In vitro studies and a lactation trial were conducted to investigate the effects of fibrolytic enzyme mixtures at different inclusion amounts. Seven enzymes in amounts designed to mimic addition of 1, 5, 15, or 30 g/d to dairy diets were incubated in vitro with either soybean hulls or alfalfa for 24 or 48 h. Enzyme treatments generally increased in vitro dry matter disappearance (IVDMD), but not volatile fatty acid production. For some enzyme mixtures, lesser amounts of enzymes led to greater increases in IVDMD, whereas for others there were no differences among the amounts tested. The enzyme mixture with the most cellulase activity was the most effective enzyme in improving IVDMD. In additional in vitro experiments, the same enzymes were used at an amount of 5 g/d, as well as at other amounts that showed promising responses in the first trial. Preincubation of substrates with enzymes before fermentation also was tested. Alfalfa, soybean hulls, corn silage, and corn gluten feed were used as substrates. Preincubation of the substrate with enzymes for 18 h before in vitro fermentation improved IVDMD. The effect on substrate solubilization of incubating substrates with the enzymes but without rumen fluid was also studied. Addition of enzymes to substrates without subsequent fermentation did not solubilize significant amounts of dry matter, indicating that the positive effect of preincubation cannot be attributed directly to hydrolysis of substrates before the in vitro fermentation with ruminal microbes. The fibrolytic enzyme that appeared most promising in vitro did not affect lactational performance when fed to dairy cows.

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The objective of these studies was to characterize some factors affecting lysine degradation by mixed ruminal bacteria and by ruminal Fusobacterium necrophorum. Mixed ruminal bacteria degraded lysine, and addition of pure cultures of F. necrophorum did not increase lysine degradation. Addition of acetic or propionic acid strikingly reduced NH(3) production from lysine by mixed ruminal bacteria at pH 6, but not at pH 7. Although typical ruminal environments with acidic pH and normal concentrations of volatile fatty acids might inhibit lysine degradation by F. necrophorum, ruminal fluid contained enough bacteria with a lysine-degrading capacity to ferment 50 mM lysine in vitro. Of 7 strains of ruminal F. necrophorum tested, all grew on both lactate and lysine as the primary energy source. Both subspecies of ruminal F. necrophorum (necrophorum and funduliforme) used lysine as a primary C and energy source. Lysine and glutamic acid were effectively fermented by F. necrophorum, but alanine and tryptophan were not, and histidine and methionine were fermented only to a minor extent. The end products of lactate fermentation by F. necrophorum were propionate and acetate, and those of lysine degradation were butyrate and acetate. Fermentation of glutamic acid by F. necrophorum yielded acetate and butyrate in a ratio near to 2:1. The minimum inhibitory concentration of tylosin for F. necrophorum was not dependent on whether bacteria were grown with lactate or lysine, but F. necrophorum was more susceptible to monensin when grown on lysine than on lactate. Although F. necrophorum is generally resistant to monensin, the ionophore may reduce lysine degradation by F. necrophorum in the rumen. The essential oil components limonene, at 20 or 100 μg/mL, and thymol, at 100 μg/mL, inhibited F. necrophorum growth, whereas eugenol, guaiacol, and vanillin had no effect. Our findings may lead to ways to minimize ruminal lysine degradation and thus increase its availability to the animal.

Aim: The present study was conducted to study the effect of propolis administration on bio-hematological parameters, antioxidant enzyme activities, and productivity of Barki ewes during late pregnancy and lactation under the arid conditions. Materials and Methods: Twenty-five pregnant Barki ewes were fed the basal diet (n=12, control) and the basal diet plus propolis (5 g/kg diet, n=13) for 1 month before parturition and continued 2 months after parturition. Milk yield and milk composition, hematological constituents, antioxidant enzyme activities, thyroid hormones, and lambs birth and weaning weights, and antioxidants were determined. Results: Significant (p<0.05) increase in white blood cells in the propolis group compared to control was observed. Mean corpuscular hemoglobin (Hb) (MCH) and corpuscular Hb (MCH concentration %) were decreased (p<0.05) in propolis compared to control group. Milk yield was increased (p<0.05) in the propolis group compared with control and continued to increase with the advancement of lactation. Milk fat and milk total solids increased (p<0.05) in the propolis group than the control. Plasma immunoglobulin A (IgA) was increased (p<0.05) in propolis compared to control with no effect in IgM and IgG. Superoxide dismutase, hydrogen peroxide (HP), and nitric oxide were decreased (p<0.01) in the propolis group compared to control. Weaning weight for lambs born to ewes fed propolis was increased (p<0.05) at week 8 after birth compared with control lambs. Malondialdehyde and HP activities were decreased (p<0.01) in lambs born to propolis ewes compared to control. Conclusion: Crude Chinese propolis (5 g/d) supplementation improved milk yield, milk composition, and the antioxidant enzymes in Barki ewes and immune functions, growth performance and antioxidant status in their lambs under arid conditions.

