using monthly test day records the genetic parameters of iranian holstein cattle in first lactation were studied. data of 277400 test-day milk records from 65320 cows and 2210 sires were analyzed by an animal random regression model using restricted maximum likelihood methodology. the model included herd-test-date, interaction between year-season of calving, days in milk (linear and quadratic) ...

The study aimed to determine factors affecting the dry period length and effect of dry days on milk yield, milk composition and lactation length in the next lactation of dairy cows. Data used for analysis included 7264 lactation records collected from 2012 to 2016 on 4737 Holstein cows raised in 152 herds. The statistical model used to determine the factors influencing the dry period length sho...

introduction productive traits such as milk production and fat and protein percentage have economic importance in the livestock industry. accurate prediction of breeding value of animals is one of the best tools available for maximizing response to selection program. it is a fact that the main objective of the breeding program, is to achieve the maximum economic benefit. for breeders of dairy c...

to estimate heritability and genetic trend for 305-d milk production and lactation persistency, a total of 130,668 monthly test day milk yields belonging to 15,183 first lactation holstein cows in 131 herds and calved from 2000 to 2009 were used. to calculate 305-d milk yield as well as lactation persistency, estimated parameters of wilmink’s exponential function were applied. the parameters of...

The aim of this study was to investigate the effect of milking frequency (three times daily vs. two times daily) on the lactation curve shape, partial and 305-d lactation performance in Holstein dairy cows in Iran. Data from February 2000 to December 2012 comprising 217345 lactations on 141364 cows distributed in 324 herds collected by the Animal Breeding Center of Iran were used. The mean milk...

milk and fat yields in 3x and 4x milking schedule in holstein cows of iran were investigatedusing 374170 milk and fat yield test day records measured on the 1st and 2nd lactions of 54580 dairycattle coming from 205 herds. the records had been collected from 2007 to 2009 by the iraniananimal breeding center (iabc). the results indicated that an increases in the milking frequency from3x to 4x inc...

background: methionine has been suggested as the firstlimitingamino acid for milk production in ruminants. it is importanthow to increase milk protein yield and milk fat in dairy ruminants.objectives: this study was set to investigate the effect of rumenprotected methionine (rpmet) on milk composition of lactatingcashmere rayeni goats. methods: 40 healthy singletoncashmere rayeni goats about 3 ...

The objective of the present study was to estimate genetic parameters for test-day milk, fat and protein yields and 305-day-yields in Murrah buffaloes. 4,757 complete lactations of Murrah buffaloes were analyzed. Co-variance components were estimated by the restricted maximum likelihood method. The models included additive direct genetic and permanent environmental effects as random effects, an...

Buffalo milk has excellent physical and chemical qualities as a consequence of the high percentage of constituents. This milk property is desirable for the dairy industry because it facilitates manufacture of mozzarella cheese. We estimated genetic parameters for milk yield, milk fat and protein and their effects on mozzarella cheese production using Bayesian inference. Using information from 4...