The effects of dietary saponins on ruminal methane production and fermentation parameters in sheep: a meta analysis

Ruminants production systems are facing a critical period within global agriculture due to their unique digestive system which, whilst allowing them to utilize low-quality fiber-rich feed, produces the potent greenhouse gas methane (CH4) as a by-product. It has been proposed that saponin-rich plants can be used to reduce CH4 emissions from ruminant livestock, although the reported results are variable in terms of efficacy. Here we use meta-analytical methods to investigate the literature to determine if saponins can contribute to reducing CH4 production and its further effects on other rumen fermentation parameters in sheep. Following defined search terms available papers on the subject were collected for the period 1990 to 2019 and inclusion and exclusion criteria were applied, an analysis was conducted on CH4 production, CH4 per dry matter intake (DMI), ruminal pH, total volatile fatty acid (VFA), acetate, propionate, butyrate, and acetate-to-propionate ratio based on a comparison between a saponin supplemented group and a control group. The standardized effect size (Hedges’ g) was calculated at the confidence interval of 95%. Q-test and I 2 statistic were used to determine heterogeneity and publication bias was identified through the Egger test. The meta-analysis determined that using saponin sources tended to decrease CH4 production (P=0.062) and acetate-to-propionate ratio (P=0.057), with a reduction in CH4/DMI (P=0.001) and an increase in propionate concentration (P=0.011). No significant difference was observed in ruminal pH, total VFA concentration, and butyrate concentration. The I 2 statistic for the parameters analyzed here was below 50% for heterogeneity with the Egger test results indicating a publication bias for CH4 production

Effects of soybean oil supplements to diets of lactating dairy cows, on productive performance, and milk fat acids profile: a meta-analysis

The aim of this paper was to investigate the effects of soybean oil, an oilseed rich in the polyunsaturated fatty acid C18:2, on dry matter intake (DMI), milk yield (MY) and milk composition (including fatty acid profile) of dairy cows by using a meta-analysis approach. In the meta-analysis, effect size for all outcomes was reported as standardized means difference with 95% confidence intervals. Q test and I2 were calculated to detect the heterogeneity, with a meta-regression also used to investigate sources of heterogeneity. Results of the meta-analysis indicated that adding soybean oil to the diet of dairy cows decreased DMI, milk fat percentage (MFP), milk fat yield (MFY) and milk protein percentage (MPP), whilst significantly increasing MY. Unsaturated fatty acids C18:2, C18:1 trans-11 and C18:2 cis-9 trans-11 conjugated linoleic acid (CLA) all significantly increased with soybean oil inclusion in the diet, whereas C18:3 was numerically higher but not significantly different. Milk composition, including MFP, MFY, MPP, short-chain and medium-chain fatty acids (C4- C20) and unsaturated fatty acids showed a significant percentage of heterogeneity. Results of the meta-regression indicated that dose of soybean oil, total fatty acids in the diet, and the concentration of C18:2 between groups receiving soybean oil and control are the most important factors affecting this heterogeneity. By performing meta-analysis and meta-regression it can be concluded that dietary supplementation of soybean oil to lactating dairy cows decreased DMI, and increased MY and the amount of unsaturated fatty acids in milk

The Effects of Dietary Saponins on Ruminal Methane Production and Fermentation Parameters in Sheep: A Meta Analysis

Ruminants production systems are facing a critical period within global agriculture due to their unique digestive system which, whilst allowing them to utilize low-quality fiber-rich feed, produces the potent greenhouse gas methane (CH4) as a by-product. It has been proposed that saponin-rich plants can be used to reduce CH4 emissions from ruminant livestock, although the reported results are variable in terms of efficacy. Here we use meta-analytical methods to investigate the literature to determine if saponins can contribute to reducing CH4 production and its further effects on other rumen fermentation parameters in sheep. Following defined search terms available papers on the subject were collected for the period 1990 to 2019 and inclusion and exclusion criteria were applied, an analysis was conducted on CH4 production, CH4 per dry matter intake (DMI), ruminal pH, total volatile fatty acid (VFA), acetate, propionate, butyrate, and acetate-to-propionate ratio based on a comparison between a saponin supplemented group and a control group.The standardized effect size (Hedges’ g) was calculated at the confidence interval of 95%. Q-test and I2 statistic were used to determine heterogeneity and publication bias was identified through the Egger test. The meta-analysis determined that using saponin sources tended to decrease CH4 production (P=0.062) and acetate-to-propionate ratio (P=0.057), with a reduction in CH4/DMI (P=0.001) and an increase in propionate concentration (P=0.011). No significant difference was observed in ruminal pH, total VFA concentration, and butyrate concentration. The I2 statistic for the parameters analyzed here was below 50% for heterogeneity with the Egger test results indicating a publication bias for CH4 production

Environmental efficiency of Saccharomyces cerevisiae on methane production in dairy and beef cattle via a meta-analysis

8 páginas, 2 tablas, 4 figuras.The objective of the present study is to examine the effect of yeast (Saccharomyces cerevisiae) on reduction of methane (CH) production in dairy and beef cattle using meta-analytic methods. After compilation of relevant scientific publications available from the literature between 1990 and 2016, and applying exclusion and inclusion criteria, meta-analyses of data from dairy and beef cattle were applied for the pooled dataset or for each animal category (dairy or beef). The results of meta-analysis of all three datasets (all cattle, dairy cattle, or beef cattle) suggested that effect size of yeast either on daily CH production or on CH production per dry matter intake (CH/DMI) was not significant. The results of Q test and I statistic suggest that there is no heterogeneity between different studies on CH production and CH/DMI. The results of meta-analysis suggest that use of yeast (Saccharomyces cerevisiae) as feed additive does not offer significant results in terms of reduction of CH production in dairy and beef cattle. Further research on the effects of different doses of yeast, use of yeast products, different strains, and experimental designs is warranted to elucidate the effects of yeasts on methane production in the rumen

Effect of Dietary Vegetable Sources Rich in Unsaturated Fatty Acids on Milk Production, Composition, and Cheese Fatty Acid Profile in Sheep: A Meta-Analysis

A meta-analysis was conducted to analyze the effects of different dietary vegetable sources rich in unsaturated FA (UFA) on sheep cheese FA profile. This study also quantified the overall effect of feeding sheep with vegetable sources rich in UFA (linseed, flaxseed, sunflower seed, canola, olive oil, bran oil, and olive cake), on milk yield (MY) and milk composition. A literature search was conducted to identify papers published from 2000 to 2019. Effect size for all parameters was calculated as standardized mean difference. Heterogeneity was determined using I2 statistic, while meta-regression was used to examine factors influencing heterogeneity. Effect size was not significant for MY, milk fat percentage (MFP), and milk protein percentage (MPP). Dietary inclusion of vegetable sources rich in UFA decreased the effect size for C12:0, C14:0, and C16:0 and increased the effect size for C18:0, C18:1 t-11, C18:1 c-9, C18:2 c-9, t-11, C18:2 n-6, and C18:3 n-3. Heterogeneity was significant for MY, MFP, MPP, and overall cheese FA profile. Meta-regression revealed days in milk as a contributing factor to the heterogeneity observed in MFP and MPP. Meta-regression showed that ripening time is one of the factors affecting cheese FA profile heterogeneity while the type of feeding system(preserved roughages vs. pasture) had no effect on heterogeneity. Overall, inclusion of dietary vegetable sources rich in UFA in sheep diets would be an effective nutritional strategy to decrease saturated FA and increase polyunsaturated FA contents in cheeses without detrimental effects on MY, MFF, and MPP