Random regression models have been widely used to estimate genetic parameters that influence milk production in Bos taurus breeds, and more recently in B. indicus breeds. With the aim of finding appropriate random regression model to analyze milk yield, different parametric functions were compared, applied to 20,524 test-day milk yield records of 2816 first-lactation Guzerat (B. indicus) c...

Genetic evaluations of Holstein bulls from the US were matched with Canadian, Italian, Mexican, and Netherlands evaluations for the same bulls. Conversion equations for milk yield were computed by least squares, Goddard, and Wilmink methods. Accuracy was assessed by splitting data and applying equations developed from one subset to the other subset. Methods were judged by mean differences betwe...

Daily milk yield over the course of the lactation follows a curvilinear pattern, so a suitable function is required to model this curve. In this study, 7 functions (Wood, Wilmink, Ali and Schaeffer, cubic splines, and 3 Legendre polynomials) were used to model the lactation curve at the phenotypic level, using both daily observations and data from commonly used recording schemes. The number of ...

test day milk records of a holstein dairy farm collected during years 2004 to 2006 on 142 cows in the 1st lactation vs. 140 cows in the 2nd lactation were used in this research. there were real milk yields of cows available in each part of lactation in this farm making it possible to compare functions based on the new criteria (squared error of estimation). five functions were compared to estim...

The effects of genes are commonly estimated using random regression models based on test-day data and only give a general gene effect. Alternatively, lactation curve models can be used to estimate biological and environmental effects, or to predict missing test-day data and perform breeding value estimation. This study combines lactation curve models and estimation of gene effects to represent ...

The ability of mathematical models to represent the lactation process varies according with their structure and database characteristics. aim current study was evaluated goodness fit empirical mechanistic applied dairy sheep curves different shapes. A total 4,494 weekly test day records were analyzed. All lactations individually fitted using two (Wood Wilmink) (Dijkstra, Pollott) models. Dijkst...

Siyah Alaca , Jersey ve Esmer süt sığırı ırklarına ait 1350 adet laktasyon kaydına Wood, ters polinomiyal, Wilmink, logaritmik kuadratik, linear, Cobby Le Du, Cappio-Borlino, Grossman, parabolik üstel Guo-Salve modelleri uygulanmış bireysel eğrileri elde edilmiştir. Alaca, sığırları ırkına bu eğrilerin karşılaştırılmasında hata kareler ortalamaları, belirleme katsayısı, düzeltilmiş Akaike bilgi...

In this study, the co-digestion of orange pulp (OP) and cattle manure (CM) were investigated. The anaerobic process (40 d) five reactors prepared according to different carbon nitrogen (C/N) ratios (17, 26, 29, 35, 43.76) was completed. Anaerobic digestion (AD) investigated in batch (1000 mL) both biogas production measured every days soluble chemical oxygen demand (SCOD) value % removals deter...

ABSTRACT The objective of this study was to estimate the components variance and genetic parameters test-day milk yield in first lactation Girolando cows, using a random regression model. A total 126,892 (TDMY) records 15,351 first-parity Holstein, Gyr, breed cows were used, obtained from Associação Brasileira dos Criadores de Girolando. To (co) variance, additive functions permanent environmen...

Abstract Heat stress represents a major concern in the US dairy industry. It negatively affects profitability by reducing production and reproductive efficiency. One efficient way to study heat is associate losses with weather data. The objective of this use data from voluntary milking system local station impact on facility Northeast. Data 124 Holsteins Jersey cows, daily records June 2020 Feb...