Assesment of the feed efficiency of slick Holsteins, wild type Holsteins and Jerseys when fed total mixed rations under heat stress

Abstract

Global warming has caused an increase in temperatures worldwide, having a direct effect on the dairy industry justifying our study of the effects of heat stress (HS) on milk yield (MY), milk composition (MC), dry matter intake (DMI), feed efficiency (FE) and some physiological responses (PR) between Jersey, wild-type Holstein (WT) and Slick Holstein (SL) cows. In Jersey and Holstein cows’ differences between DMI, MY and MC were found while no differences were observed for FE. However, no differences in PR were observed between the two breeds, but they did show above-normal averages indicating that both breeds are susceptible to HS conditions. Comparing SL and WT Holsteins, no differences were observed between MY, MC, DMI and FE, while differences were observed for PR. Therefore, SL Holsteins have a superior ability to manage HS than WT Holstein and Jersey cows.

El calentamiento global ha causado un alza en temperaturas mundialmente teniendo un efecto directo en la industria lechera por lo que estudiamos los efectos del estrés por calor (EC) en producción de leche (PL), composición de la leche (CL), consumo de materia seca (CMS), eficiencia alimenticia (EA) y algunas respuestas fisiológicas (RF) entre las vacas Jersey, Holstein no pelonas (NP) y Holstein pelonas (P). Comparando a las vacas Jersey y Holstein, se encontraron tener diferencias entre CMS, PL y CL, mientras que para EA y RF no se observaron diferencias. Sin embargo, comparando vacas NP y P no se observaron diferencias en PL, CL, CMS y EA, pero sí en las RF sugiriendo que la Holstein P tiene una capacidad superior de manejar condiciones de EC que las vacas Holstein NP y las Jersey.