Gas production from straw incubated in vitro with different levels of purified carbohydrates

In Vitro Estimation of the Effect of Grinding on Rumen Fermentation of Fibrous Feeds

Simple Summary

Intensive feeding systems for beef production are based on high proportions of concentrate at the expense of forages, which can lead to digestive disorders. However, the particle size of the different fibrous feeds can also affect the rumen fermentation pattern, and thus animal performance. Fermentation of six fiber sources (soybean hulls, sugarbeet pulp, palm kernel cake, oat hulls, dehydrated alfalfa meal, and barley straw) in two presentation forms (non-processed and ground) was studied in a closed batch in vitro system. Higher gas production was recorded when substrates were presented in ground form, except for barley straw; however, substrates ranked in the same order irrespective of their presentation form. The particle size did not markedly affect volatile fatty acids proportions. Methane production as an index of fermentation efficiency did not show major differences between feed presentation forms, or non-forage substrates as compared with straw and is related more with the magnitude of fermentation than with qualitative changes in fermentation. Considering other feed components, the comparison of substrates on rumen microbial fermentation depends not only on their fiber proportion but can also be mediated by their levels of protein and fat.

Abstract

The fermentation patterns of six fiber sources, soybean hulls (SH), sugarbeet pulp (BP), palm kernel cake (PK), oat hulls (OH), dehydrated alfalfa meal (DA), and barley straw (BS) were evaluated for this study on the effect of their presentation form (non-processed, NP and ground, GR). Substrates were tested in a conventional in vitro batch system, using rumen fluid obtained from ewes fed 0.5 alfalfa hay and 0.5 barley straw. All substrates rendered a higher gas production in GR form (p < 0.05) except for BS but ranked similarly irrespective of the presentation form. Among the substrates, when incubated NP, the highest volume of gas was recorded with BP from 8 h onwards (p < 0.05), whereas OH and BS resulted in the lowest gas volume (p < 0.05). During the first half of the incubation period, methane production was higher in GR than NP (p < 0.05). Among substrates, despite NP or GR, methane production with BP was the highest (p < 0.05). Similarly, the presentation form did not qualitatively affect fermentation, as no differences were observed in volatile fatty acids proportions. The effect of particle size of fibrous substrates does not have a major impact on the rate and extent of the rumen microbial fermentation.

Effect of Cobalt Chloride on Fermentation of Alfalfa and Smooth Bromegrass Hays by Horse Cecal Microorganisms

Effects of Co on fiber digestibility in horses are largely unknown. Our objective was to evaluate effects of Co chloride on in vitro gas production, VFA production, and dry matter (DM) disappearance (IVDMD) using cecal fluid from 4 cannulated Quarter Horses. Five grams DM of alfalfa or smooth bromegrass hay were provided as substrate with Co added at 0.0, 0.5, 5.0, 25.0, or 50.0 mg/kg substrate DM. Ten milliliters cecal fluid and 140 mL McDougall's buffer were incubated in duplicate, and pH, VFA concentrations, and IVDMD were measured after 48 hours. Gas production, used as an indicator of fermentative activity, was recorded every 15 minutes. Terminal pH was not affected by Co or forage type (P > .19). There was greater IVDMD in cultures containing alfalfa (29.2%) compared with smooth bromegrass hay (19.4%; P < .01). There was a forage × Co interaction (P < .05) in which gas production was greater in cultures containing alfalfa, and 5 mg Co/kg substrate DM led to greater gas production than 50 mg Co/kg substrate DM in cultures containing brome (P < .05). Gas production was affected by forage, Co, and time (P < .01). Production of individual and total VFA, as well as acetate:propionate (A:P) ratio were increased in cultures containing alfalfa (P < .05); however, there were no effects of Co on VFA concentrations (P > .05). While gas production was influenced by Co in cultures containing brome, no effects of Co were observed for pH, VFA, or IVDMD.

