A total of 72124 fertility records was used to estimate the genetic and phenotypic trend of fertility traits in Iranian Holstein cow from 1981 to 2007. Fertility traits in this study were: days from calving to first service (DFS), number of insemination per conception (INS), days open (DO), interval between first and last in semination (IFL), calving interval (CI) and success to first insemination (SF). The overall genetic trend in fertility traits was as desired and statistically significant. Mean breeding value of SF increase by 0.00067 percent per year. The annual genetic trends for INS, DFS, IFL, CI and DO were -0.0029 number/year, -0.062 days/year, -0.041 days/year, -0.23 days/year and -0.24 days/year, respectively. Phenotypes trends for fertility traits were unfavorable except for DFS and DO. Phenotypic trends in IFL, INS and SF were as un-desirable positive. Phenotypically DO and CI did not change over the time period. Phenotypically IFL has increased 1.6 days/year and DFS has decreased 1.6 days/year. The annual phenotypic trends for INS and SF were 0.04 and -0.018, respectively.

Introduction and Objective: Fertility is one of the most important economic traits in dairy cattle breeding which, in addition to negative effects on functional traits such as milk production, reduces the profitability of the dairy cattle breeding industry. Therefore, the aim of this study was to Meta-analyze traits related to fertility in dairy cows and determine an appropriate strategy to control and improve fertility in dairy cows. Material and Methods: For this purpose, by searching in databases, 38 articles related to fertility in different herds of dairy cows were collected and different parameters including additive genetic and residual variance components, heritability, reproducibility, descriptive characteristics of traits including mean, minimum, maximum, coefficient variation, standard deviation as well as genetic correlations between traits that were present in at least three reports were extracted as a new variable and statistically analyzed. The studied traits included age at first service, age at first calving, calving interval, open days, number of services, conception length, the first service leading to conception and non-return rate at 56 days. Data analysis was performed with SAS software version 9. 2 and Comprehensive Meta-analysis. Finally, the articles were grouped into four regions of Asia, Africa, America and Europe and different parameters including mean, heritability and reproducibility of different fertility traits were analyzed by SAS software GLM procedure and comparison of mean groups by Turkey’, s test at the level 5% probability was done. Results: Mean of open days, age at first calving, age at first service, calving interval, conception length, first service leading to conception rate, no-conception rate in 56 days and numbers of services for each conception traits were 139. 2, 888. 3, 501. 6, 411. 8, 278. 8 days, 62. 8, 21% and 2. 1, respectively. Also, the heritability of the mentioned traits was estimated to be 0. 06, 0. 2, 0. 3, 0. 06, 0. 1, 0. 1, 0. 07 and 0. 08, respectively. The reproducibility of traits were open days, calving interval, first service leading to conception, conception length and number of services per conception were 0. 1, 0. 1, 0. 07, 0. 1 and 0. 06, respectively. There was a moderate and sometimes high positive and negative genetic correlation between most of the fertility-related traits. The results of comparison of estimates in the four continents of Asia, Africa, Europe and the Americas were not significant in all fertility-related traits. Conclusion: Therefore, all the mentioned estimates, which in most cases are reliable and close to each other, indicate a low degree of heritability and repeatability of the mentioned traits, and the use of conventional breeding methods cannot determine high genetic value with good accuracy and it is recommended to improve the management of dairy cows and control environmental factors and the use of breeding programs as well as genomic evaluation of dairy cow.

The current study aimed to optimize artificial insemination in aged broiler breeder hens in two experiments. In the first experiment, the effect of (two) different diluted semen temperatures (5 and 25 °C) of Hubbard rooster (40 roosters, 58 weeks of age) on fertility, hatchability and sperm penetration (SP) rate in the perivitelline layer of Hubbard hen (180 hens) were investigated. In the second experiment, three (different) sperm concentrations (100 (C100), 200 (C200), and 400 (C400) million sperm in 0.25 mL per hen) of Hubbard roosters (40 roosters, 62 weeks of age) on fertility, hatchability and SP rate of Hubbard broiler breeder hens (270 hens) were explored. In the first experiment, the results showed that the temperature of 5 °C of diluted semen compared to the 25 °C, increased percentage of hatchability of set eggs, hatchability of fertile eggs, and SP and decreased early embryonic mortality. The results of the second experiment showed the highest percentage of fertility and SP rate were observed at treatment C400. Also, in this experiment that highest percentage of hatchability of set eggs and hatchability of fertile eggs and lowest early embryonic mortality were observed at treatment C400. Return on investment (ROI) of the treatments C200 and C400 was approximately 2.9 and 1.4, respectively. In overall, the results of this study showed that (in attention to ROI and hatchability) to optimize artificial insemination of aged broiler breeder hens we can use a sperm concentration of 200 to 400 million in 0.25 mL per hens at 5 °C.

