
Supplemental Material for "Production and nutrient use efficiency in lactating dairy cows fed fixed or variable amounts of concentrate feeds"
The objective was to investigate the effects of separate feeding of a partial mixed ration (PMR) and concentrate premixes (CMix) delivered at fixed or variable amounts using an automatic feeding system (AFS) on lactational performance, enteric CH4 emissions, ruminal fermentation variables, digestibility of nutrients, and N excretion in lactating dairy cows. Forty-eight primi- and multiparous Holstein cows averaging 91 ± 26 days-in-milk (DIM) were enrolled in a 17-wk randomized complete block design experiment, with a 2-wk covariate period, 5-wk adaptation period, and 10-wk data and samples collection period. Cows were blocked based on parity, DIM, and ECM. Cows within blocks were randomly assigned to 1 of 3 treatments: 1) CON – diet fed ad libitum as a TMR; 2) SFF – diet fed as separate feeds (SF) with ad libitum PMR and fixed amounts of CMix via an AFS; and 3) SFV – SF with variable amounts of CMix calculated by an algorithm derived based on balances of NEL and MP of individual cows and fed via an AFS. Partial mixed ration intake was increased, and milk yield was decreased by SFV compared with CON but not with SFF. Feed efficiency was decreased by both SF treatments compared with CON. Treatments did not affect ECM yield in the current study. Enteric gas emissions were not affected by SFF, but CH4 intensity tended to be increased by 10% in SFV compared with CON. The concentration of ruminal VFA and VFA profile were not affected, except for an increase in butyrate concentration by both SF treatments and a tendency for increased ammonia concentration in SFV compared with CON. Dry matter and OM digestibility were increased by SFV, whereas amylase-treated NDF and ADF digestibility were increased by both SFF and SFV. Treatments did not affect N excretion or secretion variables, except urine N excretion (as % of N intake) was decreased by SFF compared with CON. Total purine derivatives excretion tended to be decreased by SFV compared with CON but not by SFF. Overall, SFF did not affect lactational performance but decreased urinary N excretion compared with feeding a TMR. Feeding variable amounts of CMix calculated using an algorithm based on individual NEL and MP balances (i.e., SFV) had a negative effect on lactational performance and CH4 intensity, likely because of algorithm overfitting and lack of generalization.
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Work Title | Supplemental Material for "Production and nutrient use efficiency in lactating dairy cows fed fixed or variable amounts of concentrate feeds" |
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License | CC BY 4.0 (Attribution) |
Work Type | Other |
Publication Date | 2025 |
DOI | doi:10.26207/1afx-6c80 |
Deposited | February 03, 2025 |
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