Comparison of the fit of automatic milking system and test-day records with the use of lactation curves

Abstract

Objective: The aim of the paper was to compare the fit of data derived from daily automatic milking systems (AMS) and monthly test-day records with the use of lactation curves; data was analysed separately for primiparas and multiparas.Methods: The study was carried out on three Polish Holstein-Friesians (PHF) dairy herds. The farms were equipped with an automatic milking system which provided information on milking performance throughout lactation. Once a month cows were also subjected to test-day milkings (method A4). Most studies described in the literature are based on test-day data; therefore, we aimed to compare models based on both test-day and AMS data to determine which mathematical model (Wood or Wilmink) would be the better fit.Results: Results show that lactation curves constructed from data derived from the AMS were better adjusted to the actual milk yield (MY) data regardless of the lactation number and model. Also, we found that the Wilmink model may be a better fit for modelling the lactation curve of PHF cows milked by an AMS as it had the lowest values of Akaike information criterion, Bayesian information criterion, mean square error, the highest coefficient of determination values, and was more accurate in estimating MY than the Wood model. Although both models underestimated peak MY, mean, and total MY, the Wilmink model was closer to the real values.Conclusion: Models of lactation curves may have an economic impact and may be helpful in terms of herd management and decision-making as they assist in forecasting MY at any moment of lactation. Also, data obtained from modelling can help with monitoring milk performance of each cow, diet planning, as well as monitoring the health of the cow.

The effect of extended lactation on parameters of Wood’s model of lactation curve in dairy Simmental cows

“…The differences reported in other studies may be explained by different breeds and farming conditions. Different values of peak yield and day of peak was described by many authors [1,2,5,7,14]. 37 % of the total milk yield) was produced in the period between 306 and 547 days.…”

“…Abdelsayed et al [18] found out the milk yield of 8887 kg produced in the period between 305 to 610 days, with the range 2 891-19 631 kg milk. Holstein cattle from various countries reached different milk yield per lactation [4,5,17]. Table 4 shows that the milk yield per partial 100-day periods decreased with progressing lactation and the indices of persistence, based on the partial milk yields, copied Our values of IP2:1 were considerably higher because the initial dataset included the data on extended lactations (up to 732 days) in which milk yield started to decline later in lactation.…”

“…Lactations are described for many reasons, for example estimating of genetic parameters, analysing of genomic evaluation and comparison of data from milking system and test-day records [4,5,6]. The conventional length of a lactation period is 305 days.…”

“…In other study was assessed parameters of Wood's model in dairy cattle in Italy[21] with the following results: a = 11.17, b = 0.267 and c = 0.00564. Mentioned parameters was assessed also by Polish Holstein[5], respectively Jersey in Turkey[14].Dematawewa et al[9] studied the differences in parameters of Wood's model related to different lengths of lactation. They compared data on Holstein cows in the USA with the…”

Breed, heterosis, and recombination effects for lactation curves in Brazilian cattle

“…In these cases, it is common to find no recordings, or at most one recording, made before the peak yield, which makes the estimation of the cell proliferation phase of lactation and peak yield less accurate (Fathi Nasri et al, 2008). Sitkowska et al (2020) found that Wood's and Wilmink's are among the best models for modeling lactation curves; however, a different model may present a better fit depending on the type and homogeneity of data.…”