A statistical analysis was undertaken to study persistency of lactation in buffaloes, using the milk records collected on a herd of buffaloes belonging to the Ministry of Agriculture at Sakha Experiment Station. The number of buffaloes included in this report was 328 animals having 722 lactations. A formula was developed for estimating persistency of lactation in buffaloes and results obtained are as follows.

The aim of this investigation was to study the repeatability and heritability of initial milk yield and persistency of lactation in buffaloes. The interrelationships between 305 days milk yield, initial milk yield and persistency were also investigated.

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.

RAPID improvement in the indigenous poultry of this country cannot be achieved by inter-se selection alone, since it needs a long time (Hays, 1944; Lerner, 1950). Therefore, new sources for high production genes have to be sought and exploited. These are represented in the improved and more established breeds of poultry (European and American).

Weight records of a closed Ossimi flock of sheep belonging to the Animal Breeding Department, Faculty of Agriculture, Giza, covering a period of 10 years (1940–1950) were analyzed. This study was carried out to investigate the effect of inbreeding on birth weight, weaning weight and marketing weight of lambs. It has been found that inbreeding was responsible for a significant reduction in the weights of single lambs. On the other hand, the effect of inbreeding on the weights of twin lambs was not statistically significant Inbreeding of the dam had no significant effect on the weight of her offspring. Fifteen blind lambs were born during the last five years of the period of study. This defect was due to a pair of autosomal recessive genes. The frequency of this gene was estimated as 0.07.

EGYPTIAN cattle, buffaloes and high-grade shorthorns were used for studying the effect of age, lactation and fattening on heat tolerance coefficients. The method developed by Rhoad1 was used in estimating the heat tolerance, and the test was carried out twice during July 1952. The atmospheric temperature during test days ranged between 91° and 98.6° F., and relative humidity between 42 and 68 per cent. The average body temperatures of animals during March 1950 were taken as normal body temperature2.