The influence of lactation on the quantity and quality of cashmere production

Abstract

The aim of this study was to investigate the influence of lactation on cashmere production. Two groups of cashmere bearing goats, aged between 2 and 3 years, were used in this study. The control group included 12 non-lactating, non-pregnant subjects. The experimental group was made up of 12 goats that had given birth to twins or triplets and that had begun lactating in the second half of May. Lactation therefore had begun approximately 45 days prior to the beginning of the emergence of fibre on the body surface. Live weight was not affected by the physiological state under consideration. The decrease observed in January is too remote to have been an effect of lactation. One likely explanation is that after shearing the animals were obliged to use their body reserves for thermoregulation. Prolactin concentration was higher at the beginning of the study in both groups and it was not influenced by lactation. Albeit with a varied intensity, secondary follicles were found to be active during the entire trial period but activ- ity never reached 100% in either group. Lactation significantly suppressed the percentage of secondary follicle activity and this was more evident from June to September. Fibre length and diameter did not differ between the two groups, so lactation did not affect fibre dimensions. The period of growth was shorter in lactating goats (184 vs 226 d). This did not make a difference in fibre length in so much as the lactating goats manifested a higher daily aver- age growth rate (0.27 ± 0.03 vs 0.20 ± 0.03 mm/d; P lesser than 0.05) which compensated for the shorter period of growth. Lactation caused a decrease in productivity of an insignificant nature, therefore we hold that the negative effect of lactation on cashmere production does not depend upon the physiological status as such but, most probably, upon the level of productivity and the degree to which the lactation and fibre growth cycles overlap.