Effects of calcium salts of palm fatty acids on nutrient digestibility and production responses of lactating dairy cows: A meta-analysis and meta-regression

摘要

Our primary objective was to perform a meta-analysisand meta-regression to evaluate the effects of dietssupplemented with calcium salts of palm fatty acids(CSPF) compared with nonfat supplemented controldiets (CON) on nutrient digestibility and productionresponses of lactating dairy cows. Our secondaryobjective was to perform a meta-analysis to evaluatewhether experimental design affects productionresponses to supplemental CSPF. The data set wasformed from 33 peer-reviewed publications with CSPFsupplemented at ≤3% diet dry matter. We analyzed theinteraction between experimental design (continuousvs. change-over) and treatments (CON vs. CSPF) toevaluate whether experimental design affects responsesto CSPF (Meta.1). Regardless of experimental design,we evaluated the effects of CSPF compared with CONon nutrient digestibility and production responses oflactating dairy cows by meta-analysis (Meta.2) andmeta-regression (Meta.3) approaches. In Meta.1, therewas no interaction between treatments and experimentaldesign for any variable. In Meta.2, compared withCON, CSPF reduced dry matter intake [DMI, 0.56 ±0.21 kg/d (±SE)] and milk protein content (0.05 ±0.02 g/100 g), increased neutral detergent fiber (NDF)digestibility (1.60 ± 0.57 percentage units), the yieldsof milk (1.53 ± 0.56 kg/d), milk fat (0.04 ± 0.02 kg/d),and 3.5% fat corrected milk (FCM, 1.28 ± 0.60 kg/d),and improved feed efficiency [energy corrected milk(ECM)/DMI, 0.08 kg/kg ± 0.03]. There was no effectof treatment for milk protein yield, milk fat content,body weight, body weight change, or body conditionscore. Compared with CON, CSPF reduced the yieldof de novo milk fatty acids (FA) and increased theyields of mixed and preformed milk FA. In Meta.3, weobserved that each 1-percentage-unit increase of CSPFin diet dry matter reduced DMI, increased NDF digestibility,tended to increase FA digestibility, increasedthe yields of milk, milk fat, and 3.5% FCM, reducedthe content of milk protein, reduced the yield of denovo milk FA, and increased the yields of mixed andpreformed milk FA. In conclusion, our results indicateno reason for the restrictive use of change-over designsin CSPF supplementation studies or meta-analysis.Feeding CSPF increased NDF digestibility, tended toincrease FA digestibility, and increased the yields ofmilk, milk fat, and 3.5% FCM. Additionally, CSPF increasedmilk fat yield by increasing the yields of mixedand preformed milk FA.