Effect of parity and lactation stage on milk yield, udder and teat morphometric traits of Friesian-Bunaji crossed cows

Abstract

Abstract. Data for this study were collected from 40 multiparous (F1) Friesian x Bunaji cows at the dairy herd of the National Animal Production Research Institute (NAPRI) Shika, Nigeria, to assess the effect of parity and lactation stage on milk yield, udder and teat morphometric traits of Friesian-Bunaji crossed cows as well the relationships between the parameters measured. The data collected include udder circumference (UC), udder depth (UD), udder width (UW), fore teat length (FTL), and hind teat length (HTL) and were subjected to Analysis of Variance (ANOVA). The means with significant difference were separated using Duncan Multiple Range Test modelled in SAS (2004) statistical package and the correlation analysis was performed using correlation procedure in SAS to identify relationships between morphometric traits and milk yield. The results obtained showed that parity had significant (p<0.05) effect on udder circumference, hind teat length and milk yield. The highest udder circumference (23.60±2.50 cm) and hind teat length (2.80±0.34 cm), respectively, were found in parity 5 and the least ones were obtained in parity 1. Parity 2 had significantly (p<0.05) higher milk yield (8.60±0.72 litres) followed by parity 4 (7.13±1.14 litres) but similar to parity 3 (6.67±0.58 litres) and the least (6.20±1.24 litre) was obtained in parity 5 (6.20±1.24 litres) but similar with parity 1 (6.25±0.75 litres). The results for lactation stage revealed no significant (p>0.05) difference in all the parameters except milk yield. The early lactation stage had significantly (p<0.05) higher milk yield (8.15±0.35 litre) followed by mid lactation stage (5.80±0.58 litre) but similar with the milk yield (4.38±0.86 litre) at late lactation stage. The results obtained for correlation indicated that the udder and teat morphometric traits and the milk yield measured showed varying degrees of relationships. The phenotypic correlations were positive and negative, low to high ranging from 0.00 to 0.69. The highest correlation coefficient (r=0.69; p<0.01) was obtained between udder circumference and udder depth. All the udder and teat morphometric traits measured were negatively correlated with the milk yield except udder width (UW) and had no significant (p>0.05) difference. Based on the results in this study, it can be concluded that parity has effect on udder circumference, hind teat length and milk yield with second parity having the highest milk yield 8.60±0.72 litre/day), while lactation stage had no effect in all the morphometric traits except on milk yield with the early stage having the highest milk yield (8.15±0.35 litre/day). The second parity and early lactation stage are recommended for high milk yield in Friesian x Bunaji cows in the studied area.