Growth Curves in Lambs of Various Genotypes Created on the Basis of Improved Valachian and Tsigai Breeds

Changes in live weight or dimension for a period of time are explained by growth curves. The objective of this work was to evaluate the growth curves in lambs of 6 (1st experimental group) and/or 5 genotypes (2nd group) created on the basis of Improved Valachian (IV) and Tsigai (T) breed. All lambs (n = 209 and 205) were kept from birth to 9 months of age in identical conditions. Lambs of both experimental groups were weighed at birth and then every week until weaning (8 weightings totally). After weaning only breeding ewe and ram lambs were weighed (6 times totally). The growth of lambs created on the basis of IV a T breeds showed linear course till weaning expressed in regression equation y = 0.2659x + 5.352 and y = 0.2404x + 4.7364 respectively (R2 = 0.985 and/or 0.9954; x - day of raising). Weight differences between genotypes grew after weaning. The average weight of lambs at the age of 150 days was 40.15 kg in the 1st group and 38.31 kg in the 2nd group respectively. The lowest weight was in purebred IV (38.13 kg) a T lambs (34.98 kg) and the highest in the purebred Lacaune lambs (43.82 kg and/or 44.29 kg). Differences between genotypes were statistically highly significant (P < 0.001). The differences among genotypes were even more marked at the age of 9 months. Growth of lambs from birth to the age of 9 months can be expressed in the best way by means of polynomic equation (R2 = 0.99 in both experimental groups).