The Effect of Organic Trace Mineral Supplementation in the Form of Proteinates on Performance and Sustainability Parameters in Laying Hens: A Meta-Analysis.

The effect of supplementing organic trace minerals (OTM), in the form of mineral proteinates (Bioplex® Cu, Fe, Mn, and Zn, Alltech Inc., Nicholasville, KY, USA), in the diets of laying hens was examined using Comprehensive Meta-Analysis (CMA) statistical software. The impact on production performance, egg quality traits, and sustainability parameters related to the carbon footprint of egg production was assessed. Data were obtained from 32 global studies, comprising 107 dietary assessments of 30,992 laying hens. Overall pooled effect size (raw mean difference) of production performance when dietary organic trace minerals were supplemented either in basal diets, partial replacement of inorganic trace minerals (ITM), or total replacement of ITM, indicated that use of Bioplex minerals resulted in 2.07% higher hen-day production (HDP), whilst feed conversion ratio (FCR) was lower by 51.28 g feed/kg egg and 22.82 g feed/dozen eggs, respectively. For egg quality traits, daily egg mass was 0.50 g/hen/day higher and egg weight was 0.48 g per egg greater when Bioplex minerals were incorporated in the diet. The mean difference in egg loss was -0.62%. Eggshell thickness was greater by 0.01 mm, and a higher eggshell strength of 0.14 kgf was observed. Eggshell weight was heavier by 0.20 g, eggshell percentage was higher by 0.15%, and Haugh unit was 1 point higher (0.89). We also carried out a meta-regression of the effects of the study factors (location, year of study, hen breed/strain, age of hens, number of hens, and study duration) on the overall pooled effect size of the production performance and egg quality traits in response to supplementary OTM inclusion, and it indicated that certain factors had a significant (p < 0.05) impact on the results. Finally, a life cycle assessment (LCA) model was selected to evaluate the impact of feeding organic trace mineral proteinates on the carbon footprint (feed and total emission intensities) of the egg production using the data generated from the meta-analysis. Results showed that the inclusion of OTM proteinates resulted in an average drop in feed and total emission intensities per kg eggs of 2.40% and 2.50%, respectively, for a low-global-warming-potential (GWP) diet and a drop of 2.40% and 2.48% for feed and total emissions, respectively, based on high-GWP diet. Based on the overall results, the inclusion of organic trace mineral proteinates in layer diets can benefit production performance and egg quality traits while contributing to a lower carbon footprint.

Meta-analysis and sustainability of feeding slow-release urea in dairy production.

Slow-release urea (SRU) is a coated non-protein nitrogen (NPN) source for providing rumen degradable protein in ruminant nutrition. A meta-analysis was conducted to evaluate the effects of replacing vegetable protein sources with SRU (Optigen®, Alltech Inc., USA) on the production performance of dairy cows. Additionally, the impact of SRU supplementation on dairy sustainability was examined by quantifying the carbon footprint (CFP) of feed use for milk production and manure nitrogen (N) excretion of dairy cows. Data on diet composition and performance variables were extracted from 17 experiments with 44 dietary comparisons (control vs. SRU). A linear mixed model and linear regression were applied to statistically analyse the effect of SRU on feed intake and production performance. Feeding SRU decreased (P < 0.05) dry matter intake (DMI, -500 g/d) and N intake (NI, -20 g/d). There was no significant effect (P > 0.05) on milk yield, fat-corrected milk, energy-corrected milk, and milk fat and protein composition. However, SRU supplementation improved (P < 0.05) feed efficiency (+3%) and N use efficiency (NUE, +4%). Regression analyses revealed that increasing SRU inclusion level decreased DMI and NI whereas increasing dietary crude protein (CP) increased both parameters. However, milk yield and feed efficiency increased in response to increasing levels of SRU inclusion and dietary CP. The NUE had a positive relationship with SRU level whereas NUE decreased with increasing dietary CP. The inclusion of SRU in dairy diets reduced the CFP of feed use for milk production (-14.5%; 373.13 vs. 319.15 g CO2 equivalent/kg milk). Moreover, feeding SRU decreased manure N excretion by 2.7% to 3.1% (-12 to -13 g/cow/d) and N excretion intensity by 3.6% to 4.0% (-0.50 to -0.53 g N/kg milk). In conclusion, feeding SRU can contribute to sustainable dairy production through improvement in production efficiency and reduction in environmental impacts.

Long term dietary supplementation with microalgae increases plasma docosahexaenoic acid in milk and plasma but does not affect plasma 13,14-dihydro-15-keto PGF2α concentration in dairy cows.

The aims of the study were to determine the long-term effects of dietary supplementation with microalgae (SCIM) on milk and blood fatty acid (FA) composition and reproductive hormones in early lactation dairy cows. Sixty Holstein-Friesian dairy cows (30 per treatment) were unsupplemented (Control) or supplemented with 100 g of SCIM (Schizochytrium limacinum sp.) per cow per day from 25 ± 0.5 d post-partum for 98 d. Intake and milk yield were recorded daily, with milk samples collected at weeks 0, 1, 2, 4, 8 and 14, and blood samples collected from 12 representative pairs per treatment at weeks 0, 2, 4, 8, and 14 for subsequent analysis of FA, ß-hydroxybutyrate, non-esterified fatty acids and glucose. At 33 ± 0.9 d postpartum the oestrus cycle of 24 cows (12 per treatment) were synchronized and plasma 13,14-dihydro-15-keto PGF2α (PGFM) concentrations determined following an oxytocin challenge. Data were analysed by repeated measures analysis of variance. There was no effect of treatment on dry matter intake, milk yield or milk fat content, with mean values across treatments of 22.1 and 40.6, and 37.2 g/kg respectively. Milk fat concentration of C22:6 n-3 increased rapidly in cows receiving SCIM, reaching a maximum of 0.38 g/100 g FA by week 14. Similarly, blood concentration of C22:6 n-3 increased to 1.6 g/100 g FA by week 14 in cows fed SCIM. There was no effect of treatment on plasma metabolites, but plasma glucose was lower in cows fed SCIM compared to the Control at week 2, and higher in week 8. There was no effect of treatment on peak plasma PGFM concentration or area under the curve. It is concluded that feeding SCIM rapidly increases blood and milk concentrations of C22:6 n-3 which are maintained over time, but does not improve plasma PGFM in dairy cows.