| Autor: |
Różańska-Zawieja J; Department of Genetics and Animal Breeding, Poznan University of Life Sciences, ul. Wołyńska 33, 60-637 Poznań, Poland., Winnicki S; Institute of Technology and Life Sciences, Poznań Branch, ul. Biskupińska 67, 60-463 Poznań, Poland., Zyprych-Walczak J; Department of Mathematical and Statistical Methods, Poznan University of Life Sciences, ul. Wojska Polskiego 28, 60-637 Poznań, Poland., Szabelska-Beręsewicz A; Department of Mathematical and Statistical Methods, Poznan University of Life Sciences, ul. Wojska Polskiego 28, 60-637 Poznań, Poland., Siatkowski I; Department of Mathematical and Statistical Methods, Poznan University of Life Sciences, ul. Wojska Polskiego 28, 60-637 Poznań, Poland., Nowak W; Department of Animal Nutrition, Poznań University of Life Sciences, ul. Wołyńska 33, 60-637 Poznań, Poland., Stefańska B; Department of Animal Nutrition, Poznań University of Life Sciences, ul. Wołyńska 33, 60-637 Poznań, Poland.; Department of Grassland and Natural Landscape Sciences, Poznań University of Life Sciences, ul. Dojazd 11, 60-632 Poznań, Poland., Kujawiak R; Sano-Modern Animal Feeding, Lubiń, ul. Lipowa 10, 64-541 Sękowo, Poland., Sobek Z; Department of Genetics and Animal Breeding, Poznan University of Life Sciences, ul. Wołyńska 33, 60-637 Poznań, Poland. |
| Abstrakt: |
The study attempted to estimate the lactation curves of primiparous dairy cows in relation to their feeding management. Therefore, the first aim of the study was to determine and compare the lactation curves of primiparous dairy cows using Wood's model and to estimate the association between the lactation curves and feeding management. The second objective was to investigate the effect of the culling rate on improvement in the milk yield of primiparous dairy herds. The study was conducted on four commercial dairy farms of Polish Holstein-Friesian cows using different feeding systems (TMR-total mixed ration and PMR-partial mixed ration) and management (T1-one TMR throughout lactation; P1-one PMR throughout lactation; T2 and T3-three feed periods such as FRESH, TMR I and TMR II according to days in milk). The data used for the study were obtained from monthly milk performance evaluations of 1662 primiparous cows conducted by the Polish Federation of Cattle Breeding and Dairy Farmers throughout the year 2015. Wood's lactation model was used to plot curves for milk yield, fat and protein content, lactose content, and milk urea contents. The highest milk yield for the whole lactation and in the peak lactation phase was recorded for cows in herd T1. This herd reached peak lactation on day 105 of milking, with an average milk yield of 42.1 kg, which was about 5 kg more milk than in the other herds. The study showed that the culling of primiparous cows in herd T1 after 30, 60 and 90 days of lactation prevented a significant reduction in milk yield in a 305-day lactation. It also increased average milk production by 1586.9 kg per primiparous dairy cow. |
