ORBi: Rekik Boulbaba - Fitting lactation curves of dairy cattle in different types of herds in Tunisia

Reference : Fitting lactation curves of dairy cattle in different types of herds in Tunisia


	Document type :	Scientific journals : Article
	Discipline(s) :	Life sciences : Food science Life sciences : Genetics & genetic processes Life sciences : Animal production & animal husbandry
	To cite this reference:	http://hdl.handle.net/2268/25287

Title :	Fitting lactation curves of dairy cattle in different types of herds in Tunisia
Language :	English
Author, co-author :	Rekik, Boulbaba [>Ecole Supérieure d'Agriculture de Mateur, ESAM > > >Productions animales > > >]
	Ben Gara, Abderrahmen [>Ecole Supérieure d'Agriculture de Mateur, ESAM > > >Productions animales > > >]
	Ben Hamouda, Mohamed [> > > >]
	Hammami, Hedi [Université de Liège - ULg > Gembloux Agro-Bio Tech > Gembloux Agro-Bio Tech >]
Publication date :	2003
Journal title :	Livestock Production Science
Publisher :	Elsevier Science
Volume :	83
Issue/season :	2-3
Pages :	309-315
Audience :	International
ISSN :	0301-6226
City :	Amsterdam
Country :	The Netherlands
Keywords :	[en] test-day record ; lactation curve ; incomplete gamma ; herd type
Abstract :	[en] The incomplete gamma function was used to fit lactation curves of Holstein-Friesian cows in four types of herds in Tunisia. A total of 8640 records were used in the analysis. These included 1269, 637, 239, and 498 first lactation and 2986, 1441, 650, and 920 second and later lactation records in four herd groups namely investors, state, cooperative, and farmers' herds, respectively. The effects of environmental variables, production sector, herd, parity, first test-day date, calving year, and calving season on the main lactation curve traits were analysed. The factors associated with milk yield at the beginning of lactation and the decreasing phase of the curve, persistency, and peak yield varied significantly (P<0.01) with all variables. The ascending phase of the lactation curve was not affected by parity and calving year, while days in milk until peak depended only on the rank of lactation. The state herds had the lowest peak and total yields. The summer season was unfavourable for milk production. In contrast to first lactation cows, third lactation cows had the highest peak and total yields. Milk yield was highly correlated with peak yield (r = 0.79) and was not related to persistency measure. (C) 2003 Elsevier B.V. All rights reserved.
Target :	Researchers ; Students
Permalink :	http://hdl.handle.net/2268/25287
DOI :	10.1016/S0301-6226(03)00028-9
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