Forage and Feedstuff Digestion Kinetics in Ruminants

During winter and early spring, pasture supply is usually lower than the demand in New Zealand dairy farming systems and thus the ‘autumn saved pastures’ (stockpiling) are introduced to fill the gap. This study aimed to investigate the chemical, physical, and degradation characteristics of ryegrass pastures, the predominant forage in New Zealand, grown in autumn and winter. To serve as ‘autumn saved pasture’, nine ryegrass cultivars, comprising three types (three perennial, three hybrid, and three Italian), were grown in late autumn (Autumn) and early winter (Winter) and harvested after 7 and 9 weeks of regrowth, respectively. The experiment had two experimental factors: ryegrass type (or cultivar) and harvest season. These experimental factors were in a randomised block design with the forage plot as the experimental unit. The degradation characteristics were assessed in the rumen of fistulated cows using the in situ incubation technique. Perennial ryegrass had a greater neutral detergent fibre (NDF) concentration (468 g/kg dry matter (DM)) than the hybrid (435 g/kg DM) or Italian (414 g/kg DM) ryegrasses. Italian ryegrasses had the greatest soluble fraction of DM (64.2% vs. 46.7% and 40.7%) and the greatest degradation rate of an insoluble but degradable fraction of DM (0.221 vs. 0.189 and 0.145/h) than the hybrid and perennial ryegrasses. Compared with the Winter ryegrass, the Autumn ryegrass had a greater crude protein concentration (246 vs. 208 g/kg DM) and a greater NDF concentration (486 vs. 392 g/kg DM) but a lower calculated soluble carbohydrate concentration (152 vs. 263 g/kg DM). It is concluded that there are notable variations among the cultivars, highlighting distinctions in parameters, such as NDF concentration, soluble fractions, degradation rates, and nutrient content among the perennial, hybrid, and Italian ryegrasses, as well as the seasonal variations observed between autumn and winter growth. These findings will not only facilitate enhanced nutrition for dairy cows as they undergo the transition phase but also have practical implications for future research and dairy cow nutrition. Full article

In vitro gas production techniques (IVGPT) are widely used to screen feeds and feed additives to reduce the number of animals needed for experiments, which in turn, reduces costs and increases animal welfare. However, information about repeatability is scarce. The objective of this study was to evaluate the variation from in vitro gas production fermentations in the same laboratory using the same feed substrate. The source of rumen fluid used in the fermentations was from two different farms with either cannulated lactating dairy cows or cannulated fasting heifers, representing two distinct stages of production (donor types). Seventeen 24 h fermentations, undertaken during a year, were used to evaluate the variation between the following parameters: gas curve parameters, baseline-corrected total gas production (TGP (mL at Standard Temperature and Pressure (STP))/g incubated dry matter (DM)), methane concentration (%) and yield (mL gas at STP/g DM), pH and degraded dry matter (dDM). Significant differences between donor types were found for the pH of the rumen fluid from individual animals and pH of fermented fluid. However, no significant differences were observed within donor type. The means for methane concentration and yield, after 24 h of fermentation, were not significantly different between or within donor types. Rate of early gas production was significantly different between donor types, but baseline-corrected TGP was not significantly different at 24 h. No dDM differences after 24 h of fermentation between or within donor types were detected. Gas production curves were different between donor types, being either a monophasic version of the sigmoidal model or an exponential curve for the heifers and the production animals, respectively. No differences were observed within type. Repeatability of rumen fluid (CV_RF), calculated as the coefficient of variation, and the associated parameters, which were investigated, was best for methane yield (CV_RFALL = 0.3%) and least for TGP at 3 h (CV_RFALL = 3%). Repeatability was dependent on donor type. Full article

