A hierarchical three-level meta-analysis of the effects of supplemental histidine on lactational performance in dairy cows and the associated influencing factors
Description
The effect of His supplementation on the lactational performance in dairy cows as well as the potential interfering factors have not been well characterized. Nineteen peer-reviewed papers from PubMed, Web of Science, and Google Scholar databases published by December 31, 2024, were pooled to calculate the weighted mean differences (WMD) and CI for continuous variables using a stratified 3-level meta-analysis with a randomeffects model. A moderator analysis was used to evaluate the influences of cow breed, lactation stage, dietary MP supply, basal diet type, and other supplements as well as method and dosage of administration on the effects of supplemental His. Results showed that His supplementation increased DMI, milk yield, milk protein yield, and milk protein concentration, but decreased milk fat concentration in dairy cows. The effects of His on milk protein concentration was more prominent in dairy cows when they were fed an MP-deficient diet or a corn silage–based diet. More beneficial effects of His on DMI, milk protein concentration and milk protein yield, milk fat concentration, and lactose yield were found in earlylactation cows relative to mid-lactation cows. Histidine supplementation via abomasal infusion, rather than feeding a rumen-protected form, increased the milk protein concentration. Regression analysis showed that total digestible His should be supplied at 72.6 g/d to achieve the optimal milk protein yield in dairy cows. These findings provide guidelines for His supplementation to improve the lactational performance in dairy cows.
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Steps to reproduce
The terms (“histidine”) AND (“cow” OR “cattle”) were searched in PubMed, Web of Science, and Google Scholar databases up to December 31, 2024, for publications regarding the effects of supplemental His on lactational performance in dairy cows.Supplies of MP, digestible AA, and NEL were estimated by using NRC (2001) ingredient analysis and production characteristics reported in the original manuscripts, except for where indicated. An MPD diet was defined as MP supplied at or below 95% of requirement.Weighted mean difference (WMD) with CI between the treatment and control groups were calculated using the “metafor” package of R software (version 4.2.2; https://www.r-project.org) because the extracted data units were similar. Coefficients and CI may be inflated by Type I errors when covariates are unbalanced or have high leverage, particularly when the number of studies is small (Tipton, 2015), and thus a small-sample adjustment function was used in our meta-analysis model.
Institutions
- Qingdao Agricultural University