Seasonal variations in the cyclic luteal ovarian activity in the Tadmit ewe in Algeria

Abstract

Seasonal variations of the cyclic luteal activity were assessed by measurements of progesterone concentrations in peripheral plasma collected daily or every 4 days, throughout 15 months, in 16 Tadmit ewes, in Algeria. One female was cyclic at all times of the year; 15 ewes showed a period of cyclic luteal inactivity of less than 53 days in 10 animals and ranging between 2.5 and 3.5 months for the 5 others (mean duration 52 days). The onset of ovarian inactivity took place from the beginning of February to the end of April (mean data 19 March). The recovery of luteal function was much more definite; it occurred in May for 13 ewes (mean date for the 16 animals 10 May) when daylength was still increasing. These data suggest that at this latitude (36 degrees 30'N) and for this particular breed of sheep (Tadmit) declining daylength is not the major environmental stimulus for the resumption of breeding activity.

Oestrous and ovarian activities of Finn-cross ewes during the post-partum and the seasonal anoestrous periods

“…These oestrus-quiescent periods are not necessarily accompanied by ovarian inactivity (Hafez, 1952;Thimonier &Mauleon, 1969;Amir etal. 1980;Ammar-Khodja & Brudieux, 1982). The lack of natural oestrus during these periods can be overcome by hormonal treatment or managerial means (Hunter, Belonje & Van Niekerk, 1971;Lindsay, Cognie & Signoret, 1982).…”

Seasonal fluctuations in plasma progesterone concentrations in Gentile-di-Puglia and Ile-de-France ewes in southern Italy

“…The timing of sexual quiescence in ewes (autumn-early winter) is parallel to that found in males (Dell'Aquila et al, 1985). Therefore It is hard to envisage, at present, which kinds of environmental cues may regulate the breeding season in sheep such as those of the Gentile-di-Puglia breed which are characterized by reproductive activity during the longest days (Hafez, 1954;Shafer, 1964;Ammar-Khodja & Brudieux, 1982 …”

“…However, some breeds of sheep become reproductively active during the longest days (Shafer, 1964;Ammar-Khodja & Brudieux, 1982). This phenomenon occurs generally for breeds inhabiting low latitudes and it has been argued that the short-day theory may be not generalized or that it is not applicable to all environmental conditions (Ammar-Khodja & Brudieux, 1982).…”

“…This phenomenon occurs generally for breeds inhabiting low latitudes and it has been argued that the short-day theory may be not generalized or that it is not applicable to all environmental conditions (Ammar-Khodja & Brudieux, 1982). We have there¬ fore compared annual fluctuations of plasma progesterone concentrations, as a marker of ovarian activity, in ewes of the Ile-de-France and Gentile-di-Puglia breeds in southern Italy.…”

Seasonality of oestrus, ovulation and ovulation rate of Sicilo‐Sarde sheep

“…The Mediterranean breeds have a short seasonal anoestrus and management factors like a proper use of the ‘ram effect’ or strategic use of feed supplements may prove effective in limiting periods of reproductive inactivity (Lindsay, ). Within the southern shore of the Mediterranean, several studies addressed characterization of seasonal reproductive patterns of the main sheep breeds (Ammar‐Khodja and Brudieux, for the Tadmit in Algeria; Khaldi, for the Barbarine in Tunisia; Lahlou‐Kassi and Marie, for the D'Man in Morocco; Zarkawi, for the Awassi in Syria). It comes out of these studies that sheep breeds have an extended breeding season starting in spring and lasting until winter, and outside this period, a variable proportion of females maintain ovarian and oestrous cyclicity.…”