The purpose of this experiment was to evaluate changes in fermentation quality, chemical composition, aerobic stability, anti-nutritional factors, and in situ disappearance characteristics of various protein-based total mixed rations. Soybean meal (control, non-fermented), fermented cottonseed meal (F-CSM), and fermented rapeseed meal (F-RSM) group were used to prepare the TMRs with corn, whole-plant corn silage, corn stalks, wheat bran, and premix. The test groups were inoculated at 50% moisture with Bacillus clausii and Saccharomyces cariocanus and stored aerobically for 60 h. The nylon-bag method was used to measure and study the rumen’s nutrient degradation. The pH of all TMRs after 48 h of air exposure was below 4.8, whereas that of the F-CSM and control and F-RSM groups increased to 5.0 and >7.0, respectively. After 8 h of aerobic exposure, the temperatures of all groups significantly increased, and 56 h later, they were 2 °C higher than the surrounding air. The lactic acid concentration in the F-CSM and F-RSM groups increased after 12 h of aerobic exposure and then decreased. The acetic acid concentrations in the fermented groups decreased significantly with the increasing air-exposure time. The yeast population of the TMRs increased to more than 8.0 log₁₀ CFU/g before 72 h of air exposure, followed by a decrease in the population (5.0 log₁₀ CFU/g). After fermentation, the free gossypol (FG) concentration in F-CSM decreased by half and did not change significantly during the air-exposure period. Fermentation with probiotics also reduced the F-RSM’s glucosinolate concentration, resulting in a more than 50% detoxification rate. Compared with the F-CSM and F-RSM groups, the effective degradation rates of nutrients in the control group were the lowest, and the dry matter (DM), crude protein (CP), natural detergent fiber (NDF), and acid detergent fiber (ADF) all degraded effectively at rates of 28.4%, 34.5%, 27.8%, and 22.8%, respectively. Fermentation with B. clausii and S. cariocanus could improve the fermentation quality and nutrient composition, decrease the anti-nutritional factor, and increase nutrient degradation of the TMR with cottonseed meal or rapeseed meal as the main protein source, thus achieving detoxification. Full article

The modeling process has a wide range of applications in animal nutrition. The purpose of this work is to determine whether particle swarm optimization (PSO) could be used to explain the fermentation curves of some legume forages. The model suited the fermentation data with minor statistical differences (R² > 0.98). In addition, reducing the number of iterations enhanced this method’s benefits. Only Models I and II could successfully fit the fermentability data (R² > 0.98) in the vetch and white clover fermentation curve because the negative parameters (calculated in Models III and IV) were not biologically acceptable. Model IV could only fit the alfalfa fermentation curve, which had higher R values and demonstrated the model’s dependability. In conclusion, it is advised to use PSO to match the fermentation curves. By examining the fermentation curves of feed materials, animal nutritionists can obtain a broader view of what ruminants require in terms of nutrition. Full article

The objective of this study was to determine rumen degradation kinetics of new low-lignin alfalfa (Medicago sativa L.) cv. Hi-Gest^®360 (HiGest) in comparison with conventional alfalfa cv. AC Grazeland (Grazeland) in monoculture and binary mixtures at different maturity stages. Two cultivars of alfalfa (HiGest, and AC Grazeland) and their binary mixtures with hybrid bromegrass (HBG; cv. AC Success), grown in 2019 at two locations (Saskatoon and Lanigan), were cut at three maturity stages of alfalfa (1 = 10% bloom; 2 = 40% bloom; and 3 = 100% bloom). Rumen degradation characteristics, including rapidly degradable fraction (S), potentially degradable fraction (D), undegradable fraction (U), degradation rate (K_d), lag time (T₀), and effective degradability (ED) of each component were determined using in situ technique and were analyzed by a first-order kinetic equation described by Ørskov and McDonald with lag time. Generally, in alfalfa monoculture, S or D were decreased and U was increased without affecting K_d and T₀, resulting in decreased ED fraction with increasing stage of maturity. In binary mixtures, plant maturity stages have negligible effects on rumen degradation characteristics of CP. HiGest had higher effective degradability of DM (EDDM) as well as of NDF (EDNDF) than Grazeland. In conclusion, HiGest had greater DM and NDF rumen degradation potential relative to Grazeland. HiGest and Grazeland were different in DM and CP degradation patterns, with HiGest having higher EDDM and EDCP than Grazeland. Full article

The ruminal kinetics of protein sources may be changed by heat and sugar treatments. Thus, these processing methods may be used as alternatives to increase beef-cattle diets’ rumen undegradable protein (RUP). We aimed to evaluate the effects of processing cottonseed meals with autoclave, conventional, and microwave ovens, with and without using xylose, on the ruminal kinetics degradation parameters and intestinal digestibility (ID). In situ studies were conducted, and each sample was incubated in the rumen to determine dry matter (DM) and crude protein (CP) rumen degradation kinetics. In vitro studies were also conducted to evaluate ID. The control treatment had a greater soluble fraction for DM and CP than processed cottonseed meals (p < 0.05). The addition of xylose decreased both DM and CP water-soluble fractions (fraction A) of cottonseed meal heated in a conventional oven (p < 0.05). Compared to the control, we observed a decrease in effective degradability and increased RUP for all processed methods (p < 0.05). Furthermore, conventional and microwave ovens showed greater ID than the control. Moreover, xylose-treated groups heated in the autoclave and conventional ovens had greater ID than xylose-untreated cottonseed meal. Under these experimental conditions, cottonseed RUP was increased by the evaluated processing methods. Full article

