The Effect of Shearing on the Behaviour of Some Physiological Responses in Lactating Pleven Blackhead Ewes

Y. ALEKSIEV
Institute of Mountain Stockbreeding and Agriculture, BG - 5600 Troyan, Bulgaria

Abstract

ALEKSIEV, Y., 2009. The effect of shearing on the behaviour of some physiological responses in lactating Pleven Blackhead ewes. Bulg. J. Agric. Sci., 15: 446-452

Rectal temperature (RT), pulse rate (PR), and respiratory frequency (RF) were collected for 6 days before shearing and for 15 days thereafter, in the morning and in the afternoon. Morning RT values were lower in unshorn and shorn sheep compared to afternoon ones but daily differences were greater after shearing. Shearing caused a significant (P < 0.001) drop in the morning RT values (0.61°C, 0.99°C, and 1.18°C) and a less reduction in the afternoon ones (0.13°C, 0.38°C, and 0.43°C) during the first 3 days post shearing. RT increased sharply thereafter but remained lower than in unshorn ewes up to the end of the study. An increase in PR values was observed both in the morning (P < 0.05), and in the afternoon (P < 0.01) on the first day after shearing. This transient increase was then followed by a reduction, but the values remained slightly elevated compared to pre-shearing recordings. Respiratory activity fell significantly after shearing both in the morning and in the afternoon and remained reduced throughout the study. The data suggested that shearing caused modifications in nervous control mechanisms and re-adjusting of the thermoregulatory set point to a new, more economic, level. Energy-saving mechanisms appeared to play a major role in post-shearing adaptation.

Key words: sheep, shearing, rectal temperature, pulse rate, respiratory frequency
Abbreviations: RT- rectal temperature, PR-pulse rate, RF-respiratory frequency

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