Effects of genetic and environmental variance on dairy sire evaluation

Selection among Holstein-Friesian cows

“…But since average genie merit changes only very slowly, even over several years, the bias in favor of older cows must be very small. Bereskin (1963) showed that with two seasons of unequal length, as used here, more seasonal variation can be removed than if two or three seasons of equal length were used. He further found that the interaction between herds and year-seasons was larger than the main effect of yearseasons.…”

“…Differences from one year to another or between different seasons of the same year are generally much less important than differences among herds. Bereskin (1963) found that 26.8 percent of the total variance among records by different cows was due to herds, 1.9 percent was due to year-seasons, and 2.6 percent was due to the herd x year-season interaction.…”

Genetic differences in maturity in dairy cattle

“…where YS is the appropriate year-season average, HYS is the appropriate herd-year-season average excluding the cow and her paternal half-sisters, n is the number of records included in the HYS, and a was estimated as two by Bereskin (1963).…”

“…Bereskin (1963) estimate the value of a = = 2. The 0.9 is assumed to be the regression of a cow's record on her adjusted herdmate average.…”

Genetic analyses of monthly yields of milk constituents

“…The coef ficients for the expectations of the mean squares were calculated according to the usual formulas, as shown in Kempthorne (1957) Bereskin and Freeman (1965).…”