Ali Rezaee Roodbari; Hamid Kohram; Essa Dirandeh
Abstract
The objective of this study was to consider economic consequence of delayed conception of milking cows in large dairy farms in Iran. Optimum open days and milk production at peak were assumed to be 110 days and 45 kg respectively. Price of milk, feed, semen and hormones were calculated based on average ...
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The objective of this study was to consider economic consequence of delayed conception of milking cows in large dairy farms in Iran. Optimum open days and milk production at peak were assumed to be 110 days and 45 kg respectively. Price of milk, feed, semen and hormones were calculated based on average prices of autumn, 2013. Results of this study showed that increasing days in milk (DIM) from 110 to 170 has doubled costs of sperm and veterinary hormones. Delaying of each day of conception in cows with 45 kg of milk production at peak, during first; second, third and fourth estrous cycle beyond the optimum days open (110 d) cause economic losses of 308503, 572818, 812689 and 1013331 Rials, respectively. Feed costs compromise 54.7 to 56.6 percent of the loss, and any one percent change in feed price will directly cause 0.55 percent changes of the loss.
Hossein Mehrban; Seyyed Mehdi Esmaeilifard; Mojtaba Najafi; Bita Abbasi mashaei; Ebrahim Asadi-Khashoei
Abstract
A data file containing 607662 (317608) milk (open days) records belonging 294417 (177838) Holstein cows that were calved from 1983 to 2008 was used. The bivariate repeatability model was used for data analyzing so that herd, calving year, calving month, days in milk (only for milk trait) and calving ...
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A data file containing 607662 (317608) milk (open days) records belonging 294417 (177838) Holstein cows that were calved from 1983 to 2008 was used. The bivariate repeatability model was used for data analyzing so that herd, calving year, calving month, days in milk (only for milk trait) and calving age for each parity, were assumed as fixed effects and additive genetics and permanent environmental effects were considered as random. Phenotypic (genotypic) trends were estimate based on mean of phenotypic values (breeding values) on birth year by simple (segmented) regression. Heritability and repeatability for milk yield (open days) were obtained 0.20 (0.054) and 0.42 (0.120), respectively. Phenotypic trend of milk yield was 116.65 Kg per year (P<0.05) but open days wasn’t followed any trend (P>0.05). Genetic trend of milk yield before 1996 was estimated -4.15 per year (P>0.05), but after 1996 milk yield has uptrend and was observed 43.74 Kg per year (P<0.05). Genetic trend of open days before 1996 wasn’t significant, but after 1996 genetic trend of this trait was estimated 0.36 day per year (P<0.05). Phonotypic correlation between these two traits was low but positive (0.041) and genetic correlation estimated 0.46 that shows more open days for high productive cows. Genetic correlation compared to the phenotypic correlation explains that the strong relationship between these traits was covered by environmental effects. According to the results of this study, it is suggested to pay more attention to the reproductive traits in addition to productive traits in breeding programs.
