., 1997 ). The effect of tannins on PF values of browse plants has not been extensively investigated. This is largely due to the difficulty in quantifying the amount of substrate degraded in vitro . It is important to determine the PF values for browse plants because most of these plants contain condensed tannins, which may cause harmful effects on rumen microbial fermentation such as reduces the VFA concentration and ruminal microorganisms toxicity ( Jones et al., 1994 ). This study was aimed to investigate interspecies differences among three tree fodders species of different tannins levels along the two seasonal periods of Mexico ( i.e ., rainy and dry) using rumen fluid from goats and cows as inoculums donor to determine in vitro fermentation of gas production kinetics and energy utilization. 2...

The objective of this study was to evaluate the effects of three fibrolytic enzyme products (cellulase (CEL), xylanase (XYL) and a 1:1 mixture of CEL and XYL (MIX)) at three dose levels (0, 1 and 3 μL/0.5 g DM) on the in vitro fermentation of a diet for growing lambs. Bottles were incubated for 96 h at 39 °C. A mathematical model was used to estimate the parameters describing the gas production (GP) curve (b, c and L). Dry matter degradability (DMD) and fibre (NDFD and ADFD) degradability were determined at the end of the incubation period. Metabolisable energy (ME) and short chain fatty acids (SCFA) were calculated at 24 h of incubation. The asymptotic GP (parameter b) was affected (p < 0.02) by enzyme product and dose level, with a significant linear response (p < 0.05). Dose level affected ME and SCFA with a significant linear (p < 0.05) and quadratic (p < 0.01) response. The interaction between enzyme product and dose level was significant (p < 0.05) for cumulative GP up to 72 and 96 h of incubation, pH, ADFD and DMD. The results suggest that application of exogenous cellulases has the potential to alter asymptotic GP and degradability of ADF and DM of a diet for growing lambs, but most of the results depend on the interaction between enzyme product and dose level. Future studies are required to determine the ideal combination between enzyme product and dose level for optimal degradation of ruminant feeds.

The aim of this study was to evaluate the effect of different dose levels of exogenous fibrolytic enzymes (EFE) on invitro ruminal fermentation kinetics and energy utilization of foliages from three browse trees (Pithecellobium dulce, Heliocarpus velutinus and Guazuma ulmifolia). Mixture of EFE product was added to the leaves of the three browse tree species at three dose levels: 0 (control), 3.5 and 7.0mg/g of DM. Chemical composition of the foliages, including plant secondary metabolites such as total phenolics (TP), saponins (SAP) and aqueous fraction (AF), was determined. In addition, invitro assaying of ruminal gas production kinetics was determined for the three browse three foliages treated with EFE. P.dulce had the highest crude protein content (p<0.05), whereas G.ulmifolia had the highest content of neutral detergent fibre and SAP (p<0.05) and H.velutinus had the lowest content of TP (p<0.05). The interaction between tree species and dose level of EFE was significant (p<0.05) for gas production (GP) at 24h of incubation, parameters b and c of the accumulated GP curve, short-chain fatty acids (SCFA) and metabolizable energy (ME). The lowest (p<0.01) extent of accumulated GP as well as the b and c values occurred in G.ulmifolia at 0mg EFE/g DM. P.dulce had the highest (p<0.05) values for ME and SCFA at the highest dose of EFE. Tree species and dose level had significant (p<0.05) effects on all parameters describing invitro ruminal fermentation kinetics and energy utilization. Addition of EFE improved the fermentation kinetics of the browse species considered in this study.