Effects of feeding different levels of dried orange pulp and recycled poultry bedding on the performance of fattening lambs

The effects of dietary feeding different levels of recycled poultry bedding (RPB) and dried orange pulp (DOP) on the performance of fattening Shal lambs (initial BW of 28 ± 2.2 kg) were assessed using a factorial experiment (2 × 3) with a completely randomized design. Six diets, containing different levels of RPB (0 or 160 g/kg of DM) and DOP (0, 110, or 220 g/kg of DM), were randomly assigned to 6 groups of 6 lambs each for a 74-d period (14 d for adaptation and 60 d for data collection). Diets were offered as total mixed ration to ensure 10% of orts. Feed intake, growth, diet digestibility, microbial nitrogen (N) synthesis (MNS), N retention, rumen fermentation parameters, and blood metabolites were determined. Data were analyzed using the PROC MIXED of SAS. Increasing RPB and DOP levels in the diet of the lambs improved ( < 0.05) DMI, ADG, and G:F. Diet digestibility was not affected by dietary feeding of RPB ( > 0.05), but increased as DOP level increased in the diet ( < 0.05). Feeding RPB and DOP had no effects ( > 0.05) on the ruminal pH. The ruminal total VFA concentration, molar proportion of acetic acid, and acetate-to-propionate ratio increased ( < 0.05) with the increasing dietary levels of RPB and DOP, while ammonia N concentration, propionic acid proportion, total protozoa count, and subfamily number decreased ( < 0.05). Including RPB and DOP in diet enhanced ( < 0.05) MNS and N retention. Feeding RPB-containing diets caused ( < 0.05) an increase of plasma glucose concentration and decreases ( < 0.05) of cholesterol and urea N. As the dietary level of DOP increased, the plasma concentrations of glucose, triglycerides, and urea N reduced ( < 0.05). The plasma antioxidant power was not affected ( > 0.05) by feeding RPB, but increased ( < 0.05) with increasing DOP level in diet. The animal performance reached its greatest value with simultaneous feeding of 160 g of RPB and 220 g of DOP per kg of diet DM. It has been concluded that the partial dietary substitution of RPB (instead of soybean meal, wheat bran, and sugar beet pulp) or/and DOP (instead of barley grain and corn grain) in fattening Shal lambs had positive effects on feed intake, diet digestibility, ruminal microbial N, growth, and N retention. Synchronized feeding of the great levels of RPB (as an N source) and DOP (as an energy source) increased utilization efficiency of these byproducts in the fattening lambs.

Flint corn grain processing and citrus pulp level in finishing diets for feedlot cattle

Four trials were conducted to evaluate the effects of flint corn processing and the replacement of corn with citrus pulp (CiP) in diets for Nellore feedlot cattle. In a 103-d finishing trial, 216 Nellore bulls (350 ± 24 kg initial BW) were used in a randomized complete block design with a 2 × 4 factorial arrangement of treatments. Factors included 2 processing methods, either ground corn (GC) or steam-flaked corn (FC), with CiP replacing each corn type at 4 levels (0, 25, 50, and 75% of DM). All diets contained 12% sugarcane bagasse and 88% concentrate (DM basis). Treatments were also evaluated in metabolism trials, in which 10 ruminally cannulated Nellore steers (389 ± 37 kg) were assigned to 2 independent but simultaneous 5 × 5 Latin squares, each using 1 method of corn processing (GC and FC). Interactions ( < 0.05) between corn processing and CiP inclusion level were observed for final BW, DMI, ADG, G:F, and HCW. With FC-based diets, added CiP linearly decreased final BW ( = 0.04), whereas with GC-based diets, added CiP quadratically increased final BW ( = 0.002). With FC-based diets, the inclusion of CiP linearly increased DMI ( = 0.03) and linearly decreased ADG ( = 0.03) and G:F ( = 0.001). Increasing CiP in GC-based diets quadratically increased DMI ( = 0.001), ADG ( = 0.005), and HCW ( = 0.003). In FC-based diets, CiP inclusion had no effect on HCW ( = 0.21). Dressing percent, LM area, and 12th-rib fat were not affected by diet ( ≥ 0.05). For steers fed GC diets, CiP inclusion in the diet quadratically decreased the molar proportion of isovalerate ( = 0.001) but linearly increased ruminal butyrate ( = 0.006). No differences ( ≥ 0.16) were observed for total VFA concentrations, acetate:propionate ratio, and ruminal NH-N as CiP replaced GC. For steers fed FC diets, the molar proportion of acetate linearly increased ( = 0.002) whereas the proportion of propionate was linearly decreased ( < 0.001), resulting in a linear increase ( = 0.001) in the acetate:propionate ratio. Replacing corn with CiP linearly reduced NEm ( = 0.001) and NEg ( < 0.001) of FC-based diets but did not affect ( = 0.15) NE values of CG-based diets. Steam flaking flint corn improved cattle performance in this trial more than has been reported for dent corn in the published literature.