Peanut meal has an excellent total protein content but also has low rumen undegradable protein (RUP). High-performance ruminants have high RUP requirements. We aimed to evaluate the effects of processing peanut meal with an autoclave and conventional and microwave ovens, with and without using xylose on its ruminal kinetics degradation parameters and intestinal digestibility (ID). In situ studies were conducted to determine dry matter (DM) and crude protein (CP) rumen degradation kinetics. In vitro studies were conducted to evaluate intestinal digestibility (ID). The control treatment had a greater fraction A for DM and CP than peanut meals processed with an autoclave or conventional oven. The control had greater kd for CP compared with the microwave. The addition of xylose decreased fraction A, the degradation rate of fraction B (kd) and RUP, and increased the protein B fraction of autoclaved peanut meal. We observed a decrease in effective degradability (ED) and increased RUP for processed treatments in all experiments compared with the control. Processing methods did not affect the protein ID of autoclaved peanut meal compared to the control. An interaction between xylose and heating time was observed, where increasing heating time linearly reduced the ID of xylose-untreated treatments. Overall, these results suggest that the tested methods effectively increased the RUP content of peanut meal. Full article

In southeastern USA, the use of baleage has increased as an alternative technology to hay production, thereby allowing for a timelier harvest of the conserved forage. A series of studies were conducted to determine the nutritive value, fermentation parameters, and in situ disappearance of the cool-season annual forage mixtures that were ensiled with or without silage inoculant for up to 120 d. The forage mixtures were wheat (Triticum aestivum L.) + brassica hybrid (Brassica rapa L. × napus L.) (WB), wheat + crimson clover (Trifolium incarnatum L.) (WC), and annual ryegrass (Lolium multiflorum Lam.) + oat (Avena sativa L.) + crimson clover (ROC). The inoculant strategy affected the CP concentration (p < 0.05), with it increasing in WB and decreasing in ROC. Among the mixtures, the DM concentration decreased by up to 5%, and the NDF and ADF concentrations decreased by up to 10% during the ensiling period. The pH averaged 5.0, 5.0, and 5.5 for the WC, WB, and ROC mixtures, respectively. Based on our results, the baleage of the cool-season annual forage mixtures may provide a viable high-quality option to sustain animal growth and performance. Full article

Ruminants, mainly cattle, contribute to greenhouse gases (GHG) emissions as methane (CH₄) is produced by ruminal fermentation. Hence, various anti-methanogenic feed strategies have been studied, including the use of plants with secondary metabolites. This study evaluated in vitro ruminal fermentation metrics, microbial composition by digital droplet PCR (ddPCR) and the CH₄ production of the foliage of several tropical trees and shrubs: Leucaena leucocephala, Moringa oleifera, Albizia lebbeck, Enterolobium cyclocarpum, Piscidia piscipula, Brosimum alicastrum, Lysiloma latisiliquum, Guazuma ulmifolia, Cnidoscolus aconitifolius, Gliricidia sepium and Bursera simaruba, using Cynodon plectostachyus grass as control. The results showed a wide variation in the chemical composition of the foliage, as well as in the ruminal microbiota. The crude protein (CP) content ranged from 11 to 25%, whereas the content of condensed tannins (CT) and saponins (S) was from 0.02 to 7%, and 3.2 to 6.6%, respectively. The greatest dry matter degradability (DMD) after 72 h was 69% and the least 35%, the latter coinciding with the least gas production (GP). A negative correlation was found between the CT and CH₄ production, also between protozoa and fungi with the SGMT group of archaea. We concluded that the foliage of some tropical trees and shrubs has a high nutritional value and the potential to decrease CH₄ production due to its CT content. Full article

