Age-season lactation curves for production traits of cows calving in Wielkopolska region of Poland

Abstract

The objective of this study was to estimate lactation curves for cows of different age at calving in winter and summer seasons. Data consisted of 1 289 522 test-day records of cows calved in Wielkopolska region in 1992-1996. Milk, fat and protein yields in fi rst three parities were studied. Test-day model with 50 classes of days-in-milk by parity was used. Lactation curves were derived from solutions for this effect. They were fl atter for fi rst versus later lactations. Peak yield for milk production occurred in the second part of the fi rst month of production. Shape of lactation curves for different age and season classes did not vary substantially. Cows calving in winter season had higher production. Similarly, older cows had higher yields for all traits and lactations, however the evidence of age at calving by season of calving interaction was found.

Modeling lactation curves of Polish Holstein-Friesian cows. Part II: Prediction of 305-d lactation milk, fat and protein yields

“…Peak milk yields were lowest in the first lactation, and were reached later than in the second and third parities, which is consistent with results from Strabel (2004) and Sawa et al (2007). The latter authors found that cows achieved maximum milk yield (23.5 kg) on DIM 62 during the first lactation, and slightly higher yields (27.3-28.7 kg) in earlier DIM (47-50) during later lactations.…”

“…The latter authors found that cows achieved maximum milk yield (23.5 kg) on DIM 62 during the first lactation, and slightly higher yields (27.3-28.7 kg) in earlier DIM (47-50) during later lactations. Strabel (2004) showed lower milk yields at peak (16-18 kg), which were obtained in the second part of the first month of lactation (21-35 DIM). He concluded that this relatively early peak of lactation might be explained in part by the fact that the first month after calving is the most complex physiological stage of lactation, thus, very sensitive to differences in modeling.…”

Impact of thermal-humidity index on milk yield under conditions of different dairy management

“…Dairy cows calved in the winter and in the spring yielded the most milk, while dairy cows calved in the summer the least (Strabel, 2004;Broucek et al, 2005). Under Mediterranean climatic conditions, summer calvers produce less milk per lactation than winter calvers (Barash et al, 1996).…”

Comparison of Random Regression Test-Day Models for Polish Black and White Cattle

“…It has been shown that using HTD effect increases the accuracy of evaluation (Beard, 1983;Strabel and Szwaczkowski, 1995). Average lactation curves may be modeled in many alternative ways; for example, by lactation curve functions (Guo and Swalve, 1997;, fixed classes (Stanton et al, 1992;Strabel, 2004), or with the use of splines (Druet et al, 2003). Due to the differences between populations, various functions are preferred for genetic evaluation models in different countries (Liu et al, 2001;Reinhardt et al, 2002;Mrode et al, 2003).…”

“…The overall lactation curve in Poland is characterized by a relatively early peak (Strabel, 2004). Rapid changes in the beginning of lactation may require more complex functions or higher-order polynomials to describe variation in this period.…”