Glycerine as a feed supplement for beef and dairy cattle: A meta-analysis on performance, rumen fermentation, blood metabolites and product characteristics.

This study aimed to comprehensively evaluate the effects of glycerine supplementation at various concentrations on performance, rumen fermentation, blood metabolites and product characteristics of beef and dairy cattle in vivo by using a quantitative meta-analysis approach. Meta-analysis was performed by integrating a total of 52 studies from 39 articles and 182 treatments into a database. Data were constructed into an intact database and did not distinguish between beef and dairy cattle, except for the parameters of production performance and product characteristics. Data summarized were analysed by using a statistical meta-analysis that employed a fixed effect of glycerine supplementation level and a random effect of various studies for both beef and dairy cattle. Significance of an effect was stated at the probability level of p < .05, and p < .1 was considered as a tendency of significant. Results revealed that there was a linear decrease on dry matter intake (p < .01) and daily gain (p < .05) of beef cattle with the increasing levels of glycerine supplementation. Glycerine supplementation did not decrease milk production of lactating dairy cows. Molar proportion of acetate in the rumen was decreased (p < .001), whereas propionate and butyrate proportions were increased (both at p < .001) by glycerine supplementation. Generally, glycerine did not change nutrient digestibility except that it reduced fibre digestibility (p < .001). Glycerine supplementation linearly lowered triglyceride and NEFA concentrations (both at p < .05) in the blood serum, but not other blood metabolites. Glycerine tended to linearly increase (p < .1) carcass percentage in beef cattle. Increasing dietary glycerine levels decreased milk fat (p < .01) but elevated milk protein (p < .001). Glycerine tended to increase milk lactose (p < .1) by following a quadratic pattern. The proportion of MUFA was increased quadratically by glycerine supplementation (p < .05), whereas glycerine tended to decrease SFA by following a quadratic pattern (p < .1).

Silage quality as influenced by concentration and type of tannins present in the material ensiled: A meta-analysis.

Protein degradation during ensiling is a major problem. Tannins are known to prevent or decelerate protein degradation in the rumen and may be able to do so in silages as well. Therefore, the present evaluation aimed to analyse the influence of tannins on silage quality. This was done by integrating from all suitable experiments found in literature on the topic in a meta-analysis approach. A total of 122 datasets originating from 28 experiments obtained from 16 published articles and one own unpublished experiment were included in the database. Tannins in the silages originated either from the plants ensiled or from supplementations of tanniferous plants or tannins extracted from such plants. Tannin concentrations ranged from 0 to 57.8 g/kg dry matter, and the ensiling period varied from 30 to 130 days. The analysis was based on the linear mixed model methodology in which the different studies were considered as random effects and tannin-related properties (either concentration or type of tannins) were treated as fixed effects. Results revealed that greater concentrations of tannins were associated with a decrease of butyrate concentration in the silages (p < 0.05). An increasing tannin concentration was also accompanied with smaller proportions of soluble N, free amino acid N, non-protein nitrogen and NH3 -N in total silage N (p < 0.05). The relationships between hydrolysable and condensed tannins and the decline in butyrate and NH3 -N concentrations in the silages were of different magnitude (p < 0.05). A higher tannin concentration was associated with a decline in in vitro dry matter digestibility. It was concluded that tannins apparently have the ability to limit extensive proteolysis which may occur during ensiling and thus may improve the fermentative quality of silages. A desired side effect seems to be given by the tannins' apparent property to limit the activity of the butyrate-producing microbes.

Effects of wilting on silage quality: a meta-analysis.