The objective of this study was to compare the nutritional composition and the neutral detergent fiber (NDF) degradation kinetics of brown midrib (BMR) and non-BMR genotypes within and across warm-season annual grasses. Four commercial varieties (two non-BMR and two BMR) of corn, sorghum, and pearl millet were planted in plots. Forage samples were incubated in the rumen of three rumen-cannulated cows for 0, 3, 6, 12, 24, 48, 96, and 240 h. On an NDF basis, all forage types showed lower acid detergent lignin (ADL) concentrations for BMR genotypes, but the magnitude of the difference differed among forage types. The concentration of undegraded NDF (uNDF; NDF basis) differed among forage types and between genotypes. Corn had the least, pearl millet had the intermediate, and sorghum had the greatest concentration of uNDF. Non-BMR genotypes had greater concentrations of uNDF than BMR genotypes. No interaction existed between forage type and genotype for the concentration of uNDF. In conclusion, although BMR forages may show lower ADL concentrations in the cell wall and greater NDF degradability than non-BMR forages of the same forage type, BMR forages do not always have the least ADL concentration or the greatest NDF degradability when comparing different forage types. Full article

In recent years, the worrying generation of GHG from ruminant production has generated widespread interest in exploring nutritional strategies focused on reducing these gases, presenting the use of bioactive compounds (tannins) as an alternative in the diet. The aim of this research was to determine the effect of the addition of different levels of Acacia mearnsii on ruminal degradation, nutrient digestibility, and mitigation of greenhouse gas production. A completely randomized design with four treatments and six repetitions was used. The treatments were: T1, T2, T3, and T4 diets with, respectively, 0%, 20%, 40%, and 60% A. mearnsii. The rumen degradation kinetic and in vitro digestibility, and the production of gas, CH₄, and CO₂ were evaluated. In situ rumen degradation and in vitro digestibility of DM and OM showed differences between treatments, with T1 being higher (p < 0.05) in the degradation of the soluble fraction (A), potential degradation (A + B), and effective degradation for the different passage rates in percent hour (0.02, 0.05, and 0.08), compared to the other treatments. Rumen pH did not show differences (p > 0.05) between treatments. The lowest (p < 0.05) gas, CH₄, and CO₂ production was observed in treatments T1 and T2 with an approximate mean of 354.5 mL gas/0.500 g fermented DM, 36.5 mL CH₄/0.500 g fermented DM, and 151.5 mL CO₂/0.500 g fermented DM, respectively, compared to treatments T3 and T4. Under the conditions of this study, it was concluded that it is possible to replace traditional forages with up to 20% of A. mearnsii, without observing changes in the production of greenhouse gases with respect to the control treatment (0% of A. mearnsii); however, A. mearnsii is not usable because it significantly decreases rumen degradability of DM and OM, which would considerably affect the production in animals. Full article

The objective of this study was to determine the effect of autochthonous Nepalese fruits on nutrient degradation, fermentation kinetics, total gas production, and methane production in in-vitro rumen fermentation. The fruits of Terminalia chebula (HA), Terminalia bellirica (BA), and Triphala churna (TC), a commercial mixture with equal parts (33.3% DM basis) of Phyllanthus emblica, Terminalia bellirica, and Terminalia chebula, were used. These were tested at three inclusion levels of 20% 40% and 100% of the total sample (as dry matter) in maize silage (MS). MS was used as a control (0% additive). These 10 treatments were tested for two 48-h incubations with quadruplicate samples using rumen fluid from 2 heifers. Total gas production (TGP: mL at standard temperature and pressure (STP)/g DM), methane production (expressed as % and mL/g DM), and volatile fatty acids were determined. After incubations, the filtrate was used to measure pH and volatile fatty acids (VFA), while the residue was used to measure degraded dry matter (dDM) and calculate the partitioning factor (PF48) and theoretical short-chain fatty acid concentration (tVFA). Rumen fluid pH linearly (p < 0.01) decreased in all treatments with increasing dose during fermentation. The CH₄% was less in all three treatments with 100% autochthonous plants than in control, but there were no significant linear or quadratic effects for increasing BA, HA, and TC doses. The PF48 increased for all treatments with a significant linear and quadratic effect (p < 0.05) of increasing dose. Compared to MS, the inclusion of autochthonous plants increased the total volatile fatty acids, with no significant dose effects. The tVFA linearly decreased (p > 0.05) with an increasing dose of BA and HA. All treatments showed quadratic effects on tVFA (p < 0.05) with increasing dose. Increasing TC dose linearly (p < 0.05) and quadratically (p < 0.05) increased total VFA, while increasing HA dose had only a quadratic (p < 0.05) effect on total VFA. All treatments reduced total gas production (TGP) and methane concentration (CH₄%) when compared to MS. The tested autochthonous fruits can be used as additives with a basal feed diet to reduce enteric methane emissions. The most effective anti-methanogenic treatment was 40% HA, which resulted in 18% methane reduction. Full article

