Bromatological composition and ruminal degradability of Xaraés palisade grass under grazing in integrated systems

To evaluate the bromatological composition and ruminal degradability of dry matter (DM), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) of Xaraés palisade grass (Urochloa brizantha ‘Xaraes’ syn Brachiaria brizantha) under grazing in integrated crop, livestock (ICL), and forest (ICLF) systems, we conducted an in situ degradability trial in randomized blocks with three non-lactating 3/4 Gyr × 1/4 Holstein cows, provided with ruminal cannula. The management of Xaraés palisade grass was similar in both systems, differing only regarding shading in the ICLF system provided by eucalyptus trees (average 65% crown cover). Grass samples were incubated for 0, 3, 6, 9, 12, 24, 36, 48, 72, and 96 hours. Considering the passage rate 2% h-1, the Xaraés palisade grass of ICL system had greater NDF effective degradability in relation to ICLF (46.38% vs 44.98%). However, the palisade grass CP potential degradability was greater in the ICLF than in the ICL system (68.92% vs. 65.40%). The presence of trees in the pasture has effect on nutritional traits of the Xaraés palisade grass, increasing its protein content and degradability and reducing its fiber degradability.

331 Effects of Dried Distillers’ Grains Cube Supplementation Rate on Voluntary Intake and Digestibility of Bermudagrass Hay Fed to Growing Heifers

The objective of this study was to evaluate supplementation rates of dried distillers’ grains cubes (DDGS) on voluntary intake (DMI), rate and extent of digestibility, and blood parameters of growing Charolais-cross heifers (BW = 286 ± 28.9 kg) fed ad libitum bermudagrass (Cynodon dactylon) hay. For the 29-d study, heifers were randomly assigned to one of four supplementation treatments: 1) Control, no supplement (n = 6); 2) Low, supplemented 0.90 kg/d (n = 6); 3) Intermediate, supplemented 1.81 kg/d (n = 5); or 4) High, supplemented 3.62 kg/d (n = 6). Heifers were offered supplement each morning in individual stalls. From d 15 to 25, heifers were dosed twice daily with titanium dioxide in gelatin capsules (10 g/d), and fecal samples were collected via rectum at time of dosing from d 22 to 25 to estimate fecal output. Post-dosing, fecal sampling continued over 96-h from d 25 to 29 to determine passage rate (Kp) via titanium dioxide analysis. Blood was collected from each animal on d 26 via jugular venipuncture before supplementation, and 4 and 8-h post-supplementation for analysis of blood urea N (BUN), lactate, and glucose. Samples of feces, hay, and supplement were incubated in rumen-cannulated Holstein steers (n = 4; BW = 281 ± 29.5 kg) for 576-h to estimate digestibility with indigestible neutral detergent fiber as an internal marker. Data were analyzed by ANOVA using the mixed procedure of SAS (SAS Inst. Inc. Cary NC), with treatment least-squares means separated using orthogonal polynomial contrasts. Increasing DDGS linearly (P < 0.01) decreased forage DMI linearly, but linearly increased Kp, total diet DMI, and total diet digestibility. Linear increases (P ≤ 0.02) in glucose, lactate, and BUN were likewise observed with increasing DDGS. Increasing DDGS supplementation to growing calves consuming bermudagrass hay may increase productivity while reducing forage intake.

Evaluating the Protein Value of Fresh Tropical Forage Grasses and Forage Legumes Using In Vitro and Chemical Fractionation Methods

The objectives of the present study were (1) to assess the adequacy of the in vitro and chemical methods to predict post-ruminal crude protein supply (PRCP) from fresh tropical forage, and (2) to identify PRCP supply predictors. Twenty-three fresh forage grasses and 15 forage legumes commonly used in domestic cattle feeding in the tropics and subtropics were incubated in the rumen of cows to determine ruminal crude protein (CP) degradation. The PRCP supply was calculated from in situ rumen-undegraded CP and in vitro organic matter digestibility (i.e., reference method), from ammonia-nitrogen release during in vitro incubation (i.e., in vitro method), and from the concentrations of chemical CP fractions (i.e., chemical method). The adequacy was evaluated using error-index and dimensionless parameters, and stepwise regression was used to select PRCP predictors. Adequacy ranged from poor to moderate (0.53 to 0.74) for the in vitro method being lower for forage legumes at a slow rumen passage rate (0.20), and even poorer (0.02 to 0.13) for the chemical method. Hence, the in vitro method can estimate PRCP supply in tropical forages with moderate to high but not with slow passage rates. Equations developed in the present study appear to predict PRCP supply with reasonable adequacy.

Effects of Dilution Rate on Fermentation Characteristics of Feeds With Different Carbohydrate Composition Incubated in the Rumen Simulation Technique (RUSITEC)

This study investigated the impact of carbohydrate source and fluid passage rate (dilution rate) on ruminal fermentation characteristics and microbial crude protein (MCP) formation. Three commonly used feeds (barley grain [BG], beet pulp [BP], and soybean hulls [SBH]), which differ considerably in their carbohydrate composition, were incubated together with a mixture of grass hay and rapeseed meal in two identical Rusitec apparatuses (each 6 vessels). Differences in fluid passage rate were simulated by infusing artificial saliva at two different rates (1.5% [low] and 3.0% [high] of fermenter volume per h). This resulted in six treatments (tested in 3 runs): BGhigh, BGlow, BPhigh, BPlow, SBHhigh and SBHlow. The system was adapted for 7 d, followed by 4 d of sampling. Production of MCP (mg/g degraded organic matter [dOM]; estimated by 15N analysis) was greater with high dilution rate (DL; p < 0.001) and was higher for SBH compared to both BG and BP (p < 0.001). High DL reduced OM degradability (OMD) compared to low DL (p < 0.001), whereas incubation of BG resulted in higher OMD compared to SBH (p < 0.002). Acetate:propionate ratio decreased in response to high DL (p < 0.001). Total gas and methane production (both /d and /g dOM) were lower with high DL (p < 0.001). In our study increasing liquid passage rate showed the potential to increase MCP and decrease methane production simultaneously. Results encourage further studies investigating these effects on the rumen microbial population.

