Abstract
Abstract. In the present study, the prognostic values of multiple and spline regression models were tested for 305-day lactation milk yield of cows. The predictors were: HF genes proportion in cow's genotype; average milk yield for 305-day lactation from 4 first milkings of all cows in a barn, in which a cow was used in a given year; month of calving; and average daily milk yield from first four test-day milkings. Models were developed basing on 628 first lactations of BW cows with average 71% HF genes proportion. Subsequently, the predictive values of the models examined were verified on the grounds of next 105 first lactations. Prognostic differences of the models examined were determined, finding the prognosis obtained with the spline regression more accurate (smaller prediction error, higher coefficient of correlation for prognosis and real values in the model containing information from first three test-day milkings). These models are easy to construct and may be useful in practical estimation of cow lactation yields. They may be used for predicting the actual lactation yield in order to minimise production costs and achieve better production results.
Highlights
In many countries the analysis of milk yield for 305-day lactation is a basis for evaluating the breeding value of milk cattle
GRZESIAK et al.: Prediction of 305-day first lactation milk yield in cows with selected regression models being in the same lactation, calved in the same year and season and coming from the same herd
The daily milk yield of cows with a similar proportion of HF genes was very similar according to test-day milkings in successive lactation months, i.e. during the first 30
Summary
In many countries the analysis of milk yield for 305-day lactation is a basis for evaluating the breeding value of milk cattle. GRZESIAK et al.: Prediction of 305-day first lactation milk yield in cows with selected regression models being in the same lactation, calved in the same year and season and coming from the same herd. In recent years studies have been performed on the use of lactation curves for calculating the milk yield. When estimating the breeding value, the yield on the test day is taken into account (PTAK and SCHAEFFER, 1993) as well as random regression models (JAMROZIK and SCHAEFFER, 1997). Taking into account the foregoing, an attempt was undertaken in the present study to test the values of selected multiple and spline regression models based on the yields of first four test-day milkings. The received milk yield predictions for 305-day lactation were compared with the real yields obtained by a cow in that period
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