This study aimed to explore the effects of different levels of barley starch instead of corn starch on the rumen fermentation and microflora when feeding a corn-based diet to Hu sheep. Thirty-two male Hu sheep equipped with permanent rumen fistulas were selected and fed in individual metabolic cages. All sheep were randomly divided into four groups (eight sheep in each group) and fed with four diets containing a similar starch content, but from different starch sources, including 100% of starch derived from corn (CS), 33% of starch derived from barley + 67% of starch derived from corn (33 BS), 67% of starch derived from barley + 33% of starch derived from corn (67 BS) and 100% of starch derived from barley (100 BS). The experimental period included a 14 d adaptation period and a 2 d continuous data collection period. The results showed that the molar proportions of acetate, isobutyrate, butyrate and isovalerate and the ratio of acetate to propionate in the 67 BS and 100 BS groups decreased compared with the CS and 33 BS groups (p < 0.001), while the molar proportions of propionate and valerate increased (p < 0.001). The combination of 33% barley starch and 67% corn starch in the diet improved the production of TVFAs (p = 0.007). The OTUs and Shannon indexes of the CS and 33 BS groups were higher than the 67 BS and 100 BS groups (p < 0.001), and the Chao1 and Ace indexes were higher than the 100 BS group (p < 0.05). In addition, the 33 BS group had increased the relative abundances of Bacteroidetes, Prevotella and Ruminococcus and the abundances of Fibrobacter succinogenes, Ruminococcus flavefaciens, Streptococcus bovis, Selenomonas ruminantium and Prevotella brevis relative to the CS group (p < 0.05). These results indicate that the substitution of 33% of the CS with BS did not change the rumen fermentation pattern relative to the CS group, and increased the richness and diversity of the rumen microbes in Hu sheep compared with other two starch substitute groups. Full article

Our objectives were to evaluate the variability among animals regarding to the degradation rate of the potentially degradable fraction of dry matter, crude protein, and neutral detergent fiber, as well as to establish the minimum number of animals and provide a standardized design of sampling times for in situ ruminal degradation assays of tropical feeds with cattle. Seven feeds were evaluated, four concentrates and three forages. The incubations were performed using five rumen-cannulated Nellore heifers (328 ± 9.8 kg of body weight). The complete sets of incubation sampling times encompassed 16 time points for forage samples (0–240 h) and 13 time points for concentrate samples (0–144 h). The profiles were adjusted using both fixed and mixed model approaches. When the variation among animals on the degradation rate was considered using the mixed model approach, the precision of the adjusted degradation profiles was increased. Moreover, the utilization of a low number of animals increases the probability to obtain biased estimates of degradation rate and increased random variances. A minimum of three animals is recommended for in situ trials with cattle. Minimum designs of sampling times regarding number and position of incubation times were proposed, discussed, and recommended to assess the dynamics of tropical feed degradation. Full article

The increased attention drawn to the negative environmental impact of the cattle industry has fostered a host of market- and research-driven initiatives among relevant actors. While the identification of some of the most problematic environmental impacts of cattle is seemingly more or less unanimous, solutions are complex and might even point in opposite directions. Whereas one set of solutions seeks to further optimize sustainability pr. unit produced, e.g., by exploring and altering the relations between elements kinetically moving one another inside the cow’s rumen, this opinion points to different paths. While acknowledging the importance of possible technological interventions to optimize what occurs inside the rumen, we suggest that broader visions of the potential negative outcomes of further optimization are also needed. Accordingly, we raise two concerns regarding a focus on solving emissions through feedstuff development. First, we are concerned about whether the development of feed additives overshadows discussions about downscaling and, second, whether a narrow focus on reducing enteric gasses brackets other relations between cattle and landscapes. Our hesitations are rooted in a Danish context, where the agricultural sector—mainly a large-scale technologically driven livestock production—contributes significantly to the total emission of CO₂ equivalents. Full article