Growth curve analysis for body weight and dry matter intake in Friesian, Limousin x Friesian and Piemontese x Friesian cattle
In this study, body weight and dry matter intake from birth to 460 days of age of Friesian (F), Limousin x Friesian (LixF) and Piemontese x Limousin (PixF) cattle fed individually under intensive feeding system were analyzed. Growth curve parameters of body weight and dry matter intake were investigated by using Gompertz model. No significant differences between genotypes were found in growth curve parameters for dry matter intake while there was significant genotype effect on integration constant, absolute weight gain at birth, degree of maturity at birth and absolute body weight gain from birth to 6 months of age for body weight. Mean values of growth parameters for body weight in F, LixF and PixF were: mature weight 744, 801 and 743 kg; integration constant 2.97, 3.02 and 2.81; maturity rate per day 0.0045, 0.0042 and 0.0047; age at inflection point 245, 270 and 227 days; weight of inflection point 274, 295 and 273, respectively. Body weight at birth for F, LixF and PixF were 38.6, 44.4 and 49.1. Absolute body weight gain from birth to 6 months of age for F, LixF and PixF were 24.8, 21.9 and 25.3. PixF exhibited higher maturity rate and reaching mature weights younger than F and LixF. Mature weight for body weight had positive phenotypic correlations with mature weight parameter for dry matter intake whereas there was a negative phenotypic correlation between mature weight for body weight and maturity rate for dry matter intake in all genotypes. The result shows that increasing intake is a result of body weight increased. On the other hand feed intake rate decreased as body weight increased. Considering the development period, from birth to 6 months of age, there was significant difference between genotypes for absolute body weigh gain and absolute dry matter intake whereas these parameters did not differ significantly between 6 and 16 months.