Development of the brazilian milking crossbred. I. Elite cows and bulls being tested

Abstract

Crossbred bulls of european: zebu breeding, chosen on dam's milk production, are being progeny tested within Project Development of the brazilian milking crossbred, conducted by several institutions and private farmers. Presently, fourteen herds of crossbred cattle provide data for cow evaluation which are mostly of Holstein:Guzerá breeding, although other breeds are also represented. For 2300 cows evaluated, with 6092 lactations, average 305 days milk production was 2,549 kg (adjusted for parity and european blood percentage). Eleven out of the fourteen herds averaged 2,000 to 3,000 kg, one averaged 1.404 kg and the remaining two more than 3,000 kg. Fourty elite cows were selected out of 699 available, to the end of producing bulls to progeny test ten per year. Selection was based on estimated real productions ability "C", obtained by the product C = by, where y is the mean of the cow productions (ajusted for barity, european blood percentage and deviated from contemporaries average) and b = nr/ { 1 + (n-1)r , where n = number of lactations and r-repeatability (0.5). The C values were standardised,  i = (C - μ_C)^σ_C, to compare cows from different herds. The 40 selected cows had a mean superiority C = + 836 kg over their contemporaries, equivalent to i = 2.04(i ranging from 1.52 to 2.87). The mean of twenty reserve cows was C =+483kg, with i=1.38. At present, the Project has a stud of 55 mates, 24 adults, 14 one to two years old and 17 less than one year.