Teagasc (Agriculture and Food Development Authority), Ireland
Abstract
peer-reviewedThe objective of this study was to quantify the change in live weight (LWT) per unit
change in body condition score (BCS) for Irish Holstein-Friesian dairy cows. Mixed
model analyses were performed on 82 948 test-day records of BCS and LWT across
11 075 lactations from 7391 cows, representing 62 commercial and 4 research herds,
during the years 1999 and 2000. Factors included in the mixed models were parity, stage
of the inter-calving interval and the three-way interaction between herd, year and fortnight
of the calendar year at calving. Interactions between the effect of BCS and either
parity or stage of the inter-calving interval were included in some models to evaluate
the effect of these factors on the relationship between LWT and BCS. A moderate correlation
(0.49) existed between BCS and LWT in the complete dataset, but it differed
significantly with parity and stage of the inter-calving interval (range 0.36 to 0.59).
Analysis of the entire dataset yielded an estimate of 50 kg LWT change per unit change
in BCS and this coefficient ranged from 39 kg to 66 kg, depending on parity or the stage
of the inter-calving interval. Accurate values of LWT per unit BCS are important input
parameters for animal or herd-level biological models designed to evaluate the energy
demands of the animal or herd
