Intake, milk production and weight change curves for lactating Holstein x Zebu cows under grazing

S.A Santos,E Detmann,L.F Prados,S.C Valadares Filho,J.R.M Ruas,L.D.S Mariz

doi:10.1590/1678-41626201

Abstract

The purpose of this study was to evaluate feed intake and develop lactation and weight change curves for Holstein x zebu cows under grazing. Eighteen F1 cows were used, divided into three treatments; 6 were Holstein x Gir (HGI), 6 were Holstein x Guzerat (HGU), and another 6 were Holstein x Nelore (HNE), under the feeding conditions of pasture plus concentrate with 22% of crude protein (CP). To estimate individual feed intake at pasture, 2 markers were used: titanium dioxide to estimate fecal dry matter (DM) excretion, and the indigestible acid detergent fiber (iADF) to estimate individual pasture intake. The Wood (1967) model was used to evaluate milk yield and the parameters were estimated for each genetic group, as follows: HGI = 17.2667*t0.0652*e-0.00424t; HGU = 18.1470*t0.0332*e-0.00408t; and HN = 14.2836*t0.1059*e-0.00552t. The NEFA contents varied according to different genetic groups (P<0.001). It was concluded that the estimated peak DMI occurs during the sixth week of lactation, when the DMI by the different genetic groups was stabilized. The HGI cows have greater cumulative production at 305-d.

Highlights

Tropical countries, which have high average temperatures throughout the year, face challenges in milk production when usingEuropean cattle breeds because these animals suffer from heat stress and metabolic changes
It was concluded that the estimated peak Dry matter intake (DMI) occurs during the sixth week of lactation, when the DMI by the different genetic groups was stabilized
DMI as %BW did not have significant linear or quadratic parameters (P>0.05), and this was true for the DMd

Summary

Introduction

Tropical countries, which have high average temperatures throughout the year, face challenges in milk production when using. European cattle breeds because these animals suffer from heat stress and metabolic changes. There is a decrease in feed intake and efficiency, as well as pregnancy rates. It is important to study animals that are better adapted to tropical climates. The production of F1 crossbred females for dairy farms in this environment normally involves breeding zebu (Bos indicus) females with a Holstein bull to exploit the beneficial effects of heterosis. The zebu breeds most often used are Gir and Guzerat, because these animals possess milk-producing characteristics and are more docile than other zebu breeds. Research is needed to characterize the milk production and performance of these different breed combinations

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