Wide variation existed in peak flow (x = 2.13,σ= 0.70, C.V. = 33 %) and average flow (x = 1.70,σ= 0.58, C.V. = 34%). From paternal half-sib correlations, high heritability estimates of 0.65 ± 0.11 and 0.56 ± 0.10 were found for these features. Selection on peak flow could be especially effective. An accurate progeny test could be based on a sample of 25 daughters, while individual cows (bull dams) could be tested very accurately with 4 test milkings (repeatability 0.7). A correction for a standard milk yield of 7 kg was necessary for comparison.
There was a sufficient variation in percentage milk in fore quarters x = 43.5,σ= 6.05, but heritability was lower (0.26 ± 0.28). No significant correlation was found with peak flow, machine time and quantity of stripping. Selection on this character was of minor importance.
The average stripping yield by hand was 361 ml with wide variation, but very low heritability (0. 12 ± 0.24). Selection on this character was almost impossible.
|Qualification||Doctor of Philosophy|
|Award date||3 Jul 1963|
|Place of Publication||Wageningen|
|Publication status||Published - 1963|
- dairy breeds
- animal husbandry