The Baladi cattle in Egypt are kept mainly for draft work and meat production; their milk yield is really very humble. As such, this breed fits the needs of the farmer, and performs comparatively well under the standards of feeding and hushandry prevalent in the Egyptian village.With the introduction of mechanization, however, animals will be exempted from most of the draft work and the purpose of keeping cattle is thus expected to change towards milk and beef production. Baladi cattle would not compete with the exotic beef or dairy breeds, and most of their present population have to be changed to serve the new goals. The treatment of high milk producers would not be an easy job for a farmer used to a cow ofvery low milk production or to a buffalo of an average milk yield of less than 1.5 tons/lactation. A transition period to acquire the skills to the proper treatment of high milk producers is needed. Crossbreeding and grading up with dairy breeds would be an obvious way, whereby the farmer's skills could be graded up in time with the increase of exotic blood in his cattle. This work presents the results of grading up Baladi cattle in Egypt with Friesian on milk production of the first two lactations. Material and methodsData were collected from the Serw Farm belonging to the Ministry of Agriculture. The farm is situated north-east of the Nile Delta. Records on the 305-days milk yield of the first (999 records) and the second (784 records) lactations were obtained beside age at first and second calving. These data represent Baladi cattle (Damietta strain), pure Friesians and the first five Friesian grades (%, %, %, I%&, '%I). Grades of higher orders were all included in the % group. The available data covered the period from 1940 till 1971, and were classified, for analysis, in groups each of two years, except the first group which included theobservations till 1944 in the first lactation and till 1948 in the second lactation, thus having 15 year groups in the first case and 13 in the second. Table A presents the number of first lactations distributed by genotype and year. &kl = P + g, + s, + yk + e,,kl, where X,,kl is the milk yield of the I& animal, in the k& year group in the j& season of calving of the i& genotype, The model used for milk yield reads: t deceased. U.S.

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A total of 886 cows of two herds belonging to the Ministry of Agriculture, Egypt, were used in this study to investigate the effects of inbreeding and cross-breeding on dairy traits. The first herd consisted of the native breed Domiatty (D), Shorthorn (S) and different grades between them while the second of Jersey (J) and its different crosses with D. There were 1027 lactations from the first herd and 460 from the second. Inbreeding coefficient (F) averaged 0-06 in the first herd and 0-08 in the second, both ranging from 0-00 to 0-30. The range was partitioned into three classes: the first with 0-0 «S F ^ 0-1, the second 0-1 < F =S 0-2 and the third F > 0-2. Traits studied were first and second lactation 305-day milk yields, age at first calving, first calving interval and first dry period.Inbreeding had no statistically significant effect on any of the traits except dry period in the first herd. Inbreeding was not associated with decrease in yield when F < 0-2 in the first herd, while there was consistent decrease with inbreeding in the second herd. No clear trend could be observed on the effect of inbreeding on any of the other traits in the first herd whereas in the second the rise in inbreeding was always associated with greater age at first calving, with wider calving interval and with longer dry period.