Sahereh Joezy-Shekalgorabi; Ali Maghsoudi; A.R. Ghiasi; Mohammad Rokouei; Hadi Faraji Arough; Amir Zargaran
Volume 24, Issue 3 , October 2022, , Pages 247-258
Abstract
disadvantages of using sexed semen among dairy producers in terms of outcome and economic efficiency. A questionnaire containing 28 five-choice Likert scale questions was prepared to test the attitudes of respondents concerning the use of sexed sperm in terms of functional, economic, cognitive and ...
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disadvantages of using sexed semen among dairy producers in terms of outcome and economic efficiency. A questionnaire containing 28 five-choice Likert scale questions was prepared to test the attitudes of respondents concerning the use of sexed sperm in terms of functional, economic, cognitive and infrastructural aspects. The respondents were the researchers, consultants and dairy farm employees. The findings indicated that farm employees, unlike the researchers, believed that sexed sperm was effective in reducing dystocia, and the conception rate was not deleteriously affected in differentclimates (P<0.01). Better performance of sex-sorted semen in heifers compared to multiparous cows was significantly confirmed by farm employees and consultants compared to the researchers (P<0.01). According to the researchers, the use sex- sorted semen is uncommon and hence the use of this type of sperm has a higher risk (P<0.01). The results of this study indicated that the attitude of employees in large industrial dairy farms is largely consistent with the scientific facts published in the field of sex-sorted semen, and the disagreement of this
Behrouz Mohammad Nazari; Ardeshir Nejati Javaremi; Mohammad Moradi Shahre Babak; Rostam AbdolahiArpanahi
Volume 22, Issue 4 , December 2020, , Pages 515-527
Abstract
In order to evaluate the effect of genotype by environment interaction on production traits of Holstein cattle of Iran, first lactation test day records of 344170, 135000 and 156840 of milk, fat and protein yield on 34417, 13500 and 15684 cows and SNP markers of 1935 genotyped bulls were used. The ...
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In order to evaluate the effect of genotype by environment interaction on production traits of Holstein cattle of Iran, first lactation test day records of 344170, 135000 and 156840 of milk, fat and protein yield on 34417, 13500 and 15684 cows and SNP markers of 1935 genotyped bulls were used. The production data were retrieved from the Animal Breeding Center and Productions Improvement of Iran’s database which were collected from 2013 to 2018. To consider the interaction of genotype and environment, mean of temperature-humidity index (THI) in three days before each test day records as continuous environmental effect were retrieved from the 35 closest meteorological stations in the vicinity of 139 Holstein herds from 13 provinces. Variance and covariance components were estimated through a single-trait random regression model with orthogonal Legendre polynomials of second order for days in milk and THI using AIREMLF90 software. The results showed that changes in THI across lactation led tofluctuations in additive genetic variance over time. The change in heritability of milk production traits over lactation followed the same trend as additive genetic variance. The results from cross-validation analysis showed that including genomic information into the predictive model, increased prediction accuracy and including THI information increased unbiasedness. Due to the changes in milk production of daughters of bulls across days and THI , genotype by environment interaction should be considered when selecting bulls under different conditions.
shoheil mirhabibi; nasser Emam jomeh kashan; shahabodin gharahveysi
Volume 18, Issue 4 , December 2016, , Pages 671-678
Abstract
The present investigation was undertaken to study reason of culling, non genetic effects and genetic parameters of longevity with two method linear model and Weibull. A data set of information from Holstein dairy cows of Isfahan province (Iran) was used for this study. The culling date of 36340 animals ...
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The present investigation was undertaken to study reason of culling, non genetic effects and genetic parameters of longevity with two method linear model and Weibull. A data set of information from Holstein dairy cows of Isfahan province (Iran) was used for this study. The culling date of 36340 animals from 65 herds recorded in 1993-2014 was used. From 33219 culled cows in these years were 27.9 and 72.1 percent for voluntary and involuntary culling respectively. Lifespan and Length of productive life (LPL) were analyzed for longevity. Functional productive life (FPL) was estimated by adjusting LPL for first lactation milk yield relative to herd average. The mean of lifespan and length of productive life were estimated to be 954 and 1710 (days) respectively. The results with GLM procedure showed that HYS and age at the first calving had significant on length of productive life. The results with Lifereg procedure with Weibull function showed that effects of herd, year of first calving (p