The Holstein sire, No. 966, was bred at Beltsville, and proved in a cooperating herd before he was used in cross-breeding. Thirty-one of his daughters, milked three times daily for 305 days, had an average mature equivalent of 18,416 pounds of milk and 645 pounds of butterfat, compared to an average of 17,772 pounds of milk and 619 pounds of butterfat for their dams. This sire also proved to be heterozygous for color and had sired several red and white calves.

The Jersey sires were herd bulls bred at Beltsville and proved in cooperating herds. Most of the Jersey matings were made to No. 1114. The Red Danish bull had been proved in the herd at Beltsville, and all Red Danish matings until April 1944 were made to him.

All the females were weighed and measured periodically. Their ability to produce was determined in the first lactation period under uniform conditions. All were milked three times daily for a 365-day lactation period and were bred about 4.5 months after calving. During the milking period, all were barn-fed, because pastures at Beltsville vary and their beneficial effects would not appear with all cows at the same stage of lactation. The cows were fastened in stall ties and were turned out in a dry lot for a short time after milking, when weather permitted.

We crossed four breeds, and tried to keep all combinations in numerical balance. No reciprocal or reverse crosses with Guernseys were made because we had no proved Guernsey sire. Only a few matings of Jerseys and Guernseys were made because we thought they are too much alike. With the Holstein, Jersey, and Red Danish breeds, the plan was to make reciprocal crosses, but the matings of Holstein and Jersey bulls to Red Danish females were held up for a while in order that we could increase the size of the Danish herd. (A reciprocal cross is one that is the opposite of a previous mating; for example, the mating of a Red Danish bull and Holstein cow would be the reciprocal of one between a Holstein bull and Red Danish cow.) Some of the groups were upset by unbalanced sex ratios, but we are trying to bring the group to equal numbers.

The accompanying table shows the records of the crossbred cows that completed one lactation period or progressed far enough to afford an estimate of their ability. All cows that came into milk are listed—no culling was practiced. To help in making comparisons, let me point out that the average production of all cows in the Dairy Herd Improvement Association herds in 1945 was 8,592 pounds of milk and 346 pounds of butterfat and in 1941, 8,225 pounds of milk and 335 pounds of fat on two milkings daily; and 226 junior 2-year-old Holsteins included in the Advanced Register test for 1945 averaged 13,833 pounds of milk and 193 pounds of fat on three milkings daily. The average of this class has been close to 500 pounds of fat since 1933.

Some footnotes to the records are needed. One Jersey X Guernsey heifer died in her first lactation period. The Jersey-Holstein crosses X-17 and X-32 were sired by Jersey bulls other than No. 1114, and are considerably below the other six in percentage of butterfat. The early calving of X-47 came about because she was bred by a young bull in the calf barn. Five more Holstein X Red Dane heifers, sired by No. 966, were under production age when this tabulation was made. All the Red Dane X Jersey heifers were sired by D-501. Four heifers from Red Dane cows, sired by Jersey bull No. 1114, were born, but two died and two were under calving age when we compiled our records. Two more Red Dane X Guernsey heifers are in the herd; six of the seven are by sire D-501. Analyses of birth weights and growth and comparisons of daughters with their dams await results of further work and tests.

In all, 38 females of the various two-breed combinations completed production records. Their average production was 12,904 pounds of milk and 588 pounds of butterfat; the average test was 4.60 percent of butterfat, and average age at calving, 2 years and 2 months. Four incomplete records not included in the average should not materially alter it. Ten heifers had not come into milk; they will bring our total of two-cross animals to 52; in breeding large animals, that is a sizeable group, and when handled under carefully controlled conditions the results are indicative. A few records have been interfered with by mastitis, but on the whole there has been a free expression of inheritance in these cattle.

The average production of the different combinations varied somewhat, but the numbers in each group were relatively small, and a few additional animals in each group might bring the production more in line. There is a possibility of some genetic difference in the sires, however, but at this stage it appears that the heifers sired by the Holstein No. 966 and Red Dane D-501 are about equal and somewhat better than those sired by Jersey No. 1114 and the two other Jersey bulls used.

Most of the 38 crossbred heifers produced better than their dams. Since they are daughters of proved sires, it was to be expected that they would outproduce their dams. We carefully analyzed the production records of their ancestors and calculated the amount of the average increase that we could expect. We found that the actual increase in production of the daughters over dams was more than the increase we had expected. This may be due to hybrid vigor.

The answer to the question of breed intermating is slowly evolving, as more of the three-breed combinations come into production, and the limited information now available is here tabulated.

Fourteen more three-breed hybrids were sired by No. 966. Seven are from Red Dane X Jersey dams, three from Red Dane X Guernsey dams, one from a Jersey X Guernsey dam, and the other three are from dams which resulted from crosses of three breeds. This is the beginning of the second cycle of three breeds.