The objective of present study was to derive the economic values for number of inseminations to conception, calving interval, milk yield and stillbirth, using economic data of 10 Iranian Holstein herds. The economic values were derived by using the profit function methods and differentiating a profit equation with respect to the traits of interest. The cow fertility costs herd amortization or replacement cost and cow feed cost were included in the profit function. The average of feed cost per cow per day was 8.65 USD. The total feed cost comprised 61 percent of milk production, 23 percent of maintenance, 12 percent of pregnancy and 4 percent of growth. In calculation of cow feed cost, the estimated cost for each Mcal and per g protein of feed were 0.0006 and 0.165 USD, respectively. The replacement cost of each heifer per cow herd was 1719 USD. The average cost of each insemination was 30 USD. The estimated economic values for the number of insemination, calving interval, milk yield and one percent unit of stillbirth, were -82, -2.08, 0.193 and -1.27 USD per cow/per year, respectively. The results of the current study suggested that improving the number of inseminations, calving interval, milk yield and stillbirth will have a positive effect on the profit-ability of Iranian Holstein cows.

The objective of the present study was the genetic evaluation of retained placenta (RP), metritis (MET), number of inseminations to conception (INS), and days open (DO) in Holstein cows using standard (SMMs) and recursive (RMMs) mixed models. Data on 50230 first-lactation Holstein dairy cattle, collected during 2008 to 2017 in 17 large dairy herds were used. The data were analyzed using four-variate animal Threshold-Gaussian models under SMMs and RMMs. The existence of causal effects from RP on MET, INS and DO, from MET on INS and DO and from INS to DO were considered in RMMs. The causal effects of RP and MET on INS were 0. 19 and 0. 09 services, respectively; and those on DO were 4. 74 and 5. 38 days, respectively. Also, causal effect of INS on DO was obtained as 33 days. The considered causal relationships except that of RP on MET, phenotypic and residual correlations among the disorders and fertility traits were statistically significant and different under two models. Posterior means of heritability for RP, MET, INS and DO were 0. 15, 0. 17, 0. 07 and 0. 09 under SMMs, respectively; and 0. 16, 0. 17, 0. 07 and 0. 1 under RMMs, respectively. The difference between the corresponding heritability estimates under SMMs and RMMs were not statistically significant. Therefore; RMMs may be an alternative for SMMs in genetic evaluation of studied traits in first-lactation Holstein cows.

The objective of the present study was to estimate the relationship between genetic parameters for 13 linear type traits, and milk yield as well as open day in Holstein cattle of Iran. Three data sets of: 16502 (type traits), 16557 (milk yield) and 11631 (open days) records related to the first calving of the cows, and respectively taken from 1500, 1566, and 2000 herd-year-season groups, were taken into account. SAS software and Proc GLM were employed to fit the model. Genetic parameters were estimated using Restricted Maximum Likelihood along with an animal model and ASREML software. Genetic correlation among type traits and milk production ranged from 0.34 (rear udder width) to -0.31 (udder depth), and among type traits and fertility, it ranged from 0.62 (rear udder width) to -0.37 (udder depth). Most of the genetic correlations between milk production and fertility indicate that more production in cows was accompanied by a lower fertility, while cows with a lower production level benefitted from a more fertility rate.

This study aimed to estimate the genetic parameters of body weight traits in Markhoz goats, using B-spline random regression models. The data used in this study included 19549 records collected during 29 years (1992-2021) in Markhoz goat Breeding Research Station, located in Sanandaj, Iran. The model used to analyze data included fixed effects (year of birth, sex, type of birth and age of dam) and random effects including direct additive genetic, maternal additive genetic, permanent environmental and maternal permanent environmental assuming homogeneous and heterogeneous residual variance during the time. Akaike (BIC) and Bayesian (BIC) information criteria were used to compare the models and bspq.4.4.4.4 was selected as the best model. The direct heritability values for birth, 3-month, 6-month, 9-month and 12-month weights were estimated to be 0.14, 0.16, 0.08, 0.28 and 0.26, respectively. Genetic correlation between body weights at birth and 3-month, birth and 6-month, birth and 9-month, birth and 12-month, 3-month and 6-month, 3-month and 9-month, 3-month and 12-month, 6-months and 9-month and 9-month and 12-month were 0.22, 0.38, 0.21, 0.56, -0.26, 0.30, 0.62, 0.86 and 0.77, respectively. The highest phenotypic correlation was between the weight of 9-month and 12-month (0.82) and the lowest correlation was between birth weight and 3-month and 6-month (0.12). The results showed that the 9-month weight is a good criterion for selection in Markhoz goats.