OBJECTIVE: This meta-analysis aimed to evaluate the impact of wilted and unwilted silage on various parameters, such as nutrient content, fermentation quality, bacterial populations, and digestibility. METHODS: Thirty-six studies from Scopus were included in the database and analyzed using a random effects model in OpenMEE software. The studies were grouped into two categories: wilting silage (experiment group) and non-wilting silage (control group). Publication bias was assessed using a fail-safe number. RESULTS: The results showed that wilting before ensiling significantly increased the levels of dry matter, water-soluble carbohydrates, neutral detergent fiber, and acid detergent fiber, compared to non-wilting silage (p<0.05). However, wilting significantly decreased dry matter losses, lactic acid, acetic acid, butyric acid, and ammonia levels (p<0.05). The pH, crude protein, and ash contents remained unaffected by the wilting process. Additionally, the meta-analysis revealed no significant differences in bacterial populations, including lactic acid bacteria, yeast, and aerobic bacteria, or in vitro dry matter digestibility between the two groups (p>0.05). CONCLUSION: Wilting before ensiling significantly improved silage quality by increasing dry matter and water-soluble carbohydrates, as well as reducing dry matter losses, butyric acid, and ammonia. Importantly, wilting did not have a significant impact on pH, crude protein, or in vitro dry matter digestibility.

Effectiveness of herbal plants on rumen fermentation, methane gas emissions, in vitro nutrient digestibility, and population of protozoa.

Background and Aim: Herbal plants have the potential to reduce the population of metagonic bacteria and protozoa due to the bioactive compound contained in herbal plants. This study aimed to evaluate the effect of herbal plant supplementation on rumen fermentation characteristics, methane (CH4) gas emissions, in vitro nutrient digestibility, and protozoan populations. Materials and Methods: This study consisted of two stages. Stage I involved determining the potential of herbal plants to increase total gas production (Orskov and McDonald methods) and reduce the protozoan population (Hristov method). Three potential herbs were selected at this stage and used in Stage II as supplements in the palm kernel cake (PKC)-based diet (30% herbal plants + 70% PKC). Proximate and Van Soest analyses were used to determine the chemical composition. In vitro dry matter digestibility (IVDMD), organic matter (IVOMD), and rumen fermentation characteristics were determined using Theodorous method. Conway microdiffusion was used to determine ammonia concentration (NH3). Gas chromatography was used to determine the total and partial volatile fatty acid production. Results: The results of the first stage showed that seven herbal plants (Moringa oleifera, Rhodomyrtus tomentosa, Clerodendron serratum, Curcuma longa Linn., Urena lobata, Uncaria, and Parkia timoriana) significantly differed in terms of total gas production (p < 0.05). Herbal plants can increase gas production and reduce protozoan populations. The highest total gas production was observed using P. timoriana, M. oleifera, and C. longa Linn. Moringa oleifera plants were the most effective in lowering protozoa population. In Stage 2, the supplementation of herbal plants in PKC-based-diet significantly increased IVDMD, that was ranged from 56.72% to 65.77%, IVOMD that was ranged from 52.10% to 59.54%, and NH3, that was ranged from 13.20 mM to 17.91 mM. Volatile fatty acid partial and total gas production potential and CH4 gas emissions were also significantly different from those of the control (p < 0.05). Conclusion: Supplementation of M. oleifera, C. longa Linn., and P. timoriana in ruminant diet effectively increased total gas production, IVDMD percentage, and IVOMD, and reduced CH4 gas emissions and protozoa populations during rumen fermentation.

Meta-analysis of dietary chitosan effects on performance, nutrient utilization, and product characteristics of ruminants.

Chitosan (CHI) has been used as a feed additive in ruminant diets, but the effects obtained to date have been varied. This study aimed to evaluate the dietary addition of CHI on performance, nutrient utilization, and product characteristics of ruminants by using a meta-analysis approach. A total of 15 articles that composed of 21 studies and 57 data points were included in the database. Number of articles reported the effects of dietary CHI addition were six on beef cattle, seven on dairy cows, and two papers on sheep. Data analysis was based on the mixed model methodology, in which CHI addition levels were considered as fixed effects whereas different studies were treated as random effects. Results revealed that, across various studies, CHI decreased ruminal acetate proportion (p < 0.05) and increased propionate proportion (p < 0.01). Dry matter and crude protein digestibility were elevated due to CHI addition (p < 0.05). CHI decreased blood cholesterol level (p < 0.05) and increased monounsaturated fatty acid proportion in the milk (p < 0.05). However, CHI addition had no effect on dry matter intake, milk production, and milk efficiency of ruminants. In conclusion, CHI is able to modify rumen fermentation towards a favorable direction, but it limitedly affects performance of ruminants.

