Statistical approach on the pattern of development of shank length in ducks

Abstract

The present investigation entitled ‘‘statistical approach on the pattern of development of shank length in Ducks’’ has been undertaken to study the following objectives. 1. To examine the pattern of development of shank length in two breeds of ducks in University Duck Farm, Mannuthy. 2. To compare them (a) between genetic group (b) between males and females within each genetic groups (c) between males of genetic group (d) between females of genetic group and 3. To fit appropriate growth curves for prediction of body weight through shank length at different stages of growth. For this purpose shank length and body weights on 14 males and 25 females of Desi ducklings and 26 males and 26 females of White Pekin (WP) ducklings were utilized. The ducklings were reared for twelve weeks in Kerala Agricultural University Duck Farm, Mannuthy under uniform feed formula and identical management practices. In the day old and the twelfth week of age uniformity could be seen in the mean shank length of the four groups. But at the fourth and eighth week of age, mean shank length of the four groups was not uniform. Upto ninth week of age, Desi females had higher shank length than the other three groups except at the fifth week. But during the fifth, tenth, eleventh and twelfth week of age Desi males had the highest shank length. The least shank length was always observed for WP males. During the entire period, Desi ducklings had higher shank length than WP duckling. The growth pattern of body weight was not uniform in the four groups except the initial body weight. High correlation was found between the body weight and shank length. It revealed that shank length can be made a criterion for selection for higher body weight. The method of comparison of growth rates recommended by Rao (1958) was found unsuitable for the present study. Among the functional relationships worked out linear, exponential and second degree equations were found to be unsuitable for fitting shank length as a function of age. Modified exponential, logistic, Gompertz and Von-Bertalanffy equations were found to be suitable for fitting shank length over a period of time. Among these four, Gompertz was found to be the best fit. The second best fitted equation was logistic. Graphs of the best fitted equations ie. Gompertz and logistic were drawn for all the six group along with the observed values. This also confirms above result. Among the two functional relations ie. linear and exponential used for predicting body weight from shank length, exponential was found to be most suitable.