Identification of Best Growth Curve Model for Anatolian Black Cattle

Abstract

The aim of this study was to identify the model that best describes the growth trajectory from birth to 24 months of age in Anatolian Black Cattle (ABC) raised for con-servation purposes. A total of 493 weight records of 113 animals at birth, 3, 6, 12, 18, and 24 months were collected. Six different non-linear models were used to describe the growth curve of animals: 2nd degree polynomial, 3rd degreee polynomial, Logistic, Brody, Von Bertalanffy, and Gompertz models. In the study, R2 values of the models were: 0.997, 0.999, 0.953, 0.979, 0.924, and 0.862; corel values (correlation between the observed and estimated curves) were 0.994, 0.998, 0.989, 0.993, 0.961, and 0.703; Residual Standard Deviations (RSD) were 3.216, 1.388, 11.533, 3.561, 14.736, and 27.141, respectively. Given these values, it was found that the 3rd degree polynomial model was the best to describe the growth curve of ABC. As a result of the analyses, it was noticed that the values predicted by this model deviated by 1-3 kg from the observed values in all periods and in all environmental factors examined (sex, dam age, parity, birth year and birth, season). It was found that these differences increased up to 4-5 kg only in the 18-month period. The results also showed that ABC continued to grow after 24 months of age. As a result, traits such as age at sexual maturity, breeding age, and slaughter age can be easily predicted by identifying the model that best describes growth and development in herds. Določitev najboljšega modela krivulje rasti za anatolsko črno govedo Izvleček: Namen te študije je bil določiti model, ki najbolje opisuje potek rasti od rojstva do 24 mesecev starosti anatol-skega črnega goveda (ABC), vzrejenega za namene ohranjanja. Zbranih je bilo 493 podatkov o telesni teži 113 živali ob rojstvu ter pri 3, 6, 12, 18 in 24 mesecih starosti. Za opis krivulje rasti živali je bilo uporabljenih šest različnih nelinearnih modelov, in sicer polinom 2. stopnje, polinom 3. stopnje, logistični model ter modeli Brody, Von Bertalanffy in Gompertz. V študiji so bile vrednosti R2 modelov naslednje: 0,997, 0,999, 0,953, 0,979, 0,924 in 0,862; vrednosti correl (korelacija med opazovanimi in ocenjenimi krivuljami) so bile 0,994, 0,998, 0,989, 0,993, 0,961 in 0,703; ostanki standardnih odklonov (RSD) so bili 3,216, 1,388, 11,533, 3,561, 14,736 in 27,141. Glede na te vrednosti je bilo ugotovljeno, da je polinomski model 3. stopnje najbolje opisal krivuljo rasti ABC. Na podlagi analiz je bilo ugotovljeno, da so vrednosti, ki jih je napovedal ta model, za 1-3 kg odstopale od ugotovljenih vrednosti v vseh obdobjih in pri vseh preučevanih okoljskih dejavnikih (spol, starost matere, pariteta, leto rojstva in sezona rojstva). Ugotovljeno je bilo, da so se te razlike povečale na 4-5 kg le v 18-mesečnem obdobju. Rezultati so tudi pokazali, da se je ABC še naprej povečevala po 24 mesecih starosti. Posledično je mogoče lastnosti, kot so starost ob spolni zrelosti, plemenska starost in klavna starost, enostavno napovedati z določitvijo modela, ki najbolje opisuje rast in razvoj v čredah. Ključne besede: anatolsko črno govedo; živa teža; krivulja rasti; nelinearni modeli