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\hypersetup{pdftitle={Productive Performance of Holstein Friesian Cows under Tropical Conditions in Vietnam},pdfauthor={Ngoc Hieu Vu, Christine  Große-Brinkhaus, Karl Schellander, Ernst  Tholen},pdfsubject={Tropentag 2010: Abstract},pdfkeywords={HF cows, lactation length, lactation milk yield, parity, season of calving},pdfpagemode=None,colorlinks=true}
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\parbox[b]{13.4cm}{\centering \large{\textbf{Tropentag, September 14-16, 2010, Zurich}}\\[1ex] \Large{``World Food System  ---\\A Contribution from Europe''\\[2ex]}}
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\begin{center}
\Large{\textbf{Productive Performance of Holstein Friesian Cows under Tropical Conditions in Vietnam\footnote{\textbf{Contact Address:} Ngoc Hieu Vu, Universiry of Bonn, Agricultural Science and Resource Management in the Tropics and Subtropics (ARTS), Loebestr. 3, 53173~Bonn, Germany, \mbox{e-mail}: \email{vungochieu@yahoo.com}}\\[0.8ex]}}
\normalsize{\textsc{Ngoc Hieu Vu$^{1}$, Christine  Große-Brinkhaus$^{2}$, Karl Schellander$^{2}$, Ernst  Tholen$^{2}$}}
\end{center}
\begin{itemize*}
\item[]{\small{\textit{$^{1}$Universiry of Bonn, Agricultural Science and Resource Management in the Tropics and Subtropics (ARTS), Germany}}}
\item[]{\small{\textit{$^{2}$University of Bonn, Institute of Animal Science, Animal Breeding and Husbandry Group, Germany}}}
\end{itemize*}
\index[author]{Vu, Ngoc Hieu}
\index[author]{Große-Brinkhaus, Christine }
\index[author]{Schellander, Karl}
\index[author]{Tholen, Ernst }
\begin{center}
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\textbf{Abstract}
\begin{abstract}
\small{
The Holstein Friesian (HF) is one of the most common breed in the world. In Vietnam, milk production is relatively low compared to many tropical countries. Therefore, the Vietnamese government has imported large number of HF cows from Australia and USA to improve the local milk production. 



The objective of the present study is to evaluate productive performance traits of HF cows in Vietnam. The study was based on the analyses of 3242 HF cows, including imported and farm born (breed groups). The performance of these cows was tested in lactation milk yield, lactation length and birth weight of calves. The statistical model comprises the fixed effects of breed groups, calving season, parity and random effect of sire using Mixed Procedure of SAS 9.2. Covariance components were estimated through the restricted maximum likelihood (REML) procedure. 



The overall least squares means for lactation milk yield, 305-day milk yield, lactation length  and birth weight of calves were \mbox{4618.7\,kg}, \mbox{4416\,kg}, 271.5 days and \mbox{32\,kg}, respectively. The productive performance traits of imported HF cows were significantly higher than those of farm born HF. These differences could be explained by various genetic and physiological factors. However, the superiority of the imported cows indicates the high adaptability of the HF breed also under tropical conditions. The main effects of season of calving and parity were significant. The highest milk yield was observed during autumn season, whereas the maximum lactation length and birth weight were observed in cows calved during winter season. Milk yield of HF cows was higher in fourth and fifth than other parity. Along with the main effects, interactions between breed groups with season of calving and parity were also significant, but the imported cows showed higher performance than farm born cows in each season and parity. The pooled estimates of heritability for the investigated production traits ranged from 0.50 to 0.65. 



In conclusion, it was demonstrated that imported cattle in general performed better than farm born HF and that the dairy HF cows were adapted to the feeding and management systems as well as the environmental conditions in Vietnam.



}

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\noindent \textbf{Keywords:} HF cows, lactation length, lactation milk yield, parity, season of calving
\index[key]{HF cows}
\index[key]{Lactation length}
\index[key]{Lactation milk yield}
\index[key]{Parity}
\index[key]{Season of calving}
\end{document}