1. Pekin ducks (strain A-44; 108 males and 108 females) were reared on standard diets for 7 weeks, after which the following measurements were taken: body weight (X1), thickness of breast muscles (measured by means of an ultrasonic apparatus; (X2) and length of breast-bone crest (X3). The birds were slaughtered and chilled carcases were dissected, separating meat, skin with subcutaneous and intermuscular fat, and bones. 2. The data were used to derive multiple regression equations for in vivo estimation of the meat content of whole carcases (Y; g). Separate calculations were made on males and females. The above-mentioned traits--X1, X2 and X3 constitute independent variables of those equations. The following equation (calculated on the basis of the data on both sexes) may be recommended for use in breeding work: Y = 0.184X1 + 125.4X2 + 25.12X3 - 255.8 (S(Y) = 39 g).

Sixty-seven male and sixty-seven female broiler chickens were fed to appetite with standard feed mixtures and reared to six weeks of age. After the end of the rearing period, the broilers were slaughtered and their carcasses dissected into meat, skin plus subcutaneous fat, intramuscular fat, and bones. The weight of the skin plus subcutaneous fat from the carcass without the wings (X 4), and the weight of the skinless carcass (X 3) are good indicators of fat content (Z) (r = 0.97) and meat content (Y) (r = 0.96), respectively, of whole broiler carcasses. These parameters are easy to determine. The following equations can be recommended for experimental determinations:

Abstract. The studies concerned the reproduetive perfonnance of four generations of sows originating from families where the average number of piglets in the first three litters amounted to: 8.1–9.0 (group A), 9.1–10.0 (group B), 10. 1–11.0 (group C) and more than 11.0 (group D). 988 sows and 2964 litters were examined altogether. The average number of piglets reared up to the age of 21 days in the first three litters of sows-family founders has a significant effect on the fertility and feeundity levels of sows in the next generations. The best results are to be expected in the case of sows originating from families where the average number of piglets in three successive litters was higher than 10. Sows coming from families in which the average number of piglets on 21st day was lower do not show promise of equally good reproductive performance, in spite of higher weight gains and better appearance (resulting from better conditions in the periods of pre- and postnatal development). In the private sector there were no sows originating from family founders in the group < 9,0 while 95% of them belonged to groups with average piglet number >10,0.