Evaluation of ensiled soy sauce by-product combined with several additives as an animal feed.

AIM: The present experiment aimed to evaluate the use of different additives, i.e., lactic acid bacteria (LAB) inoculant, tannin extract, and propionic acid, on the chemical composition, fermentative characteristics, and in vitro ruminal fermentation of soy sauce by-product (SSB) silage. MATERIALS AND METHODS: SSB was subjected to seven silage additive treatments: Fresh SSB, ensiled SSB, ensiled SSB+LAB, ensiled SSB+2% acacia tannin, ensiled SSB+2% chestnut tannin, ensiled SSB+0.5% propionic acid, and ensiled SSB+1% acacia tannin+1% chestnut tannin+0.5% propionic acid. Ensiling was performed for 30 days in three replicates, and each replicate was made in duplicate. The samples were evaluated for their chemical composition and silage fermentation characteristics and were tested in an in vitro rumen fermentation system. RESULTS: In general, the nutrient compositions did not differ among the tested SSBs in response to the different additives used. The addition of tannins, either acacia or chestnut, and propionic acid significantly decreased the pH of the ensiled SSB (p<0.05). The addition of several additives (except LAB) decreased the ammonia concentration in SSB silage (p<0.05). The total volatile fatty acids in the in vitro rumen fermentation profile of the ensiled SSB were not significantly altered by the various additives applied. The addition of some additives, i.e., ensiled SSB+LAB and ensiled SSB+2% acacia tannin, reduced the digestibility values of the SSB (p<0.05). Different silage additives did not significantly affect methane production, although the addition of acacia tannins tended to result in the lowest methane production among treatments. CONCLUSION: The use of additives, particularly 2% acacia tannins, can reduce proteolysis in SSB silage.

Use of black soldier fly larvae (Hermetia illucens) to substitute soybean meal in ruminant diet: An in vitro rumen fermentation study.

AIM: This experiment aimed to evaluate substitution of soybean meal (SBM) by black soldier fly (BSF) larvae meal in a napier grass diet as performed by an in vitro rumen fermentation system. MATERIALS AND METHODS: Samples of napier grass, SBM, and BSF larvae age 1 week (BSF1) and 2 weeks (BSF2) were arranged according to the following dietary treatments (dry matter [DM] basis): T1, 100% napier grass; T2, 60% napier grass + 40% SBM; T3, 60% napier grass + 40% BSF1; T4, 60% napier grass + 40% BSF2; T5, 60% napier grass + 20% SBM + 20% BSF1; and T6, 60% napier grass + 20% SBM + 20% BSF2. The samples were determined for their chemical composition and were incubated in vitro using buffered rumen fluid for 48 h at 39°C. In vitro incubation was carried out in three runs and represented by two incubation bottles per run. RESULTS: Supplementation of BSF, both BSF1 and BSF2, increased ether extract, neutral- and acid-detergent insoluble crude protein contents of T3-T6 diets. The T3 or T4 diet resulted in lower ruminal ammonia concentration, in vitro DM digestibility, and in vitro organic matter (OM) digestibility as compared to those in T2 (p<0.05). Diet supplemented with BSF produced lower methane emission in comparison to that of supplemented with SBM (p<0.05). Diet containing BSF2 produced lower methane and methane per digestible OM than that containing BSF1 (p<0.05). CONCLUSION: Substitution of SBM by BSF in ruminant diet results in a lower nutritional value in vitro but with an advantage of lowering ruminal methane emission.