MODELLING OF PHENOTYPIC TRAITS AS DETERMINANTS OF BREEDING POTENTIALS OF CATTLE UNDER LOW EXTERNAL INPUT

Abstract

The breeding potentials of bulls and cows are determined by relationships between body and testicular measurements which are being used as traits for selection of the cattle. Therefore, the objective of this study is to determine the relationship between the body condition score (BCS), live weight (LW), scrotum circumference (SC) and linear body measurements, body length (BL) and heart girth (HG) in bulls under low external input operation for modelling predictive equation for breeding selection. A total of 40 bulls and cows each selected in two agroecological zones of Nigeria were used for the study. Data collected on body measurements and were subjected to Pearson’s correlation to establish relationships between the LW, BL, HG, BCS and SC in bulls and between the LW, BL, HG and BCS in cows; while Multiple regression analysis was used to develop selection models for both the bulls and cows. Pearson’s correlation results indicated that BCS had positive statistical correlation with SC (r = 0.54) and LW also indicated statistical correlation with HG (r = 0.99) in the bulls. In the cows, the result obtained indicated that LW was positively correlation with HG (r = 0.97), BL (r = 0.69) and BCS (r = 0.60). The regression model developed were Testis Circumference = -71.84 + 2.32 Age + 2.73 Hearth Girth + 0.03 Body Length – 0.32 Live Weight + 2.56 Body Condition Score for bulls, and Age at first calving = 0.75 +1.22 LW + 4.73 BCS – 3.2 Age – 1.07 HG -7.76 BL + 1.00 Age at puberty for the cows. The correlation findings suggest that increasing SC, BCS, LW and HG, and the models developed for these traits could be used for selection of bulls and cows for breeding.