Comparison of the parameters of the lactation curve between normal and difficult calvings in Iranian Holstein cows

Spanish Journal of Agricultural Research

Navid Ghavi Hossein-Zadeh¹ 

[1] University of Guilan, Faculty of Agricultural Sciences, Dept. of Animal Science, Rasht, 41635-1314

关键词: calving difficulty;    dairy cow;    mathematical model;    peak yield;    productive performance;   

DOI  :  10.5424/sjar/2019171-13673

学科分类：农业科学（综合）

来源: I N I A

【 摘 要 】

To evaluate effect of dystocia on the lactation curve characteristics for milk yield and composition in Holstein cows, six non-linear models (Brody, Wood, Sikka, Nelder, Dijkstra and Rook) were fitted on 5,917,677 test day records for milk yield (MY), fat (FP) and protein (PP) percentages, fat to protein ratio (FPR) and somatic cell score (SCS) of 643,625 first lactation Holstein cows with normal calving or dystocia from 3146 herds which were collected by the Animal Breeding Center of Iran. The models were tested for goodness of fit using adjusted coefficient of determination, root means square error, Akaike’s information criterion and Bayesian information criterion. Rook model provided the best fit of the lactation curve for MY and SCS in normal and difficult calvers and dairy cows with dystocia for FP. Dijkstra model provided the best fit of the lactation curve for PP and FPR in normal and difficult calvers and dairy cows with normal calving for FP. Dairy cows with dystocia had generally lower 100-d, 200-d and 305-d cumulative milk yield compared with normal calvers. Time to the peak milk yield was observed later for difficult calvers (89 days in milkvs.79 days in milk) with lower peak milk yield (31.45 kgvs.31.88 kg) compared with normal calvers. Evaluation of the different non-linear models indicated that dystocia had important negative effects on milk yield and lactation curve characteristics in dairy cows and it should be reduced as much as possible in dairy herds.

【 授权许可】

Free