Lactation length is different in individual cows, which is generally converted to a 305-day standard using curve fitting models for genetic and management practices. Individual curves do not have a standard shape in all cases, and can deviate from the standard pattern according to factors such as individual differences, and type of fitted models. These non-standard curves, called atypical, resulted from incorrect estimated parameters of the curves; which consist of: continuously increasing or decreasing and reversed standards. This study was conducted to investigate the importance of atypical curves in estimation of 305-day milk production, by fitting two nonlinear models? Wood (empirical) and Pollott (biological), on 7659 and 6692 test-day milk yield of 977 and 776 first calving Iranian Simmental and Jersey cows, during 2007-2020, using R software. Different patterns obtained based on the combination of increasing (b) and decreasing (c) phase parameters of curves. The number of standard curves from the Pollott and Wood models were 85.5% and 62.2% for Simmental, and 83.1% and 70.6% for Jersey cows, respectively. Only continuously increasing curves were observed in both breeds in Pollott model (14.8% and 16.9%, Simmental and Jersey cows, respectively); Whereas in Wood model, all 3 groups of atypical curves were observed, which the reversed standard was the most (22.3% and 16.5%, Simmental and Jersey cows, respectively). Based on the findings, at the time of standardizing the production of dairy cows (national evaluations), not only differences between breeds, but also special attention to the production of atypical curves, should be paid (to correct or discard them).

In order to investigate the possibility of quinoa producing in Garmsar, Iran, a factorial experiment conducted in randomized complete block design with three replications in 2018-2019 growing season at Garmsar Agricultural Research Station. The factors were planting date at three levels (March 6th, April 1st and April 6th) and the three genotypes of quinoa (Q26, Q29 and Titicaca). Results showed that the effect of planting date was significant for all studied traits except the harvest index. Also, all studied traits were significantly different in all genotypes. Titicaca planted on March 6th had the highest yield (2276 kg.ha-1).The grain yield and yield components decreased with the delaying the planting date. Compared to early plantings, Latest date, April 6th, led to reduction of all traits, especially grain yield (about 50%). The results of simple phenotypic correlation between the studied traits showed that grain yield per hectare had the highest correlation with plant yield (0.877) and then with leaf area index (0.832), panicle weight (0.815) and number of branches per plant (0.745) that was significant at the 1% probability level.

Emphasis on milk yield (MY) as well as milk yield persistency (MYP) and calving interval (CI) is necessary to achieve more sustainable production in dairy cattle. Therefore the main objective of this study was to find an optimum regression model to estimate economic values for MY, MYP and CI. Using a deterministic bio-economic model, seventy five production states differing mainly in MY, MYP and CI were studied. For each production state, the total revenue comprised income from sold milk, calves of one week of age and manure. Feed costs were obtained from energy requirements for maintenance, growth, lactation and pregnancy. Non feed costs included costs of net replacement, health, artificial insemination and some others which were modeled as a function of CI. Multiple regression analyses of annual profits for production state on the means of MY, MYP and CI were used to estimate the economic values. Two different regression models were used. Both models included the linear effect of MY and the quadratic effect of MYP. How-ever, in one model the effect of CI was linear (Model CIL) whilst it wasquadratic in the other (Model CIQ). Under both models, economic value for MY was positive (0.10 $ for model CIL and 0.32 $ for model CIQ) as was expected for the assumed milk pricing system. Economic values for MYP in the models had different signs (-118.2 $ for model CIL and 715.55 $ for model CIQ). Under model CIQ maximum profit was associated with a value of MYP greater than unity and was not consistent with the definition of persistency. Economic value of CI was negative under both models (-2.68 $ for model CIL and -6.36 for model CIQ). In the model CIQ, the profit function had a minimum value for CI (at 803 days) which was not consistent with the previously reported relationship between profit and CI. Estimates of economic values for MY, MYP and CI showed that the model CIL was superior to the model CIQ due to a lower number of fitted effects and increased consistency with the real situation of dairy systems.

The objective of the present study was to estimate genetic trends for lactation milk yield, persistency of milk yield, somatic cell count and interval between first and second calving in Holstein dairy cows of Iran. The dataset consisted of 210, 625 test day and 25, 883 first parity cows with milk yield recorded from July 2002 to September 2007 comprising 97 herds in Iran. Breeding values of animals were predicted with Best Linear Unbiased Prediction methodology under multi-trait animal model. Model included region, herd-year-season of calving and age at first calving as fixed effects and Holstein percentage (covariate) and random animal additive effect. Genetic trends of studied traits were estimated by regressing mean of breeding values on calving year. Phenotypic trends were estimated using annual averages of first lactation traits on calving year weighted by the number of animals in each year. Genetic trend was positive and significant for lactation milk yield (21 kg/yr; p<0.01). Although not significant, favorable genetic trends for most studied traits were reported. Considering that selection emphasis in Iran was on lactation milk yield, progress for this trait was low during the years of the study.

To estimate the genetic trend for lactation milk yield, a total of 38457 monthly test day records obtained from first calving of Holstein cows, recorded during 1995-2005 at Astan-e Quds-e Razavi Dairy Farm were used. A random regression test day animal model was applied to analyse the records. In the model, the environmental fixed effects of milking times, sperm origin and herd-year-month of recording were included. To take account of the shape of the lactation curve at genetic and permanent levels, orthogonal Legendre polynomials of order 4 were also fitted in the model. For progeny, genetic trend was estimated based upon regressing of mean predicted breeding value on year of zygote formation, birth and calving of animals. For sires and dams, the genetic trends were estimated based on regressing of mean predicted breeding value on the above corresponding years of their daughters. The genetic trend (based on the year of zygote formation) was 10.64 Kg per year (p<0.05) in the progeny. Non-significant genetic trends were observed for progeny based upon their year of birth and calving. For dams' population, significant genetic trends were found to be 8.77, 8.88 and 9.1 Kg per year based on year of zygote formation, birth and calving of their daughters respectively. The genetic trends in sires' population were all statistically non-significant (p>0.05).

This study was conducted to investigate the effects of energy density in dry period on subsequent milk production. Milk production and milk components of 2143 milking cows were used and NEl of the far-off and close-up period’ s diets were 1. 35, 1. 45, 1. 55, and 1. 44, 1. 54, 1. 65 Mcal/kg of dry matter. Descriptive statistics of herds were described. The results were showed as least square and standard error of means in early lactation (120 day) and whole lactation period. As energy density increased in the far-off and close-up periods, there was no difference in milk yield in early lactation period, but there was a linearly increase in whole lactation period (P < 0. 05). Milk composition until 120 d didn’ t changed with increasing energy density in the far-off diets, but milk fat percentage was linearly decreased (P < 0. 05) in whole period by increasing dietary energy in far-off and until 120 d and whole lactation period (P < 0. 05) by the close-up diets. There was a linearly increase in somatic cell count in early and whole period with increment energy density in the far-off and close-up diets. Generally, increasing energy density in dry period improved milk production and increased somatic cell count, and less milk fat content over lactation period might be independent of the dry period diet and it’ s a function of length of lactation and milk amount.