Ruminal parameters and in-situ degradability of rations with wheat middling substitution for corn

This study aimed to evaluate the effect of substituting corn with wheat middling on the in-situ degradability of foods and ruminal parameters of cattle. The experiment was conducted at the Ruminant Studies Unit and the Laboratory of Food Analysis and Animal Nutrition of Londrina State University. Five rumen-fistulated cattle with an average weight of 521 ± 38.22 kg were housed in individual stalls. The experimental design used was a Latin square with five treatments (100% C, 75% C 25% WM, 50% C 50% WM, 25% C 75% WM, and 100% WM) and five periods of 25 days each. The pH and ammoniacal nitrogen (N-NH3) concentration in ruminal fluid was measured before feeding and 2, 4, 6, and 8 h after feeding in subdivided parcels. The in-situ degradability of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) were determined by incubating silage samples and measuring concentrates in the rumen of cattle. The levels of substitution of corn by wheat middling did not alter the pH and N-NH3 values but was influenced by the collection time. The N-NH3 presented quadratic behavior with a point of maximum rumen concentration (5.31 mgdL-1) reached 1.12 h after feeding. The pH presented quadratic behavior with a point of minimum (6.04) reached 4.32 h after feeding. The effective degradability (ED) of DM with 2, 5 and 8%h-1 of passage rate was influenced by the substitution of corn by wheat middling, with increasing linear behavior. The ED 2%h-1 varied from 46.19% to 50.24%, the ED 5%h-1 varied from 33.76% to 38.68%, and the ED 8%h-1 values ranged from 28.16% to 32.92% for the 100% C and 100% WM treatments. Higher values, for treatments with higher levels of substitution of corn by wheat middling, occurred owing to the lower fiber content and to the largest soluble fractions and degradation rate of DM in rations with wheat middling. The ED of CP and NDF with passage rates of 2, 5 and 8%h-1 presented quadratic behavior. The ED 2, 5 and 8%h-1 of CP presented maximums of 75.9%, 77.9%, and 86.2%, with averages of 52.02%, 45.93%, and 42.23%, respectively. The ED 2, 5 and 8%h-1 of NDF presented minimum points of 29.6%, 34.7%, and 35.2%, with averages of 41.60%, 33.43%, and 27.76%, respectively. Wheat middling can be used for total substitution of corn without damaging ruminal pH and N-NH3, in addition to improving the degradability of rations.

Nutrition al manipulation of feeding behaviour of birds

A research to manipulate the feeding behaviour of laying hens from nutritional perspective was conducted with 504 ISA Brown. Seventeen (17) week old ISA brown with weights ranging between 1590 and 1812 g were allocated to six dietary treatments. There were seven replicates per treatment with 12 birds each making a total of 42 pens in all. Experimental diets differed in the levels of energy, levels insoluble Non Starch Polysaccharide (NSP) and the particle sizes of the NSP. Birds had free access to water and feed during which feeding observations with video cameras were made to observe and record the feeding behaviour of birds at 17, 21, 25, 29, 33 and 35 weeks of age. A computer software programme called Observer 5.0 was used to analyze the observations by one person for 30 minutes per cage. In order to gain more insight in the feeding behaviour of laying hens, 60 laying hens were used for a passage rate experiment using titanium dioxide as an inert marker: Five birds were used for each dietary treatment, and replicated twice. At t=0, three titanium capsules were offered to each bird. After five different time points (30, 90, 180, 270 and 360 minutes), these birds were sacrificed and dissected. The gut (titanium) contents from different segments of the GIT (crop, gizzard, ileum, colon and caeca) of each bird were analysed using spectrophotometer at an absorbance of 408 nm. Results from the study indicate that the feeding behaviour of laying hen can be manipulated nutritionally. Bulky diets (10.6 MJ/kg) significantly (P<0.05) increased the eating time of laying hens by 15% compared with normal energy content (11.8 MJ/kg) and this led to consumption of more feed (average 2355g) than those of normal energy diets (2175g). Similarly, the separate effect of NSP, NSP coarseness and interaction between low energy; NSP and NSP coarseness influenced the eating behaviour. Feeding layers with low density diet containing a combination of low energy high NSP coarse NSP increased the amount of time birds spent feeding by 32% and consequently increased the feed intake by 11% (average feed intake of 135g ) above normal energy low NSP mixture diet (average feed intake of 120g). The passage rate experiment showed that Low energy High non starch polysaccharide coarse (LeHnspcoarse) diet reduces the gut transit time, thus birds quickly feel hungrier after a period of satiety, possibly resulting in a short inter-meal interval. Conclusively, the interaction between low energy, high NSP and NSP coarseness influence birds' feeding behaviour necessitating increase in eating time and faster passage rate via the GIT