Influence of feeding pattern on the biological efficiency of high-yielding dairy cows

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Abstract
SUMMARY: An experiment has been made to study the effect of the pattern of distribution of a fixed amount of production compound on milk yield, milk composition and live-weight change in the first 20 weeks of lactation and any carry-over effects on performance in the remaining part. Adult British Friesian cows of predicted high yield potential were randomly allocated to a graded (G) or flat-rate (F) system of feeding.There was no significant effect of treatment on milk yield, milk composition or yield of milk constituents in the experimental period or in the whole lactation.Live-weight changes were not significantly different between treatments at any stage of lactation. Calculated energy balances showed losses until the 4th week of lactation. Thereafter positive balances occurred but it was not until the 9th week for treatment G and the 15th week for treatment F that the original zero balance was restored. The total balance was in good agreement with live-weight gain for treatment F but not for treatment G.Calculated efficiencies of utilization of metabolizable energy for milk production (Klo) were variable throughout lactation and lower than the currently accepted standards.