Effect of varying dietary protein levels on length-weight relationships and length-length relationships of hybrid (Labeo rohita ♀x Catla catla ♂) from Multan, southern Punjab, Pakistan

Abstract

Present study was conducted to analyses length-weight relationships and external morphometric parameters of hybrid (Catla catla♂ x Labeo rohita♀) fed with three graded protein diets as T1 (15%), T2 (20%) and T3 (25%), in hapas (8x6x3 ft.), at the rate of 5% of their wet body weight. Ten samples from each treatment hapa were randomly selected at the end of 90 days feeding trial for the study of length weight relationships and morphometric analysis. T3 (25%) feed showed highest values of mean wet weight, total length, and all other morphometric characters than T1 (15%) and T2 (20%) feeds. Regression analysis confirmed in LWRs (Length Weight Relationships) that the “b” value in all (T1=2.698, T2=2.846, T3=2.993) feeds was less than 3 showing negative allometric growth. Condition factor values in all (T1=2.37, T2=2.40, T3=2.86) feeds represent an increasing trend with increasing dietary protein levels observed good health condition of fish. Analysis of log total length and log wet body weight confirmed a positive correlation with different external morphometric parameters in all (T1, T2, T3) feeds. ANOVA results showed significant difference among different treatments in all morphometric parameters of hybrid. T-test results observed that mean values of different morphometric parameters in T3 (P<0.001) was found to be higher from T1 and T2.