Variation in hair characters over the body in Sahiwal Zebu and Jersey cattle

Abstract

In both Sahiwals and Jerseys, mean hair length and diameter increased posteriorly. The length/diameter ratio, and diameters of non-medullated hairs, of medullated hairs, and of the medulla itself also varied between positions, as did the percentage of medullated hairs. Jerseys had greater hair length than Sahiwals at all positions (average + 80%) though in the majority of positions Sahiwals had a greater hair diameter than Jerseys (average + 12%). Coefficients of variation in hair length were similar for the two breeds. In general, variation of hair diameter within positions was slightly greater in Sahiwals, but differences between positions in the variability of hair diameter were small. In all positions, Jerseys had greater hair length/diameter ratios than Sahiwals (average + 90%). In the majority of positions, Jerseys had a greater percentage of medullated hairs than Sahiwals. The mean percentage of medullated hairs for Jerseys was 88% and for Sahiwals 85%, whilst the mean diameters of both medulla and medullated hairs were greater in Sahiwals (39.4 and 62 1 µ) than in Jerseys (26.7 and 54.2 µ). Diameters of non-medullated hairs differed little between the two breeds, being 44.40 µ for Sahiwals and 40.82 µ for Jerseys. Only differences between the two breeds in hair length, hair length/diameter ratio, and medulla diameter were statistically significant. The percentage of medullated fibres was the only character for which the commonly used midside sample provided estimates which were within 10% of the mean over all positions for each breed. Estimates of means and coefficients of variation for other characters are likely to be misleading if based on a single sample from this region. Positions providing better estimates for other traits are: mean hair length in Sahiwals, position 2; C.V. of mean hair length in Jerseys, position 12; mean hair diameter in Sahiwals, position 4; C.V. of mean hair diameter in Jerseys, position 4; mean hair length/diameter ratio in Sahiwals, position 8.