Analysis of lactation curves, milk constituents, somatic cell count and urea in milk of cows by the mathematical model of Wood

作者：Golebiewski Marcin^*; Brzozowski Piotr; Golebiewski Lukasz

来源：Acta Veterinaria Brno, 2011, 80(1): 73-80.

DOI：10.2754/avb201180010073

• Montbeliard
• Polish Holstein Friesian
• linear regression
• dairy cows

Analysis of lactation curves of milk, basic milk constituents, somatic cell count and urea in milk provide sufficient information for efficient dairy herd management and also is significant in genetic evaluation. The aim of the study was to apply the Wood's model to fit lactation curve of milk yield as well as fat, protein, dry matter, lactose, somatic cell count and urea in cows' milk. This study was conducted on dairy cows of Montbeliard (n = 686) and Polish Holstein-Friesian (n = 933) breeds. We analyzed data on the above mentioned milk constituents in the samples collected between 1995 and 2007. Data from 5,034 lactations were collected. Type Cl of the curve typical for standard lactation was the most frequent when daily milk yield, lactose and urea were analyzed. However, curves of fat protein and dry matter were described as type C4.
The Wood's model showed the highest accuracy when milk yield and protein content were investigated; poor fitting was observed for fat content. The Wood's model brought better accuracy for Polish Holstein-Friesian cows compared to Montbeliards. Precision of mathematical models fitting is R-2 (adjusted determination coefficient). The highest values of R-2 were noticed when lactation and protein curves were investigated. The lowest R-2 was determined for urea and somatic cell count.

• 出版日期2011