Effect of feeding frequency on digestibility, milk production and composition in lactating cows: A meta-analysis and meta-regression

The objective of this study was to evaluate the effect of frequency of feeding total mixed ration (TMR) on total-tract digestibility, milk production and composition in lactating cows, using meta-analysis and meta-regression approaches. Data of fourteen experiments having containing 25 comparisons between treatment (higher feeding frequency) and control (lower feeding frequency) groups, defined selection criteria, were used. Data were analyzed using effect size method in STATA/SE. Increasing frequency of feeding decreased dry matter intake (DMI; weighted mean difference (WMD)= ‒0.134 kg/d) but had no effect on milk yield. Forage level of diet and days in milk (DIM) were the source of heterogeneity for standardized mean difference (SMD) of DMI. In this meta-analysis, higher feeding frequency had no effect on milk fat and milk protein content and yield. Increasing feeding frequency improved NDF digestibility (WMD= 5.663%). Results of univariate meta-regression showed that increasing frequency of feeding in diets containing high level of grains improved NDF digestibility, but in high forage diets lowered NDF digestion. In conclusion, delivery of TMR containing equal amounts of forage and concentrate three times vs. one times in a day decreased DMI but did not change milk yield.