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Effects of multiple births on gestation length of Iranian Holstein dairy cows

Ali Kheirandish1, Saeed Khalajzadeh1* and Jafar Yadi2

1Department of Animal Science, College of Agriculture, Saveh Branch, Islamic Azad University, Saveh, Iran; 2Department of Veterinary Science, College of Agriculture, Saveh Branch, Islamic Azad University, Saveh, Iran

 
Abstract

The present study was conducted to investigate the effect of multiple (twin and triplet) birth on gestation length (GL) of Holstein cows in four large-scale dairy herds in Iran. A total of 56,559 records within 7 parities from 21,644 pure breed Holstein dairy cows calved from 2002 through 2012 were used. Factors affecting GL including herd (H), calving year (CY), calving month (CM), parity (P), birth type (single and multiple births), calf sex, birth type within parity and H×CY interaction were examined using generalized  linear model (GLM) procedure. Of the factors examined in this research, the primary ones affecting GL were calving month, birth type and calving year respectively. Mean GL was calculated 278.54±4.88 d varied by herd from 278.17 to 278.79 d. Multiple rates increased with an increase in parity number ranging from 0.4 to 3.54% across parities. Gestation length was 4.74 d shorter (P<0.001) for multiples than singles ranging from 4.37 to 4.97 d between herds. The shortest and longest GL were observed, respectively, in parity 1 and 7 in both categories (277.59 vs 279.72 d in singles, 273.76 vs 275.23 d in multiples, P<0.01). Least square means showed GL in multiples were 3.83, 4.79, 4.62, 4.88, 5.04, 5.16 and 4.49 d shorter (P<0.001) than singles from first to seventh parity. It seems a comprehensive study to identify factors affecting GL can lead to more precise prediction of parturition date in dairy cows.

Keywords: Gestation length; birth type; parity; dairy cows
 
To cite this article: Kheirandish A, S Khalajzadeh and J Yadi, 2014. Effects of multiple births on gestation length of Iranian Holstein dairy cows. Res. Opin. Anim. Vet. Sci., 4(9): 508-511.

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