Journal Article

Estimation of lactation curves of Gyr cattle and some associated production parameters in the Colombian low tropic

Ferro, Daniela, Gil, Jhon, Jiménez, Ariel, Manrique, Carlos, Martínez, Carlos A

2022

Overview

Background: The Gyr breed is widely used in Colombian low tropic dairy production systems. During the last 10 years, the Asociación Colombiana de Criadores de Ganado Cebú† - ASOCEBU, has been leading a dairy milk control program which led to the creation of a dataset that permits to carry out the first analysis of milk yield in Gyr cattle in the country using records from several herds. Objectives: To study milk production dynamics of Gyr cattle in the Colombian low tropic through the estimation of lactation curves and four derived production parameters: total milk yield between 5 and 305 days (TMY305), peak milk yield (PMY), days at peak (DP) and persistency (P). Methods: 13,798 daily milk yield records from 1,510 cows performing in 103 herds were used; the total number of lactations was 2,480. Four models were considered: Wood, Wiltmink, Papajcsik & Bordero, and a second-degree polynomial. Mean square error, mean absolute error, mean square error of prediction, Akaike and Bayesian information criteria were used to select the model better describing each lactation using the majority rule, that is, the model selected by most criteria was the chosen one. The shape of each fitted lactation curve was checked using basic results from calculus which permitted the classification of the estimated curves into two groups: typical and atypical; only typical functions were used to compute the four aforementioned production parameters. Results: The second-order polynomial was the model most frequently selected, while the Papajcsik & Bordero model had the lowest frequency. Average TMY305, PMY, DP and P were 3,489.86 kg, 17.28 kg, 57.17 days, and 0.83, respectively, with coefficients of variation: 0.27, 0.21, 0.41, and 0.16. Conclusions: This study permitted to identify individuals with outstanding phenotypic performance. To the best of our knowledge, this is the first study of this kind involving thousands of lactations from Gyr cows performing in several regions of Colombian low tropic.

• Publisher: Universidad de Antioquía
• Subject: Animal lactation / Animal production / Bayesian analysis / Bos indicus / Bos taurus indicus / bovines / bovinos / Calculus / Cattle / Coefficient of variation / comparación de modelos / comparação de modelos / cows / Criteria / Dairy cattle / Dairy cows / Duración de la lactancia / Duração da lactação / forma da função de lactação / forma de la función de lactancia / gado / Gado leiteiro / Gado vacum / ganado / Ganado bovino / Ganado de leche / Lactación / lactancia / Lactation / Lactation duration / lactation function shape / lactation parameters / lactação / laticínios tropicais / lecherías tropicales / linear models / Linear models (Statistics) / Mathematical models / Mean square errors / Milk / Milk production / milk yield / model comparison / modelagem estatística / modelamiento estadístico / Modelos estadísticos / Modelos estatísticos / modelos lineales / Modelos lineales (Estadística) / modelos lineares / modelos no lineales / modelos não lineares / nonlinear models / Parameters / parámetros de lactancia / parâmetros de lactação / Polynomials / Producción animal / producción de leche / Producción lechera / Produção animal / produção de leite / Produção leiteira / Rendimento em leite / rendimiento lechero / statistical modelling / Statistical models / tropical dairy operations / Vaca leiteira / vacas / Vacas lecheras