Experiments were conducted to evaluate the availability to ruminants of lysine from hydroxymethyl lysine, a product potentially resistant to ruminal degradation yet able to release free lysine when subjected to the acidic environment of the abomasum. An in vitro ruminal fermentation assay that led to ammonia production from free lysine was used for initial assessments, but the hydroxymethyl lysine was inhibitory to lysine degradation at the concentrations tested in vitro; therefore, an in vivo assay with sheep, using plasma lysine concentrations as the response criterion, was used for assessment. twelve mature sheep were fed graded amounts of lysine from either a commercially available ruminally protected lysine product with known availability or from hydroxymethyl lysine. the protected lysine product provided 3 or 6 g/d of metabolizable lysine, whereas the hydroxymethyl lysine provided 3 or 6 g/d of total lysine. Plasma lysine concentrations increased linearly in response to both the ruminally protected lysine product and hydroxymethyl lysine. by slope ratio analysis, the bioavailability of lysine in hydroxymethyl lysine was estimated to be 94% of that for the commercially available product. We concluded that hydroxymethyl lysine may be used as an effective means of supplementing lysine to ruminants.

An 8-week feeding experiment was designed to examine the influences of single or/and double strains of probiotic compared to antibiotic colistin on growth, hematological variables, blood serum metabolites and caecal fermentation in post-weaning rabbits exposed to heat stress conditions. A total of one hundred (35-day-old; average initial body weights 694 ± 7.33) New Zealand White rabbits were distributed into five groups. The experimental groups were the basal diet (control), or basal diet fortified with 120 mg colistin (COL); 5 Â 10 6 cfu Clostridium butyricum (CB); 2 Â 10 8 cfu Enterococcus faecium NCIMB 11181 (EF); or 2.5 Â 10 6 cfu C. butyricum þ 1 Â 10 8 cfu E. faecium/kg diet (CB þ EF). The results demonstrated that both the EF and CB þ EF treatments enhanced (p < .05) final body weight and overall feed conversion ratio compared to control and COL treatment. The carcase yield percentage and relative organs weight were insignificantly affected in all treated groups. The COL treatment increased (p < .05) mean corpuscular volume and albumin/globulin ratio compared to the control group. Compared to the control, all probiotic and COL groups decreased (p < .05) serum total triglycerides and very low-density lipoprotein. The concentrations of Serum total protein, globulin, highdensity lipoprotein, complement component 3, and lysozyme activity were higher (p < .05) in probiotic groups than those in the control group. Probiotic application improved the caecal total volatile fatty acids, propionate concentrations, and intestinal histomorphometry parameters. In conclusion, EF and CB þ EF probiotic supplements could be used as alternatives to antibiotic colistin to enhance the growth and health of weaned rabbits under heat stress conditions. HIGHLIGHTSTwo strains of probiotics as alternatives to antibiotics were studied in rabbits under heat stress conditions. Supplemental EF and CB þ EF probiotic enhanced rabbit growth and feed utilisation. Probiotic application improved biochemical and immunological indicators. The application of the tested probiotics improved the caecal volatile fatty acids production and the intestinal histomorphometry parameters. EF and CB þ EF probiotic supplements could be used as an alternative to antibiotics to promote the growth of rabbits under heat stress conditions.

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Guava leaves (Psidium guajava, GL), a high-phenolic- and flavonoid-containing plant resource capable of substituting the high-quality forage, may help in mitigating ruminal methane (CH) emission without adverse impact on nutrient degradability if supplemented at an appropriate level. In order to test this hypothesis, rumen fermentation, CH production, and nutrient degradability of GL either solely or as a substitute of berseem hay (Trifolium alexandrinum, BH) were evaluated in a diet containing 50:50 concentrate to roughage. Five different levels of GL (0, 12.5, 25, 37.5, and 50%) were tested in vitro after 24 h incubation using a semi-automated gas production (GP) system. The current findings indicated that merely the presence of GL resulted in significantly lower values for cumulative GP (P < 0.001), CH emission (P < 0.05), truly degraded dry matter (TDDM; P < 0.001), truly degraded organic matter (TDOM; P < 0.001), and ammonia nitrogen (NH-N) concentration (P < 0.001); however, pH (P < 0.001) and partitioning factor (P < 0.001) were higher. The total and individual volatile fatty acid (VFA) concentrations were drastically declined with GL as compared to BH (P < 0.05). A negative linear correlation was recorded between the levels of GL and GP including CH production (P < 0.05). The addition of GL up to 25% did not pose any negative effect on both TDDM and TDOM values along with NH-N concentration. In addition, the inclusion of GL up to 25% did not affect the total or individual VFA concentration. Conclusively, in a medium concentrate diet, use of 25% GL and 25% BH in animal diet could be a promising alternative for mitigating the CH production without any deleterious effect on nutrient degradability.