The inheritance of milk production characteristics

Abstract

1. An analysis has been made of milk records from 3109 cattle of the six main dairy breeds in England and Wales.2. The correlation between measurements on separate lactations declined as the time interval between the lactations increased. The average correlation was 0·38 for 70 days' milk yield and 0·48 and 0·55 respectively for milk yield and fat content in the 305-day lactation.3. The heritabilities of the three measurements measured by daughter-dam regression were found for heifer lactations to be 0·36, 0·43 and 0·43 respectively. On second lactations, they were 0·09, 0·24 and 0·42.4. As a consequence of the low heritability of the second lactation yield, the average yield of the first four lactations proved to have no more value as a prediction of a cow's breeding merit for yield than did her heifer yield.5. In agreement with other workers, we found that 70-days yield was an excellent guide to the total lactation (r ~ 0·80), and that it could be used as a guide to early selection.6. There was some indication that the correlation between yield and fat content in the same lactation was more strongly negative in heifers and in the Channel Island breeds. The overall genetic correlation on first lactations was found to be − 0·66 ± 0·20, rather more strongly negative than has been found previously.

Genetic and Maternal Influence on the First Three Lactations of Holstein Cows

“…Heritability estimates from daughter-dam regression for deviations follow the pattern reported by others (3,7,8), in that the estilnates for later lactations are lower than for first lactations. The estimates from the within herdsire regression in this study were first records, .37; second records, .30; and third records, .24.…”

A genetic analysis of 305-day yield in second lactation in Red Danish cattle and Black Pied Danish cattle

“…Mygind-Rasmussen (1970), who used material from herds under official supervision (both breeds), stated that the heritability for milk and butterfat yield was apparently lower for second than for first lactation. A similar decrease has been found by Johansson (1955) and Rendel, Robertson, Asker, Khishin and Ragab (1957). The general finding of a lower heritability in second than in first lactation for production traits seems to be due entirely to the pronounced increase in the phenotypic variance from first to second lactation.…”

Comparison of Heritability Estimates from Daughter-Dam Regression and Paternal Half-Sib Correlation

“…Bradford and Van Vleck (1) reported a value of .44 from regression for 2,580 pairs and .25 from the intrasire correlation for first lactation deviations from herd-mate averages for the same artificially sired Holstein cows. Rendel et al (4) and Gravert (2) both reported better agreement between the two methods of estimation used on the same data. Van Vleek and Bradford (5) later found almost identical estimates of heritability from daughter-dam (.448) and granddaughter-granddam (.444) regression on 10,419 first-lactation trios.…”